The influence of seasonal precipitation, vegetation, geomorphology, and soils on water partitioning in an arid catchment will be investigated. Our basic premise is that hydrologic response in arid regions is complex, and depends primarily on the nature of the precipitation event, and the spatially distinct complex geomorphic landforms and associated vegetative communities in the landscape. We will quantify the hydrologic response of the Yuma Wash watershed in southwestern Arizona using state-of-the-art, automated and telemetered instrumentation, and remote sensing. Our proposed work is designed as a collaborative research effort to be supported by the National Science Foundation, and the U.S. Army Research Office (ARO). A total of six specific research questions/objectives and ten related hypotheses are proposed between the two agencies. Four of these relate to characterizing seasonal precipitation, soil moisture, runoff and geomorphic response, and will be the focus of the research proposed to the Army Research Office. Three working hypotheses relate to each of these objectives (see Appendix D). Two additional research questions/objectives focus on quantifying the vegetative response to seasonal precipitation, and comparing evapotranspiration differences across two distinct geomorphic surfaces using direct and indirect methods, and are the focus of the research proposed herein. Seven working hypotheses have been developed that relate to these objectives, and are outlined in Appendix C (attached). We expect our data to reflect seasonal patterns in hydrologic response that vary over distinct geomorphic surfaces and between vegetative communities. Data will be synthesized to verify field estimates of evapotranspiration against physically based modeled values, evaluate the erosion and sedimentation characteristics of the channel network in response to seasonal precipitation, ascertain the response of four dominant vegetative species to different storm types, and to extend and improve a meteorological database for Yuma Wash that has been maintained since 2001, with the longer term goal of developing a water budget for this arid region. By examining how water is seasonally partitioned among vegetation and soils across two distinct geomorphic surfaces, we propose a unique and integrative approach to quantifying the complex hydrologic response of an arid catchment.
Criterion Two-Broader Impacts
Additional funding for research and instrumentation will be provided by the United States Army Research Office (ARO), who has been supporting on-going hydrologic research in Yuma Wash since 2001 (see Appendices A and B). Our proposed research will support two graduate MS students and one post-doctoral scientist. Full stipend and tuition support for one graduate student will be provided by the Center for Environmental Management of Military Lands (CEMML) at Colorado State University (CSU) and the US Army Yuma Providing Grounds (YPG), as part of a cooperative agreement in support of this research. Funding for the second graduate student and one post-doctoral scientist will be provided by the U.S. Army Research Office, who is co-supporter of this research. The research proposed will thus involve an integrated effort among scientists and students from CSU, and local meteorological staff and field technicians from the YPG, to address hydrologic questions in arid lands that are relevant to military, local, and regional water resource managers. All data will be used by the military to develop management plans for arid lands, and meteorological data will be disseminated to regional forecasters such as the Western Regional Climate Center, scientific research initiatives for semi-arid lands in southwestern United States, such as the Semi-Arid Land-Surface Atmosphere program (SALSA), the Sustainability of Semi-arid Hydrology and Riparian Areas (SAHRA) program, and the North American Monsoon Experiment (NAME). Therefore, data and results will be freely shared among these users. Results will be disseminated to the broader scientific community through professional meetings and peerreview journal publications.
