Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling

Abstract Accurate simulation of reservoirs has been a challenge for global hydrological models due to highly discontinuous water management and uncertainties in reservoir shape representation. In addition, at a global scale, it is crucial to consider those reservoirs that disrupt the downstream flow...

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Main Authors: P. K. Shrestha, L. Samaniego, O. Rakovec, R. Kumar, C. Mi, K. Rinke, S. Thober
Format: Article
Language:English
Published: Wiley 2024-04-01
Series:Water Resources Research
Subjects:
Online Access:https://doi.org/10.1029/2023WR035433
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author P. K. Shrestha
L. Samaniego
O. Rakovec
R. Kumar
C. Mi
K. Rinke
S. Thober
author_facet P. K. Shrestha
L. Samaniego
O. Rakovec
R. Kumar
C. Mi
K. Rinke
S. Thober
author_sort P. K. Shrestha
collection DOAJ
description Abstract Accurate simulation of reservoirs has been a challenge for global hydrological models due to highly discontinuous water management and uncertainties in reservoir shape representation. In addition, at a global scale, it is crucial to consider those reservoirs that disrupt the downstream flow regime. We augment the mesoscale Hydrological Model with a newly developed lake module (LM) that incorporates an existing reservoir regulation scheme with non‐consumptive demand predictions from random forest. We also evaluate the sensitivity of reservoir shape on streamflow and evaporation for three shape approximations of varying complexities. We tested the LM across 31 non‐consumptive reservoirs covering an extensive range of hydroclimatic characteristics and demonstrate the applicability by using freely available global reservoir information. Streamflow simulations with reservoirs and model calibration show a median Kling‐Gupta Efficiency improvement of +0.94 (calibration) and +0.77 (validation) when compared against model simulations without reservoirs and default parameter set. We find reservoir evaporation highly sensitive to reservoir shape with half‐pyramid approximation consistently resulting in best fit at reservoirs with surveyed bathymetry. In contrast, the linear approximation (rectangular prism) produced a median bias of +114% relative to half‐pyramid, for estimating evaporation, across all the reservoirs. Streamflow simulations were insensitive to the reservoir shape. Our analysis shows that 30% of the non‐consumptive hydropower reservoirs of the GRanD data set are non‐disruptive and can be excluded without loss to model realism. Further work is necessary for testing the regulation approach in reservoirs with consumptive water usage.
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spelling doaj-art-5cc39a1b3f4342fcbfdf0a49c8b8ff122025-08-20T03:30:56ZengWileyWater Resources Research0043-13971944-79732024-04-01604n/an/a10.1029/2023WR035433Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological ModelingP. K. Shrestha0L. Samaniego1O. Rakovec2R. Kumar3C. Mi4K. Rinke5S. Thober6Department Computational Hydrosystems UFZ ‐ Helmholtz Centre for Environmental Research GmbH Leipzig GermanyDepartment Computational Hydrosystems UFZ ‐ Helmholtz Centre for Environmental Research GmbH Leipzig GermanyDepartment Computational Hydrosystems UFZ ‐ Helmholtz Centre for Environmental Research GmbH Leipzig GermanyDepartment Computational Hydrosystems UFZ ‐ Helmholtz Centre for Environmental Research GmbH Leipzig GermanyDepartment Lake Research UFZ ‐ Helmholtz Centre for Environmental Research GmbH Magdeburg GermanyDepartment Lake Research UFZ ‐ Helmholtz Centre for Environmental Research GmbH Magdeburg GermanyDepartment Computational Hydrosystems UFZ ‐ Helmholtz Centre for Environmental Research GmbH Leipzig GermanyAbstract Accurate simulation of reservoirs has been a challenge for global hydrological models due to highly discontinuous water management and uncertainties in reservoir shape representation. In addition, at a global scale, it is crucial to consider those reservoirs that disrupt the downstream flow regime. We augment the mesoscale Hydrological Model with a newly developed lake module (LM) that incorporates an existing reservoir regulation scheme with non‐consumptive demand predictions from random forest. We also evaluate the sensitivity of reservoir shape on streamflow and evaporation for three shape approximations of varying complexities. We tested the LM across 31 non‐consumptive reservoirs covering an extensive range of hydroclimatic characteristics and demonstrate the applicability by using freely available global reservoir information. Streamflow simulations with reservoirs and model calibration show a median Kling‐Gupta Efficiency improvement of +0.94 (calibration) and +0.77 (validation) when compared against model simulations without reservoirs and default parameter set. We find reservoir evaporation highly sensitive to reservoir shape with half‐pyramid approximation consistently resulting in best fit at reservoirs with surveyed bathymetry. In contrast, the linear approximation (rectangular prism) produced a median bias of +114% relative to half‐pyramid, for estimating evaporation, across all the reservoirs. Streamflow simulations were insensitive to the reservoir shape. Our analysis shows that 30% of the non‐consumptive hydropower reservoirs of the GRanD data set are non‐disruptive and can be excluded without loss to model realism. Further work is necessary for testing the regulation approach in reservoirs with consumptive water usage.https://doi.org/10.1029/2023WR035433reservoirsdisruptivityregulationevaporationreservoir bathymetrymHM
spellingShingle P. K. Shrestha
L. Samaniego
O. Rakovec
R. Kumar
C. Mi
K. Rinke
S. Thober
Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling
Water Resources Research
reservoirs
disruptivity
regulation
evaporation
reservoir bathymetry
mHM
title Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling
title_full Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling
title_fullStr Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling
title_full_unstemmed Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling
title_short Toward Improved Simulations of Disruptive Reservoirs in Global Hydrological Modeling
title_sort toward improved simulations of disruptive reservoirs in global hydrological modeling
topic reservoirs
disruptivity
regulation
evaporation
reservoir bathymetry
mHM
url https://doi.org/10.1029/2023WR035433
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