FLOW TO SUBSURFACE DRAINS WITH VARIABLE IRRIGATION RECHARGE

Abstract

Drainage of agricultural land is a removal of excess surface water from the area and to lower the groundwater below the root zone or to any specified level for getting sufficient air space within the root zone, and to reduce accumulation of soil salts, for obtaining better yields, The design of drainage system is done generally assuming the steady state condition (i.e, steady recharge all over the area) to find out a suitable spacing of drains which will keep the water level belovr the root zone or certain specified level. But in the case of irrigated lands, Most irrigation systems use periodic water application which results in a time-dependent situation. Also in humid areas, irregular precipitation patterns with variable intensities again results in varying rates of recharge to the water table. So the assumption of steady re-charge is no longer justified, under these conditions non-steady state solutions of the flow problem must be applied, Also it is important to study the fluctuation of the water table due to irregular application of irrigation recharge as this study is important to find out the crop response, its yield and toloranoe to various positions of water table and for how long it will last above that position, USING DISO E SKIt l L APFkG4H of flow to wells, a method is adopted in this dissertation to study the flow to subsurface drains and the fluctuation of water table due to applicatioii bf variable irrigation recharge in the area bounded by these drains,,