Shifting connections between shallow groundwater and surface water across arizona: implications for stream vulnerability
Danielle E. Tadych1, and Laura E. Condon1
Department of Hydrology & Atmospheric Sciences
1The University of Arizona, Tucson, AZ
Groundwater is decreasing across the southwest and loss of shallow groundwater connected to surface water bodies can severely affect surface water systems. Models have found that streamflow is highly sensitive to long-term groundwater depletion, but areas where the hydrology is controlled by human systems make validation of these results difficult, as has been seen in Arizona. Many studies have been conducted on individual river stretches, but there is yet to be an updated and comprehensive map of vulnerable streams and shallow groundwater in Arizona. The purpose of this research is to answer the following questions: 1) Where is shallow groundwater across Arizona and how has its distribution changed over time? 2) Is there a connection between historical decreases in shallow groundwater and loss (or increased intermittency) of streams? 3) Are there locations in the state where shallow groundwater and connected streams appear to be most vulnerable moving forward? Using the largest groundwater database available, this research shows where shallow groundwater has been observed in the state, calculates average groundwater depths along river reaches where possible, and identifies shallow groundwater locations not connected to surface water bodies. We will analyze if groundwater trends correlate with decreased streamflow, increased intermittency or changes in stream classification (e.g. stream loss or conversion from perennial to ephemeral) by comparing groundwater data to historical USGS stream gauge data. Finally, we intend to identify vulnerable stream reaches in Arizona and validate our results by comparing them with findings from other studies across.