Environmental Engineering Reference
In-Depth Information
Typically these plants are installed as seedlings obtained from nurseries. Such an
approach is of course impractical in situations such as restoring the large-scale wet-
lands in southern Iraq. Here, however, the reflooded marshes are being colonized
again with Phragmities, demonstrating that a regional seed bank still exists upon
which to plan future restoration efforts. In this case, simply getting the water to the
new wetlands and retaining it there provide an opportunity for growth and reestab-
lishment through colonization of natural plants.
Plants typically installed in treatment wetlands include cattails ( Typha spp.),
bulrushes ( Scirpus spp.), and the tall reed grass endemic to the Iraq marshlands
( Phragmities spp.), all of which have similar treatment performances, with the ulti-
mate choice being a matter of personal and regional interest, to some extent consis-
tent with the local ecology and expectations of regulators and wetland owners (Bays
2004). Increasingly CH2MHILL is using mixed native species to produce a resulting
flora that may be just as diverse as a nearby natural system as well as optimally func-
tional in terms of contaminant removal.
PUBLIC USE AND OPERATIONS AND MAINTENANCE
Accounts by British adventurers visiting the marshlands of southern Iraq are
filled with anecdotes about widespread infection among the resident marsh Arabs
(Thesiger 1964). Because of the overall rarity of surface water in Mesopotamia, the
poor quality of the water of the Euphrates and Tigris Rivers is even today not a detri-
ment to recreational activity (FigureĀ 18.2). Nevertheless, in situations where waste-
water effluent is a major water source to wetlands, as for example in the Las Vegas
Wash (chapters 8 and 13), public movement should be restricted to avoid contact.
In Iraq, wetland designs should try to create a series of zones of wetland treatment
FIGURE 18.2 Playing in a branching channel of the Tigris River in Syria near the Turkish
and Iraqi borders.
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