DESALINIZATION WITH SUBSURFACE DRAINAGE

The desalinization by surface irrigation of a drained two-layered saline soil in Sampla, Haryana, India was simulated for different water managements aimed at increasing leaching efficiency, The Laplace equation was solved numerically to obtain the water flow pattern and a mass flow equation was applied to individual streamtubes to give the spatial and temporal distribution of salt. The simulations showed that, for the region under study, ponding of the whole surface area for 450 h at the start of the reclamation, followed by ponding in the region midway between drains of half the area for another 450 h and then ponding of only a quarter of the area for a further 450 h, results in a 50% saving of water compared with continuous ponding of the area to achieve the same desalinization. However, the partial ponding strategy results in poor quality drainage effluent for a longer time than for continuous complete ponding when rapid improvement occurs.