There are many empirical formulae for the estimation of annual rainfall penetration (AMP), but those are not universal in their application and also regarding their methodologies. Datta et al (1973) have attempted in a classical way for assessing annual rainfall penetration with the help of annual rainfall and average clay percentage of topsoil. In the present studies, the attempt is made for estimating annual rainfall penetration using saturated hydraulic conductivity of topsoil and actual monsoon period for a village (J.L.No.388,Contai Block III) near Contai (22°36′-22°11’N latitude, 87°59′- 87°25’E longitude) in Midnapore district (presently, Purba Medinipur district), West Bengal, India. The proposed hydraulic method for assessing annual rainfall penetration showed the result as 8.82 cm/year whereas using Datta et al. (1973) formula it was 7.096cm/year. So, from the above result, it was postulated that the use of saturated hydraulic conductivity of topsoil might be directly helpful for assessing the annual rainfall penetration in an area. So, another study was planned at Kalyani (23°.5 N latitude, 89°E longitude; altitude 9.75m from m.s.l.; BCKV hostel Campus) from June 1989 to 2 January 1992. AMP was considered in those studies because there is a maximum probability of topsoil being at the saturated condition which is congenial for rainfall penetration. From the result, it was found that the rainfall penetration during the effective monsoon period was around 28 to 29 percent of average annual rainfall and during the monsoon period it is 34.115 percent and from Datta et al. formula (1973) it was 21.496 percent of the average annual rainfall of 1989 to1991, whereas the estimated annual rainfall recharge from the daily fluctuation of the water table is about 14 to 16 percent of average annual rainfall in these three years.
Water And Soil