Impacts of climate variability on the operational forecast and management of the Upper Des Moines River Basin

Abstract

Abstract. Data from the regulated 14,000 km 2 upper Des Moines River basin and a coupled forecast-control model are used to study the sensitivity of flow forecasts and reservoir management to climatic variability over scales ranging from daily to interdecadal. Robust coupled forecast-control methodologies are employed to minimize reservoir system sensitivity to climate variability and change. Large-scale hydrologic-hydraulic prediction models, models for forecast uncertainty, and models for reservoir control are the building blocks of the methodology. The case study concerns the 833.8 x 10 6 m 3 Saylorville reservoir on the upper Des Moines River. The reservoir is operated by the U.S. Corps of Engineers for flood control, low-flow augmentation, and water supply. The total record of 64 years of daily data is divided into three periods, each with distinct characteristics of atmospheric forcing. For each climatic period the coupled forecast-control methodology is simulated with a maximum forecast lead time of 4 months and daily resolution. For comparison, the results of operation using current reservoir control practices were obtained for the historical periods of study. Large differences are found to exist between the probabilistic long-term predictions of the forecast component when using warm or cool and wet or dry initial conditions in the spring and late summer. Using ensemble input corresponding to warm or cool and wet or dry years increases these differences. Current reservoir management practices cannot accommodate historical climate variability. Substantial gain in resilience to climate variability is shown to result when the reservoir is operated by a control scheme which uses reliable forecasts and accounts for their uncertainty. This study shows that such coupled forecast-control decision systems can mitigate adverse effects of climatic forcing on regional water resources.

Assessment of Folsom Lake response to historical and potential future climate scenarios

“…These findings are consistent with those of Georgakakos et al, 1998a. The value of different forecast forms is investigated, demonstrating that forecast uncertainty characterization is important for reservoir management.…”

Changing mechanism of global water scarcity events: Impacts of socioeconomic changes and inter-annual hydro-climatic variability

“…make their design robust to a wide array of future circumstances, water managers should base their estimates on a range of future scenarios thereby covering the future impacts of inter-annual variability and taking into account possible worst-case conditions (Hall and Borgomeo, 2013;Hallegatte, 2009;Klein, 2003;Wilby and Dessai, 2010). The impact of climate variability on the operational forecast and management of reservoirs was discussed earlier by Georgakakos et al (1998) for a case study in the Upper Des Moines River basin (USA). The same authors showed for a case study in Northern California (Georgakakos et al, 2012) that adaptive, risk based reservoir adaptation strategies, which have the ability to deal with increases in variability under climate change, perform more robustly under future conditions than the traditional rigid operation plans.…”

Joint variable spatial downscaling

“…This is an active research area with several past and on-going studies, including Lettenmaier and Rind 1992;Stamm et al 1994;Conway 1998;Wood et al 2004;Georgakakos et al 1998;VanRheenen et al 2004;Tanaka et al 2006;Maurer 2007;Medellín-Azuara et al 2008;Vicuna et al 2009;Georgakakos et al 2011;and Georgakakos et al 2010. Among these studies, general circulation models (GCMs) are broadly used as an important tool for quantitative impact assessment.…”