Streamflow sensitivity to drought scenarios in catchments with different geology

Abstract

Streamflow drought response depends to a large degree on groundwater recharge. To better predict and preempt streamflow droughts, the relationship between recharge deficit and streamflow response needs to be studied more systematically. We present a combined soil-Vegetation-atmosphere transfer and conceptual groundwater model experiment that applies a novel set of recharge scenarios preceding drought events in humid-Temperate catchments with different dominant aquifer types. The recharge scenarios are based on the permutation of historical time series and on modified time series matching extreme (50 year) drought events. Karstic and fractured aquifers show short-Term sensitivity to drought with an event-Specific relationship between recharge and streamflow response. Porous and complex aquifers show long-Term sensitivity and a more catchment-Controlled propagation of drought. The sensitivity of drought deficit and recovery time correlates with the water age distribution in baseflow, which is trackable in the groundwater model and a characteristic that should be exploited to improve streamflow drought prediction.