GE 113 Hydrographic Surveying PDF

ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached SIMPLIFIED COURSE PACK (SCP) FOR SELF-DIRECTED LEARNING GE 113 – Hydrographic Surveying This Simplified Course Pack (SCP) is a draft version only and may not be used, published or redistributed without the prior written consent of the Academic Council of SJPIICD. Contents of this SCP is only intended for the consumption of the students who are officially enrolled in the course/subject. Revision and modification process of this SCP are expected. SCP – GE 113 | 1 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached By 2023, a recognized professional institution providing quality, Vision economically accessible, and transformative education grounded on the teachings of St. John Paul II. Serve the nation by providing competent JPCean graduates through quality teaching and learning, transparent governance, holistic student Mission services, and meaningful community-oriented researches, guided by the ideals of St. John Paul II. Respect Hard Work Perseverance Core Values Self-Sacrifice Compassion Family Attachment Inquisitive Ingenious Graduate Attributes Innovative Inspiring Course Code/Title GE 113/Hydrographic Surveying The course covers the tidal datum planes; depth sounding and position determination; hydrographic survey systems; measurements of a stream; Course Description velocity/discharge and reservoir capacity; electronic nautical charting; introduction to physical oceanography. Course Requirement Time Frame “Based 40” Cumulative Averaging Grading System Grading System Periodical Grading = Attendance (5%) + Participation (10%) + Quiz (25%) + Exam (60%) Final-Final Grade = Prelim Grade (30%) + Midterm Grade (30%) + Final Grade (40%) Contact Details Instructor Engr. Dianne Marie A. Amora (09561735909) Dean/Program Head Engr. Kevin G. Cañada (09460385411) SCP – GE 113 | 2 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Course Map Hydrographic Surveying - Simplified Course Pack (SCP) SCP-Topics: Prelim Period SCP- Topics: Midterm Period SCP- Topics: Final Period Introduction to Hydrographic Hydrographic Positioning Surveying, Definition of terms, Methods (Three-Point and Week Methods of Determining Mean Week 1 Week 7 13 Velocity Scope and Equipment for Indeterminate and Weak Hydrography Resection) Hydrographic Positioning Week Measurement of Stream Week 2 Tides Week 8 Methods (Resection of Four 14 Discharge; Velocity-Area Method Points) Slope-Area Method and Weir Week Introduction to Underwater 15 Method of Discharge Week 3 Tides (Continuation) Week 9 Measurement Acoustic Week The capacity of Lakes and Underwater Sensors, Acoustic 16 Reservoir Week 4 Locating Soundings Week 10 Sensors Week Introduction to Physical Locating Soundings Instruments for Measuring 17 Oceanography Week 5 Week 11 (continuation) Stream Velocity Week 18 Final Examination Week 6 Preliminary Examination Week 12 Midterm Examination Course Outcomes 1. Develop skills in complying with accepted standards of accuracy and specifications for hydrographic surveys; 2. Learn the use of acoustic instruments (echo-sounders and swathe sounders/multi-beam sounders); 3. Learn methods of computing stream velocity/discharge and reservoir capacity. 4. Gain adequate insight into theoretical and practical aspects of hydrographic surveying. 5. Carry out various hydrographic surveying tasks in the field (under supervision). 6. Process data collected in the field and present data in the form of fair sheets and reports of survey. SCP – GE 113 | 3 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Welcome Aboard! This course covers an understanding of the concepts, principles, and applications of hydrographic surveying. You will be able to know the equipment used in a hydrographic survey, and the procedures as well. The scope of this type of survey will also be introduced and we will learn how to apply these theories in actual field practice. Also bear in mind that the theories here include computations of data gathered. It will be helpful for you to review your knowledge about areas, volumes, and solid geometry formula to have an easier understanding of the topics along this course. SCP-TOPICS: PRELIM PERIOD TOPICS Week 1 Introduction to Hydrographic Surveying Lesson Title What is Hydrographic Surveying? Familiarize the terminologies used in hydrographic surveying, Learning identify the equipment used together with its function/s, and Outcome(s) understand the scope and concept of hydrography Time Frame 2:00PM-4:00PM – MT / 3:00PM-4:00PM – W At SJPIICD, I Matter! LEARNING INTENT! Terms to Ponder This section is where you can have a better understanding of the definition of terminologies used in this topic and throughout the simplified course pack of Hydrographic Surveying. You may refer to this section in case of difficulties in understanding the content of the course pack. I suggest you also take these terms by heart to store the definitions in your long-term memory and use them in the next courses that you will take. Discharge is the volume of water flowing past a section of a stream, canal, flume, and other waterways and is usually expressed in cubic feet per second or cubic meters per second. Dredging is the process of scooping or sucking up mud, sand, rocks, and other material underwater to enlarge, deepen or clear channels, harbors, rivers, and other bodies of water. SCP – GE 113 | 4 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Fathom is the unit used for the measurement of water depth and is equivalent to six (6) feet. The hydrographic chart is the map or chart used in navigation and is similar to a topographic map except for that water depths, navigational markers, and the character of the underwater surface is indicated. Hydrographic Surveying is the process employed in gathering information concerning any body of water and its adjacent land areas. Hydrography is the study, description, and mapping of oceans, seas, lakes, and rivers especially about their navigational and commercial or other uses. Sounding is the process of measuring the depth of a body of water at a particular point. Stream gaging is the process of making measurements in streams and rivers to predict the rate of discharge at various water levels or stages. A stream is a current or steady flow of water running along the earth’s surface. Subaqueous contour is an imaginary line on the surface of the earth found underwater, all points of which are of the same elevation and sometimes known as depth curves or bathymetric contours. Tidal datums are specific tide levels that are used as surface of reference for depth measurements in the sea and as a base for the determination of elevation on land. Essential Content 1.1 HYDROGRAPHIC SURVEYING Hydrographic surveys are those made of a body of water such as bay, harbor, lake, ocean, sea, or river. These types of survey are made for the following purposes: ▪ To provide data for the preparation of hydrographic maps and nautical charts needed in navigation, harbor improvement, yardage, and dredging projects. ▪ For flood control, water supply, hydro-electric power development, pipeline, and underground cable crossings, and irrigation. ▪ To get the information needed for designing bridges, dams, seawalls, culverts, sewage disposal plants, lighthouses, docks, and other structures. SCP – GE 113 | 5 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached ▪ To calculate the volume of impounded water, the direction, and velocity of currents, drainage areas, and the capacity of a containing basin. ▪ To collect data needed for the establishment of tidal data. ▪ To locate navigational hazards such as submerged obstructions, sunken vessels, sand bars, rocks, shoals, and coral reefs. 1.2 SCOPE OF HYDROGRAPHIC SURVEY The hydrographic survey involves a wide range of activities and services in determining and portraying the topography above and below the water surface and to discover important marine features that may serve as vital and essential in its infrastructural, social, and physical development. To do this, the chart below shows the preparations and procedures that can be done in conducting the survey. Table 1: Preparations and procedures in conducting the survey. Determine the Survey Area this is done to choose the best way of conducting the survey and to plan the whole process of the work Define the scope and specification for the hydographic survey this is part of the planning process to have a guide on how the survey should be executed Provide details of survey planning this includes the equipment used, survey platform and methodologies for acquisition and processing of data used in the survey Determine the conduct of the hydrographic survey this includes the details of how the work was done, its starting date, the survey lines and other important informations needed for data processing and interpretation Provide competency of person/s responsible for the surveys it should be understood that there are certain qualifications as to who shall commence this survey and these details will be of use to confirm the validity of the work SCP – GE 113 | 6 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached To have a deeper view of how to conduct a hydrographic survey, we will discuss some of the basic operations. Included in the details of survey planning is the method used in acquiring data. This process includes the establishment of horizontal and vertical control, conducting a topographic survey, measurement of water depths, and preparation of a hydrographic map. Establishing the horizontal control is necessary to make your land and water features about each other. By triangulation method, horizontal controls can be determined. Previous data of established control around the area should be utilized also, as well as taking sights on all surrounding objects or structures that can be useful as control points for the topographic survey of the nearby land area. Also, in this process, the position of hydrographic signals should be established and known for reference in locating soundings. The signals could be used to define the boundaries of the survey area; therefore, these should be put up along the shoreline. Before performing the sounding operation, vertical control must be defined to reference the elevation of water properly. Setting up a tide station is also necessary to observe the fluctuations of the tide which is needed in defining the plane of reference for the soundings. This is tied to benchmarks near the area through the process of differential leveling. Data of the vertical control established will also be used for the topography Figure 1: NOAA's Office of Coast Survey, part of the National Ocean portrayed on a nautical chart. Service, is the nation's nautical chartmaker. Retrieved from https://oceanservice.noaa.gov/facts/nautical_chart.html In a hydrographic map or nautical chart, only a narrow view of the ground surface is shown thus a topographic survey is conducted to suffice the need of data for the interpretation and processing of information of the survey. With all of these, the goal of the survey which is to measure the depths of water will be met. And to complete the whole process, the preparation of a hydrographic map should be done to produce an output we call hydrographic map or nautical chart. The information from the map or chart may be of much use for different purposes depending on the user’s desire. To sum it up, proper planning is important to be certain that the time hard work poured out into the project will not be in vain, but will result in success SCP – GE 113 | 7 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached and even contribute to the needs of others who will conduct similar or related surveys in the days to come. 1.3 EQUIPMENT FOR HYDROGRAPHY There are simple and cheaper types of equipment for hydrography for small- scale operations. The list and pictures below indicate the instruments in this class. 1. Sounding Craft ▪ includes rowboats, motor launches, and vessels 2. Sounding Pole ▪ a graduated and rounded piece of lumber, about 3 meters long, used for taking soundings ▪ suitable for waters with a depth of not more than 2 and a half meter ▪ a metal shore is found at the tip to make the pole sink faster 3. Leadline ▪ usually a length of sash or hemp cord, braided flax, or nylon cord, with a sounding lead attached to one end ▪ seldom used for depths greater than 25 fathoms (150 feet) 4. Sounding Machine ▪ used for very deep waters where leadlines are not efficient ▪ a simple device where a stranded wire is used and wound on a reel mounted on a stand ▪ depth of water is measured by the length of wire run out and is indicated by a recording device on the registering sheave 5. Fathometer ▪ suitable in coastal or deep waters ▪ measuring device which automatically record soundings were taken on a moving vessel ▪ records the time required for a sound wave to reach the bottom and for the echo wave to come back 6. Signals ▪ constructed or built-in different ways but should be visible and distinct with each other 7. Tide Gauge ▪ an instrument for measuring the height of the tide ▪ classified into two groups: o non-recording gage – requires a person to observe and record the height of the tide at periodic intervals) o automatic/self-registering gage – provides a continuous record of the variation of tide level and operates though unattended for several days SCP – GE 113 | 8 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached 8. Sextant ▪ a portable and hand-held instrument used for measuring horizontal and vertical angles Sounding Sounding Sounding Pole Leadline Craft Machine Fathometer Signals Tide Gage Sextant But with the fast upgrades of technology today, reliable work is more attainable using modern equipment in conducting the survey. Most of these are complete, mobile, and self-sustaining which are helpful to make the work easier and faster. Some of these include; ultrasonic flow gauge, high-resolution boomer, multi-beam and swath sounding systems, multi-beam and angle- discriminating sonars, GPS instruments, etc. In the next lesson, we will have a detailed discussion about tides, its importance, and causes. To have an advanced understanding of these topics, I encourage you to research, read books and articles, and watch videos to exercise your mind and prepare for the next lessons to come. SELF-SUPPORT: You can click the URL Search Indicator below to help you further understand the lessons. Search Indicator Arjun, N. (2009). Hydrographic Surveying – Methods, Applications and Uses. Retrieved from https://theconstructor.org/surveying/hydrographic- surveying-methods-uses/13838/ SCP – GE 113 | 9 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Davis, R., Foote, F., Anderson, J., Mikhail, E. (1981). Surveying Theory and Practice Sixth Edition. McGraw-Hill, Inc. La Putt, J. (2011). Higher Surveying 2nd Edition. Baguio Research & Publishing Center. National Ocean Service. (2017). Hydrographic Surveys Specifications and Deliverables. Retrieved from https://nauticalcharts.noaa.gov/publications/docs/standards-and- requirements/specs/hssd-2019.pdf Office of Coast Survey. (2019). Hydrographic Survey Equipment. Retrieved from https://nauticalcharts.noaa.gov/learn/hydrographic-survey- equipment.html Sciortino, J. (2010). Hydrographic surveys. Fishing harbour planning, construction and management. Retrieved from http://www.fao.org/3/i1883e/i1883e05.pdf Survey Department. (2017). Regulations of Geomatics (Work Instructions) Part V (Hydrography). Retrieved from http://www.mod.gov.bn/survey/SitePages/GWI_PartV_Hydrographical.pd f Udoh, I., Eyoefen, I. (2013). Hydrographic Education and Standards. A Career in Hydrography: The Intricacies and its Make-Up. Retrieved from http://www.fig.net/pub/fig2013/papers/ts05e/TS05E_udoh_eyoefen_642 4.pdf SCP – GE 113 | 10 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INITIATE! Activity 1. Let’s try to check what you have learned in this course. Write your answers to the space provided after the question. 1. In your own words, define hydrographic surveying. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. What do you think is the importance of hydrographic surveying in a person’s life? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. How important is a hydrographic survey for Geodetic Engineering students? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 4. What is the significance of the hydrographic survey to marine works? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. After going through Lesson 1 of this course, give a brief and precise comparison of hydrography to hydrology and hydraulics. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 11 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INQUIRE! Activity 1. Discuss your answers to the following questions and write them on the space provided. 1. What are the similarities and differences of sounding pole and leadline in the aspect of their physical appearance and use? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. Discuss the advantages and disadvantages of small-scale and modern equipment. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. What information is required to position and orient a hydrographic survey horizontally? ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ ___________________________________________________________________________ __________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ 4. In the absence of a benchmark referenced to a vertical control, how can topography be done for a given hydrographic survey? ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 12 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. Discuss the relation of topography to the hydrographic survey. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 13 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INFER! Activity 1. Create and draw a story of the scope of hydrographic surveys. SCP – GE 113 | 14 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Week 2 Tides Lesson Title Tides (Part 1) Discuss the importance and cause of tides, identify and Learning familiarize the terminologies of tides, and identify the different Outcome(s) kinds of tidal datum. Time Frame 2:00PM-4:00PM – MT / 3:00PM-4:00PM – W At SJPIICD, I Matter! LEARNING INTENT! Terms to Ponder This section is where you can have a better understanding of the definition of terminologies used in this topic and throughout the simplified course pack of Hydrographic Surveying. You may refer to this section in case of difficulties in understanding the content of the course pack. I suggest you also take these terms by heart to store the definitions in your long-term memory and use them in the next courses that you will take. Drift refers to the speed of the current flow. Ebbtide is the period within which the water surface is falling and moving seaward. Floodtide is the period within which the water surface is rising and moving in toward the shore. High water or high tide refers to the maximum height to which the water surface rises above the standard datum plane during a given period. Low water or low tide refers to the greatest depression of the water surface below the standard datum plane during a given period. Set refers to the direction of the current flow. Slack water is the instant at which the tidal current is changing direction and flows neither in nor out. SCP – GE 113 | 15 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Stand of the tide is the period around which the greatest peak or depression of the tides is reached during which any change in height of the tide is scarcely noticeable. Tidal current is the horizontal movement of water accompanying tides and which is produced by the combined action of astronomical, hydrological, and meteorological factors. Tidal datum is a standard elevation defined by a certain phase of the tide. Tidal day consists of an idealized average period of 24 hours and 50 minutes between the occurrence of two successive high tides of the same type at the same location. Tidal waves consist of a large head or front of water generated at the surface of the ocean by force winds of hurricanes or typhoons, or by isostatic adjustment of the ocean floor accompanying a submarine earthquake. Tide is the half-daily cycle of rhythmic rise and fall of the surface of oceans, seas, lakes, bays, rivers, and other bodies of water connected with them due to the gravitational attraction of the sun and the moon acting upon the rotating earth. Tide range is the range of the tides in the difference between the high and low tides at a certain location on a given date. Essential Content 2.1 TIDES There are various ways as to how tides affect the everyday life of a person. Tides play an important role in the launching of ships and floating vessels. Tides affect fishing, navigation, and weather. Our fishermen are reliant on the tides for their catch. Diving, dredging, harbor construction projects, and marine engineering are dependent upon the tides. Even boating, swimming, and aquatic sports activities, which most of us love to do to relax and have fun, are affected by tide-induced conditions of surf and sea. Now, the question is what is the cause of the tides? Forces that contribute to tides are called tidal constituents. The Earth’s rotation is a tidal constituent. The major tidal constituent is the moon’s gravitational pull on the Earth. The closer objects are, the greater the gravitational force is between them. Although the sun and moon both exert a gravitational force on the Earth, the moon’s pull is stronger because the moon is much closer to the Earth than the sun is. SCP – GE 113 | 16 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached The relationship between the masses of the Earth, moon and sun and their distances to each other play a critical role in affecting the Earth's tides. Although the sun is 27 million times more massive than the moon, it is 390 times further away from the Earth than the moon. Tidal generating forces vary inversely as the cube of the distance from the tide-generating object. This means that the sun’s tidal generating force is reduced by 3903 (about 59 million times) compared to the tide-generating force of the moon. Therefore, the sun’s tide-generating force is about half that of the moon, and the moon is the dominant force affecting the Earth’s tides. (National Ocean Service, Tides and Water Levels: What Causes Tides?) 2.2 TIDAL DATUMS Tidal datums are specific tide levels which are used as surfaces of reference for depth measurements in the sea and as a base for the determination of elevation on land. Tidal datums should not be extended into areas having differing oceanographic features without substantiating measurements. So that they may be recovered when needed, such datums are referenced to fixed points known as benchmarks. Tidal datums are also the basis for establishing privately owned land, state- owned land, territorial sea, exclusive economic zone, and high seas boundaries. The principal tidal datums (also refer to the figure below), which will be discussed individually in this lesson, are as follows: ▪ Mean sea level ▪ Mean lower water ▪ Mean lower low water ▪ Mean low water springs 2.3 MEAN SEA LEVEL We all know that datum is the basis for all geodetic survey works. We also encounter terminologies about the reference surface where the datum is about. This reference surface used is the mean sea level. Mean sea level (MSL) is the datum for the first-order level net of many countries and is increasingly used as the base for general leveling operations. It is the average height of the sea for all stages of the tide. The average value is obtained from systematic observations of the sea level taken at equal intervals over a long time along a given coastline. For practical purposes, observations of the height of the water, where the average height is referred to, is taken every hour. Though this is used as a datum, as mentioned a while ago, it has a share of contribution and importance in hydrographic surveying. In the determination of mean sea level, the station used should be on the open coast or the shore of bays or harbors having free access to the sea. SCP – GE 113 | 17 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached 2.4 MEAN LOW WATER Mean low water (MLW) is the mean of all low waters as observed over long periods. This datum is used where depths are referred and is used on the Atlantic and Gulf Coasts of the United States, in the Canal Zone, Puerto Rico, and the coasts of Argentina, Sweden, and Norway. 2.5 MEAN LOWER LOW WATER Mean lower low water (MLLW) is the average of all heights of the lower of the two low waters that befall in each lunar day. It is usually employed when a great deal of tidal range results from a marked diurnal inequality. It has been generally adapted for hydrographic surveys along the Pacific Coast of the United States, Alaska, Hawaii, and the Philippines. Historically, MLLW has been used for navigational purposes in the marine waters of the United States and its territories. Navigational charts from the NOAA Office of Coast Survey show water depths relative to MLLW, or how far the ocean bottom extends below the MLLW line. If boaters know the tide forecast and depth of the ocean relative to MLLW, and the draft of their boat or ship or the distance between the waterline and the bottom of the hull, then they can assume if the vessel will hit the seafloor. 2.6 MEAN LOW WATER SPRINGS During full or new moons, the average tidal ranges are slightly larger. This occurs twice each month. The moon appears new when it is directly between the Earth and the sun. The moon appears full when the Earth is between the moon and the sun. In both cases, the gravitational pull of the sun is "added" to the gravitational pull of the moon on Earth, causing the oceans to bulge a bit more than usual. This means that high tides are a little higher and low tides are a little lower than average. These are called spring tides and have nothing to do with spring. Rather, the term is derived from the concept of the tide "springing forth." Spring tides occur twice each lunar month all year long, without regard to the season. At locations where spring tides are very rampant, the average elevation of low water produced by the spring tide is used. Mean low water springs (MLWS) is SCP – GE 113 | 18 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached defined as the mean of the low waters of the spring tides occurring a day or two after the new or full moon. It is determined by subtracting one-half of the range of the spring tides from the mean tide level. This datum is used on the Pacific Coast of the Panama Canal Zone, and in the coastal waters of Great Britain, Germany, Denmark, Italy, Brazil, and Chile. We will continue with tides – different types of tides, tidal current and bores, and the application of tide gaging next week. To have an advanced understanding of these topics, I encourage you to research, read books and articles, and watch videos to exercise your mind and prepare for the next lessons to come. SELF-SUPPORT: You can click the URL Search Indicator below to help you further understand the lessons. Search Indicator Anwar, S. (2018). What is Tide, why it occurs and how it is important for human life? Retrieved from https://www.jagranjosh.com/general- knowledge/what-is-tides-why-it-occurs-and-how-it-is-important-for- human-life-1506511282-1 Barr, K. (2019). Importance of Tides. Retrieved from https://sciencing.com/importance-tides-7751713.html Berg, R. (2016). MLLW. Retrieved from https://noaanhc.wordpress.com/tag/mllw/#:~:text=Mean%20Lower%20L ow%20Water%20(MLLW)%20is%20simply%20the%20lowest%20of,runs%2 0from%201983%20through%202001. Davis, R., Foote, F., Anderson, J., Mikhail, E. (1981). Surveying Theory and Practice Sixth Edition. McGraw-Hill, Inc. La Putt, J. (2011). Higher Surveying 2nd Edition. Baguio Research & Publishing Center. National Geographic Society. (2011). Cause and Effect: Tides. Retrieved from https://www.nationalgeographic.org/article/cause-effect-tides/ National Geographic Society. (2019). Tide. Retrieved from https://www.nationalgeographic.org/encyclopedia/tide/ NOAA. (2019). What are spring and neap tides? Retrieved from https://oceanservice.noaa.gov/facts/springtide.html#:~:text=A%20spring %20tide%20is%20a,without%20regard%20to%20the%20season. SCP – GE 113 | 19 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INITIATE! Activity 1. Let’s try to check what you have learned in this course. Write your answers to the space provided after the question. 1. Is tide important to you? Support your answer. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. How does tide affect surveying works? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. How important is tide for Geodetic Engineering students? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 4. What is the significance of knowing the importance and cause of tides in surveying works? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. After going through Lesson 2 of this course, give a brief and precise discussion of the cause and importance of tides. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 20 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INQUIRE! Activity 1. Discuss your answers to the following questions and write them on the space provided. 1. What is/are the similarity/ies of the tidal datum to other datums? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. What is/are the difference/s of the tidal datum to other datums? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. What is the purpose of the mean sea level in hydrographic surveying? ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ ___________________________________________________________________________ __________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ 4. What is the difference between mean sea level and mean lower low water? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 21 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. Why is mean lower low water the datum adapted in the Philippines? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 22 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INFER! Activity 1. Create a poem of what you’ve learned about tides. (Minimum of 3 stanzas with 4 lines per stanza) ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 23 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Week 3 Tides Lesson Title Tides (Part 2) Understand and illustrate the type of tides, differentiate the Learning Outcome(s) graph of different types of tides, understand tidal currents, bores, and applications of tide gaging. Time Frame 2:00PM-4:00PM – MT / 3:00PM-4:00PM – W At SJPIICD, I Matter! LEARNING INTENT! Terms to Ponder This section is where you can have a better understanding of the definition of terminologies used in this topic and throughout the simplified course pack of Hydrographic Surveying. You may refer to this section in case of difficulties in understanding the content of the course pack. I suggest you also take these terms by heart to store the definitions in your long-term memory and use them in the next courses that you will take. An estuary is an area where a freshwater river or stream meets the ocean. Surge is a sudden change in depth. Essential Content 3.1 TYPES OF TIDES Because of the combination of various tide-raising forces, there exist three main types of tides. 1. Semidiurnal Tides A semi-diurnal tide has two episodes each of approximately equal size high and low water each tidal day. Semi-diurnal tides tend to occur when the moon is directly over the equator. This is the most common type of tidal pattern. You'll see semi-diurnal tides along the U.S. Atlantic coast. 2. Diurnal Tides SCP – GE 113 | 24 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached A diurnal tide has one episode of high water and one episode of low water each day. These tides usually occur in locations when the moon is farthest from the equator. You'll find diurnal tides along the coast of the Gulf of Mexico, near Alaska, the Philippines, and the coast of China. 3. Mixed Tides Mixed tides have two high waters and two low waters each day, just like the semidiurnal tides. However, mixed tides do not rise and fall to the same levels. They can either include both sets of unequal high and low waters, or only one set of unequal high or low waters. Mixed tides usually happen when the moon is extremely far north or extremely far south of the equator. These types of tides occur mostly along the Pacific coast of the United States, and near the merging of the Pacific and Indian Oceans. SCP – GE 113 | 25 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached 3.2 TIDAL CURRENTS Tidal currents can be defined as the periodic movement of water driven principally, though not necessarily exclusively, by a head difference created by out-of-phase ocean tides at each end of a restriction. (Future Energy (Second Edition), 2014) Tidal currents are generated by tides. The rise in water level is accompanied by a horizontal movement of water called the tidal current. Tidal currents take place together with the rise and fall of the tide. The vertical motion of the tides near the shore causes the water to move horizontally, creating currents. When a tidal current move toward the land and away from the sea, it is called the flood. When it moves toward the sea away from the land, it is ebb. In some rivers, the ebb currents are stronger than the flood and sometimes reach velocities as high as 10 to 12 knots. The strongest currents can be produced at any time during the ebb stage and not necessarily at high tide. 3.3 TIDAL BORES A tidal bore takes place along a coast where a river empties into an ocean or sea. It is a strong tide that pushes up the river, against the current. It is a true tidal wave. Also, a tidal bore is a surge – a positive surge where a channel suddenly gets deeper. Not all coasts feature tidal bores. There are few places where tidal bores occur. The river must be fairly shallow and have a narrow opening to the sea. However, the estuary must be wide and flat. The coast’s tidal range must be quite large, usually at least 6 meters. When all of these conditions are met, a tidal bore is formed. 3.4 TIDE GAGING Major applications of tide gaging are usually connected to hydrographic surveys, dredging operations, or other subaqueous constructions. A short period of recordings is required during the period of operations to permit the reduction of measurements of water depths to a common datum. Careful selection is needed to look for the best tide station. It would be better to establish it in a protected area that has a depth of about 1.5 meters below the SCP – GE 113 | 26 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached predicted lowest tide, and most especially the gage should be where it won’t be affected and damaged by land or sea traffic. Next week, we will begin to focus in the topic of soundings. For you to have an advanced understanding of this, I encourage you to research, read books and articles, and watch videos to exercise your mind and prepare for the next lessons to come. SELF-SUPPORT: You can click the URL Search Indicator below to help you further understand the lessons. Search Indicator Boating Magazine. (2019). 12 Different Types of Tides Explained. Retrieved from https://www.boatingmag.com/photos/twelve-types-tides/ Horton, J. (2008). How Ocean Currents Work. Retrieved from https://science.howstuffworks.com/environmental/earth/oceanography/ ocean-current4.htm# Kay, M. (2017). The Four Different Types of Tides. Retrieved from https://sciencing.com/list-7653299-four-different-types-tides.html La Putt, J. (2011). Higher Surveying 2nd Edition. Baguio Research & Publishing Center. National Geographic Society. (2011). Tidal bore. Retrieved from https://www.nationalgeographic.org/encyclopedia/tidal-bore/ The Editors of Encyclopaedia Britannica. (2013). Tidal bore. Retrieved from https://www.britannica.com/science/tidal-bore SCP – GE 113 | 27 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INITIATE! Activity 1. Let’s try to check what you have learned in this course. Write your answers to the space provided after the question. 1. Are there any other types of a tide that you know aside from those mentioned in this lesson? What are those? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. Does tidal current affect surveying works? Why or why not? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. What is the significance of knowing the types of tides in surveying works? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 4. How important is this lesson for Geodetic Engineering students? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. Why is tide relevant in hydrographic surveys? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 28 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INQUIRE! Activity 1. Discuss your answers to the following questions and write them on the space provided. 1. What is the purpose of tidal bore? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. Are there any advantages to the tidal bore? Support your answer. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. How about the disadvantages? Give examples and reasons. ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ ___________________________________________________________________________ __________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ 4. How is semidiurnal tide different from mixed tide? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 29 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. What type of tide occurs in the Philippines? Why is that so? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 30 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INFER! Activity 1. Give an example of the application of tide gaging. Give details like purpose, importance, etc., to support your answer. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 31 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Week 4 Locating Soundings Lesson Title Locating Soundings (Part 1) Understand the structure and functions of the sounding Learning Outcome(s) party, identify the use of range lines, understand the procedure in some of the methods of locating soundings. Time Frame 2:00PM-4:00PM – MT / 3:00PM-4:00PM – W At SJPIICD, I Matter! LEARNING INTENT! Terms to Ponder This section is where you can have a better understanding of the definition of terminologies used in this topic and throughout the simplified course pack of Hydrographic Surveying. You may refer to this section in case of difficulties in understanding the content of the course pack. I suggest you also take these terms by heart to store the definitions in your long-term memory and use them in the next courses that you will take. A buoy is a floating object anchored in place in a body of water by a heavyweight to which the buoy is attached by a rope or chain. Essential Content Soundings are commonly executed either with a pole or with a lead line, according to the depth of the water. Soundings are also usually made from a boat and sounding operations generally require a party familiar with the work to be done, and equipment suitable for the work in hand. 4.1 SOUNDING PARTY The people of the sounding party depend upon the method used in locating soundings. The personnel who usually form the boat party are the following: ▪ Chief of Party – directs and supervises all operations, prepares required data and plan needed in the operation and oversees the whole team ensuring that they are safe and well-cared as well as the equipment used SCP – GE 113 | 32 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached ▪ Instrumentman – responsible for acquiring data using the necessary instruments for the survey ▪ Recorder – records all the survey data gathered made by the instrumentman ▪ Leadsman – handles the leadline or the sounding rod and makes the soundings and calls on the readings to the recorder ▪ Coxswain – responsible for driving the boat to necessary locations for soundings ▪ Lookout – keeps watching over the surrounding water for hazards which may cause danger to the vessel and party ▪ Signalman – one who alerts of the commencement of the sounding ▪ Fathometer attendant – for water surveys where a fathometer is needed, the attendant gives full attention to the instrument 4.2 RANGE LINES The lines, on which soundings are taken, are called ranges or range lines. They are laid on the shore parallel to each other and at right angles to the shoreline or radiating from a noticeable natural object. Each range line is marked at both ends by signals when onshore, or by buoys when in shallow water, or by a combination of both. Each range line should be marked using signals established at two points which should be considerably distant from each other. Direct measurement, stadia, or triangulation are some of the ways to establish the signal defining the range. The spacing of the range lines ranges from 6 to 30 meters, depending on the object of the survey and the nature of the bottom. On the other hand, buoys are required in establishing horizontal control especially when the hydrographic survey extends beyond the visibility of shore signals. 4.3 LOCATING SOUNDINGS The basic component of a hydrographic survey is defined by the implemented sounding operation. To make use of the measurement of water depth, knowing the accurate location of points where the depth was measured is very important. The process of determining the horizontal position of a measured depth concerning an established system of horizontal control is called position fixing, whose principles are similar to topographic surveys. SCP – GE 113 | 33 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached The survey is done by measuring angles and/or distances between the vessel and fixed control points on the shore. Different instruments can be used in determining those angles and distances. There are various methods used for locating soundings. These methods are dependent on the size of the water body, the number of soundings to be taken and located, and the desired accuracy and economy of the survey. Some of the hydrographic methods used in determining and locating soundings are discussed here, and some will be in the next lessons. 4.4 TIME INTERVAL ALONG A RANGE LINE First in the list of those methods is the time interval along a range line. This method is used when the length of the range is short, water is still and the accuracy required is not high. In this method, the sounding boat is rowed at uniform speed along the range and the sounding is taken at regular intervals of time. Since the length of the range line is known, by proportion soundings can be located. Also, angle readings should be taken when a change of speed is needed. This method is best used in combination with other methods. 4.5 RANGE LINE AND AN ANGLE FROM SHORE This next method is commonly used on small lakes or where range lines extend only to short distances towards the water from the shore area. In this method, the boat is kept in range line with the help of two signals on the shore. The boat is moved and the point where sounding is measuring is observed by the theodolite or sextant and angle is noted. Using this angle, we can fix the point in the range. Likewise, all other soundings are observed from different stations. To allow easy projection of range lines across the water, the signals should be far SCP – GE 113 | 34 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached enough from each other. The intersecting line of sight from the instrument to the boat should cross the range line at an angle as near 90° as practical. A continuation of these methods will be discussed in the next lesson. Please read in advance to understand the process better and faster. SELF-SUPPORT: You can click the URL Search Indicator below to help you further understand the lessons. Search Indicator Anupoju, S. (2016). Retrieved from https://theconstructor.org/surveying/methods- locating-sounding-hydrographic- surveying/19976/#:~:text=By%20tachometry- ,By%20Range%20and%20One%20Angle%20from%20the%20Shore,sextan t%20and%20angle%20is%20noted.&text=Likewise%2C%20all%20other%2 0soundings%20are%20observed%20from%20different%20stations. La Putt, J. (2011). Higher Surveying 2nd Edition. Baguio Research & Publishing Center. SCP – GE 113 | 35 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INITIATE! Activity 1. Let’s try to check what you have learned in this week’s lesson. Write your answers to the space provided after the question. 1. What is sounding? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. How important is a recorder in the survey party? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. Can leadsman become the lookout as well? Support your answer. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 4. What is/are the difference/s in roles of instrumentman and fathometer attendant? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. Can instrumentman be the fathometer attendant also? Support your answer. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 36 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INQUIRE! Activity 1. Discuss your answers to the following questions and write them on the space provided. 1. What are the range lines for? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. What is a signal? When is it useful or relevant for locating soundings? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. How about buoys? When is it useful or relevant for locating soundings? ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ ___________________________________________________________________________ __________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ________________________________________________________________________ 4. How to locate soundings? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 37 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 5. Why are range lines important in locating soundings? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 38 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INFER! Activity 1. How is sounding associated with hydrographic surveying? Be very detailed with your explanation and examples. ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ SCP – GE 113 | 39 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached Week 5 Locating Soundings (Continuation) Lesson Title Locating Soundings (Part 2) Understand the procedure in some of the methods of locating Learning Outcome(s) soundings that weren’t discussed in the previous lesson. Time Frame 2:00PM-4:00PM – MT / 3:00PM-4:00PM – W At SJPIICD, I Matter! LEARNING INTENT! Essential Content To continue with the methods in locating soundings, we’ll discuss another two of these before having the preliminary exam. 5.1 INTERSECTING RANGE LINES In intersecting range lines, the fixed range lines are located onshore and laid out to intersect at almost 90°. Signals are used to mark each range line. Here, the boat moves towards the intersection of any two range lines to take soundings. The distance between intersecting range lines will determine the survey’s precision. The precision also depends on how the points of intersection are located when actual sounding takes place. An important factor to consider in doing this method is the shape and size of the body of water and the topography of the shore. This is best practiced to small bodies of water where range signals are well- established and visible. Some of the application of this method is determining if the bottom of a river is filling or scouring, and also determining the volume of material removed during dredging operations. SCP – GE 113 | 40 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached 5.2 ONE ANGLE AND STADIA DISTANCE FROM SHORE This method of locating soundings is similar to stadia surveying and is convenient for surveys of small water bodies. This is executed by establishing the theodolite or transit onshore and the stadia rod is carried on the vessel. The instrumentman will observe the stadia interval on the rod at the instant the sounding is taken and reads the bearing or azimuth simultaneously. The main advantage of this method is its simplicity and speed with which the observed soundings can be plotted. But, this is not for locating soundings far from shore and where water is slightly rough. In the figure, you can see how this method is done. The upper and lower stadia hair readings are taken on the rod from the instrument established onshore. The stadia intercept is determined by noting the difference between the two hair readings. To continue, the distance from the instrument to the boat is calculated by multiplying the stadia interval factor with the observed stadia intercept. This will be the end of our preliminary topic. Lessons 1 through 5 are the coverage for the exam. At the beginning of the midterm discussion, we will be discussing hydrographic positioning methods and other applications related to locating soundings. Review your lessons now, and good luck with the exam! SCP – GE 113 | 41 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached SELF-SUPPORT: You can click the URL Search Indicator below to help you further understand the lessons. Search Indicator Anupoju, S. (2016). Retrieved from https://theconstructor.org/surveying/methods- locating-sounding-hydrographic- surveying/19976/#:~:text=By%20tachometry- ,By%20Range%20and%20One%20Angle%20from%20the%20Shore,sextan t%20and%20angle%20is%20noted.&text=Likewise%2C%20all%20other%2 0soundings%20are%20observed%20from%20different%20stations. La Putt, J. (2011). Higher Surveying 2nd Edition. Baguio Research & Publishing Center. SCP – GE 113 | 42 ST. JOHN PAUL II COLLEGE OF DAVAO ENGINEERING DEPARTMENT Physically Detached Yet Academically Attached LET’S INITIATE! Activity 1. Let’s try to check what you have learned about methods for locating soundings. Write your answers to the space provided after the question. 1. Who are the people involved in locating soundings by intersecting range lines? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 2. Who are the people involved in locating soundings by one angle and stadia distance from shore? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ 3. How will these methods help you in your future practice of hydrographic surveying? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ _______________________________________________________________

GE 113 Hydrographic Surveying PDF

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