Author(s): Sunjoto S.
Keywords: Pumping; Pond; Aquifer; Drawdown; Shape factor
Abstract: The pumping in the water body like ponds, lakes, rivers etc. causes zero drawdown due to there is not obstacle of inflow on the tip of casing. On the contrary when pumping on the aquifer the flow into the tip of casing has a problem of reduction of area and water must flow through the inter-granular space or through pore of the soil were the tip of casing lied and this condition caused drawdown. But till nowadays computation of hydraulic pumping power in the aquifer still implement the equation for pumping in the infinite water body. The other problem is the drawdown can reach upper side perforated casing or bottom of the tip of impermeable casing and this occurrence will create aeration on pumping system. This paper introduces a parameter of shape factor to compute the drawdown. With shape factor parameter, the drawdown can be computed and real hydraulic head can be defined as a real condition with the value is equal to the built-up as a consequence of recharging based on Forchheimer (1930) equation. With this method the choice of drawdown value especially for pumping in the coastal area can be taken into account definitely for example to avoid sea water intrusion, with the relationship of drawdown is function of discharge, coefficient of permeability and shape factor.