Restoration of estuarine wetlands using thin cover placement: A pilot application in Brunswick, Georgia

This paper presents the design concepts and basis for using a thin layer cover (TLC) of sand to restore historically impacted wetlands in Georgia’s Brunswick estuary. The project site is a mix of tidal creeks, marshes, brackish estuary, and an adjacent upland area that has been affected by historical industrial operations. A pilot project to test cover placement methodology and performance in advance of future full-scale TLC implementation was completed in 2018. It involved placing 6-9 inches of material in a 2/3-acre marsh area. Two material types — sand and higher organic content fines — were tested. The contractor, Sevenson Environmental Services, identified the appropriate equipment, means, and methods to hydraulically convey and place the TLC material within the pilot area in accordance with stated performance objectives. A mat-based access road was installed to enable equipment to move the pipeline and spray nozzle for fine placement control within the pilot marsh area. The thin cover placed in the field ranged from 6-12 inches thick (versus the design thickness of 6-9 inches) to meet the minimum required thickness and account for over placement. A 30- to 45-degree spray yielded the best distribution of materials for the equipment used. Placement of sandy material was faster and more uniform than fines due to the material’s enhanced settling characteristics and ease of distribution. A modified topsoil-fines mix with a baffle plate eventually permitted optimal placement of fines within the study area while maintaining the target organic content. Turbidity in the water discharged from the pilot area was minimized by environmental controls (e.g. perimeter hay bales) installed by the contractor. The mat-based access road initially experienced some settlement due to loading on the soft sediments and marsh root mat; the road required restoration following project completion. Physical and vegetative monitoring conducted in six-month increments over a two-year period indicated strong natural recolonization of vegetation and the re-establishment of benthic species including fiddler crab. This paper presents lessons learned, design implications, and best management practices for future thin cover placement projects in estuarine settings.

Evaluating direct and strategic placement of dredged material for marsh restoration through model simulations

Dredged material can be used for marsh restoration by depositing it on the marsh surface (thin-layer placement), by releasing it at the mouth of channels and allowing tidal currents to transport it onto the marsh platform (channel seeding), or by creating new marshes over shallow areas of open water. We investigate the efficacy of these different methods using a comprehensive 2D marsh evolution model that simulates tidal dynamics, vegetation processes, bank and wave erosion, and ponding. Total marsh area is assessed over 50 years in an idealized microtidal marsh under different relative sea level rise (RSLR) scenarios. For a given volume of total sediment added, the frequency of deposition is relatively unimportant in maximizing total marsh area, but the spatial allocation of the dredged material is crucial. For a given volume of sediment, thin-layer deposition is most effective at preserving total marsh area, especially at high rates of RSLR. Channel seeding is less efficient, but it could still provide benefits if larger amounts of sediment are deposited every 1-2 years. Marsh creation is also beneficial, because it not only increases the marsh area, but additionally slows the erosion of the existing marsh. The 2D model is highly computationally efficient and thus suited to explore many scenarios when evaluating a restoration project. Coupling the model with a cost assessment of the different restoration techniques would provide a tool to optimize marsh restoration.

The vegetation of a relict salt marsh area in the Pisan coast in the context of brackish wetlands of Tuscany

The paper presents the results of phytosociological surveys carried out in Galanchio-Cornacchiaia, a salt marsh area on the Pisan coast (northern Tuscany), which survived the agricultural reclamation. The vegetation surveys confirm the brackish features of the site, while highlighting three substantially different subareas in terms of prevailing vegetation. The phytosociological study allowed the identification of 11 marsh phytocoenoses attributable to 12 associations (Crypsidetum aculeatae; Parapholidetum filiformis; Suaedo maritimae-Salicornietum patulae; Suaedetum maritimae; Puccinellio festuciformis-Halimionetum portulacoidis; Puccinellio festuciformis-Sarcocornietum perennis; Elytrigio elongatae-Inuletum crithmoidis; Limonio narbonensis-Juncetum gerardi; Puccinellio festuciformis-Aeluropetum litoralis, Junco maritimi-Spartinetum junceae; Juncetum maritimi-acuti; Phragmitetum australis). These plant communities are referable to 3 brackish habitats and related subtypes, reported in 92/43 ECC Directive habitats. This biotope, although part of the neighboring area of the Regional Park of Migliarino San Rossore Massaciuccoli, is currently in an extremely precarious balance and threatened by the surrounding agricultural activities. The knowledge of its naturalistic peculiarities and remarkable biodiversity, can contribute to its increased protection and conservation. This study add new data to the knowledge of the brackish vegetation of Tuscany.

Investigation and assessment of ecological water resources in the salt marsh area of a salt lake: A case study of West Taijinar Lake in the Qaidam Basin, China

The water ecology of salt marshes plays a crucial role in climate regulation, industrial production, and flood control. Due to a poor understanding of water ecology and the extensive mining of salt resources, concerns are mounting about declining groundwater levels, shrinking salt marshes, and other problems associated with the simple yet extremely fragile water ecosystem of salt marshes in arid salt lake areas. This study assessed the ecological status of water resources in the downstream salt marsh area of West Taijinar Lake in the Qaidam Basin, China (2010–2018). Using data from a field investigation, the water ecosystem was divided into an ecological pressure subsystem, an environmental quality subsystem, and a socio-economic subsystem according to an analytic hierarchy process. Each subsystem was quantitatively assessed using the ecological footprint model, the single-factor index, and available data for the salt marsh area. The results showed that water resources were always in a surplus state during the study period, whose development and utilization had a safe status. Surface water had low plankton diversity with no evidence of eutrophication, but its Cl- and SO42- concentrations were too high for direct industrial water uses. Groundwater quality was classified into class V because of high salt concentrations, which could be considered for industrial use given the demand of industrial production. The socio-economic efficiency of water resources was high, as distinguished by decreased water consumption per 10,000 yuan GDP and excellent flood resistance. In conclusion, the ecological status of water resources was deemed good in the study area and this could help sustain regional development. However, since the water ecology in this area is mainly controlled by annual precipitation, it would be challenging to deal with the uneven distribution of precipitation and flood events and to make full use of them for groundwater recharge. This study provides insight into the impact of salt lake resource exploration on water ecology, and the results can be useful for the rational utilization of water resources in salt marshes in other arid areas.

Ladislavella occulta (Jackiewicz, 1959) – a species of aquatic snails new for Hungary with remarks on its distribution in Central and Eastern Europe

A finding of the lymnaeid species Ladislavella occulta (Jackiewicz, 1959) [Mollusca: Gastropoda: Lymnaeidae] in Hungary is reported, which is the first record of this snail in the country. The shells of L. occulta were found in 1989 in the marsh area of the Bátorliget Nature Reserve. The current distribution of this species in Eastern and Central Europe is reviewed. It is hypothesized that L. occulta represents a relic species, whose origin may be traced back to the Pleistocene

Heavy metals, Sediments, Al-Delm Heavy Metals in Sediments of Al-Delmaj Marsh, Al-Qadisiya /Wasit Governorates – Iraq

The regional and seasonal study of heavy metals were taken during February 2018 to November 2018, we determined the concentrations of seven heavy metals (Cd, Cr, Cu, Zn, Ni, Pb, Fe), by using Flame Atomic Absorption Spectrophotometer (FAAS) for sediment at Ten stations along Al-Delmaj lake they are (St.1, St.2 before feeding, St.2 after feeding, St.3, St.4, St.5 before discharge, St.5 after discharge, St.6, St.7, St.8), the stations were selected to cover all the marsh area. The Total Organic Carbon (TOC%) were analyzed. The results obtained for the sediment samples were low except for Fe and Pb which were relatively high. They were followed in order as: (Fe PbZnNiCrCu Cd). Higher concentrations of some heavy metals in sediments indicated that the sediments acted as a sink and source for these metals. Also the lowest mean concentration in some stations because of the fewness sources of pollution in this region whereas the highest mean concentration in other station because of there are a lot of pollution sources such as: Sewage pollutants, Municipal Waste, and Fertilizer waste. there is a variation in the values of studied elements they were ranged as follows: Cd: (0.222 - 0.283g/g), Cr: (1.472 - 1.685g/g), Cu: (0.305 - 0.362g/g), Zn:(1.947 - 2.826g/g), Ni: (1.738 - 2.206g/g), Pb: (3.696 -4.921g/g), Fe: (10.95 - 13.247g/g), The recorded concentrations of heavy metals are very importance to know the locations of pollution, its percentage and causes, sources and methods of treating pollution to preserve public health. The rate of Total Organic Carbon in this study (0.55- 0.97), the influence of the sediments with an equipped source for the organic materials, due to the degradation process that occurs on some neighborhoods in the region.

Evaluation of Marsh Terraces for Wetland Restoration: A Remote Sensing Approach

Marsh terracing is a wetland restoration technique that is being implemented in the northern Gulf of Mexico. Marsh terraces are segmented berms of soil built within shallow coastal ponds, designed to increase marsh area and reduce wave energy. Approximately 980 linear km of marsh terraces have been constructed over almost 30 years in Louisiana and Texas to combat subsidence and sea-level rise; however little research has been conducted to determine their effectiveness. The objective of this study was to assess marsh terrace performance. The change in marsh terrace areas was measured over time through remote sensing. This analysis was conducted using one-meter resolution imagery from the National Agriculture Imagery program (NAIP) from 2003 until 2017 from five Louisiana coastal parishes. Twenty terrace fields of study between 10 and 14 years old were randomly selected within each parish. Results show more predominant deposition (55%) than erosion (45%) in marsh terraces. Terrace fields with high channel density and thereby an external sediment supply show more deposition compared to low channel density fields. This is the first study assessing multiple marsh terrace fields performance. Results are promising, especially considering the current rate of sea level rise and subsidence in Louisiana.

Effect of spalling thickness on transverse axial bearing capacity of pile foundation under different corrosion depths

The transverse and axial bearing characteristics of bridge pile foundation in salt marsh area are studied by numerical simulation. This paper mainly analyses the change of transverse and axial bearing characteristics of pile foundation caused by the change of spalling thickness of bridge foundation. The results show that the transverse and axial bearing capacity and displacement of pile foundation will be affected by the change of concrete spalling thickness under the condition of pile corrosion. When the peeling thickness is above 9.0cm, the transverse and axial bearing characteristics of pile foundation are obviously different with the change of corrosion depth of pile body. When the peeling thickness increases and the corrosion depth of the pile body is different, the negative displacement below the zero point of the first displacement of the pile body is continuously reduced, and the displacement curve above the first displacement zero point in the direction of the pile body begins to shift. When the peeling thickness reaches 15.0cm, the pile top displacement increases to 3.75mm. The research results are of great significance to the establishment of safety evaluation system of highway bridge pile foundation in alpine salt marsh area, and provide a basis for the structural design of highway bridge pile foundation in alpine salt marsh area.