Hydrology is the science that treats the waters of the earth, their occurrence, circulation, and distribution, their chemical and physical properties, and their reaction to their environment, including their relation to living things.
The domain of hydrology embraces the full life history of water on the earth. The application of hydrologic knowledge to practical problems requires a great deal of experience and sound judgment of the hydrologist.
Branches of hydrology
- Chemical Hydrology: It is the study of the chemical characteristics of water.
- Ecohydrology: It is the study of interactions between organisms and the hydrologic cycle.
- Hydrogeology is the study of the presence and movement of groundwater.
- Hydroinformatics is the adaptation of information technology to hydrology and water resources applications.
- Hydrometeorology is the study of the transfer of water and energy between land and water body surfaces and the lower atmosphere.
- Isotope hydrology is the study of the isotopic signatures of water.
- Surface hydrology is the study of hydrologic processes that operate at or near Earth’s surface.
- Forest hydrology: It is the hydrology of forestland. It deals with the effects of forest and wildland vegetation on the hydrologic cycle including the effects on erosion, water quality, and microclimate.
Application of Hydrology
- Determining the water balance of a region.
- Determining the agricultural water balance.
- Mitigating and predicting flood, landslide, and drought risk.
- Real-time flood forecasting and flood warming.
- Designing irrigation schemes and managing agricultural productivity.
- Part of the hazard module in catastrophe modeling.
- Providing drinking water.
- Designing dams for water supply or hydroelectric power generation.
- Designing bridges.
- Designing sewers and urban drainage systems.
- Analyzing the impacts of antecedent moisture on sanitary sewer systems.
- Predicting geomorphologic changes, such as erosion or sedimentation.
- Assessing the impacts of natural and anthropogenic environmental change on water resources.
- Assessing contaminant transport risk and establishing environmental policy guidelines.
Importance of Hydrological Knowledge in Natural Resource Management
Water is an integral part of natural resources. So without proper knowledge of water, it is almost impossible to manage natural resources in the right way.
Some of the examples of natural resources management that can be enhanced by knowledge of hydrology are:
- Without knowledge of hydrological determination of hydropower potential is impossible.
- Hydrological knowledge is essential to know the extent and quantity of groundwater potential.
- To become safe from high floods and drought hydrological knowledge is required.
Thus, without hydrological knowledge determination of crop water requirement is impossible, leading to less agricultural production.
Human’s influence on Hydrological Cycle
- Urbanization: Impermeable concrete and tarmac surfaces reduce infiltration but drains carry water quickly to river channels. Flooding is more likely with flashy hydrographs with short lag times.
- Irrigation: Removes water and therefore lowers discharge.
- Land use: Deforestation reduces interception and evapotranspiration. Infiltration occurs until saturation point when water flows as overland flow to rivers. Deforestation raises discharge and increases flood risk. Afforestation has the opposite effect.
- River management schemes: Dams, reservoirs, and balancing lakes all even out river discharge. Straightening and dredging of channels may speed up channel flow.
- Human activities like the use of chemicals, pesticides, and the dumping of wastes on water bodies lead to the total destruction of the hydrological cycle.
