Short to medium range probabilistic streamflow forecasting for Tel river using the Hydrologic Ensemble Forecast Service M. Sarath, V. V. Srinivas Department of Civil Engineering , and Interdisciplinary Center for Water Research (ICWaR) Indian Institute of Science, Bangalore, India
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Short to medium range probabilistic streamflow forecasting for Tel river using the
Hydrologic Ensemble Forecast Service
M. Sarath, V. V. Srinivas
Department of Civil Engineering , and
Interdisciplinary Center for Water Research (ICWaR)
Indian Institute of Science, Bangalore, India
Streamflow forecasting - Applications
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Kerala floods 2018 (google)
Overtopping of dam in Kerala
Lead time of forecast
Applications
Short range flood forecasts(up to 3 days)
• Flood warning • Flood control
system management for savings lives and some assets
Medium-range flood forecasts (3–15 days)
• Flood control system management for preserving additional livelihood assets
• Planning and management of water resources (e.g., for agriculture, hydropower, Industry)
Streamflow Forecasting Approaches3
ANN
Data-driven/statisticalProcess-driven
Meteorological
forecast
(Source: essc.psu.edu)
Hydrologic models are forced with meteorological forecasts from NWP models, considering basin initial
conditions
StreamflowPredictorsARIMAANN
ANFISk-NN
ANFIS
Deterministic forecast
Flood
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Forecast uncertainty Causes
Complex nature of system
Imperfect models
Lack of data
Measurement errors, etc.
Quantification of uncertainty
Ensemble (instead of single valued forecast)
Probabilistic forecast
Flood threshold
~25 % probability of flooding
Forecasting Flow in a River using Hydrologic Ensemble Prediction Systems (HEPS)
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Generate ensemble forecasts of streamflow to quantify forecastuncertainty
Increasingly used by flood forecasting centres
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HEPS name Region
Global Flood Awareness System (GloFAS) Global
European Flood Awareness System (EFAS) Europe
Hydrologic Ensemble Forecast Service (HEFS)
United States
Climate Forecast Applications in Bangladesh (CFAB)
Bangladesh
Joint Flood Forecasting System UKFrench Hydro-meteorological Ensemble
Prediction SystemFrance
Watershed simulation and forecasting system (WSFS)
FinlandOperational/pre-operational HEPS
source: HEPEX
Can the HEPS provide skilful streamflow forecasts for Indian rivers? Do we need India specific ensemble forecasting system?
Forecasting Flow in a River using Hydrologic Ensemble Prediction Systems (HEPS)
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Studies in India
Priya, Satya, William Young, Thomas Hopson, and Ankit Avasthi. 2017. Flood Risk Assessment and Forecasting for the Ganges-Brahmaputra-Meghna River Basins. Washington, DC: World Bank.
Forecasting Flow in a River using Hydrologic Ensemble Prediction Systems (HEPS)
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HEPS name Region
Global Flood Awareness System (GloFAS) Global
European Flood Awareness System (EFAS) Europe
Hydrologic Ensemble Forecast Service (HEFS)
United States
Climate Forecast Applications in Bangladesh (CFAB)
Bangladesh
Joint Flood Forecasting System UKFrench Hydro-meteorological Ensemble
Prediction SystemFrance
Watershed simulation and forecasting system (WSFS)
FinlandOperational/pre-operational HEPS
source: HEPEX
Forecasting River Flow using Hydrologic Ensemble Prediction Systems (HEPS)
Demargne, J., Wu, L., Regonda, S.K., Brown, J.D., Lee, H., He, M., Seo, D.J., Hartman, R.,Herr, H.D., Fresch, M., Schaake, J., Zhu, Y., 2014. The science of NOAA’s operationalhydrologic ensemble forecast service. Bull. Am. Meteorol. Soc. 95, 79–98.
Fig: Streamflow forecast generated using HEFS on September 15, 20082008
2008
HEFS: Hydrologic Ensemble Forecast Service
September 20, 2008
During flood
September 7, 2008
Mahanadi
Before flood
Brahmani
18th Sep
19th Sep
Results - Streamflow forecasts28
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CLIM: climatology/climatological forecast
HEFS: Hydrologic Ensemble Forecast Service
Results – Streamflow forecasts
CRPSS: (Continuous Ranked Probability Skill Score)
ARIMA (4,0,1)
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HEFS (Hydrologic Ensemble Forecast Service )
Schematic diagram of HEFS
Meteorological forecasts
(precipitation, temperature)
Ensemble meteorological
forecasts
Raw ensemble streamflow forecast
Postprocessed ensemble streamflow forecast
I: MEFP
II: Hydrologic Processor
III: EnsPost
Model meteorological uncertainty
Model hydrologic uncertainty
Simulate streamflow, propagate uncertainty
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ESP: GR4J model is forced with CLIM forecasts of precipitation andPETHEFS-RAW: GR4J model is forced with MEFP-GEFS forecasts ofprecipitation and PETHEFS-POST: Postprocessed ensemble streamflow forecast generated usingEnsPost