Assessing Groundwater and Surface Water Contributions to Evapotranspiration in a Semi Arid Watershed

Explore how actual evapotranspiration (AET) dynamics in the North Saskatchewan River Basin are influenced by groundwater (GWET) and surface water (SWET) contributions. Discover the implications of climate change on water balance in semi-arid regions and gain insights from HydroGeoSphere model findings.
Abstract:
In semi-arid regions of mid-to-high latitude zones, actual evapotranspiration (AET) can surpass annual precipitation or govern the water balance. Despite existing studies on spatiotemporal variations of AET and potential changes due to future climate change scenarios, the contribution of different water sources to AET is not well understood at a regional scale. This research developed, calibrated, and validated a HydroGeoSphere model to study the AET from groundwater (GWET) and surface water (SWET) in the North Saskatchewan River Basin (NSRB) in western Canada under historical and future periods. This watershed spans diverse ecohydro(geo)logical (EHG) regions such as Mountains, Foothills, and Plains. Findings indicate that across all EHG regions, subsurface transpiration contributes the most to AET, followed by subsurface evaporation and surface evaporation. Regarding water sources that supply AET, SWET has the greatest contribution to annual AET in most areas across all EHG regions. On the other hand, GWET accounts for the majority of the annual AET in riparian areas and the northeastern Plains, with the highest contributions of GWET to AET driven by high atmospheric evapotranspiration demand, large Leaf Area Index, and deep-rooted plants accessing shallow groundwater. Simulations for future climate change scenarios project an increase in AET across the NSRB, with the greatest rise occurring in the Mountains. In the Foothills and Plains, the projected increases in AET may lead to groundwater depletion, reducing GWET contributions, with more substantial groundwater impacts in the Plains. In riparian areas and groundwater discharge zones of the northeastern Plains, GWET contributions are expected to increase.
About the presenter:
Luis Carlos Serrano Diaz is a Groundwater Modeller at AER/AGS with over seven years of professional experience in hydrogeology, fieldwork, data management, data analytics, petroleum geology, and geological and hydrogeological modelling. During his recent MSc research at the University of Alberta, he focused on groundwater and surface water interactions, as well as actual evapotranspiration, by integrating multiple datasets and implementing a physically-based model. He is passionate about advancing the understanding of groundwater-surface water feedback through three-dimensional modelling techniques to address both scientific and practical challenges. In his free time, he finds joy in connecting with nature and history through hiking and travel.
About HydroGeoSphere (HGS):
HGS is a hydrologic simulation engine for water resources engineers that integrates all key components of the terrestrial water cycle, seamlessly tracking the movement of water between surface water, soil water, and groundwater systems with a physics based numerical approach. As a fully physics-driven platform, HGS is the best modelling tool to evaluate the impact and risk associated with climate change for water resources.
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