SOME FACTORS AFFECTING BASEFLOW

For a shallow aquifer and a fully penetrating stream, the ideal baseflow curve does not plot as a straight line on semilog paper, and its recession rate continuously decreases with time. For a deep aquifer and a shallow‐entrenched stream, the ideal baseflow generally decays exponentially, and its recession rate decreases with increasing stream entrenchment. In the case of loss from evapotranspiration, the baseflow curves steepen progressively with time, and the stream may become influent. In the case of gain from confined aquifers, the baseflow curves become flatter. The recharge results in shifting of the baseflow curves upward in magnitude or laterally in time. The baseflow peak occurs at about 0.75T from the beginning of recharge to the aquifer, where T denotes the effective duration of recharge. The lag between the total flow peak and the baseflow peak depends on rainfall, soil, and basin factors. The variability of these factors precludes the notion of a constant lag. © 1968 by the Chinese Geophysical Society