Sonoran Desert Vegetation Shifts and Watershed-Scale Ecohydrological Dynamics during the North-American Monsoon
Abstract
Semiarid ecosystems are shaped and constrained by water availability. In the Arizona Sonoran desert, rainfall often occurs in short, high intensity summer storms associated with the North American monsoon. Along with natural or anthropogenic disturbances, monsoon conditions have acted to transform these landscapes from desert grassland to woody savannas over the last century. Changes in vegetation properties, structure and patterns in turn impact critical zone water and energy fluxes, including soil moisture and temperature dynamics, evapotranspiration and runoff production. In this study, we present observational and modeling activities conducted in a small watershed located in the Santa Rita Experimental Range, AZ. The desert basin is representative of the landscape vegetation shift and has been characterized by hydrologic and photographic observations over the last 30 years. More recently, we deployed a high-resolution environmental sensor network consisting of 6 rain gauges, 21 soil moisture and temperature profiles, 4 channel runoff flumes and an eddy covariance tower with a complete set of radiation, energy, carbon and water fluxes. In addition, a high-resolution digital terrain model was obtained from LiDAR measurements and a field dGPS survey, allowing characterization of the watershed terrain and plant cover distributions. Using the network, we present preliminary analyses of the temporal and spatial distributions of rainfall, soil moisture and temperature, and channel runoff in the watershed during the summer 2011, as well as land-atmosphere fluxes at the tower location. The field observations are also used for one-dimensional simulations of the TIN-based Real-time Integrated Basin Simulator (tRIBS) designed to explore the influence of the vegetation shifts on the landscape dynamics. Ultimately, applications of the distributed model in the desert basin will allow us to gain insight on the impact of shifting vegetation patterns on the watershed-scale runoff patterns and explore implications on the site geomorphology.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.H31A1135P
- Keywords:
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- 1813 HYDROLOGY / Eco-hydrology;
- 1879 HYDROLOGY / Watershed