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

GROUNDWATER FLOW MODELLING
Historically high levels of abstraction throughout the Birmingham Aquifer caused a large
drop in regional water levels resulting in reduced groundwater discharge and river flows. The
impact of changes to the regional head gradient and river levels is examined in more detail in
the next section.
6.9 Investigation of the effect of changes in river level and regional head.
6.9.1 Conceptual model
For a variety of reasons, changes may occur in river level or the regional groundwater head
gradient towards the river. Scenarios that might produce these alterations include climate
change resulting in increased or decreased recharge and river stage. A variation in
groundwater abstraction rates may reduce or increase the regional groundwater levels.
Sewage treatment works and industrial discharges to the river, which currently provide > 40%
of flow, may alter. River levels may rise as a result of reduced flow velocities owing to
channel engineering or weed growth. Both the MODFLOW and FAT3D models were used to
investigate the effect on contaminant flux to the river that may result from these changes in
the future.
6.9.2 Application of the Models
A sensitivity analysis of groundwater discharge to the river was undertaken. Changes in river
level and the regional head were simulated by raising or lowering the fixed head conditions by
a uniform amount under steady-state conditions. The changes occur in isolation whereas in
reality there would be greater interdependency, but some interesting points can be made.
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