CEHY0322 Hydrology 1 PDF

Material 1 CEHY0322: Hydrology Introduction to Hydrology Hydrology is that branch of physical geography which is concerned with the origin, distribution, and properties of the waters of the earth. The science that treats the waters of the Earth, their occurrence, circulation and distribution, the...

Material 1 CEHY0322: Hydrology Introduction to Hydrology Hydrology is that branch of physical geography which is concerned with the origin, distribution, and properties of the waters of the earth. The science that treats the waters of the Earth, their occurrence, circulation and distribution, their chemical and physical properties and their reaction with the environment, including their relation to living things. Hydrology in Engineering Hydrology is used in engineering mainly in connection with the design and operation of hydraulic structures. Practical applications of hydrology are found in such tasks as the design and operation of hydraulic structures, water supply, wastewater treatment and disposal, irrigation, drainage, hydropower generation, flood control, navigation, erosion and sediment control, salinity control, pollution abatement, recreational use of water, and fish and wildlife protection. Hydrology and other Geosciences Hydrology as Science behind Water Resource Problems Importance of Hydrology 1. The variation of water production from catchments can be calculated and described by hydrology. 2. Engineering hydrology enables us to find out the relationship between a catchments' surface water and groundwater resources 3. The expected flood flows over a spillway, at a highway at a culvert, or in an urban storm drainage system can be known by this very subject. 4. It helps us to know the required reservoir capacity to assure adequate water for irrigation or municipal water supply in droughts condition. CEHY0322 Hydrology Material 1  5. It tells us what hydrologic hardware (e.g. rain gauges, stream gauges etc.) and software (computer models) are needed for real-time flood forecasting. 6. Used in connection with design and operations of hydraulic structure. 7. Hydrology is an indispensable tool in planning and building hydraulic structures. 8. Hydrology is used for city water supply design which is based on catchments area, amount of rainfall, dry period, storage capacity, runoff evaporation and transpiration. Division of Hydrology Engineering Hydrology Engineering hydrology deals with the planning, design and operation of engineering projects for the control and use of water Applied Hydrology Applied hydrology is the study of hydrological cycle, precipitation, runoff, relationship between precipitation and runoff, hydrographs, Flood Routing Chemical Hydrology Study of chemical characteristics of water. Eco-hydrology Interaction between organisms and the hydrological cycle. Hydrogeology Also referred to as geo-hydrology, is the study of the presence and movement of ground water. Hydro-informatics he adaptation of information technology to hydrology and water resource applications Hydrometeorology It is the study of the transfer of water and energy between land and water body surfaces and the lower atmosphere. Isotope Hydrology It is the study of isotropic signatures of water (origin and age of water). Surface Water Hydrology It is the study of hydrologic processes that operate at or near earth’s surface. Ground Water Hydrology It is the study of underground water Hydrologic Cycle The hydrologic cycle represents the process and pathways involved in the circulation of water from land and water bodies to the atmosphere and back again. Hydrologic Processes Evaporation Evaporation is the net loss of water from a surface resulting from a change in the state of water from liquid to vapor and the net transfer of this vapor to the atmosphere. The majority of evaporation that occurs within the hydrologic cycle originates from large surface CEHY0322 Hydrology Material 1 water bodies, such as the world’s oceans. Water vapor gathers in the atmosphere and forms clouds through condensation. When the clouds become moisture rich precipitation may occur. Condensation Condensation is the transformation of evaporated water vapors into liquid water droplets suspended in the air as clouds or fog. It is important process to convert the evaporated water into liquid state enabling formation of clouds with the aid of condensation nuclei. Precipitation Precipitation is the discharge of water, in a liquid or solid state, out of the atmosphere, generally onto a land or water surface. Hydrologists view precipitation as the major input to a watershed. Transpiration Transpiration is the net loss of water from plant leaves by evaporation through leave stomata. Evapotranspiration (ET) Evapotranspiration is evaporation from soils, plant surfaces, water bodies, and water losses through plant leaves. Surface Runoff or Overland Flow Surface runoff or overland flow is water that flows over the soil surface and occurs from areas that are impervious or locally saturated or from areas where rainfall rate exceeds the infiltration capacity of the soil. Surface runoff or overland flow can cause erosion, create landforms, and fill waterway, such as rivers, streams, and lakes. Infiltration Infiltration is the process by which water enters the soil surface; water movement downward through the soil is called percolation. Water that infiltrations, creates soil moisture for crops and percolation into the groundwater system or aquifer. CEHY0322 Hydrology Material 1