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Tiner, Ralph W.

English

https://scholarworks.umass.edu/umpress_tidal_wetlands_primer_images/1002/thumbnail.jp

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Chapter 1, Figure 1.3

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Figure 1.7. The Ganges-Brahmaputra Delta has a shape quite different from the Mississippi Delta due to a strong marine influence from extremely high tides. This delta contains the largest continuous stand of mangroves in the world. (Copyright Geospatial Division, MDA Information Systems Inc., Gaithersburg, MD)Figure 1.8. The Nile Delta is a wave-dominated delta where strong wave action from the Mediterranean Sea smooths the seaward edge of the formation. (NASA image)

Chapter 1, Figure 1.8

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18  Chapter 1Figure 1.15. Swale marsh between ridges on a South Carolina barrier island.by their position in the estuary (e.g., barrier island, barrier beach, bay, coastal pond, river, headland, or ocean). Water flow path is bidirectional due to tidal forces, except where tidally restricted or controlled. Specific estuary types are also defined (e.g., drowned river valley, bar-built, tectonic, and fjord ), and modifiers are available to describe tidal range (microtidal, mesotidal, or macrotidal ) and hydrologic circulation patterns.Other classifications have been devel-oped for scientific research. A few are introduced below. A geomorphology-based  classification system classifies Maine salt marshes ( Kelley et al. 1988). Four types have been recognized: back-barrier, fluvial, bluff-toe, and transitional ( Figure 1.14). Back-barrier salt marshes form behind bar-rier islands and spits. Fluvial salt marshes develop in drowned valleys along rivers and streams (fluvial-major and fluvial-minor). Where cliffs are eroding and depositing sediment into the estuary below, bluff-toe marshes become established. Transitional salt marshes are those that form where saltwater invades low-lying freshwater wetlands. Another geomorphic classification system was created for investigating marsh evolution and sedimentation rates in bar-rier island systems (Oertel and Woo 1994). Three landscape settings are recognized and several marsh types occur within each setting ( listed in parentheses): 1) mainland fringe-marshes (valley, headland, inter-fluve, hammock, and tidal-channel ); 2) mid-lagoon marshes (tidal-channel, marsh island, platform, and hammock); and 3) back-barrier fringe-marshes (washover-fan, storm-surge platform, swale, flood-delta, and platform; Figure 1.15). The National Oceanic and Atmospheric Admin-istration ( NOAA) is creating a hierarchical marine and estuarine ecosystem and habitat classification system to provide a national 

Chapter 1, Figure 1.15

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Chapter 11, Figure 11.4

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Chapter 1, Figure 1.1

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Chapter 11, Figure 11.7

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354  Chapter 11A  common example of rehabilitation is restoring tidal flow to a tidal wetland with limited tidal influence due to tide gates or undersized culverts.Wetland creation involves building a wet-land where one did not exist since Colonial times, for example. It is not the site of a former wetland, but either upland (dryland ) or water. Constructing a wetland in those locations seeks to increase wetland extent and functions. Wetlands can be created by excavating an upland (dryland ) area to an elevation subject to frequent tidal flooding or by depositing sufficient fill in water to raise the bottom to the level of the intertidal zone. Creating a marsh by adding fill to a mudflat is typically considered wetland creation, while it could be viewed as a type of enhancement since the mudflat is techni-cally a wetland. Sometimes the line is blurry between what constitutes wetland restora-tion or creation. For example, if the shallow bottom to be filled was a former marsh that was lost due to coastal subsidence and erosion, creating marsh there would be con-sidered wetland restoration, although the restoration practices would be more typical of those used in creation projects.Wetland enhancement is the act of modifying a wetland to attain a level of a desired function above or different from that which the wetland type is normally capable of reaching. The targeted function may even be a function that the wetland did not perform. The wetland is altered in some way to satisfy the management objec-tive. It may change the wetland to another type (e.g., tidal marsh to aquatic bed ) or affect the wetland’s hydrology, vegetation, wildlife use, or other properties. Enhance-ment could be applied to a pristine wetland or a degraded one. In either case it modifies the wetland’s characteristics for the benefit of one or more functions at the expense of other functions. Examples include diking of natural tidal wetlands to create waterfowl Figure 11.1. Three examples of potential  restoration projects: (a) diked former tidal wetland now pasture ( Bandon Marsh National Wildlife Refuge, OR); ( b) filled wetland lacking structures; and (c) common reed marsh (Phragmites australis) has established on this former salt marsh whose tidal connection is altered by a causeway and an undersized culvert. (a: Roy Lowe, U.S. Fish and Wildlife Service)a bc

Chapter 11, Figure 11.1

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Chapter 11, Figure 11.2

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bFigure 11.3. Series of photographs showing growth of smooth cordgrass (Spartina alterniflora) plantings in just a single season ( 2009) at the Poplar Island restoration site ( MD): (a) May 4; ( b) June 2; (c) July 6; and (d ) September 21. This project involves rebuilding a lost island and associated wetlands with dredged material. (Griff Evans)adc

Chapter 11, Figure 11.3

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Figure 1.4. Coastal ponds are common along Rhode Island’s south shore ( Trustom and Card Ponds). Note that temporary inlets are closed by sand deposits but are visible by their  nonvegetated surfaces.Figure 1.5. Chesapeake Bay and Delaware Bay are excellent examples of drowned river  valley estuaries: Susquehanna and Delaware Rivers, respectively. (Copyright Geospatial  Division, MDA Information Systems Inc., Gaithersburg, MD)

Chapter 1, Figure 1.5

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Chapter 1, Figure 1.6

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