‘SODEPT’ A Software for Design of Percolation Tank

Abstract

Percolation tanks are widely used for increasing recharge of ground water resources. This has been used from centuries in arid and semi arid regions of India and is known by different indigenous name, viz. rapat, nadi etc. However not much work has been done on standardization of the design parameters of these tanks, and therefore most of the time, tanks are either over designed or under designed. The design parameters of the percolation tank and amount of water recharged to groundwater during different months depend upon area of catchment, hydrological cover complex characteristics of the catchment, rainfall characteristics of the area, evaporation loss and seepage rate of the tank bed. Since rainfall and evaporation are stochastic variables, their distribution should also be accounted for. Further the dimensions of the tank will vary with the level of probability of design. With this in view, a software has been developed for giving the design parameters of the percolation tank. The input data are long term daily rainfall and evaporation data, seepage rate of the tank bed which is a function of textural characteristics and hydraulic conductivity, area of catchment, hydrological complex characteristics defined by curve numbers, area available for construction of the tank (length and width) for excavated type of the percolation tank or width of the gully and slope of the drainage way for impounded type of the tank, and cost of the earthwork for different depths and lead. The output is capacity of the tank for most economic recharge per unit investment, total recharge during the year, recharge during monsoon and recharge during post monsoon months and expected storage level at the end of the monsoon.