Irrigation Cooling Capacity in Agricultural and Urban Settings of Central Arizona: A Multiyear Assessment

Abstract:

Irrigation water use associated with agricultural activities and urban green spaces provides substantial cooling effects and ameliorates heat in central Arizona. In this arid and semiarid area, evaluating the effect of irrigation on land surface temperature (LST) for different types of land use can improve decision making related to water resources management. In this work, we improved the simulation of urban and agricultural irrigation in the Variable Infiltration Capacity model at high spatiotemporal resolution through the use of remotely-sensed vegetation and irrigation parameters from multiple remote sensing products (NAIP, MODIS, and Landsat). We then conducted a multiyear (2004-2013) assessment of simulated LST with respect to ground observations and remotely-sensed products (GOES and MODIS) finding overall good agreement. Numerical experiments with the validated model reveal the spatiotemporal variations of irrigation cooling efficiency under conditions of climatological and dynamic vegetation and irrigation parameters. We find that irrigation water use leads to LST reductions that are of higher magnitude and greater spatiotemporal variability in croplands as compared to urban areas. Furthermore, the role of interannual variations in cropping practices is more critical than year-to-year differences in climatic conditions for the evaluation of irrigation cooling capacity. Thus, remotely-sensed vegetation products can serve a valuable purpose in evaluating LST reductions and quantifying irrigation requirements to achieve a target of heat amelioration.