THE EFFECTS OF CLIMATE CHANGES ON AQUIFER STORAGE AND RIVER BASEFLOW

The effects of changes in climate on aquifer storage and groundwater f low to rivers have been investigated using an idealized representation of the aquifer/river system. The generalized aquifer/river model can incorporate spatial variability in aquifer transmissivity and is appli ed with parameters characteristic of Chalk and Triassic sandstone aqui fers in the United Kingdom, and is also applicable to other aquifers e lsewhere. The model is run using historical time series of recharge, e stimated from observed rainfall and potential evaporation data, and wi th climate inputs perturbed according to a number of climate change sc enarios. Simulation'S of baseflow suggest large proportional reduction s at low flows from Chalk under high evaporation change scenarios. Sim ulated baseflow from the slower responding Triassic sandstone aquifer shows more uniform and less severe reductions. The change in hydrologi cal regime is less extreme for the low evaporation change scenario, bu t remains significant for the Chalk aquifer.