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Accueil du site → Doctorat → États-Unis → 2013 → Impact of Climate Change on Surface and Subsurface Water Interaction and Riparian Vegetation : Linkage between Hydrology and Invasive Tamarisk in a Semi-Arid Basin

UNIVERSITY OF NEVADA, RENO (2013)

Impact of Climate Change on Surface and Subsurface Water Interaction and Riparian Vegetation : Linkage between Hydrology and Invasive Tamarisk in a Semi-Arid Basin

Bhattarai, Mahesh P.

Titre : Impact of Climate Change on Surface and Subsurface Water Interaction and Riparian Vegetation : Linkage between Hydrology and Invasive Tamarisk in a Semi-Arid Basin

Auteur : Bhattarai, Mahesh P.

Université de soutenance : UNIVERSITY OF NEVADA, RENO

Grade : Doctor of Philosophy (PhD) 2013

Résumé _Long-term assessment of climate change impacts on water resources is essential for developing management strategies. They are even more important in semi-arid basins of the southwestern United States where effects of changes in precipitation and temperatures are likely to be intensified by the semi arid nature of the basin. Proliferation of tamarisk (salt cedar) has negatively impacted the ecology and hydrology of riparian ecosystems in the southwestern United States. Riparian systems are undergoing perturbations in hydrology from anthropogenic factors such as aquifer pumping, climate change, and impoundment. In this study, the Lower Virgin River Basin (LVRB) in southeastern Nevada, southwestern Utah and northwestern Arizona was used to evaluate hydrologic response of a semi-arid basin under current and future climatic conditions. Hydrologic simulation was performed using a fully integrated physically based surface subsurface model, Hydrogeosphere (HGS). Hydrologic parameters derived from the simulations and bioclimatic variables were then used to develop a species distribution model (SDM), Maxent, to evaluate future competitiveness of tamarisk, and its success or failure under Special Report on Emission Scenarios (SRES) A2. The LVRB subsurface system is comprised of many aquifers, but to meet research objectives, the focus of the study was limited to the upper aquifers (channel-fill deposits, Tmc1 and Tmc2). These upper aquifers are in direct contact with surface water, support riparian vegetation and are the source for most groundwater withdrawal in the basin. The simulation period for current conditions spanned from 2007 to 2010, in which 2007 to 2008 was used for calibration and 2009 to 2010 for validation. The model simulation results showed that stream hydrographs were similar to observed peak flows and dry weather flows. The Pearson correlation coefficients for Littlefield and near Overton were 0.93 and 0.81, respectively, and Nash-Sutcliffe efficiencies were 0.95 and 0.41, respectively, for the simulation period 2007 to 2010. However, both stations were negatively biased due to low subsurface discharge to the Virgin River. The model was useful in identifying losing and gaining sections of the river. Statistical errors calculated for a continuously monitored well showed that mean residual error (MRE), mean absolute residual error (MARE) and root mean square error (RMSE) were 0.71 m, 1.10 m, and 1.37 m, respectively. Comparison of simulated and actual ET for 2010 at the Virgin River meteorological station yielded correlation coefficient (R2) and RMSE of 0.98 and 0.50 mm/d, respectively for the period. In general, simulations were good and use of a coupled, physically based model helped to identify losing and gaining sections of recharge and discharge areas, runoff generation, and spatial and temporal distributions of actual ET.

Présentation (GradWorks)

Page publiée le 27 octobre 2013, mise à jour le 7 octobre 2017