Precipitation which includes rain snow hall and sleet is the primary sources of water.Rainfall is the most important components of the precipitation.As it fails on the ground a portion of it is intercepted by vegetarians and depression storage.A part of it is lost by evapotranspiration,a certain portion precolates into the ground water reserivour.
1.Sources of water
a.Pond and lake: A pond is a natural small depression and a lake is a larger one on the ground into which water flow from streams and is finally stored.After teaching ponds quality due to sedmentation and force of self and requries treatment prior to the supply.Village side ponds are generally polluted due to the various activites like nathing, washing clothes, cleaning cattle etc.Larger lake yeild better quality than smaller ones.The qauntitative is seidom satified by pond.
b.Stream and river: The quality and quantity of water flowing in rivers and streams varses with time.During the intial periods of runoff water contains all sort of impurities the quality depend on the nature of the soli tranversed by water.Also it is depend on the extent to which the adjacent land are inhabited because the waste water of these communitis are generally dicharged into them through the mechanisms of self purification such as "dillution, sedimentation,areation and sunlight" ect.
Purify the water some effect of pollution always remains water from up lands regions of highrain fall is generally soft where as that from low land region of low rain fall and high evapotranspiration is hard.Hence the river water, especially in their lower reaches has to be treated prior to the supply for consumption however they yield much water thus from important source of water supply.
c.Impounding reservoirs: These are artificial lakes formed by the constitution of dams across valleys containing water course the storage reservoirs impound water during high rate of flow and supply it during period of high demand rate. the high quality of water is almost same as that natural lake and hence requries treatment.
Yield from surface source
The quantity of water available from surface so can be determined by
1.computation of minimum and maximum discharge by
a.River gauging
The depth of the water across the river width measure at rectangular intervals of time and area of are computed.The corresponding velocities are measured by the use of floats, velocity rods curred meter etc.The products of area of flow and velocity give the discharge.If the such discharge value are available at least 8 years period,then the Minimum and maximum value which can possibly occur in 30 years of found by statistical method
2.Subsurface source: These are also called as ground water resources when rain fall on the ground a part of its precolates downward under the influence gravity until it reaches an impervious stratum.
The portion of the earth through which lateral movement takes place is known as the zone of saturation and water in it is called "ground water".
a.Aquifer: The water bearing geologic formation or stratum which yields significants quality of water for economic extraction is called aquifer.The top most aquifer is called unconfined aquifer the aquifer which is sandwitched between two impervious layers is called confined aquifer.
b.Aquiclude: A geologic formation which can only store water but can not transmit significant amount is called aquiclude.
c.Water table or phreatic surface: It is the upper surface of the zone of saturation in the unconfined aquifer in other words it is the free surface of ground water reserivour.