Wetland Creation, Restoration, and Conservation

Water-dominated landscapes include wetland areas. The term “wetland” has not been commonly used until quite recently. It is believed to be a euphemistic equivalent of “swamp.” Every year on the second day of February, World Wetlands Day marks the adoption of the convention on Wetland by Ramsar, the Iranian city that has a special place in Iranian history. Flood protection, water quality improvement, shoreline erosion control, natural products, recreation, and aesthetics are some of the many advantages of wetlands, as well as the fact that they are vital habitats for a variety of animals and plants. Several studies illustrated the importance of wetlands in reducing carbon emissions and regulating climate on a global scale. In recent years, these advantages of wetlands have been recognized by governments worldwide and have led to legislation, regulations, and management plans creating wetlands for conservation, protection, and restoration. Unfortunately, the destruction of wetlands is a concern since they are among the planet's most productive areas.

Numerical Study of Bamboo Breakwater for Wave Reduction

Flood inundation and shoreline erosion have long occurred in Sayung, Demak area, the northern coast of Central Java Province, Indonesia. The people of Sayung planted mangroves to reduce the flood inundation and shoreline erosion in that area. They built the bamboo array to protect the juvenile mangroves from incoming waves. The bamboo acts as a breakwater and is considered an environmentally friendly permeable structure to reduce wave energy and stimulate sedimentation. This paper discusses three bamboo arrays’ effectiveness in wave reduction using Numerical Wave Tank (NWT). The interaction of regular waves with a permeable structure comprising a single row of vertical circular poles was conducted based on the Smoothed Particle Hydrodynamics (SPH) method. The effect of different waves and structural dimensions on the permeable structure was investigated based on the structure’s transmission coefficient (Kt) performance. The investigations have revealed that structures with the combination of Vertical-Horizontal formation (VH) attenuate more wave energy than Vertical Only (VO) and the combination of Vertical-Diagonal formation (VD). As the wave steepness increases, the transmission coefficient decreases. Likewise, the transmission coefficient (Kt) is decreasing when the wave height is increasing. On the other hand, the transmission coefficient (Kt) increases as the wave period increases. As the structure spacing ratio between end-to-end and center-to-center spacing (e/S) rises, the transmission coefficient (Kt) also increases. The diameter (D) has a slight effect on the transmission coefficient (Kt). However, the center-to-center spacing (S) has a more significant impact than the diameter on the transmission coefficient, affecting an inclination on the transmission coefficient (Kt) when center-to-center spacing (S) goes up.

Remote Sensing Approach for Monitoring Coastal Wetland in the Mekong Delta, Vietnam: Change Trends and Their Driving Forces

Coastal wetlands in the Mekong Delta (MD), Vietnam, provide various vital ecosystem services for the region. These wetlands have experienced critical changes due to the increase in regional anthropogenic activities, global climate change, and the associated sea level rise (SLR). However, documented information and research on the dynamics and drivers of these important wetland areas remain limited for the region. The present study aims to determine the long-term dynamics of wetlands in the south-west coast of the MD using remote sensing approaches, and analyse the potential factors driving these dynamics. Wetland maps from the years 1995, 2002, 2013, and 2020 at a 15 m spatial resolution were derived from Landsat images with the aid of a hybrid classification approach. The accuracy of the wetland maps was relatively high, with overall accuracies ranging from 86–93%. The findings showed that the critical changes over the period 1995/2020 included the expansion of marine water into coastal lands, showing 129% shoreline erosion; a remarkable increase of 345% in aquaculture ponds; and a reduction of forested wetlands and rice fields/other crops by 32% and 73%, respectively. Although mangrove forests slightly increased for the period 2013/2020, the overall trend was also a reduction of 5%. Our findings show that the substantial increase in aquaculture ponds is at the expense of mangroves, forested wetlands, and rice fields/other crops, while shoreline erosion significantly affected coastal lands, especially mangrove forests. The interaction of a set of environmental and socioeconomic factors were responsible for the dynamics. In particular, SLR was identified as one of the main underlying drivers; however, the rapid changes were directly driven by policies on land-use for economic development in the region. The trends of wetland changes and SLR implicate their significant effects on environment, natural resources, food security, and likelihood of communities in the region sustaining for the long-term. These findings can assist in developing and planning appropriate management strategies and policies for wetland protection and conservation, and for sustainable development in the region.

Morphological Changes along the shoreline of the arcuate Niger Delta from Parts of Delta State to Akwa Ibom State between 1986 and 2016

This study analyzes the morphological changes occurring at the arcuate Niger Delta shoreline by identifying factors that contribute to erosion-induced shoreline changes and the rate of shoreline change from Forcados (Delta State) to Ibeno (Akwa Ibom State). Shoreline changes were compared from 1986 to 2016 as well as among western, central and eastern sections of the arcuate Niger Delta using Landsat satellite imagery within Geographic Information System (GIS) environment. In the assessment of the entire shoreline, accretion was 5,477.814Ha (1.2%) in 1986 and 19181.53Ha (4.1%) in 2016. For erosion, it was 48,400.03 (10.3%) in 1986 and 68398.84Ha (14.5%) in 2016. This indicates that accretion increased by 2.91% and erosion also increased by 4.25% in 30 years. The major accretion was detected within Brass (Bayelsa State), Bonny (River State), Andoni (River State) and Ibeno (Akwa Ibom State). Forcados South Point (Delta State), Sombreiro River mouths and eastern Obolo recorded the highest level of shoreline erosion. For land use/land cover (LULC), vegetation was 27.4% in 1986 but reduced to 22.9% in 2016; a change I attributed to massive conversion of vegetative cover for anthropogenic activities in the area. The study concluded that major erosion cases are due to the changing climate and the velocity of flow of major estuaries into the ocean. The activities that contribute to the shoreline change aside the challenging natural factors are sand mining, hard and engineered structures on the shore and other commercial and social activities. The occurrences of shoreline erosion have contributed to the degradation of these coastal ecosystems, loss of human settlements and livelihood. It is therefore essential to implement precautionary measures to mitigate the risk of shoreline erosion within this sensitive zone

Multi-Decadal Deltaic Land-Surface Changes: Gauging the Vulnerability of a Selection of Mediterranean and Black Sea River Deltas

Areal changes over delta surfaces determined by land and water ratios are a promising tool for identifying spatial and temporal changes in deltas that may reveal subsidence and shoreline erosion. Such changes can also provide the basis for more detailed studies on variations in land-cover and vegetation. Changes in land and water areas over a 35-year period (1984–2019) were determined for a selection of ten river deltas in the Mediterranean (Nile, Rhône, Po, Ebro, Moulouya, Ceyhan-Seyhan, Medjerdja, Ombrone, Arno) and the Black Sea (Danube), with a particular focus on aspects of subsidence and shoreline erosion. With the exception of the Ombrone, Arno, and Moulouya, and to lesser extent the Medjerdja, where notable changes dominate in the coastal zone and are tantamount to net erosion, the spatial pattern is largely dominated by delta-plain changes characterized by increasing areas of water. The pattern reflects a mix of shoreline erosion, land-use and land-cover changes, such as the ecological restoration of wetlands, but also increasing subsidence in these deltas, all of which have been exposed to a declining fluvial sediment supply due to human influence. The use of data on land-water ratios needs to be complemented by more detailed studies devoted to each delta in order to clearly disentangle changes related to land-use, vegetation, and subsidence. It is also important to determine how wetlands are interpreted in such ratios, as these important ecological elements are sensitive to ratio variations. It would also be interesting in future studies to examine how these variations play out over time, notably in deltas where changes have been significant over the period 1984–2019.