ESTIMATING RECHARGE FROM EPHEMERAL STREAMS IN ARID REGIONS - CASE-STUDY AT KAIROUAN, TUNISIA

On the assumption that the behavior of an aquifer is linear, it is shown that recharge from an ephemeral stream can be computed by deconvolution of the fluctuations of the piezometers in the vicinity of the stream. First, the ‘impulse response’ of the piezometer has to be determined, either from an exceptional flood event or with the help of a digital model of the aquifer. Application of this method to the plain of Kairouan (Tunisia) proved to give estimates of recharge during a 5‐year period within the same order of magnitude as direct volume estimates obtained by an automatic contouring technique of the recovery of the aquifer after infiltration (kriging). An empirical runoff‐recharge relationship was then determined to extend the estimation of recharge to a 23‐year period. Copyright 1978 by the American Geophysical Union.