MOVEMENT OF EFFLUENT DISCHARGE TOWARDS LATERAL DRAIN UNDER DIFFERENT IMPERVIOUS LAYERS AND WATER TABLE DEPTHS

An experiment was conducted in a permeability tank constructed at the Laboratory of Department of Land and Water Management. Two soils with different textures collected from Khesana Mori and Nasarpur were used in the experiment. Soils were analyzed for the textural class and hydraulic conductivity. The soil collected from Khesana mori was sandy with hydraulic conductivity of 6.9 m/day, while the soil brought from Nasarpur was clay loam with hydraulic conductivity of 0.0564 m/day. Three impervious layers were imposed at 100, 200, and 300mm depths and four water table depths were maintained from soil surface at 0.0, 30.0, 60.0, 90.0 mm depths above the lateral. The effluent discharge was measured by volumetric method and same was calculated using Hooghoudt’s formula. The results showed that the effluent discharge from laterals was maximum when the water table depth was maintained at soil surface under both sandy and clay loam soils. The effluent discharge decreased with the increase in the depth of impervious layer. Hydraulic head above the lateral influenced the effluent discharge. When the hydraulic head increased the effluent discharge also increased. The study also found that the sandy soil with higher value of hydraulic conductivity collected from Kesana Mori had more effluent discharge compared to that of clay loam soil with lower value of hydraulic conductivity collected from Nasarpur. Therefore the drain spacing must be decided on the basis of water table depth, location of impervious layer, soil texture and hydraulic conductivity.