Search Results (104)

Grass-covered levees commonly protect river and estuarine areas against flooding. Climate-induced water level changes may increasingly expose these levees to overflow events. This study investigates whether grass-covered levees can withstand such events, and under what conditions failure may occur. Between 2020 and 2022, full-scale overflow tests were conducted at the Living Lab Hedwige-Prosperpolder along the Dutch–Belgian Scheldt Estuary to assess erosion resistance under varying hydraulic conditions and vegetation states. A custom-built overflow generator was used, with instrumentation capturing flow velocity, water levels, and erosion progression. The results show that well-maintained levees with intact grass cover endured overflow durations up to 30 h despite high terminal flow velocities (4.9–7.7 m/s), without structural damage. In contrast, levee sections with pre-existing surface anomalies, such as animal burrows, slope irregularities, surface damage, or reed-covered soft soils, failed rapidly, often within one to two hours. Animal burrows facilitated subsurface flow and internal erosion, initiating fast, retrograde failure. These findings highlight the importance of preventive maintenance, particularly the timely detection and repair of anomalies. Once slope failure begins, the process unfolds rapidly, leaving no practical window for intervention. Full article

We consider a multilevel atom, such as a hydrogen atom, interacting with the quantum electromagnetic field in the dressed ground state of the interacting system. Using perturbation theory within the dipole approximation, we evaluate the dressed ground state and investigate the effect of atomic self-dressing on several field and atomic observables. Specifically, we obtain general expressions of the renormalized electric and magnetic field fluctuations and energy densities around the atom, and analyze their scaling with the distance from the atom, obtaining approximated expressions in the so-called near and far zones. We also investigate nonlocal spatial field correlations around the atom. We stress how the quantities we evaluate can be probed through two- and three-body nonadditive Casimir–Polder dispersion interactions. We also investigate the effect of self-dressing—namely, the virtual transitions occurring in the dressed ground state—on atomic observables, such as the average potential energy of the electron in the nuclear field. This also allows us to obtain a more fundamental quantum basis for the Welton interpretation of the Lamb shift of a ground-state hydrogen atom, in terms of the atomic self-dressing processes. Full article

This paper analyzes the chemical evolution of Nuntași-Tuzla Lake (Romania) in the context of human intervention. Situated on the shore of the Black Sea, approximately 35 km north of Constanța, Nuntași-Tuzla Lake is part of the Razim–Sinoe Lake complex and a component of the Danube Delta Biosphere Reserve. This area has undergone significant transformations over the past 120 years: canalization of the connecting channels with the St. George arm, construction of polders for agriculture, closure of the connections to the Black Sea, and construction of the Razim–Sinoe irrigation system. After the irrigation system stopped working (around 2000), due to the isolation of the lake and the low flow coming from the two rivers that supply the lake with fresh water, it completely dried up in 2020. All these interventions have led to the ecological, hydrological, and chemical deterioration of the lake’s water. The main effects are (i) a decrease in water salinity and (ii) reduction in the production of sapropelic mud as the salinity decreases due to the influx of fresh water. Full article

Rural areas are undergoing a transformation, shifting from traditional agriculture to green and leisure industries, driven by urban–rural imbalances and environmental challenges. This transition, however, presents the growing conflicts between preserving spatial features and promoting industrial development. Based on the unique rural spatial typology of polders, this study integrated theories from cultural, landscape, ecological, economic, and social perspectives to construct a conceptual framework of the interactive relationship between spatial features (SFs) and industrial development (ID). Then, an evaluation index system was constructed to measure the current status of SFs and ID, using data from field surveys, satellite imagery, and 2020 yearbooks, with the Gaochun Polder District, Nanjing (China), as the case study. Next, the coupling coordination degree (CCD) model and a scenario analysis based on orthogonal design were applied to assess the coherence and development between SFs and ID, and to identify strategies for optimizing rural industrial development. The results show that (1) the current SFs and ID are in the break-in and basic coordination stage, with ID lagging behind SFs, and (2) the 25 scenarios generated through orthogonal design were categorized into three groups: high-level coordination with synchronization between the two systems, high-level coordination but ID lagging behind SFs, and basic coordination where ID lags behind SFs. To achieve a high-level coordination with synchronization, specific strategies were proposed to enhance agricultural input–output benefits, improve agricultural scale–quality benefits, and, overall, protect the SF system while making minor adjustments to the village dwelling subsystem. Therefore, the findings provide recommendations for traditional polder villages to optimize their rural industries while preserving the distinctive SFs of the rural cultural landscape. Full article

Urban flooding is a growing concern, particularly in coastal lowland cities where climate change exacerbates hazards through rising sea levels and intense rainfall. Traditional flood defenses like fluvial polders often exacerbate urban fragmentation and maintenance costs if poorly integrated into planning. This study proposes a multifunctional assessment design framework to evaluate polder design effectiveness considering both the hydraulic and social–environmental dimensions, emphasizing blue–green infrastructure (BGI) for flood control, leisure, and landscape integration. Three design scenarios for Rio de Janeiro’s Jardim Maravilha neighborhood were modeled hydrodynamically: S1 (dike near urban areas, pump-dependent) and S2/S3 (dikes along the riverbank, gravity-driven). Results show S2/S3 outperformed S1 in storage capacity (2.7× larger volume), freeboard resilience (0.42–0.43 m vs. 0.25 m), and urban integration (floodable parks accessible to communities), though S1 had faster reservoir emptying. Under climate change, all scenarios sustained functionality, but S1’s freeboard reduced by 86%, nearing its limit. The framework’s standardized scoring system balanced quantitative and qualitative criteria, revealing trade-offs between hydraulic efficiency and urban adaptability. The optimized S3 design, incorporating external storage and dredging, achieved the best compromise. This approach aids decision-making by systematically evaluating resilience, operational feasibility, and long-term climate adaptation, supporting sustainable flood infrastructure in coastal cities. Full article

This work investigates the impact of sea level rise (SLR) of up to 3 m on flood protection and freshwater availability in the Netherlands. We applied an exploratory modeling approach to consider the large degree of uncertainty associated with SLR. The results show the current degree of flood protection can be technically and financially maintained for up to three meters of SLR. A primary finding of this work is that a similar degree of safety against floods can be maintained. There are, however, several challenges: First, maintaining this degree of safety against floods requires considerable spatial allocations to maintain and upgrade flood defenses, often in populated areas with limited space. Second, the supply of sand for coastal nourishments will be challenging due to other functions in the North Sea (wind energy, shipping) and explosive remnants of war. Third, an acceleration in the rate of SLR may impact the overall feasibility of maintaining flood defenses. Maintaining the freshwater strategy will be challenging due to SLR-induced salt intrusion, which aggravates climate impacts including droughts. Continued flushing of salinized areas of regional water systems and polders with fresh river water will increasingly compete with other demands. Our analysis highlights the vulnerabilities of the flood protection and freshwater strategies and gives input to follow-up analyses on societal impact and perspectives of actions for adaptation. Full article

Agriculture in the Indian Sundarbans deltaic region primarily depends on a rice-based monocropping system during the rainy season, with the subsequent season often remaining fallow. To mitigate this issue, a series of experiments using zero tillage and straw mulching (ZTSM) potato cultivation were conducted over eight consecutive years (2017–2024) across various islands in the Sundarbans Delta, West Bengal, aimed to intensify the cropping system and ensure the betterment of the land use pattern using climate-smart agricultural practices. In the initial two years, the experiments concentrated on assessing different potato cultivars and nutrient dosages under zero tillage and paddy straw mulching conditions. During the subsequent years, the focus shifted to field demonstrations under diverse climatic conditions. The research included the application of different macronutrients and growth regulators, in combination with different depths of straw mulching. In the final years of the study, the intervention was dedicated solely to the horizontal expansion of cultivated land. These initiatives aimed to enhance agricultural productivity and sustainable land use in the polders, promoting climate-resilient farming practices. From the sets of experiments, we standardized the sustainable nutrient management strategies and selection of appropriate potato cultivars vis-à-vis depth of straw mulching and, finally, the overall best agronomic practices for the region. The adoption of the ZTSM potato cultivation system demonstrated considerable success, as evidenced by the remarkable increase in the number of farmers employing this sustainable agricultural practice. The number of farmers practicing zero tillage potato cultivation surged from 23 in the initial year to over 1100, covering an area of more than 15 ha, highlighting the effectiveness of the technology. The analysis of the estimated adoption also showed that more than 90% adoption is likely to be achieved within a decade. This potential expansion underscores the benefits of the ZTSM potato cultivation system in improving soil health, conserving water, and reducing labour and costs. As more farmers recognize the advantages of zero tillage potato mulching, this approach is poised to play a pivotal role in sustainable agriculture, enhancing productivity while promoting environmental stewardship. Full article

Mangroves have been used for coastal protection in Bangladesh since the 1960s, but their integration with embankment designs has not been fully explored. This paper investigates the effect of existing mangroves on required embankment performance, with a focus on the wave-damping effect of mangroves. Existing mangroves reduce the required thickness of embankment revetment by up to 16–30% in the west, 47–82% in the central region, and 53–77% in the east. Notable mangrove sites include the belt south of polder 45 (Amtali), with an average width of 1.77 km, and the Kukri-Mukri polder, with an average width of 1.82 km. These mangroves reduce the need for thick slope protection, allowing the replacement of concrete revetments with softer materials, such as clay or grass, combined with mangrove foreshore. Additional large mangrove belts are found in Sandwip and Mirersarai. By replacing or reducing revetment requirements, mangrove forests can minimize carbon emissions from construction while providing carbon sequestration and other ecosystem services. This study can inform future sustainable investments in coastal protection systems by identifying areas where mangroves offer the greatest wave-damping benefits, which could be focus of follow-up feasibility studies. Full article

In recent years, flood hazards have occurred increasingly worldwide, posing significant threats to the safety of life and property in lacustrine and riverine environments. To mitigate the devastating impacts of floods, it is crucial to explore optimal strategies for joint flood diversion of flood diversion and storage measures (FDSM). The FDSM management of Poyang Lake in China focuses on studying semi-restoration polder areas (SR Polders) and flood storage and detention areas (FS Detentions), which are subjects of ongoing research. Existing studies primarily focus on SR Polders or FS Detentions, with limited research on the joint flood diversion potential of these two measures, particularly regarding optimal scheduling. This study takes 185 SR Polders and the Kangshan flood storage and detention area (KS Detention) as the primary research objects. By integrating hydraulic theory, numerical simulation techniques, and survey data, we develop a hydraulic model for the SR Polders and a hydrodynamic model for the KS Detention to carry out flood diversion simulation. The 1998 flood is chosen as a typical case to simulate and analyze their flood diversion processes under various schemes. The results indicate that altering the operation criteria for FDSM influences both the maximum diversion discharge and the timing of the main diversion period. For the SR Polders, under the current flood control scheme, raising the operation water level (OWL) of SR Polders-I by 1.0 m increases the maximum diversion discharge by 894 m³/s. Additionally, raising the OWL of SR Polders-II by 0.37 m delays the main diversion period by one day. For the KS Detention, higher flood diversion water levels correspond to greater discharge capacities. Furthermore, a fuzzy optimization method is applied to optimize nine joint schemes of the SR Polders and KS Detention. The results indicate that the optimal joint flood diversion strategy for Poyang Lake is operating SR Polders-I, SR Polders-II, and KS Detention at a Hukou water level of 21.65 m, 22.05 m, and 22.50 m, respectively. Finally, the study provides insights and recommendations for flood control management at Poyang Lake. The results of this study not only have important guiding significance for flood control management of large plain lakes but also provide references for the joint operation of flood diversion and storage areas in other regions. Full article

In constructed wetlands (CWs) with multiple plant communities, population structure may change over time and these variations may ultimately influence water quality. However, in CWs with multiple plant communities, it is still unclear how population structure may change over time and how these variations ultimately influence water quality. Here, we established a CW featuring multiple plant species within a polder to investigate the variation in plant population structure and wastewater treatment effect for drainage water over the course of one year. Our results showed that the total species decreased from 52 to 36; however, 20 established species with different ecological types (emerged or submerged) remained with the same functional assembly for nutrient absorption, accounting for 94.69% of relative richness at the initial stage and 91.37% at the last state. The Shannon index showed no significant differences among the initial, middle, and last states. Meanwhile, regarding nutrient content, the total phosphorus (TP) concentration decreased by 57.66% at the middle stage and by 56.76% at the last state. Total nitrogen (TN) decreased by 50.86% and 49.30%, respectively. Chemical oxygen demand (COD) decreased by 36.83% and 38.47%, while chlorophyll a (Chla) decreased by 72.36% and 78.54%, respectively. Redundancy analysis (RDA) results indicated that none of the selected environmental variables significantly affected the species community except for conductivity. Our findings suggest that when utilizing multiple species for CWs, it is essential to focus on the well-established species within the plant community. By maintaining these well-established species, water purification in CWs can be sustained. Full article

At present, a sustainable and wise management of water resources requires more insight into drainage/irrigation practices in river valleys. Since efficient sub-irrigation, based on reliable hydrometeorological forecasts, has been extensively considered with respect to water saving, the proper modeling tools were subsequently developed. An original, conceptual model for the management of drainage/irrigation systems was presented, taking into account the water inflow and storage in the soil profile. The aim was to propose a relatively simple procedure with parameters that relate to easily obtainable variables, e.g., groundwater table depth in the form of uncomplicated equations. The results of this tool were compared with the groundwater heads simulated using the recognized, common Modflow model. The comparisons proved a close match of the modeled variables and point at possibilities to calibrate it on polder areas. Full article

The flow of water in plain river network areas is significantly influenced by various factors, including human activities, upstream water influx, downstream tidal forces, and local rainfall. This leads to a complex situation where poor drainage and flooding are frequent occurrences. Polders play a crucial role in water management and agriculture in China by facilitating drainage and flood control, as well as supporting irrigation and aquaculture. As agriculture and water resource management continue to modernize, the monitoring and analysis of changes in water bodies and levels within polders become increasingly important. This paper primarily focuses on the detection of open water features in polder regions, mainly employing Sentinel-2 satellite imagery. By analyzing these data, we can effectively monitor the changes in the surface areas of water bodies within the polders. For our study, we have selected the Lixiahe region in China as it frequently experiences both flooding and drought conditions and houses a considerable number of polder zones. This region provides an ideal case study to explore the intricate relationship between water management infrastructure and natural hydrological phenomena. The importance of this research is manifold and significant. It advances the capabilities of remote sensing technologies and provides valuable insights for improved water level management in complex agricultural landscapes. The research introduces new methods and technical support for the remote sensing of water level changes in polders, contributing scientific support for enhanced water management and agricultural water conservation. Full article

Climate change has become a major global concern, and it has severe consequences for all communities. Coastal areas of Bangladesh are vulnerable to climate change because of their geophysical condition and geographical position. Although climate change affects people’s sustainable livelihood strategies in coastal regions of Bangladesh, it has gained limited attention in academic discourse. This study, hence, aimed to investigate the impact of climate change on the sustainable livelihood strategies of coastal people. Utilizing an explanatory sequential mixed research approach, including stakeholders’ consultations, household surveys, in-depth interviews (IDIs), focus group discussions (FGDs), and key informant interviews (KIIs), the study was carried out in Char Kukrumukri union in Bhola District, one of the climate-vulnerable areas of the country. Our study findings revealed that climate change primarily affects natural and physical capital, which in turn impacts financial, human, social, and political capital, and in the end, creates different forms of vulnerabilities. The study also explored a significant association between increasing waterlogging areas and reducing arable lands ($X^2$ = 38.02; p < 0.001), and the reduction in fresh water sources and damages in agricultural production ($X^2$ = 80; p < 0.001). The study further highlighted that the government efforts, such as polderization, aimed at preventing salinity in coastal areas, have failed due to the lack of integration with the representation of local people. The lack of integration between the local community’s voices and government actions poses additional challenges to maintaining people’s sustainable livelihood strategies. Thus, the study suggests a successful integration of localized practices and government interventions to address the climate-induced livelihood challenges to coastal people. Full article

Polder landscapes, as a representative of lowland agriculture landscapes, possess diverse natural and cultural values. However, polder landscapes are facing multiple challenges arising from economic and climate changes, including increasing flood threats and the fragmentation of landscape patterns. These issues have severely threatened the safety and regional characteristics of the polder landscape. Therefore, this study aims to preserve the regional characteristics of polder landscapes while promoting the sustainable development of lowland environments, and the objective is to provide a foundation and baseline for the management and planning of polder landscapes. In this study, the Dongting Lake Area (DLA) was selected as a representative case of polder landscapes. To identify the landscape character and delineate the landscape management zones, this study employed the Landscape Character Assessment (LCA) method in conjunction with a polder typology method at two scales. As a result, the polder landscape types were identified and visualized at two different scales. At the Lake Scale, a comprehensive identification method for polder unit types and polder landscape regions was established, achieving a stepwise transition from polder areas to polder clusters and ultimately to individual polder units. At the Local Scale, an integrative analysis of landscape character diversity (LCD) and land construction suitability (LCS) was employed to establish five landscape management zones for polder landscapes, thereby realizing a balance between the conservation of polder landscape diversity with the sustainable development of wetland environments. This study contributes a set of cross-scale ideas and methods for identifying landscape characters and delineating management zones in polder landscapes, which could be expanded to other lowland agricultural landscapes. Full article