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

CONCLUSIONS
8. The existing regional groundwater models (Greswell, 1992 and Robinson, 2001) could be
refined and used in conjunction with groundwater quality data to obtain better estimates of
geochemical mass flux to the river. The model should include increased resolution along
the river and calibration against surface water hydrographs. Abstraction well, land use,
rainfall and pollutant-loading data could be combined in the model to develop a
geochemical mass balance for the aquifer.
9. Computer modelling of the flood plain and river channel could be undertaken to examine
the extent of the hyporheic zone, the surface water exchange with it, and the variation in
residence times of both groundwater and surface water within this zone. The model could
be used to simulate flood events to determine the contribution of groundwater to surface
water flows, which has relevance to flood defence planning and surface-water quality
during these events. The modelling should be three dimensional, incorporating the
hyporheic zone, the effect of recharge and unsaturated flow processes. The effect of an
increase in riverbed conductivity due to particle entrainment under high flows could also
be examined.
10. Further information is required on the processes controlling the variability of groundwater
contaminant flux to the surface water over time, on both the catchment scale and for
individual plumes. Repeat sampling of riverbed piezometers and surface waters should be
conducted to determine how variations in groundwater discharge quality are related to the
level of baseflow and recharge. Continuous conductivity measurements from the Water
Orton gauging station may be of use in this study.
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