Abstract
The potential benefits of seasonal streamflow forecasts for the hydropower sector have been evaluated for several basins across the world, but with contrasting conclusions on the expected benefits. This raises the prospect of a complex relationship between reservoir characteristics, forecast skill and value. Here, we unfold the nature of this relationship by studying time series of simulated power production for 735 headwater dams worldwide. The time series are generated by running a detailed dam model over the period 1958–2000 with three operating schemes: basic control rules, perfect forecast-informed, and realistic forecast-informed. The realistic forecasts are issued by tailored statistical prediction models—based on lagged global and local hydro-climatic variables—predicting seasonal monthly dam inflows. As expected, results show that most dams (94 %) could benefit from perfect forecasts. Yet, the benefits for each dam vary greatly and are primarily controlled by the time-to-fill and the ratio between reservoir depth and hydraulic head. When realistic forecasts are adopted, 25 % of dams demonstrate improvements with respect to basic control rules. In this case, the likelihood of observing improvements is controlled not only by design specifications but also by forecast skill. We conclude our analysis by identifying two groups of dams of particular interest: dams that fall in regions expressing strong forecast accuracy and have the potential to reap benefits from forecast-informed operations, and dams with strong potential to benefit from forecast-informed operations but fall in regions lacking forecast accuracy. Overall, these results represent a first qualitative step towards informing site-specific hydropower studies.
Highlights
Hydropower is the leading form of renewable power, contributing to 16% of global electricity production and 62% of all renewable electricity generation (IHA, 2019)
Evaluating months when a higher percentage of dams is significantly correlated with predictors, some well-known climatic teleconnections can be observed—e.g., El Niño Southern Oscillation (ENSO) and winter-spring streamflow in North America and Europe, North Atlantic Oscillation (NAO) and spring-summer peak flows in the northern extratropic regions, and PDO and summer streamflow in southeastern North America and central South America (Figure S3)
27%, 37%, 28%, 20%, and 36% of the reservoir catchments are significantly correlated with ENSO, NAO, PDO, AMO, and snowfall, respectively
Summary
Hydropower is the leading form of renewable power, contributing to 16% of global electricity production and 62% of all renewable electricity generation (IHA, 2019). Total hydropower production is expected to double by 2050, with substantial growth in Asia, Africa, and South America (Zarfl et al, 2015; Zhang et al, 2018). The sustainable operation of hydropower facili ties, is challenged by hydro-climatic variability, namely seasonal and inter-annual fluctuations in streamflow—and hydropower output—driven by large-scale climate drivers. Examples include the North Atlantic Oscillation (NAO), affecting hydropower in Europe (De Felice et al, 2018), or the El Niño Southern Oscillation (ENSO), affecting one third of the world’s hydropower dams (Ng et al, 2017). An attractive management option to limit these fluctuations is the use of adaptive reservoir operating policies based on seasonal streamflow forecasts (Troin et al, 2021).
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