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1	Characterization of drought in Texas using NLDAS soil moisture data Sullivan, John R., Jr. 29 October 2013 (has links) From June to August 2011, Texas experienced the hottest summer ever recorded in the history of the United States, and the state suffered a water shortage that made its vulnerability to drought painfully plain. This disaster sparked new interest in methods of defining drought severity, especially with regard to the variation of soil moisture levels. This thesis assesses the suitability of information from the North American Land Data Assimilation System (NLDAS), an assemblage of land surface models forced with observations data, for quantifying soil moisture levels in Texas. The potential for combining NLDAS data with the Soil Survey Geographic (SSURGO) Database’s available water capacity data is explored. It is discovered that because NLDAS is a hydrological model and SSURGO an agricultural dataset, they employ different definitions of soil moisture storage. Moreover, the temporal variation of soil moisture levels in the SSURGO polygons cannot be inferred from NLDAS data due to the vastly different spatial scales of the two datasets. A relative measure of soil saturation from 0–100% is developed instead and determined to be a more useful indicator of drought than the soil moisture level itself. Calculated solely from NLDAS data, it is used to map the severity of drought in Texas, with the results displayed at the county scale. The temporal variation in soil moisture storage across the state is compared with variations in the gravity anomaly measured by NASA’s Gravity Recovery and Climate Experiment (GRACE) satellites and variations in Texas surface water reservoir levels, both of which are physical measurements of water storage changes. This analysis suggests that the NLDAS data, which is derived from a land surface model, accurately describes subsurface moisture variations. Also, the GRACE gravity anomaly data reveals that during the 2011 drought, the total water storage in Texas was approximately 100 cubic kilometers less than normal. NLDAS data indicates that more than 50% of this deficit was due to losses from the top one meter of the state’s soils. / text Drought Soil moisture NLDAS Texas
2	Evapotranspiration Estimation: A Study of Methods in the Western United States Lewis, Clayton S. 01 May 2016 (has links) This research focused on estimating evapotranspiration (i.e., the amount of water vaporizing into the atmosphere through processes of surface evaporation and plant transpiration) under both theoretical and actual conditions. There were two study areas involved: one, on a large scale where 704 agriculturally-representative, electronic weather stations were used to evaluate the drivers and calculated reference evapotranspiration of a NASA gridded weather forcing model in the 17 western states in the contiguous U.S.; and two, transpiration of invasive saltcedar (Tamarix sp.) in the floodplain of the lower Colorado River, California, with Bowen ratio, eddy covariance, and groundwater fluxes. In this study, a fire destroyed the saltcedar forest, which allowed comparison of evapotranspiration before and after\ this event Comparison of the input weather parameters showed some variance between the electronic weather stations and the gridded model, but calculated reference evapotranspiration performed well by relying on the better input and more highly weighed variables of air temperature and downward shortwave radiation. Only in the southern portions of California, Arizona, and New Mexico were the evapotranspiration estimates using the gridded dataset not well correlated with the electronic weather stations and not recommended for prediction. Saltcedar evapotranspiration was found to match more recent and conservative estimates for the phreatophyte than what was historically portrayed in the literature. Horizontal advection from the surrounding desert was also observed to affect the riparian energy balance. Annual average total evapotranspiration before a fire varied from 0.60-1.44 meters/year to 0.25-1.00 meters/year post fire. Evapotranspiration groundwater NLDAS saltcedar Civil Engineering
3	Process-Based Calibration of WRF-Hydro Model in Unregulated Mountainous Basin in Central Arizona January 2020 (has links) abstract: The National Oceanic and Atmospheric Administration (NOAA)’s National Water Model (NWM) will provide the next generation of operational streamflow forecasts at different lead times across United States using the Weather Research and Forecasting (WRF)-Hydro hydrologic system. These forecasts are crucial for flood protection agencies and water utilities, including the Salt River Project (SRP). The main goal of this study is to calibrate WRF-Hydro in the Oak Creek Basin (OCB; ~820 km2), an unregulated mountain sub-watershed of the Salt and Verde River basins in Central Arizona, whose water resources are managed by SRP and crucial for the Phoenix Metropolitan area. As in the NWM, WRF-Hydro was set up at 1-km (250-m) resolution for the computation of the rainfall-runoff (routing) processes. Model forcings were obtained by bias correcting meteorological data from the North American Land Data Assimilation System-2 (NLDAS-2). A manual calibration approach was designed that targets, in sequence, the sets of model parameters controlling four main processes responsible for streamflow and flood generation in the OCB. After a first calibration effort, it was found that WRF-Hydro is able to simulate runoff generated after snowmelt and baseflow, as well as magnitude and timing of flood peaks due to winter storms. However, the model underestimates the magnitude of flood peaks caused by summer thunderstorms, likely because these storms are not captured by NLDAS-2. To circumvent this, a seasonal modification of soil parameters was adopted. When doing so, acceptable model performances were obtained during calibration (2008-2011) and validation (2012-2017) periods (NSE > 0.62 and RMSE = ~2.5 m3/s at the daily time scale). The process-based calibration strategy utilized in this work provides a new approach to identify areas of structural improvement for WRF-Hydro and the NWM. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2020 Civil engineering Flood forecasting Flood management Hydrological model NLDAS-2 forcing Water resources management WRF-Hydro model
4	Development of a Reservoir System Operation Model for Water Sustainability in the Yaqui River Basin Mounir, Adil 05 July 2018 (has links) No description available. Civil Engineering Agricultural Economics Agricultural Engineering Atmospheric Sciences Atmosphere Computer Science Environmental Science Hydrologic Sciences Hydrology Operations Research Water Resource Management Sustainability Environmental Engineering Engineering sustainability nonlinear programming optimization hydrologic simulation reservoir system GAMS HEC-HMS reservoir operation Yaqui River Basin Python water resources remote sensing NLDAS bias correction water allocation hydrology water

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