Cited by 415Hydrology and Watershed Management StudiesGeophysics and Gravity MeasurementsSoil Moisture and Remote Sensing

Sensitivity of simulated global-scale freshwater fluxes and storages to input data, hydrological model structure, human water use and calibration

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Müller Schmied, H., Eisner, S., Franz, D., Wattenbach, M., Portmann, F. T., Flörke, M., Döll, P.·2014·Hydrology and Earth System Sciences

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Abstract

Abstract. Global-scale assessments of freshwater fluxes and storages by hydrological models under historic climate conditions are subject to a variety of uncertainties. Using the global hydrological model WaterGAP (Water – Global Assessment and Prognosis) 2.2, we investigated the sensitivity of simulated freshwater fluxes and water storage variations to five major sources of uncertainty: climate forcing, land cover input, model structure/refinements, consideration of human water use and calibration (or no calibration) against observed mean river discharge. In a modeling experiment, five variants of the standard version of WaterGAP 2.2 were generated that differed from the standard version only regarding the investigated source of uncertainty. The basin-specific calibration approach for WaterGAP was found to have the largest effect on grid cell fluxes as well as on global AET (actual evapotranspiration) and discharge into oceans for the period 1971–2000. Regarding grid cell fluxes, climate forcing ranks second before land cover input. Global water storage trends are most sensitive to model refinements (mainly modeling of groundwater depletion) and consideration of human water use. The best fit to observed time series of monthly river discharge or discharge seasonality is obtained with the standard WaterGAP 2.2 model version which is calibrated and driven by daily reanalysis-based WFD/WFDEI (combination of Watch Forcing Data based on ERA40 and Watch Forcing Data based on ERA-Interim) climate data. Discharge computed by a calibrated model version using monthly CRU TS (Climate Research Unit time-series) 3.2 and GPCC (Global Precipitation Climatology Center) v6 climate input reduced the fit to observed discharge for most stations. Taking into account uncertainties of climate and land cover data, global 1971–2000 discharge into oceans and inland sinks ranges between 40 000 and 42 000 km3 yr−1. Global actual evapotranspiration, with 70 000 km3 yr−1, is rather unaffected by climate and land cover uncertainties. Human water use reduced river discharge by 1000 km3 yr−1, such that global renewable water resources are estimated to range between 41 000 and 43 000 km3 yr−1. The climate data sets WFD (available until 2001) and WFDEI (starting in 1979) were found to be inconsistent with respect to shortwave radiation data, resulting in strongly different actual evapotranspiration. Global assessments of freshwater fluxes and storages would therefore benefit from the development of a global data set of consistent daily climate forcing from 1900 to present.

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Research works printed but not linked: 3

  1. Kaspar, F.: Entwicklung und Unsicherheitsanalyse eines globalen hydrologischen Modells, Ph.D. thesis, University of Kassel, Germany, 2003.
  2. Schulze, K. and Döll, P.: Neue Ansätze zur Modellierung von Schneeakkumulation und - schmelze im globalen Wassermodell WaterGAP, in: Tagungsband zum 7. Workshop zur großskaligen Modellierung in der Hydrologie, edited by: Ludwig, R., Reichert, D., and Mauser, W., Kassel University Press, Kassel, 2004.
  3. Shuttleworth, W. J.: Evaporation, in: Handbook of Hydrology, edited by: Maidment, D. R., McGraw-Hill, New York, 4 4.1-4.53, 1993.

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Authors
Müller Schmied, H., Eisner, S., Franz, D., Wattenbach, M., Portmann, F. T., Flörke, M., & Döll, P.
Affiliations
  • University of Kassel (DE)
  • GFZ Helmholtz Centre for Geosciences (DE)
  • Goethe University Frankfurt (DE)
Corresponding author
  • Eisner, S.
  • Franz, D.
  • Wattenbach, M.
Venue
Hydrology and Earth System Sciences
Published
2014-09-10
Volume
18
Issue
9
Pages
3511-3538
ISSN
  • 1027-5606 (ISSN-L)
  • 1607-7938
OpenAlex
W2114721961
Cited by
415
References
100
Citations by year
2026: 13 · 2025: 36 · 2024: 26 · 2023: 38 · 2022: 32 · 2021: 66 · 2020: 51 · 2019: 37 · 2018: 36 · 2017: 33 · 2016: 25 · 2015: 16 · 2014: 6
FWCI
20.29
Type
journal article
Language
en
Open access
Locations
  • Hydrology and earth system sciences (publishedVersion, cc-by)
  • Publication Database GFZ (GFZ German Research Centre for Geosciences) (submittedVersion, cc-by)
  • Publication Database GFZ (GFZ German Research Centre for Geosciences) (submittedVersion, other-oa)
  • Publication Server of Goethe University Frankfurt am Main (Goethe University Frankfurt) (submittedVersion, cc-by)
Topics
  • Physical Sciences › Environmental Science › Water Science and Technology › Hydrology and Watershed Management Studies
  • Physical Sciences › Earth and Planetary Sciences › Oceanography › Geophysics and Gravity Measurements
  • Physical Sciences › Environmental Science › Environmental Engineering › Soil Moisture and Remote Sensing
Keywords
freshwater flux, model uncertainty, human water use, river discharge, actual evapotranspiration, radiative forcing, land cover, model calibration, groundwater depletion, renewable water resources, climate reanalysis data, CRU TS, shortwave radiation

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