Water management models have evolved through three basic stages. The earliest models dealt with the problem of getting water to where it was needed. Adequate supplies of sufficiently high cudlity were assumed to exist, and thus these models attempted to determine optimal distribution networks. In 1966 J.A. Dracup developed a model of this form to explore alternate sources of supply to meet industrial and municipal demands, agricultural demand, and demand for water to provide artificial recharge of groundwater aquifers. The next developments in water management were due to the emerging awareness of the environmental impacts of water use. These models were primarily concerned with maintaining certain quality levels within the natural water system (rivers, streams, estuaries). They tended to ignore the quantity of water within the system, being concerned with optimizing over the distribution system and quality control through the use of by-pass piping, on-site and regionalized treatment plants. The final category of models is one in which both quality and quantity considerations are allowed to enter as decision variables. The most general model of this type was developed by D.E. Pingry and T.L. Shaftel in 1979. This model allows for any configuration of sources, users, piping, disposal areas, and treatment plants. Thus the problem of distribution and quality control are both handled. This model also employs realistic nonlinear cost functions through economies of scale in treatment, and diseconomies of scale in treatment efficiency. The major limitation of their model, and others of the same type, is that they have been applied only to closed water systems which do not include rivers, streams, etc., and therefore ignore the environmental impacts of the water development on the complete natural water systems (e.g., a river basin). The Pingry-Shaftel model has been expanded to allow for the integration of a river system into an optimization model where the distribution system, quality control, source development, recycling of wastewater, and other management strategy alternatives are all allowed to enter as decision variables. At the same time the quantity requirements and quality standards are being monitored in order to analyze their impacts on cost. Decomposing the problem and making use of a large-scale transportation algorithm permit a solution to be obtained in an efficient manner. The model has sufficient flexibility to permit the comparison of impacts of various natural, technological, economic, and legal constraints. The model has been applied to the Colorado River Basin under varying assumptions in order to determine the economic and environmental implications of various water supply allocations and salinity treatment strategies.

Forecasts of hydrological information are vital for many of society's functions. Availability of water is a requirement for any civilization, and this necessitates quantitative estimates of water for effective resource management. The research in this dissertation will focus on the forecasting of hydrological quantities, with emphasis on times of anomalously low water availability, commonly referred to as droughts. Of particular focus is the quantification of uncertainty in hydrological forecasts, and the factors that affect that uncertainty. With this focus, Bayesian methods, including ensemble data assimilation and multi-model combinations, are utilized to develop a probabilistic forecasting system. This system is applied to the upper Colorado River Basin for water supply and drought forecast analysis. This dissertation examines further advancements related to the identification of drought intensity. Due to the reliance of drought forecasting on measures of the magnitude of a drought event, it is imperative that these measures be highly accurate. In order to quantify drought intensity, hydrologists typically use statistical indices, which place observed hydrological deficiencies within the context of historical climate. Although such indices are a convenient framework for understanding the intensity of a drought event, they have obstacles related to non-stationary climate, and non-uniformly distributed input variables. This dissertation discusses these shortcomings, demonstrates some errors that conventional indices may lead to, and then proposes a movement towards physically-based indices to overcome these issues. A final advancement in this dissertation is an examination of the sensitivity of hydrological forecasts to initial conditions. Although this has been performed in many recent studies, the experiment here takes a more detailed approach. Rather than determining the lead time at which meteorological forcing becomes dominant with respect to initial conditions, this study quantifies the lead time at which the forecast becomes entirely insensitive to initial conditions, and estimating the rate at which the forecast loses sensitivity to initial conditions. A primary goal with this study is to examine the recovery of drought, which is related to the loss of sensitivity to below average initial moisture conditions over time. Through this analysis, it is found that forecasts are sensitive to initial conditions at greater lead times than previously thought, which has repercussions for development of forecast systems.

This research presents the Colorado River basin as a social-ecological system. Utilizing event data on cooperative and conflictive interactions over fresh water, the system is decomposed to look for evidence of outcomes of resilience enhancement. The Animas-La Plata Project in the upper San Juan basin is presented as a case study, and qualitative methods are used to analyze interactions that led to its construction in order to assess social-ecological outcomes. In the upper San Juan basin, cooperative interactions over fresh water outnumbered conflictive ones. Interactions over water rights and infrastructure were most common, and the most cooperative interactions focused on these issue types. Many of these interactions focused on the Animas-La Plata Project compromise, which ultimately enhances social-ecological resilience in the Colorado River basin. / Graduation date: 2012

The vast majority of large river systems in the United States cross (or comprise) one or more state lines, creating numerous administrative challenges. Addressing these multijurisdictional challenges in an efficient and equitable manner often requires the development of sophisticated institutional arrangements. Several types of "regional organizations" have been created for this purpose, including compact commissions, interstate councils, basin interagency committees, interagency-interstate commissions, federal-interstate compact commissions, federal regional agencies, and the single federal administrator format. These organizations feature a wide variety of authorities and responsibilities; what they inevitably share in common is a hostile political environment, a consequence of political geography and bureaucratic entrenchment. In this study, the challenges associated with the governance, administration, and management of interstate water resources are examined, using the Colorado River Basin as a case study. The Colorado is the only major river in the United States utilizing the "single federal administrator" format, an institutional arrangement that is often criticized for its subordination of the states and its concentration of policy-making authorities in the hands of administrators. When evaluated against carefully defined normative criteria, the Colorado is shown to feature many institutional deficiencies that are, in part, derivative of the Colorado's unique institutional arrangements. The primary objective of this study is to determine if the governance and management of the Colorado could be improved by the establishment of an alternative form of regional water organization. It is concluded that a type of federal-interstate compact commission, if carefully tailored to the political realities of the region, could improve many of the observed institutional deficiencies. This study also presents a widely-applicable methodology for the description and evaluation of institutional arrangements.