This dissertation reports on economic studies of Texas Interbasin Water Transfers (IBT) as a way to lessen expected water shortages, Texas minimum freshwater inflows requirements (FWIB) to protect environmental flows and the general policy setup when generators of environmental commodities might be able to sell credits in multiple markets. The Texas-based studies address economic, hydrological and environmental impacts, focusing on welfare gain, water demand, environmental flows and complementary relationship of environmental commodities. Conduct of the two Texas studies required development of a Texas surface water model. The developed model incorporates: (a) uncertain weather patterns and supply of water; (b) river flows in most of the Texas river basins - twenty-one basins excluding only the Rio Grande; (c) demand for water by agricultural, municipal and industrial/ mining water; (d) IBT possibilities; (e) evaporation losses; and (e) return flows across the modeled basins. In studying the interbasin water transfers, three IBT projects where chosen as economically justified relocating water largely for municipal and industrial/mining uses. These IBT projects had the effect of increasing water use and instream flows in the IBT destination basins, but decreasing those in the source basins. In studying the freshwater inflows the study revealed that the suggested inflow constraints were met on average and that the inflow levels for two basins had to be lowered for the constraints to be feasible. This suggests that the contemplated limits are too high and that either multiple basin or flow dependent limits need to be developed. The results also showed that under the average FWIB constraints and IBT implementation, welfare loss from the FWIB constraints was greatly reduced due to the IBT projects which were simultaneously implemented. In the study of multiple environmental commodity markets, the results indicate that generated credits should be sold in multiple markets only when market caps are set up close to socially efficient (so called first-best) caps: this implies that marginal benefit curves are very steep. However, restricting selling into just single market achieved the same net benefits as multiple markets did when market caps were set up at levels less than the first-best caps.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (p. 127-139).

Diss.--Hamburg, 1965. / Part of illustrative matter in pocket. Bibliography: p. 224-226.

Thesis (Ph. D.)--Civil & Environmental Engineering, Georgia Institute of Technology, 2004. / Dr. Paul Work, Committee Member ; Dr. Philip Roberts, Committee Member ; Dr. Mustafa Aral, Committee Chair ; Dr. Terry Sturm, Committee Member ; Dr. Turgay Uzer, Committee Member. Vita. Includes bibliographical references (leaves 442-466).

We use a physical model to investigate how changes in the distribution of subglacial hydrology affect ice motion of Antarctic ice streams. Ice streams are modeled using silicone polymer placed over a thin water layer to mimic ice flow dominated by basal sliding. Dynamic similarity between modeled and natural ice streams is achieved through direct comparison of the model force balance and the observed force balance of Whillans Ice Stream (WIS). The WIS force balance has evolved over time due to increased basal resistance. We test two hypotheses: 1) the subglacial water distribution influences the ice flow speed and thus the force balance and; 2) shear margins are locations where transitions in water layer thickness occur. The velocity and force balance are sensitive to pulsed water discharge events and changes in lubrication associated with sticky spots, and model shear margins tend to overlie water lubrication boundaries. Local changes in basal lubrication near margins (possibly as a result of the presence of sticky spots or subglacial lakes) influences the stability of the margin position and may be responsible for large and rapid shifts in margin location. / text

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

Soil moisture is a measure of the water content in a soil that is dependent upon precipitation, evapotranspiration, runoff, drainage, and irrigation. Nebraska is one of the few states that measures soil moisture in an extensive network that records weather variables on a daily basis. Daily soil moisture observations are collected from depths of 10, 25, 50, and 100 centimeters and analyzed in this research. Data from these stations are evaluated on the spatial and temporal scales using spatial interpolations, time-series analysis, and cross-correlations to better understand the variations of soil moisture in the Northern Great Plains. Spatial interpolation grids were created for May through October of 2005, after the data were grouped into datasets of weekly, biweekly, and monthly observations. These datasets were imported into a Geographic Information System (GIS) and the Ordinary Kriging method was applied for spatial interpolation. The interpolation parameters were set to create output surfaces of 4x4, 16x16, 32x32, and 64x64 kilometer grids for analysis of their variations. As expected, it is found that soil moisture content is higher in southeastern Nebraska and lower in the northwest. Changes in the grid size render small scale variations, however, the general pattern of estimated soil moisture distribution does not change. The temporal analysis concluded that the soil's physical properties have a much greater effect on soil moisture than a station's location within the east-west moisture gradient. Sandy soils were consistently drier, while silt and clay soils retained water for a longer duration. The topmost layer of soil experiences the greatest variation due to interactions with the surface boundary layer. The highest water content values for silty soils were observed in the summer months, while the highest values for sandy soils were observed in the spring and fall months. The most soil moisture variation occurs in the summer and fall, while the least amount of variation occurs in spring and winter. Cross-correlations, measuring the time-lag relationship, demonstrated the impact of soil physical properties on soil moisture by depth, the influence of precipitation on 10 and 25 cm depth soil moisture, and the impact of near-surface soil moisture on maximum surface temperature. A stronger relationship was observed between soil moisture and maximum surface temperatures than with precipitation and soil moisture at various depths.

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Land surface albedo is the ratio of reflected to incident solar radiation. It is a function of several surface parameters including soil color, moisture, roughness and vegetation cover. A better understanding of albedo and how it changes in relation to variations in these parameters is important in order to help improve our ability to model the effects of land surface modifications on climate. The objectives of this study were 1) To determine empirical relationships between smooth bare soil albedo and soil color, 2) To develop statistical relationships between albedo and ground-based thematic mapper (TM) measurements of spectral reflectances, 3) To determine how increased surface roughness caused by tillage reduces bare soil albedo and 4) To empirically relate albedo with TM data and other physical characteristics of mixed grass/shrubland sites at Walnut Gulch Watershed. Albedos, colors and spectral reflectances were measured by Eppley pyranometer, Chroma Meter CR-200 and a Spectron SE-590, respectively. Measurements were made on two field soils (Gila and Pima) at the Campus Agricultural Center (CAC), Tucson, AZ. Soil surface roughness was measured by a profile meter developed by the USDA/ARS. Additional measurements were made at the Maricopa Agricultural Center (MAC) for statistical model testing. Albedos of the 15 smooth, bare soils (plus silica sand) were determined by linear regression to be highly correlated (r²=0.93, p>0.01) with color values for both wet and dry soil conditions. Albedos of the same smooth bare soils were also highly correlated (r²≥0.86, p>0.01) with spectral reflectances. Testing of the linear regression equations relating albedo to soil color and spectral reflectances using the data from MAC showed a high correlation. A general nonlinear relationship given by y=8.3661n(x)+37.802 r²=0.71 was determined between percent reduction in albedo (y) and surface roughness index (x) for wet and dry Pima and Gila field soils. Measurements of albedo, color and spectral reflectance at the Walnut Gulch Watershed indicated that albedo values were highly correlated with percent rock & gravel, color value and reflectance data (TM bands 1-4).