Soil salinization significantly threatens agriculture and food security, leading to profound soil degradation and desertification, negatively impacting ecosystems. The accumulation of excessive salts has negative effects on soil structure, fertility, plant growth, crop yield, and microorganisms. This phenomenon is attributed to natural factors, such as dry climates and high evaporation rates, and human-induced factors, including not optimal irrigation practices, inadequate drainage systems, and excessive fertilizer use. The increased frequency of weather extremes driven by climate change exacerbates this global issue, especially along coastal areas where millions of people live. Here, the sea-level rise, and recently also drought, are causing, especially in river deltas, a progressive land degradation, which negatively impacts the sustainable development of coastal agriculture. The lack of rainfall leads to scarce river discharge and consequently favours marine water inland flow intrusion. Anthropogenic activities (e.g., dams, mining) are exacerbating the phenomenon. Urgent mitigation strategies are therefore necessary. This study explores the potential of Nature-based Solutions (NbS) as sustainable and resilient response to soil salinization, offering benefits to agriculture through revitalizing ecosystem services. In detail, we addressed the challenges and limitations of implementing natural barriers, wetlands, buffer zones, conversion to aquaculture, straw incorporation, microbial-based solutions, organic fertilizers, and low impact water storage facilities. In detail, we should start re-introducing, where possible, wetlands through renaturalisation strategies, aiming to create a virtuous ecological equilibrium in agricultural landscapes. Indeed, wetlands can offer a natural barrier to saltwater intrusion. Soil remediation of degraded areas, especially for those interested in sand mining or oil refineries, is necessary to make soils more resilient and reestablish missed ecosystems. Agriculture must be sustainable and adopt conservation practices to keep and improve soil organic carbon content (SOC). Soils rich in SOC can retain more water and are more resilient; thus, they are more prepared for prolonged pressure given by water scarcity and soil salinization.

How to cite: Tarolli, P., Park, E., Luo, J., and Masin, R.: Preserving coastal agriculture: Nature-based solutions for the mitigation of soil salinization , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4213, https://doi.org/10.5194/egusphere-egu24-4213, 2024.

Sea surface salinity ( ) is a key parameter for the thermohaline circulation of global oceans, as well as the global hydrologic cycle. Near the deltas, inland streamflow through large catchments plays a crucial role in mediating salinity, which is vital for maintaining an agro-hydrological balance in the deltas. With recent remote sensing data sources providing both   and streamflow at global scales, we calculated the statistical associations of   with simulated basin streamflow ( ) at a monthly scale in 48 major deltas across the globe. The monthly   data was downloaded globally at   intervals from the SMAP RSS L3 products. The hourly streamflow data was extracted from HYMAP streamflow routing simulations (available at   spatial grids) within NASA’s LIS modeling framework. The streamflow data was spatiotemporally aggregated before performing the statistical analyses. We calculated the associations over different monthly-lags and plume distances and obtained the optimal correlations. The optimal correlation coefficients ( ) reveal strong anticorrelation phenomenon between   and   (  for seasonal data at 28 deltas, and   for de-seasoned data at 21 deltas). In addition to basin streamflow, we considered a number of sea surface climate forcings (precipitation, sea surface temperature, and wind speed) to perform similar statistical comparisons with  . The results revealed that   near the deltas are more influenced by basin streamflow in general. From a physical science perspective, we found consistent outcomes in the majority of deltas, with some irregularities in deltas with strong anthropogenic and management influences (e.g., deltas containing low forest cover and high reservoir areas). The anticorrelation phenomenon was more prominent in large deltas, specifically located near the tropical climates, which experience high streamflow and no ice-melting. We also found that the anticorrelations are more profound in river dominated deltas (e.g., deltas where the fluvial dominance ratio is greater than 1). The findings of this research will be useful for delta researchers aiming to devise global scale strategies amidst the rising threats of salinity intrusion.

How to cite: Khadim, F. K., Getirana, A., Bindlish, R., and Kumar, S.: Statistical associations of basin streamflow on sea surface salinity variability across major global deltas., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21205, https://doi.org/10.5194/egusphere-egu24-21205, 2024.

Water management decision-making typically adopts either a top-down or a bottom-up approach. Presently, Bangladesh is exploring participatory planning, emphasizing consultations with local communities. This paper presents a framework for linking the top-down with the bottom-up approaches and discusses three case studies. The first one is about Tidal River Management in the South West Delta Bangladesh, and subsequently the framework is applied to Haor and Dhaka.

The livelihoods of communities in the South-West Delta face challenges due to environmental changes and socio-economic dynamics. Traditional approaches, inspired by Dutch polder development, have led to adverse effects such as increased salinity and drainage congestion. Local dissatisfaction with these solutions has manifested in events where farmers breach embankments to address these issues, while others turn to shrimp farming. A top-down approach to water management hampers effective communication and collaboration between experts and local communities.

The key challenge lies in managing the complex interactions among diverse stakeholders within the heterogeneous community. The Water Custodian framework aims to address this challenge by incorporating local community mapping into decision-making processes. The framework recognizes the diversity of stakeholders, including large landowners, subsistence farmers, and landless laborers, each with unique perspectives and incentives.

The primary objective of the framework is to enhance decision-making processes by incorporating humane elements, focusing on the inclusion of local communities and their vulnerability profiles. This involves developing a decision support process and tool to facilitate the inclusion of local knowledge and expertise in water management decision-making.

The approach is based on 'mental models' and 'life stories,' aiming to bridge geo-physical criteria with socio-economic and livelihood criteria. The Water Custodian framework uses fictional archetypal characters called Local Families, akin to personas in marketing and user interaction development, to represent different user groups. These personas help experts and decision-makers understand the diverse needs, experiences, behaviors, and goals of local communities. A serious board game is developed in which participants roleplay the various life-stories and have to prioritize the interventions based on their perspectives. The process is supported by a non-complex rapid impact assessment software, to provide rapid assessment of the scores obtained on the defined indicators.

The Water Custodian approach's adaptability to various contexts has been demonstrated by its application in the South-West Delta, the Haor region for integrated flood management, and for urban sustainability in Dhaka and Mumbai.  By using serious gaming for mapping and understanding the local context, the framework remains effective in addressing the unique challenges of each region.

Beyond its application in Bangladesh, the Water Custodian framework holds potential for various contexts worldwide. In natural resource management, it can be adapted to scenarios involving water resources, forests, or agricultural lands. The framework's inclusive approach can also find application in urban planning and development, disaster management, and educational initiatives.

In conclusion, the Water Custodian concept transcends geographic boundaries and application domains, serving as an anchor for inclusive and participatory approaches in decision-making.

How to cite: Van Deursen, W., Wasim, S. K., and Ahmad, M.: Bridging Perspectives: Lessons from the Water Custodian approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17963, https://doi.org/10.5194/egusphere-egu24-17963, 2024.

Global food security is challenged by lack of fresh water availability and increasing salinity. Water and soil salinity have increased during the last few decades and are projected to increase in the future which will adversely effect the food security. Effect of climate change will exacerbate the situation. Previous researches have predominantly focused on the impact of either soil or water salinity on agriculture and food security. An assessment of combined impact of soil and water salinity at global scale is required. We have considered global datasets on soil and water salinity to locate areas with higher impact of salinity and combined indicators on climate, water availability, source of irrigation, cropping pattern, soil characteristics and level of salinity to identify regions with higher vulnerability to salinization. The impact of salinity on crop (wheat, rice and maize) yield was considered to produce a primary estimate of potential loss of food production. Combining soil and water salinity data indicate that currently the southeast and southwest coast of USA, southern part of Africa, southeast regions of Australia and coastal regions of Bangladesh are mostly impacted by salinity.  The MENA region, sub-saharan regions, large parts of Australia, southern Europe, southwestern coast of USA, eastern China, as well as the coast of Vietnam, GCC states, the eastern part of Indonesia, northern parts of India, coastal regions of Bangladesh and southeastern regions of Africa are identified as vulnerable regions for increasing salinity. The potential crop yield loss due to salinity is highest for Maize and lowest for Wheat.  Global cropping pattern shows that rice and maize are being cultivated more in salinity vulnerable areas than wheat, even though wheat is the most saline tolerant of the three. Identification of saline hotspot areas and regions vulnerable to increasing salinity will assist in development location specific of policies, regulation and adaptation strategies to counter the adverse impact of salinity in the future. More in depth analysis on Ganges-Brahmaputra-Meghna (GBM), Mekong and Nile delta will be carried out for regional verification of salinity hotspot and vulnerable location identification.

How to cite: Islam, M. F., Snethlage, J., Biemans, H., Terwisscha van Scheltinga, C., and de Miguel García, Á.: Identification of global hotspots for salinity vulnerability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9392, https://doi.org/10.5194/egusphere-egu24-9392, 2024.

Seawater intrusion (SWI) is an escalating concern in coastal regions globally, with alterations in weather patterns and sea-level rise emerging as pivotal factors contributing to the occurrence of SWI in both surface waters and groundwater. This phenomenon poses a significant risk to low-lying agricultural areas, leading to soil salinization with substantial adverse effects on soil quality and crop yields. In the Po River Delta, Italy's broadest agricultural region impacted by SWI, summer droughts play a pivotal role in driving SWI dynamics. Within this extensive lowland area, the deficiency in rainfall during the summer months reduces river flow, facilitating the inland movement of seawater. The escalating frequency of drought events and exceptionally high temperatures in recent summers, has highlighted the necessity for a thorough understanding of the impact of SWI on cropland, both on vegetation and soil, to detect any possible correlations between SWI, accumulation of salts and plant stress. The objective of this study is to combine multi-temporal remote sensing from satellite imagery, to monitor plant greening, with on-site observations of soil electrical conductivity (EC). Normalized Difference Vegetation Index (NDVI) maps for the summer period 2023 were elaborated from satellite data, classifying cropland with a machine-learning algorithm to filter bare soil and surface water from green vegetation. In the same time period, two experimental sites located in the delta region were periodically sampled with a Time Domain Reflectometry (TDR) probe to monitor soil temperature, moisture and EC. Soil samples were also collected and analyzed to measure EC of the water extracts. Although summer 2023 was not characterized by extreme drought, the combined results offered a quick method for identifying salinization trends within the delta cropland area, pinpointing the most susceptible areas both on a regional scale and on a local scale.

How to cite: Ghiardelli, A., Straffelini, E., Cucchiaro, S., and Tarolli, P.: Combining Remote Sensing and On-site Observations to Explore Salinization Dynamics in the Po River Delta , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9307, https://doi.org/10.5194/egusphere-egu24-9307, 2024.

Riverbank erosion is one of the world’s major hazards in delta areas. The Mekong Delta of Asia is one among them which is facing many sediment-related issues, particularly riverbank erosion. Extreme flood events and sea level rise due to climate change increase the risk of riverbank and coastal erosion in the Mekong Delta. This study aims to assess riverbank stability using the BSTEM model, investigate the level of vulnerability of local communities to riverbank erosion and understand their adaptive strategies to cope with riverbank erosion problems. The study focuses on Kaoh Soutin (KS) and Ruessei Srok (RS) communes which are next to the Mekong River in the delta area of Cambodia. Linking with flow velocity and water level from the HEC-RAS  2D model, the BSTEM model was set up to examine riverbank stability at two locations in KS and two locations in RS. The study used soil samplings and the laboratory test to investigate critical shear stress and erodibility coefficient for the BSTEM model. The results indicate that river water level and groundwater level are crucial factors influencing the overall stability of the riverbank. Higher water levels result in increased confining pressure on the riverbank, leading to a higher factor of safety. Soil erosion also has significantly impacted the riverbank at the study location. The level of vulnerability in two communities was determined based on IPCC’s livelihood vulnerability index (LVI) and coping strategies were determined based on field survey questionnaires and focus groups interviewed. It is found that KS is slightly more vulnerable to riverbank erosion than RS, as indicated by LVI values of 0.49 and 0.46 for KS and RS, respectively. The Chi-square test was carried out to identify vulnerability indicators that are statistically different between KS and RS. The current adaptive strategies based on interviews include reducing expenses, resettlement, diversifying income sources, and seeking support from various entities, including local authorities, NGOs, and government interventions during riverbank erosion. Large-scale monitoring and modeling systems are necessary for developing early warning systems and identifying hotspots. Riverbank protections both infrastructure-and nature-based solutions and migration plans are required to support livelihood adaptation.

How to cite: Piman, T., Tha, T., and Ruangrassamee, P.: Modeling riverbank stability and assessing vulnerability and adaptive strategies on riverbank erosion in the Mekong Delta, Cambodia , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20488, https://doi.org/10.5194/egusphere-egu24-20488, 2024.

Concern for climate change impacts to the Vietnamese Mekong Delta is rapidly increasing due to the compound risks of a changing climate, environmental change and sensitivity and social-economic transformation. The Delta, located in the downstream section of the Mekong River is considered globally as one of the three most vulnerable deltas to climate change. Variations in precipitation, temperature changes, sea-level rise, progressive saline instructions, riverbank erosion, flooding and extreme weather events all aggravate the risk to the existing socio-ecological system.

Using Ben Tre Province as an in-depth case study, this paper develops a social vulnerability index (SVI) to understand the water hazards-modified by climate change in terms of their association between vulnerability, existing infrastructures and socio-economic patterns. A mix-method of qualitative and quantitative approaches was framed to procure and analyse data. This consisted of group discussions, individual surveys and key informant panel interview. Spatially mapped results of cluster analysis showed a strong spatial trend of SVI increasing from upstream to the downstream areas The multivariate regression model found linear correlations between the SVI and the proximity to the dike system and waterways. Additionally, the Moran’s I autocorrelation indicated the statistically significant difference between the SVI spatially of various household clusters. These findings contribute y to the understanding of the array of biophysical and socio-ecological impacts, their variability and their interlinkages.

How to cite: Phan, T., Van, T., Downes, N., and Thai, T.: Understanding Social Vulnerability to Climate Change-Modified Water Hazards in the Vietnamese Mekong Delta Coastal Zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8332, https://doi.org/10.5194/egusphere-egu24-8332, 2024.

Deltas are often densely populated and support much of the world’s fishes, forest products and agriculture. Protecting livelihoods and ecosystem services in deltas is therefore of global importance. The environmental degradation and the climate change are one of the multiple pressures experienced by deltas affecting the ecosystem services that pose risk in the livelihoods of the locals as well as the global population living in these areas. There is a need for new strategies for sustainable development to help deltas mitigate the effects of climate change as well as adapt to the changing conditions in a context of increasing uncertainty of hazards. Coastal areas of the Vietnamese Mekong Delta (VMD) are highly vulnerable due to land use changes and extreme climate hazards. This study will explore the specific aspects of deltas from a complexity-based approach, and analyse Nature-based Solutions as alternatives towards sustainable development in these areas. This examines Nature-based solutions (NbS) as a complementary or alternative approach to managing hazards in the Vietnamese Mekong Delta. We investigated the potential NbS as a complementary and sustainable method for mitigating the impacts of coastal disaster risks, mainly cyclones and floods. Finally, we address this gap by conducting a systematic literature review to assess the existence of policy instruments such as the Law on Natural Disaster Prevention and Mitigation (2009), Flood and Storm Prevention and Control (2000), Law on Dykes (2006), that adopt NbS and to evaluate the existence of specific examples of NbS.

How to cite: Banerjee, S., Ho, L. H., and Pal, I.: Policy implications to encourage the adoption of Nature-based Solutions in Vietnamese Mekong Delta (VMD)., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-512, https://doi.org/10.5194/egusphere-egu24-512, 2024.

Climate change dominates the nexus between water resources management needed for farm farmland irrigation and food security insurance. The challenge increases when the population proliferates and the demand for food and water rises. This study will explore how climate change may affect food production and water use in the Nile Delta, Egypt, through higher temperatures and sea level rise. It also aims to investigate the best management practices (BMPs) that can be used to tackle these issues. In the Delta, where irrigated agriculture is practiced, sea level rise is a major potential impact of climate change since it significantly impacts the salinity of the water and soil. Furthermore, higher temperatures directly influence evapotranspiration, a crucial component of crop yields and water balance. To determine this interdisciplinary nexus between climate, water, and food, integrated hydro/hydrogeological and crop models will be created by calibrating and simulating the current baseline situation. For that purpose, a basic crop model will be merged with the coupled SWAT_MODFLOW hydro(geo)logical simulation software. Additionally, a range of forecasting scenarios will be run to represent the impact of multiple climate change scenarios. The outcomes of operated scenarios will be evaluated regarding socioeconomic and environmental aspects to support the decision-making process and define how far the BMPs can be implemented on ground in this study area.

How to cite: Gomaa, S., Fleskens, L., Carvalho Nunes, J., and Badr, M.: An Integrated Modelling Approach to Support Sustainable Water Resources Management and Climate Change Adaptation for Irrigated Agriculture in the Nile Delta, Egypt., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-693, https://doi.org/10.5194/egusphere-egu24-693, 2024.

ABSTRACT

Natural hazards significantly impact school education, particularly in developing countries owing to their low coping capacity to hazards. The world’s 10 percent of tropical cyclones are experienced by Indian coastlines, together with the high probability of extreme rainfall events often leading to flood hazards. A comprehensive literature review highlighted the needs for thorough research on the differential impacts of climatic hazards on Sundarbans school education system and its societal linkages for adaptation strategies, hence promoting the resilient community.

This research aims to explore the impacts of multiple hazards and associated disruptions in school education, and attempts to identify determinants of resilience of school education to multiple hazards. The study aims to formulate an indicator library for vulnerability assessment of school education in the deltaic region. The research comprises of the conceptual background of vulnerability assessment, the indicators for education systems in the delta, the methodology for indicator library, and the indicator library table for school education systems in a comprehensive way. The study aims at developing a comprehensive library of school vulnerability indicators that will academically contribute as a reference for future researchers in the field of school vulnerability assessment.

How to cite: Pal, A., Tsusaka, T. W., Sundaram, M., Ahmad, M. M., and Nguyen, T. P. L.: A Comprehensive Indicator Based Vulnerability Assessment Method for School Education System: A Case Study of Sundarban Delta, India, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-684, https://doi.org/10.5194/egusphere-egu24-684, 2024.