!. HYDROGEOLOGY OF ARID REGIONS
27
nomic implications of developing groundwater in these and similar systems
have been discussed by Maxey ( 1968 ).
IX. Artificial Changes in the Hydrogeology of Deserts
Groundwater development in desert regions of the world will increase
drastically in réponse to an increase in agricultural products (Simpson,
1968). Also, many of the coastal deserts of the world have mild climates
well suited for recreational development (Meigs, 1966). Water-supply
problems for this development will be even more severe than has been
experienced in the semiarid part of southern Spain during the expansion
of the tourist industry during the past two decades (1950-1970).
Inasmuch as water is such a critical factor in the biology of natural
deserts, a summary of some of the potential changes caused by groundwater development might be a somber but useful conclusion to this
chapter.
The most striking effect of groundwater development will be the eventual destruction of springs and areas of phreatophytic vegetation. All desert
aquifers, except those near perennial sources of water, will be eventually
depleted owing to the virtual lack of recharge. As water levels in the subsurface become lower, springs will tend to disappear (Fig. 14).
Another common effect where certain geologic conditions are present
is the creation of perched bodies of water in zones which have been previously dry. Excess irrigation water may tend to pile up near the surface
and in some places may produce new swampy areas.
If drainage is poor, the water added to the surface may evaporate to
leave a salty residue which, in turn, may kill some types of vegetation.
Eventual depletion of groundwater reservoirs in desert regions will have
the most drastic effects on irrigated agriculture. Maxey (1968), however,
has pointed out that from a strictly economic standpoint, this need not
be a disaster. In the first place, groundwater in an almost static condition
represents a resource similar to oil and gas. Unless it is taken out of the
ground, it has little economic value. Mining ground water can be a profitable enterprise, therefore, provided that proper plans are made for the entire life of the extraction process. Second, and perhaps most important,
is the fact that groundwater extraction can help build a vigorous economy
in a region which then, at a later date, can develop alternative sources
of water when groundwater becomes depleted.
As new projects are planned, biologists should be fully aware of the
numerous changes which may take place within the area of potential development as well as at distant points within the groundwater basin. These
27
nomic implications of developing groundwater in these and similar systems
have been discussed by Maxey ( 1968 ).
IX. Artificial Changes in the Hydrogeology of Deserts
Groundwater development in desert regions of the world will increase
drastically in réponse to an increase in agricultural products (Simpson,
1968). Also, many of the coastal deserts of the world have mild climates
well suited for recreational development (Meigs, 1966). Water-supply
problems for this development will be even more severe than has been
experienced in the semiarid part of southern Spain during the expansion
of the tourist industry during the past two decades (1950-1970).
Inasmuch as water is such a critical factor in the biology of natural
deserts, a summary of some of the potential changes caused by groundwater development might be a somber but useful conclusion to this
chapter.
The most striking effect of groundwater development will be the eventual destruction of springs and areas of phreatophytic vegetation. All desert
aquifers, except those near perennial sources of water, will be eventually
depleted owing to the virtual lack of recharge. As water levels in the subsurface become lower, springs will tend to disappear (Fig. 14).
Another common effect where certain geologic conditions are present
is the creation of perched bodies of water in zones which have been previously dry. Excess irrigation water may tend to pile up near the surface
and in some places may produce new swampy areas.
If drainage is poor, the water added to the surface may evaporate to
leave a salty residue which, in turn, may kill some types of vegetation.
Eventual depletion of groundwater reservoirs in desert regions will have
the most drastic effects on irrigated agriculture. Maxey (1968), however,
has pointed out that from a strictly economic standpoint, this need not
be a disaster. In the first place, groundwater in an almost static condition
represents a resource similar to oil and gas. Unless it is taken out of the
ground, it has little economic value. Mining ground water can be a profitable enterprise, therefore, provided that proper plans are made for the entire life of the extraction process. Second, and perhaps most important,
is the fact that groundwater extraction can help build a vigorous economy
in a region which then, at a later date, can develop alternative sources
of water when groundwater becomes depleted.
As new projects are planned, biologists should be fully aware of the
numerous changes which may take place within the area of potential development as well as at distant points within the groundwater basin. These