Hydrology and Climatology ES 1104 Lecture Notes PDF

HYDROLOGY and CLIMATOLOGY ES 1104 Assessment procedure End semester examination – Theory Paper (2 hours) 70% Continuous Assessments 30% 2 quizzes 2 assignments/presentations/group works Attendance  Course ILOs On successful completion of...

HYDROLOGY and CLIMATOLOGY ES 1104 Assessment procedure End semester examination – Theory Paper (2 hours) 70% Continuous Assessments 30% 2 quizzes 2 assignments/presentations/group works Attendance  Course ILOs On successful completion of the course, the student will be able to describe the basic components of hydrological cycle apply runoff estimation methods for watersheds explain the unique characteristics of the atmosphere in controlling the global climate demonstrate the use of instruments for measuring atmospheric parameters recognize potential causes of climate change  Why do we need to know about hydrology? Water is at the center of economic and social development It is vital to maintain health, grow food, generate energy, manage the environment, and create jobs For agricultural graduates? Grow food Manage the environment Manage water resources Manage soil Manage nutrients  Demand for water = Demand for hydrologists According to the U.S. Geological Survey Students who plan to become hydrologists need a strong emphasis in mathematics, statistics, geology, physics, computer science, chemistry and biology As hydrologists with an agricultural background, your role is really important for the sustainable development  What is Hydrology? Hydrology is the science that encompasses the occurrence, distribution, movement and properties of the waters of the earth and their relationship with the environment within each phase of the hydrologic cycle  Hydrology can be classified as Scientific hydrology (concerned with academic aspect) Engineering or applied hydrology (Concerned with engineering applications; estimation of water resources, precipitation, runoff, study of flood and droughts etc.)  Hydrological cycle The endless movement of water between the earth’s biosphere, atmosphere, lithosphere, and hydrosphere is called the hydrologic cycle  Biosphere (ecosphere): worldwide sum of all ecosystems composed of living organisms (biota) and the abiotic (nonliving) factors from which they derive energy and nutrients Lithosphere: the rigid, outermost shell of a terrestrial-type planet or natural satellite Hydrosphere: the total amount of water found on, under, and above the surface of a planet Atmosphere: a layer of gas or layers of gases that envelope a planet, and is held in place by the gravity of the planetary body Hydrological cycle https://youtu.be/al-do-HGuIk Hydrological cycle Cont.. Hydrological cycle Cont.. What are two processes change liquid water into vapor that can ascend into the atmosphere? Evaporation 90% Transpiration 10% Evaporation The process by which liquid water is transformed into a gaseous state Primary mechanism for surface to atmosphere water transport Evaporation into a gas ceases when the gas reaches saturation Evaporation vs Precipitation Evaporation and precipitation; about equal on a global scale Most water evaporated from the oceans falls back into the ocean as precipitation 10% of water evaporated from the ocean is transported over land and falls as precipitation Over land, precipitation exceeds evaporation  Transpiration The process of water loss from plants through stomata. (Stomata are small openings found on the underside of leaves that are connected to vascular plant tissues.) Passive process that depends on: - humidity of the atmosphere - the moisture content of the soil Helps to transports nutrients from the soil into the roots and distribute them to the various cells of the plant Keep tissues from becoming overheated  Transpiration Cont.. Accounts for ~ 10% of the moisture in the atmosphere Depends on: Temperature Humidity Precipitation Soil type and saturation Wind Land slope What percent of the Earth’s total volume of water is stored in the atmosphere? 0.001% Water vapor Clouds Precipitation The vapor that accumulates or freezes on condensation nuclei is acted on by gravity and falls to earth’s surface rain, sleet, snow, or hail primary connection in the water cycle that provides for the delivery of atmospheric water to the Earth Precipitation types The two most common and familiar forms of precipitation are:  rain (drops of water that fall from a cloud and have a diameter of at least 0.5 millimeter)  snow (precipitation in the form of ice crystals or, more often, aggregates of ice crystals). Precipitation types Cont.. Other forms include:  sleet (falling small particles of ice that are clear to translucent)  hail (hard, rounded pellets or irregular lumps of ice produced in large cumulonimbus clouds) drizzle (smaller droplets of rain, yet larger than mist) mist (smallest water droplets visible) Precipitation types Cont.. Importance of hydrological cycle Recycles water and nutrients It brings freshwater to people, animals and plants all around the world Clouds travel all around the world by wind currents and can bring precipitation to every part of the world  Formation of precipitation (refer) The Collision Coalescence theory The Bergeron Findeisen theory Measurement of precipitation Precipitation is expressed in terms of the depth to which rainfall water would stand on an area if all the rain were collected on it. Rain, the most common form of precipitation, is probably the easiest to measure The most common instruments used to measure rain are:  the standard rain gauge (non-recording type)  the tipping bucket gauge and weighing gauge, both of which record the amount of rain (recording type) A standard rain gauge (Symons’ rain gauge)  Preparation of data Before using the rainfall records of a station, it is necessary to first check the data for continuity and consistency The continuity of a record may be broken with missing data The missing data can be estimated by using the data of the neighboring stations Estimation of missing data Simple arithmetic method Normal ratio method Modified normal ratio method Inverse distance method Linear programming method Estimation of missing data Normal Ratio method P1,P2 annual precipitation values at neighboring stations N1, N2 Normal annual precipitation of each station M Number of neighboring stations Example: The normal annual rainfall at station A,B,C and D in a basin are 80.97, 67.59, 76.28 and 92.01 cm respectively. In the year 2013, the station D was inoperative and the stations A, B and C recorded annual precipitations of 91.11, 72.23 and 79.89 cm respectively. Estimate the rainfall at station D in that year. PD = 92.01/3 [ ( 91.11/80.97) + (72.23/67.59) + (79.89/76.28)] = 30.67( 1.125+1.069+1.047) =30.67*3.241 = 99.401 cm