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

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2.1) and surface water may on occasion recharge the groundwater (Toth, 1963, Nield et al.,
1994). Hence a reduction in flow or contamination in one will often affect the other.
Woessner (2000) states that groundwater flow to a river channel is dependent on:
1. the distribution and magnitude of the hydraulic conductivities within the river channel, the
associated fluvial plain sediments and the underlying bedrock;
2. the relation of river stage to the adjacent groundwater gradients; and
3. the geometry and position of the river channel within the fluvial plain.
Groundwater is influent to the river channel when the groundwater head at the channel
interface is greater than the river stage. Conversely, surface water is effluent from the channel
when the river stage is higher than the groundwater head. Groundwater through-flow may
occur when the groundwater head is higher than the river stage on one bank but lower on the
other (Townley et al., 1992). Groundwater flow may also occur parallel to the river in which
case only limited groundwater/surface water exchange may occur. During periods of high
recharge, groundwater ‘mounding’, (ie, rapid increases in head) may occur in the thin
unsaturated zone adjacent to surface-water bodies which may temporarily influence
groundwater/surface water interactions (Winter, 1983).
A key reference by Winter et al. (1998) summarised the current understanding of
groundwater/surface water interactions and their relationship to water supply, water quality
and the aquatic environment, in a variety of settings. A unifying framework based on the
concept of hydrologic landscapes is used to present conceptual models containing common
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