Hyper-resolution Distributed Hydrological Simulations of Soil Moisture and the Partitioning of Evapotranspiration in the Jornada Experimental Range, Southwestern U.S.

In water-limited ecosystems, detailed knowledge of the soil, vegetation, and atmosphere interactions is critical to understand the processes that control the partitioning of energy, water fluxes, and biogeochemical cycles within the critical zone. In this study, we propose the use of a physically-based distributed hydrological model to estimate energy fluxes, soil moisture, and the partitioning of evapotranspiration (ET) within the Jornada Experimental Range of the U.S. Department of Agriculture in southern New Mexico, U.S.

The model inputs can be summarized into terrain, atmospheric forcing, soil, and vegetation parameters. A small size watershed (∼ 69 km2) has been delineated and selected as the study zone encompassing two Eddy Covariance (EC) stations and multi-layer and spatially distributed soil moisture sensors. The watershed divide was extracted using a 30 m resolution Digital Elevation Model (DEM) from The National Map (3DEP Program - USGS) to derive the Triangular Irregular Network (TIN) that the model uses to run.

The TIN-based Real-Time Integrated Basin Simulator (tRIBS) is used to simulate five variables at the watershed scale during the North American Monsoon (NAM) season (July-September): sensible heat flux, latent heat flux, ground heat flux, surface and root-zone temperature, and surface and root-zone soil moisture (as soil water content). Calibration and validation years are 2019 and 2020, respectively. The validated model is used to understand the effects of the terrain spatial heterogeneity on the distribution of such processes including the effect of vegetation activity on the partitioning of evapotranspiration, soil moisture (and thus the water cycle), and the components of the surface energy budget.