scholarly journals Projections of salt intrusion in a mega-delta under climatic and anthropogenic stressors

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Sepehr Eslami ◽  
Piet Hoekstra ◽  
Philip S. J. Minderhoud ◽  
Nam Nguyen Trung ◽  
Jannis M. Hoch ◽  
...  
Keyword(s):  
Policy Development ◽  
Environmental Changes ◽  
Numerical Models ◽  
Mekong Delta ◽  
Environmental Stressors ◽  
Groundwater Extraction ◽  
Climate Change Projections ◽  
Salt Intrusion ◽  
Rapid Urbanization ◽  
Anthropogenic Processes

AbstractRising temperatures, rapid urbanization and soaring demand for natural resources threaten deltas worldwide and make them vulnerable to rising seas, subsidence, droughts, floods, and salt intrusion. However, climate change projections in deltas often address climate-driven stressors in isolation and disregard parallel anthropogenic processes, leading to insufficient socio-political drive. Here, using a combination of process-based numerical models that integrate both climatic and anthropogenic environmental stressors, we project salt intrusion within the Mekong mega-Delta, in the next three decades. We assess the relative effects of various drivers and show that anthropogenic forces such as groundwater extraction-induced subsidence and riverbed level incisions due to sediment starvation can increase the salinity-affected areas by 10–27% compared to the present-day situation, while future sea level rise adds another 6–19% increase. These projections provide crucial input for adaptation policy development in the Mekong Delta and the methodology inspires future systemic studies of environmental changes in other deltas.

The past and future dynamics of salt intrusion in the Mekong Delta

2021 ◽  
Author(s):  
Sepehr Eslami ◽  
Maarten van der Vegt ◽  
Philip Minderhoud ◽  
Nam Nguyen Trung ◽  
Jannis Hoch ◽  
...  
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Policy Development ◽  
Environmental Changes ◽  
Mekong Delta ◽  
Environmental Drivers ◽  
Salt Intrusion ◽  
Rapid Urbanization ◽  
The World ◽  
Anthropogenic Drivers

<p>In the context of global rising temperatures, rapid urbanization and excessive demand for natural resources (e.g., freshwater and sand) stress the livelihood of the world deltas. Sea Level Rise, land subsidence, discharge anomalies, floods, drought, and salt intrusion are common challenges facing these ecologically essential and economically crucial coastal landscapes. Climate change projections in deltas regularly isolate climate-driven stressors and disregard anthropogenic environmental drivers. This often leads to insufficient socio-political drive at times when the short window of opportunity to save the world’s largest deltas is closing. Here, by integrating both climatic and anthropogenic drivers of exposure and vulnerability, we project salt intrusion within the Mekong mega-Delta for the next three decades. Leveraging modern numerical codes and computation capacity, by applying a high-resolution 3D model we capture the 3D dynamics of saline water intrusion, and by covering the entire delta (from 400 km upstream to 70 km offshore) we eliminate/minimize the boundary effects at the areas of interest. We differentiate the relative effects of various drivers and demonstrate that while sea level rise can increase areas affected by salinity by 5-19%, anthropogenic drivers such as extraction-induced subsidence and riverbed level incisions due to sediment starvation can further amplify that by additional 10-27%. The results are crucial input for climate adaptation policy development in the Mekong Delta and provides a blueprint for systemic assessment of environmental changes and developing environmental pathways at scale of a delta.</p>

scholarly journals Social Evaluation of Public Open Space Services and Their Impact on Well-Being: A Micro-Scale Assessment from a Coastal University

2021 ◽  
Vol 13 (8) ◽  
pp. 4372
Author(s):  
Abdullah Addas ◽  
Ahmad Maghrabi
Keyword(s):  
Open Space ◽  
Environmental Changes ◽  
Positive Impact ◽  
Well Being ◽  
Social Evaluation ◽  
Open Spaces ◽  
Rapid Urbanization ◽  
Public Open Space ◽  
The Impact ◽  
Public Open Spaces

Public open spaces services have been shown to be profoundly affected by rapid urbanization and environmental changes, and in turn, they have influenced socio-cultural relationships and human well-being. However, the impact of these changes on public open space services (POSS) remains unexplored, particularly in the Saudi Arabian context. This study examines the socio-cultural influence of POSS on the King Abdulaziz University campus, Jeddah, Saudi Arabia and the impact of these services on well-being. A field survey and questionnaire were used to collect data. Non-parametric tests (Kruskal–Wallis and Mann–Whitney tests) were used to find significant differences in the importance of POSS as perceived by stakeholders based on socio-demographic attributes. Factor analysis was performed for 14 POSS to identify those that are most important. The study showed that (i) university stakeholders are closely linked to services provided by public open spaces (POS) and dependent on POSS, (ii) there were significant differences in the perceived importance of POSS according to gender, age, and social groups, and (iii) 70 to 90% of stakeholders reported POSS as having a positive impact on well-being. Thus, the findings will help design and plan POSS to meet the needs of society and promote well-being.

RELATIONSHIP BETWEEN POPULATION GROWTH WITH CHANGING LAND-USE PATTERN AND ENVIRONMENTAL CHANGES IN KOLKATA, WEST BENGAL

2021 ◽  
pp. 57-61
Author(s):  
Arunima Dasgupta
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Population Growth ◽  
Environmental Degradation ◽  
Urban Sprawl ◽  
West Bengal ◽  
Environmental Changes ◽  
Capital City ◽  
Special Focus ◽  
Rapid Urbanization

Given that urbanization is considered as one of the most signicant anthropogenic alteration of the overall environment, the present study attempts to understand spatial-temporal characteristics of urban population growth and its implications on land-use as well as understanding their relationship with environmental degradation with special focus on the Kolkata, the capital city of West Bengal. Urbanization is one of the major driving forces behind the development of today's land-use and land cover system. A large number of contemporary urbanization has been characterized as urban sprawl namely in an extensive form of land-use for urban uses that have environmentally detrimental effects. There are indications of Urban sprawl and city expansion in our Study Area of Kolkata indicating expansion of settlements and built-up area and thus causing environmental degradation in the city area. The process of urbanization always had signicant implications that can affect cumulative changes in demographic characteristics and/or transformation of the physical environment; unplanned, unsystematic and rapid urbanization can cause intense impacts on various environmental aspects, specically on land and air and water. A thorough understanding of the dynamic relationship between urbanization and its generated land-cover changes thus becomes completely essential for managing environmental changes and enabling sustainability of the environment and its resources.

scholarly journals Modeling the Effect of Desert Urbanization on Local Climate and Natural Dust Generation: A Case Study for Erbil, Iraq

Urban Science ◽  
2020 ◽  
Vol 4 (4) ◽  
pp. 46
Author(s):  
Sherzad T. Tahir ◽  
Huei-Ping Huang
Keyword(s):  
Land Surface ◽  
Numerical Models ◽  
Surface Wind ◽  
Surface Fluxes ◽  
Slight Reduction ◽  
Rapid Urbanization ◽  
Near Surface ◽  
Local Climate ◽  
Surface Dust ◽  
Dust Generation

This study uses a suite of meteorological and land-surface models to quantify the changes in local climate and surface dust fluxes associated with desert urbanization. Formulas connecting friction velocity and soil moisture to dust generation are used to quantify surface fluxes for natural wind-blown dust. The models are used to conduct a series of simulations for the desert city of Erbil across a period of rapid urbanization. The results show significant nighttime warming and weak but robust daytime cooling associated with desert urbanization. A slight reduction in near-surface wind speed is also found in the areas undergoing urbanization. These findings are consistent with previous empirical and modeling studies on other desert cities. Numerical models and empirical formulas are used to produce climatological maps of surface dust fluxes as a function of season, and for the pre- and post-urbanization eras. This framework can potentially be used to bridge the gap in observation on the trends in local dust generation associated with land-use changes and urban expansions.

scholarly journals Salt intrusion in multi-channel estuaries: a case study in the Mekong Delta, Vietnam

2006 ◽  
Vol 10 (5) ◽  
pp. 743-754 ◽  
Author(s):  
A. D. Nguyen ◽  
H. H. Savenije
Keyword(s):  
River Discharge ◽  
Single Channel ◽  
Mekong Delta ◽  
Salt Intrusion ◽  
Predictive Equations ◽  
Alluvial Estuaries ◽  
Tidal Characteristics ◽  
Mixing Behaviour ◽  
Sloping Bottom

Abstract. There is a well-tested theory for the computation of salt intrusion in alluvial estuaries that is fully analytical and predictive. The theory uses analytical equations to predict the mixing behaviour of the estuary based on measurable quantities, such as channel topography, river discharge and tidal characteristics. It applies to single-channel topographies and estuaries that demonstrate moderate tidal damping. The Mekong delta is a multi-channel estuary where the tide is damped due to a relatively strong river discharge (in the order of 2000 m3/s), even during the dry season. As a result the Mekong is a strongly riverine estuary. This paper aims to test if the theory can be applied to such a riverine multi-channel estuary, and to see if possible adjustments or generalisations need to be made. The paper presents salt intrusion measurements that were done by moving boat in 2005, to which the salt intrusion model was calibrated. The theory has been expanded to cater for tidal damping. Subsequently the model has been validated with observations made at fixed locations over the years 1998 and 1999. Finally it has been tested whether the Mekong calibration fits the overall predictive equations derived in other estuaries. The test has been successful and led to a slight adjustment of the predictive equation to cater for estuaries that experience a sloping bottom.

scholarly journals An efficient modelling approach for probabilistic assessments of present-day and future fluvial flooding

2020 ◽  
Author(s):  
Hieu Ngo ◽  
Roshanka Ranasinghe ◽  
Chris Zevenbergen ◽  
Ebru Kirezci ◽  
Dikman Maheng ◽  
...  
Keyword(s):  
Land Subsidence ◽  
Return Period ◽  
Flood Risk ◽  
Flood Hazard ◽  
Mekong Delta ◽  
Flood Risk Management ◽  
Groundwater Extraction ◽  
Model Simulations ◽  
Can Tho City ◽  
Modelling Approach

Abstract. Flood risk management and planning decisions in many parts of the world have historically utilised flood hazard or risk maps for a very limited number of hazard scenarios (e.g. river water levels), mainly due to computational challenges. With the potentially massive increase in flood risk in future due to the combination of climate change effects (increasing the hazard) and increasing population and developments in floodplains (increasing the consequence), risk-informed flood risk management, which enables balancing the risk with the reward, is now becoming more and more sought after. This requires a comprehensive and quantitative risk assessment, which in turn demands multiple (thousands of) river and flood model simulations. Performing such a large number of model simulations is a challenge, especially for large, complex river systems (e.g. Mekong) due to the associated computational and resource demands. This article presents an efficient modelling approach that combines a simplified 1D hydrodynamic model for the entire Mekong Delta with a detailed 1D/2D coupled model and demonstrates its application at Can Tho city in the Mekong Delta. Probabilistic flood hazard maps, ranging from 0.5 yr to 100 yr return period events, are obtained for the urban centre of Can Tho city under different future scenarios taking into account the impact of climate change forcing (river flow, sea-level rise, storm surge) and land subsidence. Results obtained under present conditions show that more than 12 % of the study area is inundated by the present-day 100 yr return period water level. Future projections show that, if the present rate of land subsistence continues, by 2050 (under both RCP4.5 and RCP8.5 climate scenarios), the 0.5 yr and 100 yr return period flood extents will increase by around 15-fold and 8-fold, respectively, relative to the present-day flood extent. However, without land subsidence, the projected increases in the 0.5 yr and 100 yr return period flood extents by 2050 (under RCP4.5 and RCP8.5) are limited to between a doubling to tripling of the present-day flood extent. Therefore, adaptation measures that can reduce the rate of land subsidence (e.g. limiting groundwater extraction), would substantially mitigate future flood hazards in the study area. A combination of restricted groundwater extraction and the construction of a new and more efficient urban drainage network would facilitate even further reductions in the flood hazard. The projected 15-fold increase in flood extent projected by 2050 for the twice per year (0.5 yr return period) flood event implies that the do nothing management approach is not a feasible option for Can Tho.

scholarly journals MODELLING LONG TERM IMPLICATION OF CLIMATE CHANGE PROJECTION ON SHORE MORPHOLOGY OF NORTH NORFOLK, UK, COMBINING TOMAWAC AND SCAPE

2011 ◽  
Vol 1 (32) ◽  
pp. 61 ◽  
Author(s):  
Nicolas Chini ◽  
Peter Stansby ◽  
Mike Walkden ◽  
Jim Hall ◽  
Judith Wolf ◽  
...  
Keyword(s):  
Climate Change ◽  
Global Climate Change ◽  
Large Scale ◽  
Numerical Models ◽  
Global Climate ◽  
Stationary Processes ◽  
Climate Change Projections ◽  
Future Evolution ◽  
The Future

Assessment of nearshore response to climatic change is an important issue for coastal management. To predict potential effects of climate change, a framework of numerical models has been implemented which enables the downscaling of global projections to an eroding coastline, based on TOMAWAC for inshore wave propagation input into SCAPE for shoreline modelling. With this framework, components of which have already been calibrated and validated, a set of consistent global climate change projections is used to estimate the future evolution of an un-engineered coastline. The response of the shoreline is sensitive to the future scenarios, underlying the need for long term large scale offshore conditions to be included in the prediction of non-stationary processes.

scholarly journals Antibiotics shift the temperature response curve of Escherichia coli growth

2020 ◽  
Author(s):  
Mauricio Cruz-Loya ◽  
Elif Tekin ◽  
Tina Manzhu Kang ◽  
Alejandra Rodriguez-Verdugo ◽  
Van M. Savage ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
High Throughput Screening ◽  
Environmental Changes ◽  
Temperature Response ◽  
Thermal Response ◽  
Ecological Systems ◽  
Environmental Stressors ◽  
Optimal Temperature ◽  
Key Features ◽  
Temperature Responses

AbstractTemperature variation—through time and across climatic gradients—affects individuals, populations, and communities. Yet how the thermal response of biological systems is altered by environmental stressors is poorly understood. Here we quantify two key features—optimal temperature and temperature breadth—to investigate how temperature responses vary in the presence of antibiotics. We use high-throughput screening to measure growth of Escherichia coli under single and pairwise combinations of 12 antibiotics across seven temperatures that range from 22°C to 46°C. We find that antibiotic stress often results in considerable changes in the optimal temperature for growth and a narrower temperature breadth. The direction of the optimal temperature shifts can be explained by the similarities between antibiotic-induced and temperature-induced damage to the physiology of the bacterium. We also find that the effects of pairs of stressors in the temperature response can often be explained by just one antibiotic out of the pair. Our study has implications for a general understanding of how ecological systems adapt and evolve to environmental changes.

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