Evaluating seasonal hydrological extremes in mesoscale (pre-)Alpine basins at coarse 0.5° and fine hyperresolution

Buitink, Joost; Uijlenhoet, Remko; Teuling, Adriaan J.

Hydrological models are being applied for impact assessment across a wide range of resolutions. In this study, we quantify the effect of model resolution on the simulated hydrological response in five mesoscale basins in the Swiss Alps using the distributed hydrological model Spatial Processes in Hydrology (SPHY). We introduce a new metric to compare a range of values resulting from a distributed model with a single value: the density-weighted distance (DWD). Model simulations are performed at two different spatial resolutions, matching common practices in hydrology: 500 m inline-formula× 500 m matching regional-scale models, and 40 km inline-formula× 40 km matching global-scale modeling. We investigate both the intra-basin response in seasonal streamflow and evapotranspiration from the high-resolution model and the difference induced by the two different spatial resolutions, with a focus on four seasonal extremes, selected based on temperature and precipitation. Results from the high-resolution model show that the intra-basin response covers a surprisingly large range of anomalies and show that it is not uncommon to have both extreme positive and negative flux anomalies occurring simultaneously within a catchment. The intra-basin response was grouped by land cover, where different dominant runoff-generating processes are driving the differences between these groups. The low-resolution model failed to capture the diverse and contrasting response from the high-resolution model, since neither the complex topography nor land cover classes were properly represented. DWD values show that, locally, the hydrological response simulated with a high-resolution model can be a lot more extreme than a low-resolution model might indicate, which has important implications for global or continental scale assessments carried out at coarse grids of inline-formula M4inlinescrollmathml normal 0.5 × normal 0.5 48pt11ptsvg-formulamathimg93606b8150708994ab85cde53b8434f1 hess-23-1593-2019-ie00001.svg48pt11pthess-23-1593-2019-ie00001.png inline-formula or inline-formula M6inlinescrollmathml normal 0.25 × normal 0.25 64pt11ptsvg-formulamathimg9e2401fb8bdf3f03e4a114f8aa487c4b hess-23-1593-2019-ie00002.svg64pt11pthess-23-1593-2019-ie00002.png resolution.



Buitink, Joost / Uijlenhoet, Remko / Teuling, Adriaan J.: Evaluating seasonal hydrological extremes in mesoscale (pre-)Alpine basins at coarse 0.5° and fine hyperresolution. 2019. Copernicus Publications.


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