Hydrology Lecture Notes PDF

CE082 HYDROLOGY LECTURE BY: ENGR. JEZREEL S. BENLIRO  COURSE SYLLABUS 1. Course Introduction 5. Evaporation Definition of Hydrology Physics of evaporation 2. The Hydrologic Cycle...

CE082 HYDROLOGY LECTURE BY: ENGR. JEZREEL S. BENLIRO  COURSE SYLLABUS 1. Course Introduction 5. Evaporation Definition of Hydrology Physics of evaporation 2. The Hydrologic Cycle Factors affecting evaporation Measurements of different factors for evaporation 3. Precipitation Available methods/procedures for estimating evaporation Formation of Precipitation from open water Different Types of Precipitation 6. Basic Subsurface Flow Rainfall characteristics (Depth, Duration, Intensity, Law of Darcy confined and unconfined Aquifers. Hyetograph) Ground water flow in Confined Aquifer Point Rainfall Measurements Estimation of Missing rainfall data Groundwater flow in unconfined aquifer Radial ground water flow in Confined Aquifer Different Types of Rain gauges Radial Ground water flow in unconfined aquifer Conversion of Point rainfall to areal rainfall Double Mass Analysis Travel time of ground water in confined aquifer 4. Infiltration 7. Rainfall-Runoff Relation Definition of infiltration Definition of Hydrograph Hydrograph Separation Factors affecting infiltration, and infiltration measurements Unit Hydrograph Horton Model and Phillip’s equation Green-Ampt model Estimation of discharge using unit hydrograph Rational Formula Ponding time SCS Curve Method Fitting infiltration models to infiltration data using Excel GRADING SYSTEM 50% - MAJOR EXAMINATION (ME) – Prelim, Midterm, and Final Examination 25% - LONG QUIZ (LQ) - Plates 15% - SHORT QUIZ (SQ) - Homework/Research Work 10% - ASSESSMENT TASK (AT) FORMULA FOR COMPUTING THE PERIODICAL GRADES: PG/MG/PFG = ME (50%) + LQ (25%) + SQ (15%) + AT (10%) FORMULA FOR COMPUTING THE FINAL GRADE: FG = PG (30%) + MG (30%) + PFG (40%) Note: Periodical/Final grade is rounded off up to the nearest two decimal places before it is transmuted to grade point equivalent with 1.00 as the highest and 5.00 as the lowest. A final rating of at least 60% or grade point 3.00 is necessary for the course to be considered passed and for the unit/s to be credited REFERENCES Bedient, P.B., Huber W.C. and Vieux, B.E. Hydrology and Floodplain Analysis, Pearson 4th Ed., Philippine edition copyright 2010 David Chin, Water Resources Engineering, 3rd Ed., Pearson , 2013 McCuen, R.H., Hydrologic Analysis and Design, Prentice Hall, 1989 Linsley, R.K., M.A. Kohler and J.L.H. Paulhus, Hydrology for Engineers by; McGraw-Hill, 1988 Applied Hydrology by VenTe Chow, David Maidment and Larry Mays; McGRAW-HILL International Editions; 1988  HYDROLOGY Hydro Logos Hydrology = = Water Study The study of water is called Hydrology. Or The Science about Water is known as Hydrology. Hydrology is the science of water: It is the science that deals with the occurrence, circulation, and distribution of water of the earth and earth’s atmosphere. It is concerned with water in streams and lakes, rainfall and snowfall, snow and ice on the land, and groundwater. It is of inter-disciplinary nature.  HYDROLOGY Origin Interaction with living Occurrence organisms Water Hydrology Properties Circulation Distribution OR The study of water in all its forms (rain, snow and water on the earth’s surface, etc.), and from its origins to all its destinations on the earth is called hydrology. Hydrology is an essential field of science since everything from tiny organisms to individuals, to societies, to the whole of civilization - depends so much on water. In general, hydrology deals with Estimation of water resources. The study of processes such as precipitation, runoff, evapotranspiration and their interaction. The study of problems such as floods and droughts and strategies to combat them. Origin & History of Hydrology It was along the Indus in Pakistan, the Tigris and Euphrates in Mesopotamia, the Hwang Ho in China, and the Nile in Egypt that the first hydraulic engineers created canals, dams, subsurface water conduits, and wells as early as 5000-6000 years ago. Advances in the 18th century included the Bernoulli piezometer and Bernoulli's equation, by Daniel Bernoulli, the Pitot tube etc. The 19th century saw development in groundwater hydrology, including Darcy's law, the Dupuit-Thiem well formula, and Hagen-Poiseuille's capillary flow equation. Jacqui (1987) traced the history of hydrology to ancient China and postulated three stages of the development of the study of hydrology. 1. Stage of geographical hydrology 2. Stage of engineering hydrology 3. Stage of social development Stages in the history of Hydrology 1. Stage of geographical hydrology Establishment of hydrological cycle and concept of water balance 2. Stage of engineering hydrology Design of control structures and quantitative analysis of hydrological phenomena 3. Stage of social development It is the stage in which the water demand is more and large scale of use of water resources is occurring. Coupled with the development of new techniques brought about a new stage of water resources involving resource analysis and management Branches of Hydrology Hydrology can generally be divided into two main branches: 1. Pure Hydrology Hydrological cycle, precipitation, runoff, relationship between precipitation and runoff, hydrographs, Flood Routing 2. Engineering Hydrology Planning, design and Operation of Engineering Projects for the control and use of water Branches of Hydrology Hydrology can be divided into the following branches Chemical Hydrology: Study of chemical characteristics of water Ecohydrology: Interaction between organisms and the hydrological cycle Hydrogeology: Also referred to as geohydrology, is the study of the presence and movement of ground water Hydroinformatics: is the adaptation of information technology to hydrology and water resource applications Branches of Hydrology Surface water Hydrology: is the study of hydrologic processes that operate at or near earth’s surface Ground water Hydrology: is the study of underground water Drainage basin management: covers water storage in the form of reservoir and flood protection Water quality: includes the chemistry of water in rivers & lakes Isotope Hydrology: is the study of isotropic signatures of water (origin and age of water) HYDROLOGIC CYCLE Hydrologic Cycle The main processes involved in hydrological cycle are Evaporation: The act or process of converting or changing water into vapor form with the application of heat. Condensation: The act or process of reducing a gas or vapor to a liquid or solid state (sublimation). Precipitation: The process by which atmospheric moisture falls onto a land or water surface as rain, snow, hail, or other forms of moisture. Interception: The process of storing rain or snow on leaves and branches which eventually evaporates back to the air. Infiltration: The penetration of water through the ground surface into sub-surface soil Percolation: The movement of water downward and radially through subsurface soil layers, usually continuing downward to ground water. Transpiration: The process by which water vapor is lost to the atmosphere from living plants. Runoff: Drainage or flood discharge that leaves an area as surface flow or as pipeline flow. Hydrologic Cycle Advantages: This Hydrological Cycle recycles the earth’s valuable water supply. In other words, the water keeps getting reused over and over. Provides water for our population, animals and plants. Evaporation and infiltration help to remove impurities from water. Provides fish to eat. Water in that glass could have been a liquid, a solid, and a gas countless times over thanks to the water cycle. Hydrologic Cycle Disadvantages: Cannot add or remove water from the system. Acid rain. The water can end up in the flood place, causes flood to occur. Global Water Availability m3/capita/year 500 1350 3850 10000 37500 325000 World Population by Freshwater Availability Population and Water Use 1 km3 = 1,000,000,000 m3 9000 8000 Withdrawal (km3/yr) 7000 Population (million) 6000 5000 4000 3000 2000 1000 0 1950 1960 1970 1980 1990 2000 2010 2020 Global Water Resources 105,000 km3 or 0.0076% of total water Global Freshwater Global Water Water Availability vs Population  World Population by Freshwater Availability 2000 Total population: 6 million Relative sufficiency: 92% Stress: 5% Scarcity: 3% 2025 Total population: 7.82 billion Relative sufficiency: 62% Stress: 31% Scarcity: 7% *600 million people face water scarcity Application of Hydrology Determining the water balance of a region Determining the agricultural water balance Mitigating and predicting flood, landslide and drought risk Flood forecasting and flood warnings Designing irrigation schemes and managing agricultural productivity Designing bridges Designing dams for water supply or hydroelectric power generation Designing sewers and urban drainage system Designing irrigation schemes and managing agricultural productivity Sources of Data The data normally required: Weather records ( temperature, humidity, wind velocity) Precipitation data Stream-flow records Evaporation and transpiration data Infiltration characteristics of the area Groundwater characteristics Physical and geological characteristics