Abstract:
Restoring lost and degraded wetlands is essential to ensure the health of our watersheds. Over
the past 200 years, historic tidal wetlands have been destroyed at an alarming rate (EPA
factsheet, 2001). Such reduction of tidal wetlands hamper various functions like water quality
protection, habitat for fish and other wildlife, and flood protection. Unless reserving the tide
of wetland loss, the quality of waters will continue to be threatened and part of natural
haritage will be lost.
Restoration is the return of a degraded wetland or former wetland to its preexisting, naturally
functioning condition, or a condition as close to that as possible (EPA factsheet, 2001). It is a
complex process that requires expertise, resource and commitments from many different
stakeholders. The timing of the restoration activities will be important not only to avoid
disturbing wildlife species but also to ensure that earlier phases of the restoration have been
successful before altering other habitat. It will be necessary to carefully monitor conditions as
the restoration proceeds, and adapt the restoration plans to ensure overall project goals are
achieved. Restoration projects require planning, implementation, monitoring and
management, using a team with expertise in ecology, hydrology, engineering and
environmental planning. Shallow estuaries are extremely dynamic regions where fluid
motions are associated with both surface waves and current. Its restoration requires a number
of factors to be taken into consideration.
The proper design as well as construction and maintenance of restoration work needs the
exact knowledge of hydrodynamics. There are several physical conditions that will affect the
feasibility of restoring tidal marshes: presence of channels, availability of material for levees,
pond subsidence, potential for flooding, and infrastructure impediments (bridges, harbours,lock gates, etc.). The insight of spatial and temporal variability of flow velocity is the major
factor controlling the morphology of the system. The erosion and sedimentation processes of
tidal marsh have an important effect on the proper functioning of estuary. The use of
numerical models in the restoration of a nature reserve has a great importance in terms of
development and evaluation of ever changing tidal system. Therefore, the hydrodynamic
investigation is chosen to be a major part of a nature reserve restoration project.
