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8
Groundwater resources and

environmental management

8.1 Introduction resources have a number of positive advantages com-
pared to surface reservoir developments that include:
The development of groundwater resources for (i) a large storage volume that can be developed
public, agricultural and industrial uses can create in stages as demand for water arises; (ii) resilience
environmental conflicts. Groundwater abstractions to drought conditions because of the large storage
capture recharge water that might otherwise flow to volume; (iii) relatively low environmental impact of
springs and rivers and so diminish the freshwater well-field developments; and (iv) no loss of storage
habitats dependent on groundwater discharge. In volume to evaporation. With current awareness that
the current era of integrated river basin manage- surface water and groundwater resources should
ment (see Section 1.8), sufficient volume of water is be managed together, it is useful to conceive this
required to maintain freshwater (or saline) ecosys- approach in the context of a water balance equation
tems. In this way, the fraction of available recharge that equates demand for water against abstraction
needed for environmental benefits is accounted for, requirements and environmental needs.
together with the fraction required for human and
economic benefits in order to achieve sustainable
groundwater development (see Fig. 1.1). 8.2.1 Water balance equation
In this chapter, examples of sustainable and non-
sustainable groundwater resources development The basic raw resource within a catchment is pre-
schemes at large and regional scales are discussed cipitation (P) and, as shown in Fig. 8.1, precipitation is
together with examples of modern groundwater either lost to evaporation and transpiration (usually
management techniques including artificial storage combined and referred to as evapotranspiration, ET)
and recovery and riverbank filtration schemes. The (see Section 5.3) or routed through the hydrological
adverse environmental impacts of groundwater pathways of overland flow and interflow to give surface
exploitation are illustrated with reference to the sens- water runoff (S ) and groundwater discharge (G )
R R
itivity of river flows and wetlands to groundwater (see Fig. 5.26). The groundwater discharge component
inputs. Lastly, the possible changes in groundwater is supplied by groundwater recharge and includes
resources, both quantity and quality, as a result of natural discharge to springs and rivers (the river base-
climate change are reviewed based on current know- flow, Q ) and artificial abstractions (Q ). Depending
G A
ledge of predicted scenarios of future climate. on the catchment geology, the groundwater catch-
ment may or may not coincide with the surface
catchment area such that additional components of
8.2 Groundwater resources schemes cross-formational groundwater flow (Q ) may need
U
to be considered. Now, assuming that the surface water
The assessment and development of groundwater and groundwater catchments coincide, the following
resources is central to hydrogeology. Groundwater catchment water balance equation can be written: