Hydroclimatic Prediction to Guide Robust Water Market-Scale Agricultural Water Resource Decision-Making for Semi-Arid, Water Rights Managed Basins: Application to the Elqui Valley, Chil

In regions where surface water scarcity challenges the equitable, efficient distribution of water resources, water rights and corresponding markets have emerged as legal and economic instruments to promote resource sustainability through a system of limited access permits. Where the annual water right allocation value is uncertain and based on existing reservoir storage and expected future streamflow conditions, which may be driven principally by climate and hydrology, coupling season-ahead streamflow (reservoir inflow) forecasts with reservoir allocation models, and subsequently linking forecast allocations with market-scale economic models may be useful in guiding water rights holder decision making where trading of rights is permitted.;This dissertation explores market-scale water resource use efficiency, applying skillful predictive information of expected future conditions to reservoir management and agricultural planning, within the limits of the existing water rights law. A novel model framework is presented in five phases and calibrated to the agriculture dominated, semi-arid Elqui Valley of North Central Chile. The first phase focuses on producing multi-stage statistically-based water right allocation forecasts which are skillfully produced at leads of up-to four months ahead of allocation issuance by reservoir managers. Phase two illustrates how, independent of forecast information, perennial (grape) farmers may achieve gains from temporary water market engagement by coupling a crop water model with an agricultural-economic model. Phase three considers how perennial and annual (potato) farmers as surrogates for high and low value farmers should interact as water-trading cooperatives, such that market-scale water use efficiency and economic benefits are maximized under existing water rights law. Phase four reintroduces season-ahead forecasts, describing forecast value to both farmer types in comparison with climatological benchmarks. Phase five introduces forecast trust heterogeneity, modelling changes in farmer water right investment behavior with respect to sequential forecast skill to assess forecast option value.;The results suggest that season-ahead forecasts, when appropriately tailored and integrated with end-user water-trade decision making timeframes and actions, hold value over climatological benchmarks in long-term economic measures. The broader insights indicate that market efficiencies are possible without institutional policy change when users collaborate to reveal water market price and quantity and agree to transparent engagement strategies.