The predicted response within 50 years, relative to present day, is generally a small recovery in surface water Acid Neutralising Capacity (ANC) across the region Figure 1. However, a clear difference is predicted between recovery at moorland and forested sites; Mean ANC recovery at moorland sites is 21 ueq/l in comparison to 11 ueq/l at forested sites. In addition, all moorland sites are predicted to show an increase in ANC, whereas, despite the emission reductions, 11 of the forested sites are predicted to undergo a further drop in ANC. It is pertinent to note that the present day observed mean stream ANC is likely to be overestimated, since the monthly sampling regime was unable to capture the acidic pulses observed during high winter flows. Despite the predicted general increase in surface water ANC, soil base saturation is generally predicted to continue to decrease slightly over the next 50 years with a mean decrease for the region of -0.9, expressed as a percentage of cation exchange capacity.
Figure 1 Simulated 1997 ANC and predicted 2045 streamwater ANC for the Welsh region
