London scoping - ukcip

metres AOD
Final Report
24
Figure 3.11 Groundwater levels at Trafalgar Square, 1845-2001
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Potable groundwater resources may be impacted adversely by a range of residues originating
from agriculture, landfill or accidental spills. Concentrations of nitrates, phosphates and total
organic carbon are generally low in the London chalk aquifer due to the clay cover protection
from surface pollutants. However, localised contamination by solvents and hydrocarbons has
occurred via existing boreholes and other conduits. Shallow groundwater has also been
contaminated by urban waste within the gravels aquifer (EA, 2001b).
3.8 Tidal Levels
An anticipated consequence of global warming is a rise in mean sea-level, due to the thermal
expansion of ocean water and the melting of land glaciers (Woodworth et al., 1999; Shennan,
1993). Since 1933, the Permanent Service for Mean Sea Level (PMSL) has been responsible
for the collection, archiving, and analysis of sea level data from a global network of tide gauges
(Woodworth, 1991). This data set currently holds records for over 50 stations around the
British Isles, of which about a dozen have records that are at least 30 years in length.