Title: Inferred inflow forecast horizons guiding reservoir release decisions across the United States

Abstract

Abstract. Medium- to long-range forecasts often guide reservoir release decisions to support water management objectives, including mitigating flood and drought risks. While there is a burgeoning field of science targeted at improving forecast products and associated decision support models, data describing how and when forecasts are applied in practice remain undeveloped. This lack of knowledge may prevent hydrological modelers from developing accurate reservoir release schemes for large-scale, distributed hydrology models that are increasingly used to assess the vulnerabilities of large regions to hydrological stress. We address this issue by estimating seasonally varying, regulated inflow forecast horizons used in the operations of more than 300 dams throughout the conterminous United States (CONUS). For each dam, we take actual forward observed inflows (perfect foresight) as a proxy for forecasted flows available to the operator and then identify for each week of the year the forward horizon that best explains the release decisions taken. Resulting “horizon curves” specify for each dam the inferred inflow forecast horizon as a function of the week of the water year. These curves are analyzed for strength of evidence for contribution of medium- to long-range forecasts in decision making. We use random forest classification to estimate that approximatelymore » 80 % of large dams and reservoirs in the US (1553±50 out of 1927 dams with at least 10 Mm3 storage capacity) adopt medium- to long-range inflow forecasts to inform release decisions during at least part of the water year. Long-range forecast horizons (more than 6 weeks ahead) are detected in the operations of reservoirs located in high-elevation regions of the western US, where snowpack information likely guides the release. A simulation exercise conducted on four key western US reservoirs indicates that forecast-informed models of reservoir operations may outperform models that neglect the horizon curve – including during flood and drought conditions.« less

Authors:

Turner, Sean W. D. ;

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Xu, Wenwei; Voisin, Nathalie

• Search DOE PAGES for author "Voisin, Nathalie"
• Search DOE PAGES for ORCID "0000-0002-6848-449X"
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Publication Date:

2020-03-19

Research Org.:

Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1605466

Alternate Identifier(s):

OSTI ID: 1616683

Report Number(s):

PNNL-SA-142797
Journal ID: ISSN 1607-7938

Grant/Contract Number:  

59534; AC05-76RL01830

Resource Type:

Published Article

Journal Name:

Hydrology and Earth System Sciences (Online)

Additional Journal Information:

Journal Name: Hydrology and Earth System Sciences (Online) Journal Volume: 24 Journal Issue: 3; Journal ID: ISSN 1607-7938

Publisher:

European Geosciences Union (EGU)

Country of Publication:

Germany

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES