9
According Light's equation, the suggested monthly values of 12-h snow melt in
clear weather within latitute 400 to 480 (after Wilson as in Garg, 1988) is as
below :
Month
Snow melt occurring in half day
In clear weather in cm
.
March
0.89
April
1.07
May
1.22
June
1.35
(Source : S.K. Garg, 1988)
Rain-gauge Net Work :
Rain fall varies from place to place even in the same basin. For all hydrological
studies, it is essential to understand the rainfall pattern and average rainfall in a
basin or over large terrain. A number of rain gauge stations need to be installed,
i.e. net work of rain gauge stations in such a fashion so as to be representative
of the area. Selection of rain gauge stations needs to be carefully chosen,
depending upon the purpose of the study. TheWorld Meteorological Organisation
has given the following guidelines for minimum density of rain gauges in a
catchment area :
(1)
For flat regions of temperate Mediterranean and Tropical Zones : One
station per 600-900 sq.km. For countries with limited funds, population
or other factors such as communication, the density may be reduced to
one station per 600-3000 sq.km.
(2)
For Mountainous regions of temperate Mediterranean and Tropical
Zones : One station per 100-250 sq.km. For countries with problems as
mentioned above, the density may be reduced to one station per
250-1000 sq.km.
(3)
For arid and polar zones : The minimum density may be one station per
1500 - 10,000 sq.km. depending upon the feasibility.
