Impact of Precipitation Spatial Resolution on the Hydrological Response of an Integrated Distributed Water Resources Model

Abstract

Precipita on is a key input variable to hydrological models, and the spa al variability of the input is expected to impact the hydrological response predicted by a distributed model. In this study, the eff ect of spa al resolu on of precipita on on runoff , recharge and groundwater head was analyzed in the Alergaarde catchment in Denmark. Six diff erent precipita on spa al resolu ons were used as inputs to a physically based, distributed hydrological model, the MIKE SHE model. The results showed that the resolu on of precipita on input had no apparent eff ect on annual water balance of the total catchment and runoff discharge hydrograph at watershed outlet. On the other hand, groundwater recharge and groundwater head were both aff ected. The impact of the spa al resolu on of precipita on input is reduced with increasing catchment size. The eff ect on stream discharge is rela vely low for a catchment size above 250 km 2 , and the eff ect is negligible when the en re catchment area of approximately 1000 km 2 is considered. In the present case the highest resolu on of 500 m was found to result in the best representa on of the hydrological response at subcatchment scale. Stream discharge, groundwater recharge, and groundwater head were also aff ected by the method for correc on of systema c errors in precipita on measurements. The results underscored the importance of using a spa al resolu on of the precipita on input that captures the overall precipita on characteris cs for the considered catchment or subcatchment. As long as the average precipita on of the considered catchment or subcatchment is accurately es mated, the spa al resolu on seems less important when the integrated response in the form of stream fl ow is considered.Precipita on is the most important input to hydrological models, and an accurate representation in space and time is critical for reliable predictions of the hydrological responses. However, a complicating factor is that precipitation oft en exhibits large spatial and temporal variations within a catchment. Particularly it is diffi cult to measure or infer the spatial structure from standard gauge measurements, and an improper spatial representation constitutes a signifi cant source of uncertainty in hydrological modeling (Berne et al., 2004). Spatial variability of precipitation impacts the predictions of the hydrological processes such as seasonal fl ow in streams, fl oods, evapotranspiration, recharge, and groudwater heads. Moreover, it is of signifi cant importance for the closure of the water balance of a watershed or a region (Vischel and Lebel, 2007).Over the years considerable research into the eff ect of precipitation on runoff response has been performed (Obled et al., 1994;Sigh, 1997;Koren et al., 1999;Bell and Moore, 2000;Berne et al., 2004;Smith et al., 2004;Segond et al., 2007). Many studies have analyzed the impact of the spatial density of rain gauges on runoff mechanisms and found that generally the quality of the model simulations deteriorates when the density of the gauge ...

Evaluating Global Reanalysis Datasets as Input for Hydrological Modelling in the Sudano-Sahel Region

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Spatial sensitivity analysis of snow cover data in a distributed rainfall-runoff model

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Historical trends in precipitation and stream discharge at the Skjern River catchment, Denmark

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