The effect of reservoir networks on drought propagation

Human interventions in response to drought can both alleviate and enhance drought. Developments of infrastructure for freshwater storage, groundwater abstraction and irrigation have proved to be effective in overcoming meteorological and agricultural drought in many locations worldwide. At the same time such developments may exacerbate hydrological drought, especially during and following extended periods of (meteorological) drought. In order to effectively manage drought, there is an urgent need to better understand and evaluate the drivers of such events. This means that we need to separate between human and natural factors that affect hydrological processes in basins. In this paper, we demonstrate how the Downstreamness concept can be used for Drought Diagnosis. This is done for a subcatchment of the Jaguaribe basin in Northeast Brazil. Our diagnosis focuses on the propagation of three severe multi-year droughts that have developed during the period 1979-2016. Our study shows how a network of surface water storage reservoirs has affected the propagation of drought. Applying the proposed approach is helpful for the spatiotemporally-explicit assessments of droughts and their propagation. Strategic and operational water (and drought-risk) management relies on valuations of trade-offs between commitments of upstream and downstream uses and technical implementations of upstream and downstream measures. Our study offers valuable insights through the inclusion of sub-basin points of view as an integral part of a river basin perspective. In this way, the effects of anthropogenic processes affecting drought propagation can be better understood.