The Isle of Wight is a small island off the south coast of England. As with much of the developed world the island’s water supply is effectively universal, and is secure against all but the worst droughts. However, the frequency and magnitude of future droughts are anticipated to be worse than those on historic record due to the influence of climate change. While preparations against future water shortage are important, such measures must be efficient in terms of cost and abstractions due to pressure to keep costs to consumers low and minimize the impact on the environment. The development of a representation of future climate change which balances precision with the need to fully represent uncertainty is fundamental to water planning where such efficiency is required. In this, the Isle of Wight can also represent a useful case study for climate change forecasting methodology applicable to the wider UK and beyond.
A second challenge is presented by the geological and hydrological complexity of the island. Erosional and tectonic forces have altered the island’s geology and, as an island, a dense network of small catchments determines drainage to sea. This Thesis presents a complete modelling process for the assessment of changing water resource availability in such a case of high heterogeneity in which few assumptions can be made regarding hydrological processes. Empirical techniques are employed to determine functional groundwater units and detect correlations between river flows and groundwater elevations. Projections of climate change are reconciled against the distribution of historic observations. Finally, a modified drought index is introduced, allowing the impact of changed drought distributions on multiple water sources to be compared with historic events.