Salinity Management in Arid Regions - Restorative Redevelopment of Devastated Ecocultural Landscapes - page 426

Los Angeles sells it as drinking water and so it has a huge value. And like the Iraqi
marshlands, Owens Lake has more desiccated land than available water such that the
desire to establish more habitat must be balanced against a very water-limited envi-
ronment (Dickey and Madison 2004). One of the big management trade-offs of not
having enough water is the development of farming in the bottom of a lakebed in an
area that historically had a high water table. But simply putting water back into such
areas and creating open-water marsh areas and wet playa regions would create new
problems. The already high water table would be raised higher such that a subsurface
drainage system would be needed in order to remove the groundwater from under the
salt grasses or they would also turn white with salt during evaporation. So the sub-
surface drip infrastructure helps to keep salt from the surface, and the deep drainage
infrastructure allows percolation to collect that saltwater and move it to other areas
for alternative habitat creation (Dickey and Madison 2004).
The Sacramento Valley Basin-wide Management Plan is another relevant example
(Dickey and Madison 2004). As in southern Iraq, the valley is bordered by moun-
tains that provide a rain-on-snow hydrology system. There are huge silt loads and
big floods in the river, the presence of many dams, problems with salinization, and
widespread destruction of wetlands. Thus, there are many parallels with the marsh-
lands of Iraq. The Sacramento Valley is primarily used for irrigated rice production
and so has to remain fairly fresh, and again like the Iraqi marshes, it is not very
tolerant of salinity.
In the 1960s, background measures of soil salinity showed a good deal of flush-
ing taking place and the resulting presence of a high-quality and abundant water
supply. This was compromised by drought and regulatory pressures in the 1980s and
1990s, and by 1994 salinity was found to have increased fourfold over the previous
three decades. Impacts were starting to be noticed on rice yields due to less water
flushing through the system. This is very similar to the Iraqi marshes and other loca-
tions where problems are felt hardest in areas that have the most significant natural
drainage limitations. Field irrigation practices had not changed over this period, so
the problem was due to having a drainage and irrigation system that was set up for
flushing but with no flushing actually taking place. As a result, there is a new dimin-
ished water supply that has become mismatched with the unchanged facilities and is
now causing problems. The take-home message is that if the water supply is going
to be changed, the operations and facilities have to be changed as well (Dickey and
Madison 2004). So this means that the operations of the Iraq marshes will also have
to change given the drastic alteration in water supply that has occurred there over the
last twenty years.
The chain of cause and effect in the Sacramento example is that the drought has
resulted in a restricted water supply. Water detention in fields is a matter of course
in rice production, and this means that in order to continue agriculture more and
more of the water needs to be recycled. And as more water is recycled, it becomes
more saline and rice production begins to be impaired. The basin then shifts to a
more saline equilibrium condition with more and more areas becoming hotspots in
which salinity thresholds are exceeded. Criteria therefore aren't being met, and there
is a need for altering facilities management to avoid the continued and increasingly
precipitous trend toward reduced crop production.