Application of Satellite Products in Surface Hydrological Modeling of the Colorado River Basin

Abstract:

As a major water resource in the southwestern United States and northwest Mexico, the Colorado River is experiencing decreases in naturalized streamflow and predicted to face severe challenges under future climate scenarios. To understand the reasons of these changes and better quantify them, it is crucial that the scientific community establishes a reasonably accurate understanding of the basin hydrologic patterns and characteristics. In this study, we employ remote sensing products from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Soil Moisture Active Passive (SMAP) mission to assess the application of a macroscale hydrological model (Variable Infiltration Capacity, VIC) over the Colorado River Basin for the period between 2003 and 2018. Land surface temperature (LST) simulated by the model applied at hourly, 6-km resolution can generally reproduce the spatial patterns observed from MODIS with an average correlation coefficient greater than 0.90. Inconsistencies in LST that were identified between MODIS and VIC are attributable to the limit of the satellite data quality and uncertainties related to the calculation of LST for canopy and inter-canopy areas, and snow-covered regions. We propose model enhancements to help reduce these inconsistencies. Finally, we conduct a comparison of simulated soil moisture aggregated to the spatiotemporal resolution of SMAP as a first step toward the development of a data assimilation approach. These efforts highlight the value of Earth observing satellites of hydrological predictions and provide a roadmap for building confidence in the spatiotemporal simulations from macroscale hydrological models that are often employed for assessing the sensitivity of the Colorado River to climate change.