In an era of global-scale climate change, agricultural production faces a unique challenge due to its reliance on stochastic natural endowments, including temperature, precipitation, and water availability for irrigation. This dissertation presents a series of essays to examine how agricultural producers react and adapt to challenges presented by climate change and scarce irrigation water allocated through the prior appropriation doctrine. The dissertation approaches the problem from three distinct perspectives: institutional differences, climate and water availability, as well as producers' expectation on future endowments. Chapter 2 presents an institutional perspective, in which I investigate how different water allocation mechanisms within the prior appropriation doctrine result in differences in producers' crop allocation decisions. I find that water users in irrigation districts are able to plant more water-intensive crops than farmers outside irrigation districts. Chapter 3 presents the interaction between nature and human systems, in which I examine how the physiological complementarity of temperature and water availability diffuses from crop yield (at the intensive margin) to crop allocation strategies (at the extensive margin). Using a theoretical model I show that the observed complementarity reflects a combination of two mechanisms: yield impact through physiological complementarity, and adaptation response through shifting crop allocation patterns. Using an empirical model, I find that farmers adapt to changing climate conditions by growing more profitable crop mixes when presented with more growing degree-days (GDD), precipitation and groundwater access. Chapter 4 presents a behavioral perspective, in which I test how producers' expectation formation processes lead to short term over-adjustments to weather and water availability fluctuations. Using a fixed-effect regression on lagged weather and water realizations, I find that agricultural producers engage in a combination of cognitive biases, including the availability heuristic and the reinforcement strategy. Adopting these alternative learning mechanisms causes farmers to significantly over-react to more recent fluctuations in weather and water availability when making ex ante acreage and crop allocation decisions. / Ph. D. / In an era of global-scale climate change, agricultural production faces a unique challenge due to its reliance on variable natural factors, including temperature, precipitation, and water availability for irrigation. This dissertation presents a series of essays to examine how agricultural producers react and adapt to challenges presented by climate change and scarce irrigation water allocated through the prior appropriation doctrine. Chapter 2 presents an institutional perspective, in which I investigate how different water allocation regimes result in differences in producers’ cropping decisions. I find that irrigation districts benefit its users by allowing them to plant more water-intensive crops than farmers outside irrigation districts. Chapter 3 presents a natural science perspective, in which I examine how temperature and water availability jointly affect agricultural production and adaptation. I find that farmers significantly adapt to changing climate conditions by growing more profitable crop mixes when presented with higher temperature, precipitation, and groundwater access. Chapter 4 presents a behavioral perspective, in which I test how agricultural decision making are affected by how producers form expectations over future climate. I find that agricultural producers engage in a combination of cognitive biases when forming expectations, and as a result over-react to more recent fluctuations in weather and water availability when making acreage and crop allocation decisions.

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.

From the Proceedings of the 1974 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 19-20, 1974, Flagstaff, Arizona / The doctrine of prior appropriation used in the arid western states has encouraged rapid exploitation of our natural water resources. Those who beneficially used the water first, regardless of type of use or efficiency, obtained a perpetual right to always be first. As frontiers for exploiting our natural resources shrink, the Appropriation Doctrine is changing under the stresses of the 1970's. Our water allocations system is changing as new water -use priorities emerge along with changing quality standards. Government at all levels, along with planners and engineers, must understand the institutional and legal constraints put on water development by our historic water rights system so that intelligent decisions can be made in developing and maintaining our natural water resources.

Tribal water rights and instream flows for species listed under the Endangered Species Act (ESA) have been a source of tensions in the western United States, particularly when tribes have undetermined water rights to support tribal fisheries listed under the ESA. Understanding the mechanics of past tribal settlements and their strengths and weaknesses in resolving disputes over instream flows for tribal trust fisheries listed under the ESA will allow parties involved in negotiations to evaluate whether similar provisions should be incorporated into future settlements. A review of the 27 congressionally approved tribal water settlements for instream flow and ESA provisions revealed that instream rights were either established as junior rights or reallocated from existing rights. The ESA was a factor in many of the settlements; however, only one actively incorporated ESA tools as part of the benefits of the settlement. After this preliminary evaluation, a comparative analysis framework with 28 criteria for evaluating environmental conflict resolution was applied to the Nez Perce Water Rights Settlement and Pyramid Lake Paiute Water Rights Settlement to identify strengths and weaknesses of using tribal water settlements as a means to resolve disputes involving instream flow claims. From my analysis, I conclude that tribal water settlements offer unique opportunities to shift the status quo and address historic inequities while minimizing harm to existing water users; however, settlement agreements may not result in an outcome that reduces conflict without a concerted effort to establish a fair process and minimize the impacts of the agreement on other parties. Furthermore, despite the many benefits of settlement agreements, since they have not delivered time-immemorial rights for fisheries, other options will likely be a continued consideration for tribes seeking to restore fisheries. However, while litigation presents a risky though lucrative outcome, rights under state law are in line with what has been granted in settlements. Given the time, effort and cost associated with settlements, I suggest that since tribal water right settlements generally use state tools to establish instream flows, states and tribes may reduce future conflict by proactively working together to establish instream flows through existing state water reallocation mechanisms. / Graduation date: 2012