Abstract
The hydrologic balance of unconfined water is composed of the following factors:
a) increase and decrease in storage volume,
b) recharge from infiltration,
c) lateral undrflow of ground water.
Now, the mechanism of lateral underflow of ground water decides the direction and the property of hydrologic balance (an amplitude of the variation of ground water level, the time of maximum or minimum level and their type etc, ) in a drainage area.
So, it is an important factor in case when we make a water utilization plan and forecast the variation of ground water storage volume and the effects of irrigation on the former.
In general, the lateral underflow of ground water is shown by the decrease curve of ground water level and the formula of curve is as follows:
H=Ha+(Ho-Ha)e-et
H; ground water level in elapsed time, “t”
Ha; basic level of ground water
Ho; ground water level of the beginning
c; coefficient
Now, the coefficient “c” expresses decrement of this curve or magnitude of lateral underflow of ground water and we can consider it as one of the guides of hydrological classification of an irrigated land. In this paper, the writer particularly examined and illustrated it with the example.
