The impact of urban groundwater upon surface water - eTheses ...

CONCLUSIONS
investigated using archived gauging station data from the Environment Agency and discharge
measurements along the river. Computer modelling was used to investigate groundwater flow
to the river at several scales during dry weather flow and during a river flood event. Analysis
of the chemical quality (and flow) data sets was undertaken to discern trends, quantify mass
fluxes and understand physical-chemical controlling processes.
9.2 Conclusions
Detailed conclusions specific to each aspect of the work have already been summarised in the
relevant chapters (6,7,8,9). Key conclusions arising from the study and their generic relevance
are summarised for each of the study objectives below.
Objective 1. To characterise and quantify the contribution of groundwater-derived
contaminants to the surface water quality of an urban river at the subcatchment scale.
Groundwater comprises up to 60% of the dry-weather flow at the downstream end of the
study reach. The remainder is derived from pipe-end discharges which contain a high
proportion of imported water from outside the catchment. At the downstream end of the study
reach an estimated 6% of the mean dry weather flow and 6.7% of the surface water
geochemical (inorganic) mass flux is derived from the Birmingham Aquifer and the overlying
drift deposits.
Urban groundwater beneath Birmingham, particularly the shallow groundwater, is
contaminated relative to the natural background levels as measured in Sutton Park. However,
the estimated contaminant mass flux from the groundwater to the river was not sufficient to
cause a significant reduction in the current surface water quality based on the U.K.
environmental quality standards for freshwater. In some cases the groundwater improved the
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