Engineering hydrology may be understood as the branch of engineering that deals with the study of water resources. It is also commonly referred to as water resources engineering. Precisely, engineering hydrology may be defined as the multidisciplinary specialization of civil engineering that deals with the occurrence, circulation and distribution of water on Earth. Engineering hydrology is a very important branch of civil engineering as it is necessary for the construction of various types of water resource-related infrastructures. Mostly, engineering hydrology is focused on the scientific study of the water cycle, water resources and water resource sustainability. It mainly focuses on the planning, design, analysis, and operation of water-related projects and constructions by the utilization and efficient management of the water resources.
HISTORY OF ENGINEERING HYDROLOGY
Engineering hydrology has been an important study for a very long time. Ever since the dawn of civilization, various hydraulic structures have been constructed by the use of hydrological tools. For example, during the Mesopotamian civilization dams were constructed for protecting the Mesopotamian towns from flood. Numerous aqueducts were built by the Greeks and Romans. Irrigation activities were evident since the history of Chinese development. The development and advancement of engineering hydrology began from the first century BC. Robert Elmer Horton is regarded as the “Father of Modern Engineering Hydrology”. He was an American civil engineer and soil scientist.
IMPORTANCE OF HYDROLOGY IN CIVIL ENGINEERING
Engineering Hydrology and its applications are inevitable for planning and building hydraulic structures. It is important for solving the various existing water-related problems such as problems regarding the quantity of water, control and mitigation of flood, irrigation etc. Some of the importance of engineering hydrology can be listed as follows:
1. It is necessary for determining the maximum probable flood at the proposed construction site. For example, dam construction.
2. It facilitate engineers and hydrologists for establishing the relation between surface water of catchment and underground water resources.
3. It enables one to determine the flow over various hydraulic structures such as spillway, highway culvert, urban storm drainage system etc.
4. It is important for studying the on-site drainage and seepage condition before the commencement of any engineering construction.
5. The nature of variations of water flow, rainfall pattern etc can be obtained from the use of engineering hydrology applications.
6. It is necessary for determining the reservoir capacity in order to assure an adequate supply of water for domestic and other purposes.
APPLICATION AREAS OF HYDROLOGY IN CIVIL ENGINEERING
The main application areas in the field of civil engineering can be listed as follows:
1. Irrigation Projects and Schemes.
2. Hydroelectric Power Generation Projects and Dam Constructions.
3. Water Supply Projects.
4. Disaster Prevention or Flood Control Projects.
SCOPE OF ENGINEERING HYDROLOGY
The main scope of engineering hydrology is briefly described as follows:
1. Determination of Maximum Probable Flood:
The maximum probable flood at a proposed site can be determined by the techniques of engineering hydrology. It is necessary to determine the frequency and occurrence of flood for designing and building hydraulic structures such as dams, flood control structures and reservoirs.
2. Determination of Maximum Intensity of Storm:
The determination of the maximum intensity of the storm is necessary to determine the drainage conditions at the site and to design the needed drainage systems.
3. Determination of Water Yield of Basin:
For the design and construction of various structures such as municipal water tanks, reservoirs, inland navigation etc; it is necessary to determine the yield of basin i.e. the occurrence, frequency and quantity of water that can be obtained from the basin.
4. Ground Water Development Study:
Engineering hydrology facilitates the study of groundwater and its development.
Hydrological Cycle is commonly referred to as the Water Cycle. The hydrological cycle may be defined as the process in which water from all the freshwater sources, oceans and land move to the atmosphere and back in the form of precipitation. It is inevitable for the balance in the ecosystem and biological system of the earth. It is inevitably necessary for the cycling and processing of the solar energy, sediments and other elements that are necessary for sustaining life on Earth. Hydrological cycle consists of a series of processes such as evaporation, precipitation, percolation, runoff etc. It is a continuous cycle.
COMPONENTS OF HYDROLOGICAL CYCLE
The main components of the hydrological cycle can be listed as follows:
It refers to the forms of water that fall from the atmosphere to the surface of the earth such as rain, drizzle, snow etc
It refers to the physical process in which water from the land and water on the surface of the earth is converted to vapour form.
It refers to the process in which water from the soil is absorbed by the plants (roots) and discharged back to the atmosphere through the leaves (through little pores present in the leaves which are known as stomata).
It is the combined process of evaporation and transpiration and involves the transfer of water to the atmosphere both from the water sources and vegetation.
It refers to the movement of water from the ground surface to the underlying soil layers.
It refers to the movement of the subsurface water to the water table.
7. Overland Flow:
It refers to the runoff that flows through the surface of the ground to a stream or river channel.
8. Surface Runoff:
It refers to all the overland flow as well as the precipitation that flows to a stream or river channel.
MAJOR ASPECTS OF ENGINEERING HYDROLOGY
The engineering hydrology is mainly concerned with the following aspects:
1. Analysis and estimation of the water resources of the earth (both overground and underground).
2. Study and analysis of the hydrological cycle, its components and the interactions among the components.
3. The study, analysis, forecast and mitigation of water-related disasters such as flood, drought etc.