Water Resources
Water resources are natural resources of water that are potentially useful. Uses of water include agricultural, industrial, household, recreational and environmental activities. All living things require water to grow and reproduce.
Importance of water resources:
Water is the most important resource of a country, and of the entire society as a whole, since no life is possible without water. It has this unique position among other natural resources, like minerals, fuels, forests, livestock etc. because a country can survive in the absence of any other resources except this one.
Necessity for conservation and development of water resources: Among 97% of the water on the earth is salt water and only three percent is fresh water, slightly over two third of this is frozen in glaciers and polar ice caps. The remaining unfrozen fresh water is found mainly as ground water, with only a small fraction present above ground or in the air.Fresh water is a renewable resources, yet the world’s supply ground water is steadily decreasing with depletion occurring most prominently in Asia, South America and North America, although it is still unclear how much natural renewal balances this usage and weather ecosystems are threatened.
Factor affecting water resources:
1. Population growth, particularly in water-short regions.
2. Movement of large numbers of people from the county side to towns and cities.
3. Demands for greater food security and higher living standards.
4. Increased competition between different uses of water resources.
5. Pollution from factories, cities and farmlands.
Hydrology
The science of studying the different forms of water available above the earth surface or below the earth surface is known as hydrology. It includes the following points
1. The measurement of precipitation.
2. The study of water losses due to transpiration, evaporation, absorption and infiltration.
3. Estimation of run-off and peak flow.
4. The procedure of river gauging.
5. Precipitation of hydrograph to predict maximum flood discharge.
6. The procedure of river training works.
7. The procedure of flood forecasting and flood control works.
8. Availability of underground water.
Important of hydrology:
1. Determination of the capacity of a reservoir from the rainfall records and the yearly discharge
observation of river.
2. Determination of peak flow of a river.
3. Determination of suitable site for hydroelectric power generation.
4. Sources of water supply in a town or city.
5. Methods to be adopted for the flood control.
Catchment area: The catchment area of a river of a river means the river means the area from where the surface run off flows to that river through the tributaries, streams, springs etc. The area is bounded by watershed line.
Run-off: Runoff is the downward movement of surface water under gravity in channels ranging from small rills to large rivers. Channel flows of this sort can be perennial, flowing all the time, or they can be ephemeral, flowing intermittently after periods of rainfall or snowmelt.
Hydrological Cycle: The hydrological cycle is a global sun-driven process whereby water is transported from the ocean to the atmosphere, from atmosphere to the land and then back to the sea.Of the many processes involved in the water cycle, the most important are evaporation, transpiration, condensation, precipitation, and runoff. Although the total amount of water within the cycle remains essentially constant, its distribution among the various processes is continually changing.
E- Rain drop evaporation
I-Interception
T-transpiration
E-Evaporation of the land
mass
E-Evaporation from water
bodies
R- Surface Runoff
Evaporation is the transfer of water from a liquid state to a gaseous state, i.e., it is the conversion of liquid to the vapour phase.
Precipitation is the deposition of water on the earth’s surface in the form of rain, snow, hail, frost and so on.
Interception is the short-term retention of rainfall by the foliage of vegetation.
Infiltration is the movement of water into the soil of the earth’s surface.
Percolation is the movement of water from one soil zone to a lower soil zone.
Transpiration is the soil moisture taken up through the roots of a plant and discharged into the atmosphere through the foliage by evaporation.
Storage is the volume of water, which gets stored in natural depressions of a basin.
Runoff is the volume of water drained by a river at the outlet of catchment.
Precipitation is the fall of water in various forms on the earth from the clouds. The usual forms are rain, snow, sleet, glaze, hail, dew etc.