Using Integrated Hydrologic Modeling to Investigate the Spatiotemporal Characteristics of Droughts in Catchments with Human Water Management
Benjamin D. West1 and Laura E. Condon1
1Department of Hydrology and Atmospherics Sciences
The University of Arizona, Tucson, AZ 85721, USA
Droughts have had a growing impact on both natural resources and human infrastructure. In a changing climate drought duration and intensity are both expected to change, and the past 40 years have already shown an unusually large number of droughts of extreme intensity and duration. However, the connections between drought severity and drought recovery are not well understood. This is only further complicated by the fact human operations can influence drought evolution and impacts through a complex system of trade-offs. Our understanding of the trade-offs in water management decision-making and watershed dynamics is extremely limited because most models of human operations make critical simplifications in their representation of the surrounding environment. Here, we use ParFlow, a fully integrated physical hydrology model, to examine watershed storage and streamflow dynamics during drought with varying levels of water management. ParFlow is well suited for this purpose as it directly represents the vadose zone and its role groundwater-surface water interactions that are crucial to the full picture of watershed dynamics. With ParFlow, we model several idealized watersheds under various drought conditions. Drought conditions are simulated for a baseline scenario (with no human operations), and with different groundwater pumping strategies. By comparing these simulations, we gain important insights into the role of drought duration on recovery as well as the impacts of water management decision-making. We are also able to look at how changed antecedent conditions, either from natural causes such as preceding dry or wet years, or anthropogenic causes such as groundwater depletion due to long term pumping, change drought evolution and recovery. This work could help design drought mitigation strategies that enhance water resource sustainability in an era of increasing drought intensity.