Conventional water resource management has been based on the assumption of stationarity in the characteristics of the water resource systems. However, the validity of this assumption is questionable due to changing climate and increasing human activities. The current level of uncertainty inherent in the projection of future natural and anthropogenic conditions has also complicated water resource planning and management. As a result, there is a fundamental need to acknowledge the uncertainty associated with water resource systems and propose improved management schemes under uncertainty.
This thesis presents three developments to assist in understanding system behavior under historical and changing conditions, and to propose an alternative framework for decision making under uncertain conditions. The three parts are put together and applied to the Saskatchewan River Basin (SaskRB) in Saskatchewan, which is a strategically important water resource system in western Canada. In brief, first a Sustainability-oriented Water allocation, Management, and Planning (SWAMPSK) model is developed using the System Dynamics approach. This water resource model captures the causal relationships among system components and combines various aspects of the water resource system, such as water allocation, irrigation demand, and economic evaluation within an integrated system. Second, SWAMPSK is used to map the vulnerability and sectorial trade-offs in the SaskRB in Saskatchewan under changing water availability and irrigation expansion. Using a bottom-up approach, a wide range of streamflow conditions is stochastically generated to accommodate likely scenarios of change in water availability. The streamflow ensemble and alternative irrigation expansion scenarios are used in SWAMPSK for evaluating the water resource system’s performance under potential changes in natural conditions and irrigated areas. Third, an innovative probabilistic framework is proposed to evaluate the risk in system behavior under changing conditions and to identify the contributions of various changing conditions on the overall system performance. For this purpose, the empirical probability distributions of system performance are used to quantify the individual and joint impacts of changing conditions on the system performance with the goal of proposing policies that minimize the risk of undesired changes in system.
This thesis provides a set of new and strategically-important insights to the water resource system in Saskatchewan. In brief, increase in irrigation area can raise the total economic benefit except in extremely dry flow conditions, but with some cost of decreasing water availability in downstream regions. Saskatchewan can meet the inter-provincial commitment under changes in flow regime and irrigation expansion. Results also show that no one specific policy can provide the optimal option for water resource management under all changing flow and irrigation expansion conditions and the joint impacts of changing water availability, policy, and irrigation expansion are complex nonlinear functions of individual drivers. This thesis also offers a set of new modeling tools that can be used to assist decision making under uncertainty. In particular, the proposed risk-based framework allows an explicit understanding of the variations in the system performance as a result of changing natural and/or anthropogenic conditions and can be transferred to decision making applications
