Salinity Management in Arid Regions - Restorative Redevelopment of Devastated Ecocultural Landscapes - page 423

water, or reducing salt load through avoiding adding new salt in industry or with
saline groundwater. For example, sometimes saline aquifers exist that are over-
charged by inefficient irrigation and then end up recharging rivers with extremely
saline water. There are good programs in the Colorado River Basin that have been
implemented to avoid that sort of salt loading just by shifting to a more efficient sys-
tem of irrigation. Sequestration of salt upstream in soil and groundwater or surface
waters is another option. Here, salt is simply stored in a salt pan without any water
running through.
In-marsh solutions include recycling and the encouragement of tolerant ecosys-
tems that nevertheless have value. The high value attributes of the historic marsh
ecosystem (France 2012) will no doubt be very important parts of the future of the
marshes (France 2011), but if there are also opportunities to recycle water and create
more saline habitat that has value of other sorts, that may be a good way to expand
the marsh opportunities (Dickey and Madison 2004). Sequestration, flushing, leach-
ing, and disposal are all valid management options. The ample drainage opportuni-
ties that now exist in the Iraqi marshes are going to be needed, perhaps not in their
entirety, but certainly for some strategic use to route salt out to the ocean.
RELEVANT APPLICATIONS
California has many similarities with Iraq: it is arid, it has a desert agriculture that
is very developed, it has many water control structures, and it has areas where water
once was but now is not. California has also lost most of its wetlands to a degree even
greater than that occurring in Iraq (France in Reed 2005), and it is struggling to try
to restore some of these.
In most of the American West and other places around the world where ground-
water is harvested, total dissolved solids (TDS) increase as irrigation utilizes
groundwater (Dickey and Madison 2004). Pumping the water out to irrigate a crop
evapotranspires water through the crop and leaves behind a salt residue. The result of
this is that in many arid areas where the groundwater is deep, the salts will eventually
leach back to groundwater. Over time, if large amounts of groundwater are pumped
out and the freshwater is evaporated, the amount of salt that goes back to ground-
water will increase its TDS, occasionally to levels such that the system becomes no
longer usable for crop irrigation. Such a scenario can be prevented through the adop-
tion of more efficient irrigation or by reducing the area irrigated. The goal here is to
balance the amount of water extracted by crop evapotranspiration with the amount
that comes back into the system through either rainfall or groundwater recharge,
toward an end of maintaining the freshwater in the long-term with a constant con-
centration of salt getting cycled through the system. Such systems don't really make
salt, but they also don't really destroy it, though they can concentrate it if crops are
grown and freshwater is used.
One hypothetical example (Dickey and Madison 2004) illustrates how, for an
eighty-acre farm in California, salt accumulation becomes a severe problem rep-
resentative of issues developing in dry-land agriculture around the world (see also
chapter 22). The rainfall in the area is about five inches, amounting to about 10 mil-
lion gallons per year of freshwater almost free of salt. At only five inches per year,