Title: advancing forecast-informed reservoir operation and planning for the west gulf through integration of climate forecasts and reservoir water balance predictions competition:…

Title: advancing forecast-informed reservoir operation and planning for the west gulf through integration of climate forecasts and reservoir water balance predictions competition: NOAA-OAR-CPO-2024-2008268, mapp-nidis abstract: for decades, the southwestern united states has been plagued by extreme droughts and floods with devastating societal and economic consequences. Specifically, the west gulf region, which spans much of texas and new mexico, is under constant threat of droughts that is amplified by population growth and aggravated by a warming climate. To address the challenge of sustaining water supply under this latent threat, an increasing number of reservoir operators, water managers, and policy makers in the region have taken an interest in integrating weather and hydrologic forecasts in reservoir operation and drought planning. Today, forecast-informed reservoir operation (FIRO) has emerged as one strategy for improving water reliability in the region. A centerpiece of contemporary FIRO practice relates to accounting for inherent uncertainties in forecasts. The national weather service (NWS) has long recognized this, and is implementing hydrologic ensemble forecast service (HEFS) nationwide that is capable of conveying forecast uncertainties for a range of lead times. In evaluating HEFS seasonal forecasts in the texas FIRO pilot, the proposal team uncovered a number of critical limitations, including a lack of sufficient ensemble spread, and large biases in the projection of various components of reservoir water budgets, both natural and anthropogenic. Collectively, these limitations hinder the effective use of the forecasts by reservoir operators. To overcome these challenges, we propose a research initiative aimed at augmenting HEFS ensemble hydrologic forecasts to better inform reservoir operation and planning. The initiative comprises three thrusts, namely 1) integrating forecasts from dynamic climate models to create supplemental ensemble traces, 2) developing forecasts of water use, releases, and reservoir evaporation that can be employed in conjunction with inflow forecasts to better predict reservoir level and release, 3) performing hindcasts using augmented HEFS with the enhancements and collaboratively determining the robustness of forecasts to guide practical decisions. The proposed project will be conducted in close collaboration with the NWS west gulf river forecast center, the texas water development board, two major reservoir operators in the region, and the developers at NOAA geophysical fluids dynamic lab (GFDL). The investigation will focus on two major reservoir systems, one in texas operated by the US army corps of engineers, and the other in northern new mexico owned by the US bureau of reclamation. The proposed project addresses the following priorities, namely (1) improve accounting and monitoring of the water budget in the west and (2) explore the utility and limitations of climate and earth system models, and prediction systems in correctly simulating drought events. In particular, the project will yield 1) assessment of the potential of the GFDL spear and north american multimodel ensemble (NMME) in anticipating the onset, intensification and demise of droughts; and 2) enhancements to HEFS that allow for more realistic depictions of the range of possibilities with respect to inflows and sources/sinks for major reservoirs. This effort will help advance model-based understanding, monitoring, prediction, predictability, and model representation of drought by producing probabilistic forecasts of hydrologic droughts that account for uncertainties in the forecast climate conditions and impacts of water use.