Interrelationships among water cycle fluxes and stores in a semi-arid urban environment

This thesis research was performed to quantify and analyze the interrelationships among water cycle fluxes and stores in a semi-arid urban environment. In September 2007, a hydrologic observation network was installed in a residential area of the Salt Lake City metropolitan area to collect continuous observations of precipitation, dry and wet weather runoff, and soil moisture. In addition, companion studies in the same catchment were simultaneously collecting evapotranspiration and water use data. For the time period studied, precipitation was normal; conversely, the ratios of runoff to rainfall (i.e., runoff coefficient) for the storm events observed were much smaller than expected (0.04 for spring and fall months and 0.006 for summer months), with significant variability noted. Soil moisture was found to have at least a 20% variation between irrigated and nonirrigated areas, which can be expected; however, the increase of nonirrigated soil moisture in response to rainfall was surprisingly small. Dry weather runoff was found to be nearly 8% of the total outflow volume (wet weather plus dry weather), and outdoor water use was shown to influence soil moisture, which in turn was observed to influence the evapotranspiration rate. The continuous observations quantified several uncertain fluxes and stores in semi-arid cities and identified relationships among stores and fluxes useful for developing predictive models of the interactions among urban hydrologic fluxes, stores, and climate.