Discharge simulations performed with a hydrological model using bias corrected regional climate model input

S C Van Pelt,A H Weerts,P Kabat,B J J M Van Den Hurk,H W Ter Maat

doi:10.5194/hess-13-2387-2009

S C Van Pelt, A H Weerts + Show 3 more

Open Access

https://doi.org/10.5194/hess-13-2387-2009

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Abstract

Abstract. Studies have demonstrated that precipitation on Northern Hemisphere mid-latitudes has increased in the last decades and that it is likely that this trend will continue. This will have an influence on discharge of the river Meuse. The use of bias correction methods is important when the effect of precipitation change on river discharge is studied. The objective of this paper is to investigate the effect of using two different bias correction methods on output from a Regional Climate Model (RCM) simulation. In this study a Regional Atmospheric Climate Model (RACMO2) run is used, forced by ECHAM5/MPIOM under the condition of the SRES-A1B emission scenario, with a 25 km horizontal resolution. The RACMO2 runs contain a systematic precipitation bias on which two bias correction methods are applied. The first method corrects for the wet day fraction and wet day average (WD bias correction) and the second method corrects for the mean and coefficient of variance (MV bias correction). The WD bias correction initially corrects well for the average, but it appears that too many successive precipitation days were removed with this correction. The second method performed less well on average bias correction, but the temporal precipitation pattern was better. Subsequently, the discharge was calculated by using RACMO2 output as forcing to the HBV-96 hydrological model. A large difference was found between the simulated discharge of the uncorrected RACMO2 run, the WD bias corrected run and the MV bias corrected run. These results show the importance of an appropriate bias correction.

Highlights

During the last few decades the world has become subject to a changing climate unprecedented in the last millennia
The simulated discharges for 2071–2100 are higher than the current discharges, but there is a large variability between the different RACMO2 runs
The original RACMO2 run overestimates the discharge, which is related to the temperature and precipitation bias

Summary

Introduction

During the last few decades the world has become subject to a changing climate unprecedented in the last millennia. According to IPCC (IPCC, 2007), winter precipitation is projected to increase over Northwest Europe. A large fraction of precipitation received by river basins is buffered in natural reservoirs, like soils, aquifers, lakes and artificial reservoirs from which water is released only slowly. In a temperate climate such as is prevailing over the Meuse and Rhine basin, this generally results in a continuous flow of water. It is more likely to react stronger to the effect of global climate change (Uijlenhoet et al, 2001). Another aspect, which increases the variability of the system, is the substrate characteristics of the Meuse. The restricted dimension of the floodplain of the Ardennes Massif offers little room for natural flood retention areas, so water moves downstream relatively quickly

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