Agriculture in the Western United States is almost entirely dependent upon irrigation. Irrigation has transformed the desert lands into fertile, producing valleys. It has made possible communities and settlement areas which would otherwise be impossible. Although the achievements of irrigation have been great, there still remains millions of acres of fertile land that will never be reclaimed because there is not available water.

Surface water availability models often use monthly simulation time steps for reasons of data availability, model parameter parsimony, and reduced computational time. Representing realistic streamflow variability, however, requires modeling time steps with sub-monthly or daily temporal resolution. Adding daily time step simulation capability to the Water Rights Analysis Package (WRAP) and the Texas Water Availability Modeling (WAM) System is a growing area of need and interest in water rights permitting, water supply planning, and environmental protection. This research consisted of the following tasks: 1. Key modeling issues are identified that are relevant to daily time step modeling, but are otherwise not considered with monthly simulations. These key modeling issues include disaggregating monthly naturalized flows into daily flows, routing changes to flow through the stream network, reducing impacts to water availability in a priority order based water right system through the use of streamflow forecasting, distributing water right targets from monthly to daily amounts, and integrating flood control reservoir operations into the existing conservation reservoir modeling framework. 2. Two new programs for WRAP are developed to address the key daily time step modeling issues. The new programs include a pre-processor program, DAY, and a daily simulation program, SIMD. 3. A case study of the Brazos River Basin WAM is presented using daily time steps with SIMD. The purpose of the case study is to present an implementation of the daily modeling capabilities. 4. The case study simulation results are used as a basis to draw conclusions regarding monthly versus daily simulation outcomes. The research, as presented through the Brazos River Basin WAM case study, illustrated that incorporating realistic daily streamflow variability into the simulation of a priority order based water allocation system can substantially affect the results obtained for time series of critical period reservoir storage contents, the determination of long-term water right reliability, and the distribution of unappropriated and regulated flows. The modeling capabilities developed by this research advance the state of water availability modeling with sub-monthly time steps by addressing the key modeling issues related to streamflow variability and routing.

The authorities in charge of managing our Andean basins work in unimaginable water-powered landscapes from the Peruvian legislator point of view. They should generate and apply peculiar mechanisms. Why? Because the national legislator is traditionally positioned on the coast, a region very different to the Andean highlands and punas. The use of ethnographic evidence coming from a drainage basin in the Central Andes (Mantaro River, Junin) lets me depict in detail how public officers appeal to mechanisms of location, adaptation and regulation in order to adjust the official regulations, to cover the needs of the farming organizations of watering, and to affirm their positions as representatives of the Peruvian government. The consequence is that they exceed and also violate the regulatory channels that control their administrative functions. In this way, they incorporate a new function to their official position, that is, to develop peculiar administrative patterns to process the tightness between the inflexibility of the State Water Right and the demands of recognition and balance that the andean watering organizations propose to the Government. / Las autoridades encargadas de gestionar nuestras cuencas andinas ejercen sus funciones en paisajes hidráulicos inimaginables para el legislador peruano. Para ello deben generar y aplicar mecanismos peculiares. ¿Por qué? Porque el legislador nacional se encuentra tradicionalmente parapetado en la costa, una región muy diferente a las sierras y punas andinas. El uso de evidencia etnográfica proveniente de una cuenca hidrográfica de los Andes Centrales (Río Mantaro, Junín) me permite detallar cómo los funcionarios estatales apelan a los mecanismos de localización, adaptación y regularización con el fin de modular la normatividad oficial, atender las necesidades de las organizaciones campesinas de riego y afirmar su papel como representantes del Estado peruano. El resultado es que desbordan y hasta violan los cauces normativos que regulan sus funciones administrativas. De este modo, incorporan una nueva función a su papel oficial que consiste en desarrollar peculiares prácticas administrativas para procesar la tensión entre la rigidez del derecho estatal de aguas y las demandas de reconocimiento y articulación que los regantes andinos le plantean al Estado.

The economic growth and the increase in population has led to an increased demand for water for various purposes such as domestic consumption, irrigation, industrial use, power generation, navigation, recreation, and ecological requirements. With the increase in population, the per-capita water availability is continuously decreasing. Due to increase in demand and accompanying scarcity of water the conflict among the potential users of the resource is on raise. Hence, the allocation of the available water resource is a big challenge as the intersect oral and inter-regional water allocation is often competing and conflicting in nature. In the above context a good model to manage the available water resources would require reliable inputs on the available water resources. In the first part of this thesis we compare different techniques that are typically used for modeling the river water flow. Time series analysis (ARIMA) is compared with machine learning techniques such as support-vector regression (SVR) and neural network models. The performance of these techniques is compared by applying them to a long-term time-series data of the inflows of three tributaries of the river Cauvery into the Krishnaraja Sagar reservoir (KRS). Flow data over a period of 30 years from three different observation points established in upper Cauvery river sub-basin is analyzed. Specifically, a multi-layer feed forward network trained with a back-propagation algorithm and support vector regression with epsilon-insensitive loss function is compared with the ARIMA models. It is found that the performance of support vector regression model is superior to those of the other techniques considered. The second part of our thesis is to develop a model for optimal water allocation to the different sectors with the aim of maximizing the total utility of available water resource in a river basin. A hydro-economic modeling framework is developed that incorporates the economic assessment of the value of water. This inter-sectoral allocation problem is studied in the context of enforcing certain minimum water rights to every person for domestic use and a certain minimum irrigation need set out by the contingency plans of the state agriculture department in Cauvery river basin. A non-linear optimization model is built to obtain an optimal inter-sectoral water allocation policy. The study evaluates the economic impact of different parameters of competing demands such as water availability, population, basic water right (quantity), ground water contribution, and crop benefit. The optimal policies that implements the water allocation priorities as set out by the National Water Policy (2012) are compared. Further, results show that the basic water right can be secured for essential needs with optimal management of available surface and ground water resources. In the third part of thesis, we study the conflict of water sharing that arises between sectors/regions. We consider the river water-sharing problem between two agents along a river. Each agent has a stated claim to the river water. The Absolute Territorial Sovereignty (ATS) and Absolute Territorial Integrity (ATI) principles are promoted by different agents along the river as a means to maximize their individual benefit. However, these principles are invariably considered to be unjust by one or more of the other agents. Hence, it is preferred to have a negotiated water treaty that is perceived to be equitable and just by all. A one way downstream stream bilateral bargaining model can be used to guide the negotiated water treaty between the agents. In this bargaining framework we introduce the issue of negative externalities imposed by the upstream agent on the downstream agent/s in the form of pollution and/or flooding. This imposes a cost on the downstream agent to mitigate losses due to the negative externalities. A bargaining model that incorporates the impact of negative externalities is developed to guide the negotiated treaties. We identify individually rational bargaining strategies for a two agents transferable utility one way downstream river water sharing problem. The results characterize the agreement and disagreement points for bilateral trading