Abstract
Abstract. Precipitation is a crucial variable for hydro-meteorological applications. Unfortunately, rain gauge measurements are sparse and unevenly distributed, which substantially hampers the use of in situ precipitation data in many regions of the world. The increasing availability of high-resolution gridded precipitation products presents a valuable alternative, especially over poorly gauged regions. This study examines the usefulness of current state-of-the-art precipitation data sets in hydrological modeling. For this purpose, we force a conceptual hydrological model with multiple precipitation data sets in >200 European catchments to obtain runoff and evapotranspiration. We consider a wide range of precipitation products, which are generated via (1) the interpolation of gauge measurements (E-OBS and Global Precipitation Climatology Centre (GPCC) V.2018), (2) data assimilation into reanalysis models (ERA-Interim, ERA5, and Climate Forecast System Reanalysis – CFSR), and (3) a combination of multiple sources (Multi-Source Weighted-Ensemble Precipitation; MSWEP V2). Evaluation is done at the daily and monthly timescales during the period of 1984–2007. We find that simulated runoff values are highly dependent on the accuracy of precipitation inputs; in contrast, simulated evapotranspiration is generally much less influenced in our comparatively wet study region. We also find that the impact of precipitation uncertainty on simulated runoff increases towards wetter regions, while the opposite is observed in the case of evapotranspiration. Finally, we perform an indirect performance evaluation of the precipitation data sets by comparing the runoff simulations with streamflow observations. Thereby, E-OBS yields the particularly strong agreement, while ERA5, GPCC V.2018, and MSWEP V2 show good performances. We further reveal climate-dependent performance variations of the considered data sets, which can be used to guide their future development. The overall best agreement is achieved when using an ensemble mean generated from all the individual products. In summary, our findings highlight a climate-dependent propagation of precipitation uncertainty through the water cycle; while runoff is strongly impacted in comparatively wet regions, such as central Europe, there are increasing implications for evapotranspiration in drier regions.
Highlights
Precipitation is a key quantity in the water cycle since it controls water availability, including both blue and green water resources (Falkenmark and Rockström, 2006; Orth and Destouni, 2018)
Runoff and ET are modeled with a conceptual hydrological model, the simple water balance model (SWBM)
Runoff simulations are impacted by precipitation uncertainty, while the ET simulations are much less influenced by precipitation uncertainty, as indicated by the regression slope
Summary
Precipitation is a key quantity in the water cycle since it controls water availability, including both blue and green water resources (Falkenmark and Rockström, 2006; Orth and Destouni, 2018). Indirect evaluation of the data sets through application in hydrological modeling is a valuable alternative in this context as precipitation is translated into variables with more reliable observations, such as runoff, as long as runoff is measured in catchments with near-natural dynamics (Thiemig et al, 2013; Nerini et al, 2015; Beck et al, 2017a, b, 2019a, b; Fereidoon et al, 2019; Ehsan Bhuiyan et al, 2019; Mazzoleni et al, 2019; Arheimer et al, 2020; Dembélé et al, 2020) While this approach relies on the propagation of precipitation uncertainty into runoff, it is largely underexplored with respect to when and where this propagation pathway is active.
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