Enhancing the Accessibility, Applicability, and Interactions of Satellite-Informed Hydrologic Projections Under Climate and Forest Changes for Water Managers

Escalating climate change risk and impacts require urgent shifts in scientific research towards more actionable and accessible information for environmental decision-making. In the context of water management of the Colorado River Basin (CRB), the impacts of intensifying forest disturbances (wildfire, mortality, thinning) under climate change are anticipated to have major consequences that are not well understood. Sizeable differences amongst climate models, including disagreements in projected precipitation trends across the CRB, also necessitate a screening process that considers water manager perspectives for impact studies. Though modeled streamflows are often provided to water operations models, managers also typically lack access to large volumes of other relevant simulation outputs. To address this, we (1) designed a stakeholder engagement and modeling process that integrated satellite Earth Observation (EO) products to assess the impact of these changes on CRB hydrology, and (2) developed a user-centered web-based tool, CRB-Scenario-Explorer, to provide interactive visual assessments of the model results and detailed documentation. We used the Variable Infiltration Capacity (VIC) model to generate scenarios that were designed according to water manager feedback. We integrated advances in VIC using EO (MODIS- and Landsat-) based products for more realistic land surface conditions. Simulation scenarios were forced with two climate model products representing Warm/Wet and Hot/Dry futures and included differing forest reduction levels. Simulated streamflow conditions improved with extreme forest reductions by end of 21^st century (CRB mean annual streamflow up to 12% larger than without disturbance) due to smaller snowpack reductions and evapotranspiration losses. Larger forest reductions reversed warming-driven declines in future supply efficiency (average runoff and baseflow, per unit of precipitation) under the Warm/Wet climate, but not the Hot/Dry climate due to the overriding effect of aridification. Stakeholders confirmed the effectiveness of the web-based tool in assisting with the key discovery that future CRB hydrology appears more sensitive to climate uncertainty than forest disturbances, which can be used to brief leaders and spark discourse around risk management. They emphasized that the web-tool provides an effective way to understand the underlying EO-model framework, which can be adopted to answer additional management questions. Our stakeholder-driven web-tool and underlying EO-model framework thus exemplifies a novel and effective method to increase the accessibility, applicability, and transparency of environmental science research.