An ecosystem characterisation of the Bay of Bengal

This study summarises the high level drivers on ecological systems of the BOBLME. The ecological characterisation resulted in the identification of 29 subsystems. The report recommends the development of fully integrated approaches that considers human needs and the ecological system, involving stakeholders in a transparent way

Sediment and terrestrial organic carbon budgets for the offshore Ayeyarwady Delta, Myanmar: Establishing a baseline for future change

Large river deltas serve as globally important archives of terrestrial and shallow marine biogeochemical signatures and because of rapid sedimentation have the potential to impact global biogeochemical cycling. The Ayeyarwady Delta in Myanmar ranks as the world\u27s third largest river delta in terms of sediment supply; however, modern increases in regional anthropogenic impacts risk severe alteration to sediment and TerrOC loads within this major system. By investigating modern sediment and terrestrial organic carbon (TerrOC) accumulation within the offshore Ayeyarwady Delta this study estimates baseline sediment and TerrOC budgets for this understudied mega-delta. Using 210Pb geochronology of 27 sediment cores collected from the continental shelf, we estimate that 405 (+52/-47) Mt of sediment, or ~70-80% of fluvial sediment discharged from the Ayeyarwady and Thanlwin rivers (the main inputs to the delta), accumulates there annually. Sediment not retained on the shelf is likely partitioned between the Ayeyarwady floodplain, shoreline accretion, and minor deep-sea export. Estimates of TerrOC (based on δ13C mixing models) were coupled with modern sediment accumulation rates to determine an annual burial of 1.93 (+1.09/-0.15) Mt C on the shelf, with TerrOC burial fluxes being highest in the foreset beds of the subaqueous delta, coincident with the area of highest sediment accumulation rate. Based on estimates of the Ayeyarwady and Thanlwin rivers\u27 TerrOC delivery, an apparent ~100% of TerrOC input is preserved on the continental shelf. However, an across shelf trend of increasing TerrOC degradation with distance offshore is also observed, indicating that while the shelf has high apparent TerrOC sequestration, carbon remineralization is also occurring prior to deposition within the subaqueous delta. Based on these conflicting outcomes, we suggest that input of TerrOC from additional sources other than the Ayeyarwady and Thanlwin rivers roughly balance the observed carbon remineralization. Main additional sources of TerrOC include the Sittang and several smaller rivers, and the Ayeyarwady delta plain below the river gauging station. As anthropogenic development within the Ayeyarwady and Thanlwin watersheds continues to increase, these sediment and TerrOC budgets provide a baseline from which future changes within the offshore Ayeyarwady Delta can be monitored

Tsunami and the effects on coastal morphology and ecosystems: A report

Tsunamis are one of the most destructive natural hazards that affect the coastal areas. Tsunami waves that impact the coast with enormous energy are capable of destroying the objects on the coast and re-shaping the coastal geography, geomorphology and ecosystem. These waves can also cause extensive damage and disruption to human lives, their livelihood, infrastructure and economic activities. The 26 December 2004 Sumatra-Andaman earthquake, one of the largest recorded and deadliest tremor, created an unparalleled catastrophic tsunami wiping out thousands of human lives and throwing millions homeless. This event attracted the interest of several geoscientists in India and stimulated extensive scientific research. This article summarizes the tsunami related research work carried out in India during the past four years

What Is the Future of the Lower Mekong Basin Struggling against Human Activities? A Review

The Mekong River (MR) is recognized the 12th biggest rivers in the world. The Mekong watershed is the biggest one in Southeast Asia (795,000 km2), is densely populated (70 million people), is considered as the most productive one in Southeast Asia and is economically essential to the region. However, nowadays, the Lower Mekong River (LMR) and its delta are facing several emerging and critical anthropogenic stressors (dams construction, climate change, water poor quality, delta sinking). This review attempts to: (i) present the Mekong regional characteristics (geography, topological settings, climatic conditions, hydrology, demographic features and the anthropogenic activities), (ii) present the different factors that endanger the LMR, including the dam’s impacts, the climate change, the delta subsidence, and the degradation of the water quality, (iii) make comparison with different big rivers around the world and (iv) promote future decisions in order to minimize the negative impacts and seek for a trajectory that assures well-being and sustainability. International consultation and cooperation leading to sustainable management is now of a pivotal importance to try to avoid the deterioration of the LMR and its delta

River delta morphotypes emerge from multiscale characterization of shorelines

Delta shoreline structure has long been hypothesized to encode information on the relative influence of fluvial, wave, and tidal processes on delta formation and evolution. We introduce here a novel multiscale characterization of shorelines by defining three process-informed morphological metrics. We show that this characterization yields self-emerging classes of morphologically similar deltas, that is, delta morphotypes, and also predicts the dominant forcing of each morphotype. Then we show that the dominant forcings inferred from shoreline structure generally align with those estimated via relative sediment fluxes, while positing that misalignments arise from spatiotemporal heterogeneity in deltaic sediment fluxes not captured in their estimates. The proposed framework for shoreline characterization advances our quantitative understanding of how shoreline features reflect delta forcings, and may aid in deciphering paleoclimate from images of ancient deposits and projecting delta morphologic response to changes in sediment fluxes

Urban megaprojects and water justice in Southeast Asia: Between global economies and community transitions

Available online 1 April 2021Within the Southeast Asian context, urban megaprojects are often delivered in aquatic or semi-aquatic contexts, transforming local hydrological systems used for sanitation, agriculture, sustenance, resource use and cultural purposes by the local populations. This paper addresses a key knowledge gap on the impacts of urban mega-projects on water security and water-related human rights in Southeast Asia through a literature review, field observations and digital earth observation. Three case studies in Cambodia, Vietnam and Myanmar were used to develop a picture of urban megaproject impacts on urban water landscapes and the human rights of local communities. The paper adapts recent human rights frameworks developed specifically for megaproject life cycles and applies them to the selected urban megaproject case studies. The seven stages in the megaproject life cycle are linked with specific accountability measures for duty bearers. Current challenges and opportunities for the global urban development community are developed in relation to water justice and megaprojects. Further the question of a just urban transition is developed to mediate between megaproject proponents and local communities in the Global South.Scott Hawken, Behnaz Avazpour, Mike S. Harris, Atousa Marzban, Paul George Munr

Sediment Dynamics in Irrawaddy River, Myanmar

Master'sMASTER OF SOCIAL SCIENCE

Global distribution of modern shallow marine shorelines. Implications for exploration and reservoir analogue studies

Acknowledgments Support for this work came from the SAFARI consortium which was funded by Bayern Gas, ConocoPhillips, Dana Petroleum, Dong Energy, Eni Norge, GDF Suez, Idemitsu, Lundin, Noreco, OMV, Repsol, Rocksource, RWE, Statoil, Suncor, Total, PDO, VNG and the Norwegian Petroleum Directorate (NPD). This manuscript has benefited from discussion with Bruce Ainsworth, Rachel Nanson and Christian Haug Eide. Boyan Vakarelov and Richard Davis Jr. are thanked for their constructive reviews and valuable comments that helped to improve the manuscript.Peer reviewedPostprin

Hydro-geomorphological Attributes and Distribution of Urban Land and Population in River Basins

Global urbanization is a major trend in the 21st century and imposes a significant impact on the hydrologic cycle, climate, and biodiversity. In particular, Asia and Africa are expected to experience the fastest urbanization rate in the following decade, manifested by impervious land cover construction and urban population growth. Therefore, accurate information on spatial distribution of urban land and population at the present stage can attribute to a better understanding of urbanization processes in the future. Meanwhile, the knowledge of hydrological responses on the land use and land cover (LULC) change can provide valuable insights into sustainable development strategies. This dissertation aims to answer three fundamental questions: (1) How do natural environmental factors that relate to water resource, climate, and geomorphological attributes constrain the distribution of current urban land and population? (2) How will the global urban growth in the near future affect the urban exposure to natural disasters such as fluvial flood, drought, and ecosystem degradation? (3) How will land change impact hydrologic processes within a river basin? To solve the research questions, studies presented in this dissertation are organized into three parts. Part one analyzes the spatial distribution of urban ratio, population density, and urban population density in 11 river basins in Asia and Africa, considering average annual precipitation, surface freshwater availability, and access to coastal zone as three influencing factors. Then, a set of regression models is conducted for the Yangtze River Basin as a more comprehensive investigation. Part two examines the global and regional patterns of urban growth from 2000 to 2030 as well as the change of urban area’s exposure to floods and droughts. Part three is an assessment of streamflow in the Chao Phraya Basin based on different precipitation and LULC scenarios. The Soil and Water Assessment Tool (SWAT) is used to develop the hydrological model. The results reveal that higher urban ratio and human concentration occur in the vicinity of a stream network and a coastal zone; while precipitation does not effectively influence the distribution of urban land and population as expected. The emerging coastal metropolitan regions in Africa and Asia will be larger than those in the developed countries and will have larger areas exposed to flood and drought. The case study of Chao Phraya River Basin demonstrates that land change will increase both the risk of drought and flood hazards

Contribution of hurricane-induced sediment resuspension to coastal oxygen dynamics

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 8 (2018): 15740, doi:10.1038/s41598-018-33640-3.Hurricanes passing over the ocean can mix the water column down to great depths and resuspend massive volumes of sediments on the continental shelves. Consequently, organic carbon and reduced inorganic compounds associated with these sediments can be resuspended from anaerobic portions of the seabed and re-exposed to dissolved oxygen (DO) in the water column. This process can drive DO consumption as sediments become oxidized. Previous studies have investigated the effect of hurricanes on DO in different coastal regions of the world, highlighting the alleviation of hypoxic conditions by extreme winds, which drive vertical mixing and re-aeration of the water column. However, the effect of hurricane-induced resuspended sediments on DO has been neglected. Here, using a diverse suite of datasets for the northern Gulf of Mexico, we find that in the few days after a hurricane passage, decomposition of resuspended shelf sediments consumes up to a fifth of the DO added to the bottom of the water column during vertical mixing. Despite uncertainty in this value, we highlight the potential significance of this mechanism for DO dynamics. Overall, sediment resuspension likely occurs over all continental shelves affected by tropical cyclones, potentially impacting global cycles of marine DO and carbon.Support for J. Moriarty was provided by the USGS Mendenhall Program