Verification of Ensemble Water Supply Forecasts for Sierra Nevada Watersheds

He, Minxue; Whitin, Brett; Hartman, Robert; Henkel, Arthur; Fickenschers, Peter; Staggs, Scott; Morin, A.J.; Imgarten, Michael; Haynes, Alan; Russo, Mitchel

doi:10.3390/hydrology3040035

Cited by 14 publications

(10 citation statements)

References 63 publications

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“…The first one uses statistical regression equations that relate to future seasonal runoff to a snow index, antecedent streamflow, and precipitation, as well as forecasted precipitation [26]. The other one relies on a coupled snow and runoff model (NWSRFS) [66][67][68][69] and forecasted precipitation and temperature to generate seasonal runoff forecasts. The snow module (SNOW-17) [70-72] of this model applies a maximum snowmelt parameter to cap out the possible snowmelt rate.…”

Section: Discussionmentioning

confidence: 99%

Potential Changes in Runoff of California’s Major Water Supply Watersheds in the 21st Century

He¹,

Anderson²,

Schwarz³

et al. 2019

Water

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This study assesses potential changes in runoff of California’s eight major Central Valley water supply watersheds in the 21st century. The study employs the latest operative climate projections from 10 general circulation models (GCMs) of the Coupled Model Intercomparison Project Phase 5 (CMIP5) under two emission scenarios (RCP 4.5 and RCP 8.5) to drive a hydrologic model (VIC) in generating runoff projections through 2099. Changes in peak runoff, peak timing, seasonal (major water supply season April–July) runoff, and annual runoff during two future periods, mid-century and late-century, relative to a historical baseline period are examined. Trends in seasonal and annual runoff projections are also investigated. The results indicate that watershed characteristics impact runoff responses to climate change. Specifically, for rain-dominated watersheds, runoff is generally projected to peak earlier with higher peak volumes on average. For snow-dominated watersheds, however, runoff is largely projected to peak within the same month as historical runoff has, with little changes in peak volume during mid-century but pronounced decreases during late-century under the higher emission scenario. The study also identifies changes that are common to all study watersheds. Specifically, the temporal distribution of annual runoff is projected to change in terms of shifting more volume to the wet season, though there is no significant changing trend in the total annual runoff. Additionally, the snowmelt portion of the total annual runoff (represented by April–July runoff divided by total annual runoff) is projected to decline consistently under both emission scenarios, indicative of a shrinking snowpack across the study watersheds. Collectively, these changes imply higher flood risk and lower water supply reliability in the future that are expected to pose stress to California’s water system. Those findings can inform water management adaptation practices (e.g., watershed restoration, re-operation of the current water system, investing in additional water storage) to cope with the stress.

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Section: Discussionmentioning

confidence: 99%

Potential Changes in Runoff of California’s Major Water Supply Watersheds in the 21st Century

He¹,

Anderson²,

Schwarz³

et al. 2019

Water

Self Cite

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“…The seasonal snowpack stores water in the winter and releases it as snowmelt in late winter through early summer, alleviating the temporal mismatch between the maximum precipitation during winter and the maximum water demand for urban and agricultural consumption in the summer (Dettinger and Cayan 1995;Vano et al 2015). In California, accurate and timely seasonal streamflow forecasts help mitigate risks in water management (He et al 2016a) and provide a basis for water allocation decisions that are resilient to climate variability and drought (Tanaka et al 2006). Seasonal streamflow forecasts thus help decision-makers facilitate timely coordinated regional responses in order to mitigate impacts of water shortages on agriculture (Scanlon et al 2012) and associated industries (Scott et al 2008), as well as other groups with a stake in the shared water resources (e.g., Vicuña et al 2011).…”

Section: Introductionmentioning

confidence: 99%

The Value of Accurate High-Resolution and Spatially Continuous Snow Information to Streamflow Forecasts

Lettenmaier

Margulis

et al. 2019

Journal of Hydrometeorology

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Previous studies have shown limited success in improving streamflow forecasting for snow-dominated watersheds using physically based models, primarily due to the lack of reliable snow water equivalent (SWE) information. Here we use a hindcasting approach to evaluate the potential benefit that a high-resolution, spatiotemporally continuous, and accurate SWE reanalysis product would have on the seasonal streamflow forecast in the snow-dominated Sierra Nevada mountains of California if such an SWE product were available in real time. We tested the efficacy of a physically based ensemble streamflow prediction (ESP) framework when initialized with the reanalysis SWE. We reinitialized the SWE over the Sierra Nevada at the time when the Sierra Nevada had domain-wide annual maximum SWE for each year in 1985–2015, and on 1 February of the driest years within the same period. The early season forecasts on 1 February provide valuable lead time for mitigating the impact of drought. In both experiments, initializing the ESP with the reanalysis SWE reduced the seasonal streamflow forecast errors; compared with existing operational statistical forecasts, the peak-annual SWE insertion and the 1 February SWE insertion reduced the overall root-mean-square error of the seasonal streamflow forecasts by 13% and 23%, respectively, over the 13 major rivers draining the Sierra Nevada. The benefits of the reanalysis SWE insertion are more pronounced in areas with greater snow accumulation, while the complex snow and runoff-generation processes in low-elevation areas impede the forecasting skill improvement through SWE reinitialization alone.

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“…10.1029/2020WR028392 13 of 48 from historical weather observations. This verification procedure is quite common in short-, mediumand long-range hydrological forecasting (Alfieri et al, 2014;Brown et al, 2014;Greuell et al, 2018;He et al, 2016).…”

Section: Verification Of Ensemble Streamflow Forecastsmentioning

confidence: 99%

“…These hindcasts are compared with a reference simulation to determine the prediction consistency of the EHS; the reference simulation is carried out with the same hydrological models and retrospective ICs as the hindcasts, but the forcing inputs are taken from historical weather observations. This verification procedure is quite common in short‐, medium‐ and long‐range hydrological forecasting (Alfieri et al., 2014; Brown et al., 2014; Greuell et al., 2018; He et al., 2016).…”

Section: Ensemble Streamflow Forecasting: An Overviewmentioning

confidence: 99%

Generating Ensemble Streamflow Forecasts: A Review of Methods and Approaches Over the Past 40 Years

Troin

Arsenault

Wood

et al. 2021

Water Resources Research

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 This work summarizes the 40 years of research in the generation of streamflow forecasts based on an exhaustive review of studies.  Ensemble prediction systems are categorized into three classes: statistics-based, climatology-based and numerical weather prediction-based hydrological ensemble prediction systems.  For each ensemble forecasting system, thorough technical information is provided.  Findings from the success of the model-based ensemble forecasting approaches are analysed, as are prospective future developments.

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Verification of Ensemble Water Supply Forecasts for Sierra Nevada Watersheds

Cited by 14 publications

References 63 publications

Potential Changes in Runoff of California’s Major Water Supply Watersheds in the 21st Century

Potential Changes in Runoff of California’s Major Water Supply Watersheds in the 21st Century

The Value of Accurate High-Resolution and Spatially Continuous Snow Information to Streamflow Forecasts

Generating Ensemble Streamflow Forecasts: A Review of Methods and Approaches Over the Past 40 Years

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