Multi-Temporal Remote Sensing Data for Modeling of Dryland Evapotranspiration and Land Cover Change

Abstract:

Water security is an increasing concern around the globe. The goal of this research is to better understand the complex relationships which exist between land cover change and water use within a dryland ecosystem. The Santa Cruz watershed in southeastern Arizona is experiencing increasing population growth and reduced water resources, highlighting a direct relationship between land cover change and water use. Using multi-source and multi-scale data sets including multispectral imagery, thermal imagery, and climate variables, we present the following three-step research approach: 1) land cover change, 2) evapotranspiration modeling, and 3) data validation. Assessment of land cover change between 2003 and 2013 was performed using Landsat data and validated via high resolution imagery. Regional evapotranspiration was calculated using the Mapping EvapoTranspiration at high Resolution with Internalized Calibration (METRIC) model. Validation of the METRIC model was performed using measurements from multiple flux towers within the watershed. With the capability to observe historical changes as well as current events, this approach integrates multiple public data sources representing varying scales to accurately monitor and assess environmental change. Overall, this approach demonstrates how remote sensing capabilities combined with surface measurements can be utilized to ascertain and validate complex ecosystem relationships. Preliminary results suggest that land cover change alters the amount of evapotranspiration within the Santa Cruz watershed. We also show that METRIC performed better in agricultural areas compared to naturally vegetated shrubland areas. Finally, this research will be used as a prototype to evaluate other dryland regions of the Americas.