Modelling study to quantify the impact of future climate and land use changes on water resources availability at catchment scale

Muhammad Afzal,Nikolaos Vavlas,Ragab Ragab

doi:10.2166/wcc.2020.117

Muhammad Afzal, Nikolaos Vavlas + Show 1 more

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https://doi.org/10.2166/wcc.2020.117

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Abstract

Abstract The focus of this study was to investigate the impact of climate and land-use changes on water resources and to find suitable drought indices to identify the occurrence, frequency and severity of the past and future drought events. The Ebbw catchment, Wales, UK was selected for this study. Data for the 1961–2012 period were used as input to the DiCaSM model. Following model calibration and validation, the model was run with UKCP09 future climate scenarios for three periods (30 years each) up to 2099 under three emission scenarios. The reconnaissance drought index, the standardized precipitation index, soil moisture deficit and the wetness index were able to reproduce the past drought events. The data of UKCP09, simple change factors to temperature (± °C) and rainfall (%) using Joint Probability plot and daily values of the weather generator were input to the model. The projections indicated that the streamflow and groundwater recharge are likely to increase in winter and to decrease in spring, summer and autumn. Under all emission scenarios, the greatest decrease in groundwater recharge and the streamflow is projected in the 2050s and 2080s under high emission scenario. Moreover, under medium and high emission scenarios, severity and frequency of the drought events are likely to be high. Land use change from grass and/or arable to woodland had significant impact on water resources.

Highlights

Climate change projections for the UK (Harris et al ; Smith et al ; Watts et al ) and historic trends observed by Alexander et al ( ) and Marsh et al ( ) suggest that it is likely that the UK, in the future, will experience wetter winters and drier summers and might experience more frequent summer droughts
In order to use the model for future predictions using UKCP09 scenarios, a successful calibration and validation was necessary to obtain the best set of catchment parameters that would lead to credible predictions
The streamflow projections under both the simplified change factors and the weather generator (WG) indicated that the streamflow is likely to increase in winter and to decrease in spring, summer and autumn, relative to the baseline period, under all emission scenarios (Figure 9)

Summary

Introduction

Climate change projections for the UK (Harris et al ; Smith et al ; Watts et al ) and historic trends observed by Alexander et al ( ) and Marsh et al ( ) suggest that it is likely that the UK, in the future, will experience wetter winters and drier summers and might experience more frequent summer droughts. The most severe drought in recent times occurred in the summer of 1976 and affected the whole country, the south-east of England where eight water companies introduced hosepipe bans that affected 15.6 million people and placed water consumers under intense pressure to use water wisely (Taylor et al ). Another significant drought event, mainly affecting the north and west of the UK, occurred in 1995 (Marsh ).

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