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Journal ArticleDOI

Indirect Environmental Effects of Dikes on Estuarine Tidal Channels: Thinking Outside of the Dike for Habitat Restoration and Monitoring

01 Apr 2004-Estuaries (Springer-Verlag)-Vol. 27, Iss: 2, pp 273-282
TL;DR: In this article, the authors analyzed historical photos of the Skagit River delta marshes (Washington, U.S.) and compared changes in estuarine marsh and tidal channel surface area from 1956-2000 in the Wiley Slough area of the South Fork Skagits delta, and from 1937-2000 on the North Fork delta.
Abstract: While the most obvious effects of dike construction and marsh conversion are those affecting the con- verted land (direct or intended effects), less immediately apparent effects also occur seaward of dikes (indirect or unintended effects). I analyzed historical photos of the Skagit River delta marshes (Washington, U.S.) and compared changes in estuarine marsh and tidal channel surface area from 1956-2000 in the Wiley Slough area of the South Fork Skagit delta, and from 1937-2000 in the North Fork delta. Dike construction in the late 1950s caused the loss of 80 ha of estuarine marsh and 6.7 ha of tidal channel landward of the Wiley Slough dikes. A greater amount of tidal channel surface area, 9.6 ha, was lost seaward of the dikes. Similar losses were observed for two smaller North Fork tidal channel systems. Tidal channels far from dikes did not show comparable changes in channel surface area. These results are consistent with hydraulic geometry theory, which predicts that diking reduces tidal flushing in the undiked channel remnants and this results in sedimentation. Dikes may have significant seaward effects on plants and animals associated with tidal channel habitat. Another likely indirect dike effect is decreased sinuosity in a distributary channel of the South Fork Skagit River adjacent to and downstream of the Wiley Slough dikes, compared to distributary channels upstream or distant from the dikes. Loss of floodplain area to diking and marsh conversion prevents flood energy dissipation over the marsh surface. The distributary channel has responded to greater flood energy by increasing mean channel width and decreasing sinuosity. Restoration of diked areas should consider historic habitat loss seaward of dikes, as well as possible benefits to these areas from dike breaching or removal. Habitat restoration by breaching or removal of dikes should be monitored in areas directly affected by dikes, areas indirectly affected, and distinct reference areas.

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Citations
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Journal ArticleDOI
TL;DR: It is concluded that the best way to protect salt marshes and the services they provide is through the integrated approach of ecosystem-based management.
Abstract: Salt marshes are among the most abundant, fertile, and accessible coastal habitats on earth, and they provide more ecosystem services to coastal populations than any other environment. Since the Middle Ages, humans have manipulated salt marshes at a grand scale, altering species composition, distribution, and ecosystem function. Here, we review historic and contemporary human activities in marsh ecosystems—exploitation of plant products; conversion to farmland, salt works, and urban land; introduction of non-native species; alteration of coastal hydrology; and metal and nutrient pollution. Unexpectedly, diverse types of impacts can have a similar consequence, turning salt marsh food webs upside down, dramatically increasing top down control. Of the various impacts, invasive species, runaway consumer effects, and sea level rise represent the greatest threats to salt marsh ecosystems. We conclude that the best way to protect salt marshes and the services they provide is through the integrated approach of ecosystem-based management.

770 citations

Journal ArticleDOI
TL;DR: In this article, the authors developed a remote-sensing method to assess change over ~4000 km of the Yellow Sea coastline and discovered extensive losses of the region's principal coastal ecosystem associated with urban, industrial, and agricultural land reclamations.
Abstract: In the Yellow Sea region of East Asia, tidal wetlands are the frontline ecosystem protecting a coastal population of more than 60 million people from storms and sea-level rise. However, unprecedented coastal development has led to growing concern about the status of these ecosystems. We developed a remote-sensing method to assess change over ~4000 km of the Yellow Sea coastline and discovered extensive losses of the region's principal coastal ecosystem – tidal flats – associated with urban, industrial, and agricultural land reclamations. Our analysis revealed that 28% of tidal flats existing in the 1980s had disappeared by the late 2000s (1.2% annually). Moreover, reference to historical maps suggests that up to 65% of tidal flats were lost over the past five decades. With the region forecast to be a global hotspot of urban expansion, development of the Yellow Sea coastline should pursue a course that minimizes the loss of remaining coastal ecosystems.

369 citations

Journal ArticleDOI
TL;DR: In this article, the authors explore restoration concepts, examples, and challenges from the Pacific and Gulf coasts and review the concepts of ecosystem trajectories, alternative restoration approaches, and the ideal attributes of functional self-sustaining restoration in the context of realities of restoration planning, design, and implementation.

217 citations

Journal ArticleDOI
TL;DR: In this article, the authors focus on ecosystem recolonization by the biota and their functioning and separate Type A Ecoengineering, where the physico-chemical structure is modified on the basis that ecological structure and functioning will then follow, and Type B Ecoengineering where the Biota are engineered directly such as through restocking or replanting, where suitable physical conditions, especially hydrography and sedimentology, are created to recover estuarine ecology by natural or human-mediated colonisation of primary producers and consumers.
Abstract: Ecological Engineering (or Ecoengineering) is increasingly used in estuaries to re-create and restore ecosystems degraded by human activities, including reduced water flow or land poldered for agricultural use. Here we focus on ecosystem recolonization by the biota and their functioning and we separate Type A Ecoengineering where the physico-chemical structure is modified on the basis that ecological structure and functioning will then follow, and Type B Ecoengineering where the biota are engineered directly such as through restocking or replanting. Modifying the physical system to create and restore natural processes and habitats relies on successfully applying Ecohydrology, where suitable physical conditions, especially hydrography and sedimentology, are created to recover estuarine ecology by natural or human-mediated colonisation of primary producers and consumers, or habitat creation. This successional process then allows wading birds and fish to reoccupy the rehabilitated areas, thus restoring the natural food web and recreating nursery areas for aquatic biota. We describe Ecohydrology principles applied during Ecoengineering restoration projects in Europe, Australia, Asia, South Africa and North America. These show some successful and sustainable approaches but also others that were less than successful and not sustainable despite the best of intentions (and which may even have harmed the ecology). Some schemes may be ‘good for the ecologists’, as conservationists consider it successful that at least some habitat was created, albeit in the short-term, but arguably did little for the overall ecology of the area in space or time. We indicate the trade-offs between the short- and long-term value of restored and created ecosystems, the success at developing natural structure and functioning in disturbed estuaries, the role of this in estuarine and wetland management, and the costs and benefits of Ecoengineering to the socio-ecological system. These global case studies provide important lessons for both the science and management of estuaries, including that successful estuarine restoration is a complex and often difficult process, and that Ecoengineering with Ecohydrology aims to control and/or simulate natural ecosystem processes.

129 citations

Journal ArticleDOI
TL;DR: A new SD model is developed and test which simulates the dynamics between the farmers' economic system and their rice agriculture operations, and uniquely, integrates the role of fluvial sediment deposition within their dyke compartment, and is used to explore a range of alternative rice cultivation strategies.

105 citations

References
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Book
01 Jan 1982
TL;DR: This book is a blend of erudition, popularization, and exposition, and the illustrations include many superb examples of computer graphics that are works of art in their own right.
Abstract: "...a blend of erudition (fascinating and sometimes obscure historical minutiae abound), popularization (mathematical rigor is relegated to appendices) and exposition (the reader need have little knowledge of the fields involved) ...and the illustrations include many superb examples of computer graphics that are works of art in their own right." Nature

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TL;DR: A blend of erudition (fascinating and sometimes obscure historical minutiae abound), popularization (mathematical rigor is relegated to appendices) and exposition (the reader need have little knowledge of the fields involved) is presented in this article.
Abstract: "...a blend of erudition (fascinating and sometimes obscure historical minutiae abound), popularization (mathematical rigor is relegated to appendices) and exposition (the reader need have little knowledge of the fields involved) ...and the illustrations include many superb examples of computer graphics that are works of art in their own right." Nature

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"Indirect Environmental Effects of D..." refers background in this paper

  • ...Tidal channel allometry follows from a more general fractal theory of landforms (RodriguezIturbe and Rinaldo 1997), and the scaling of perimeter with surface area is a common reflection of landform fractal geometry (Mandelbrot 1983; Sugihara and May 1990)....

    [...]

01 Jan 1987

3,987 citations

Book
01 Jan 1995
TL;DR: Fluvial processes in geomorphology, Fluvial Processes in Geomorphology as discussed by the authors, fluvial processes and geomorphological processes in the field of geology.
Abstract: Fluvial processes in geomorphology , Fluvial processes in geomorphology , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

1,781 citations


"Indirect Environmental Effects of D..." refers background in this paper

  • ...Greater adjustment in width relative to depth with changing discharge is consistent with hydraulic geometry theory (Leopold et al. 1964)....

    [...]

  • ...Because high sinuosity is associated with small channel width relative to depth (Leopold et al. 1964), the observed correlation between changes in sinuosity and in mean channel width suggests that distributary channel widths changed to a greater degree than channel depths....

    [...]

  • ...As a final error check, meander bends in tidal channels were examined at scales ranging from 1:1,000 to 1:10,000 to determine whether erosion had occurred in the cut banks of the meanders and sediment deposition at the point bars, in accord with theoretical expectations (Leopold et al. 1964)....

    [...]

  • ...Sinuosity was the ratio of sinuous length to straight length (Leopold et al. 1964)....

    [...]