A risk-based framework for water resource management under changing water availability, policy options, and irrigation expansion

Long-term water resource management requires the capacity to evaluate alternative management options in the face of various sources of uncertainty in the future conditions of water resource systems. This study proposes a generic framework for determining the relative change in probabilistic characteristics of system performance as a result of changing water availability, policy options and irrigation expansion. These probabilistic characteristics can be considered to represent the risk of failure in the system performance due to the uncertainty in future conditions. Quantifying the relative change in the performance risk can provide a basis for understanding the effects of multiple changing conditions on the system behavior. This framework was applied to the water resource system of the Saskatchewan River Basin (SaskRB) in Saskatchewan, Canada. A “bottom-up” flow reconstruction algorithm was used to generate multiple realizations for water availability within a feasible range of change in streamflow characteristics. Consistent with observed data and projected change in streamflow characteristics, the historical streamflow was perturbed to stochastically generate feasible future flow sequences, based on various combinations of changing annual flow volume and timing of the annual peak. In addition, five alternative policy options, with and without potential irrigation expansion, were considered. All configurations of water availability, policy decisions and irrigation expansion options were fed into a hydro-economic water resource system model to obtain empirical probability distributions for system performance - here overall and sectorial net benefits - under the considered changes. Results show that no one specific policy can provide the optimal option for water resource management under all flow conditions. In addition, it was found that the joint impacts of changing water availability, policy, and irrigation expansion on system performance are complex and resemble nonlinear functions of changes in individual drivers. The proposed risk-based framework can be linked to any water resource system assessment scheme to quantify the risk in system performance under changing conditions, with the larger goal of proposing alternative policy options to address future uncertainties and management concerns.