Groundwater-Related Risk Assessment - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 755

17.1.3.3 Impact of a Revised Quantitative Groundwater Regime
Any changes in the quantitative groundwater regime, it should be realised, are also
going to impact groundwater quality. In wetlands, since strongly dependent on
groundwater, the increase in temperature, sea-level rise and changes in precipita-
tion will strongly affect the hydrological regime. In many wetlands the groundwater
table is very shallow and reduction of the groundwater level could lead to drying
out of the wetland. In addition, groundwater-level lowering processes very often
result in a general worsening of groundwater quality. Sea-level rise, on the other
hand, could produce coastal erosion and sea water intrusion into coastal wetlands
and deltas.
Similar effects may be seen in urban areas, where the water regime is influenced
by the large contribution of covered areas, including built-up areas. However, Lerner
( 2002 ) showed that total urban recharge is similar to or higher than rural recharge for
two main reasons: excess rainfall is often routed to groundwater through soakaways,
and covered surfaces are frequently more permeable than they appear and so allow
some infiltration while suppressing plant growth and evapotranspiraton.
The groundwater quantity and quality may also become modified as an indi-
rect result of water losses in urban water supply and sewerage systems. Losses
from urban water supply distribution networks result in an increase in groundwater
recharge. In the Alicante village of Vergel (Spain), for example, more than 45% of
the water circulating through the urban supply system was lost due to poor mainte-
nance of the infrastructure (De la Orden Gómez 2006 ). And losses from sewage
pipelines can lead to groundwater contamination. The leakage rates from water
mains are typically 25% (De la Orden Gómez 2006 ). Both exfiltration from and
infiltration into sewers occur with only a small net effect on groundwater quantity,
but exfiltration from sewers can have a significant effect on groundwater quality
(Chisala and Lerner 2008 ; Lerner 2002 ).
In Spain, the Spanish Geological Survey (IGME) carried out a study to assess the
influence on groundwater quality of both the accidental spills in sewage nets and the
spills coming from industries located inside the municipalities (De la Orden Gómez
2006 ).
Urbanization in some coastal areas with recreational facilities, along the
Mediterranean coast for example, has also impacted the hydrological regime and,
hence, the quality of the aquifers. Recycled waste water that is used to irrigate
golf courses may increase recharge and impact water quality. On the other hand, if
groundwater is used for irrigation of the golf course, the total amount of permeation
could diminish instead.
17.1.4 Scope of the “Groundwater-Related Aspects (Part V)”
With regard to the water-saturated zone , the “Groundwater-Related Aspects
(Part V)” primarily focuses on the second position of groundwater mentioned in
Section 17.1.2 , that is, groundwater from the perspective of a transportation mean