WATER BALANCE ANALYSIS FOR THE UPPER LAKE MARY PAIRED-WATERSHED, ARIZONA

Climate change induced aridity and historical European settlement have altered the natural forest structures of large portions of the Ponderosa pine forests in northern Arizona. The increased occurrence of high-severity wildfires due to these changes has led to the establishment of various forest restoration programs to protect the region's forests and their watersheds. Several studies have looked at the impact of forest restoration on watershed hydrology, however information on the influences these restoration projects have on the large-scale hydrology of the forests is still minimal. To properly assess the effects of these projects on northern Arizona forest hydrology, a paired-watershed study was implemented in 2014 to compare the impacts of differing levels of restoration in seven different subwatershed study sites within the Upper Lake Mary watershed. The goal of this study is to accurately describe pretreatment hydrologic conditions for the study watersheds that future studies, posttreatment, can use to properly assess the impacts of forest restoration activities on forest hydrology. In this study legacy precipitation, discharge, groundwater recharge, soil moisture, and runoff data, combined with novel evapotranspiration (ET) data, were synthesized to create a holistic water balance for each subwatershed that describes the hydrologic conditions of each site. We created a water balance for the study subwatersheds, uncover pretreatment hydrologic trends that correlate with climate, utilize the water table fluctuation (WTF) method to calculate groundwater recharge, and devise a reliable method for calculating ET within the forests. The results of this study lay the foundation for a greater understanding of how forest restoration alters northern Arizona’s forest hydrology, and will provide crucial information that should be used in future water policy and water resource decision-making as the region plans for future water availability.