Recharge from intermittent flow

Abstract

Streams in (semi-)arid areas usually flow intermittently because they are fed by an irregular and often scarce rainfall; even perennial streams (fed by groundwater) usually show very large differences between baseflow and floods. Percolation losses from streams during flood periods are often the most important source of natural groundwater recharge, though are seldom more than five percent of the annual precipitation. This chapter therefore starts with a section on the hydrology of intermittent streams. In Section 3.3 a description is given of the recharge processes and in the following section the methodology to estimate recharge from ephemeral streams is discussed. In Section 3.5 man enhanced recharge from, for example, irrigation, village tanks, or artificial recharge structures fed by intermittent streams, is described. Section 3.6 presents quantitative field data on groundwater recharge by intermittent streams as derived from the small number of fully described case histories located in the literature.