Effect of river management on regional groundwater levels

Abstract

The aim of this work is to determine if long-term trends of declining groundwater levels can be explained by the engineering of braided rivers for flood management. A braided river can be considered as a “river system” consisting of surface channels and an intrinsically linked subsurface gravel reservoir, the “braidplain aquifer” (Wilson et al., 2024). This conceptualisation implies that for settings where the river system is hydraulicallydisconnected to the regional aquifer, groundwater recharge is largely governed by braidplain aquifer width. Additionally, for settings where the river system is hydraulically connected to the regional aquifer, river bed levels will have a large control on recharge rates since they determine the hydraulic gradient. Consequently, the effect of river management on groundwater recharge will depend on the hydraulic setting of the river system