The impact of flooding on aquatic ecosystem services

Assessing the ecohydrological impact of hydropower-induced flow regulation on fish habitats in the Jinsha River

The large-scale construction of hydropower projects and ongoing plans along the Jinsha River result in degradation and depletion of fish habitats. However, the impact of specific flow regulation patterns on mitigating the adverse effects of hydropower development on fish habitats remains inadequately understood. In this study, an ecohydrological model was developed to evaluate how modified flow patterns affect river hydrodynamics and fish habitats suitability. Two endemic fish species, Schizothorax prenanti, an economically consequential species, and the endangered Schizothorax davidi were designated as focal species. Seven discrete scenarios, entailing progressive adjustments in flow frequency and magnitude, were simulated utilizing multi-year averaged monthly flows as the baseline. Model simulation revealed that flow regulation exerted transformative effects on critical habitat constituents for fish, including flow velocity, water depth, and substrate composition. The degree of habitat alteration was contingent upon the regulation mode. Specifically, flow frequency regulation had a negligible impact on fish habitat, while changes in flow magnitude significantly affected habitat quality. Notably, increased flow magnitudes led to habitat loss, while decreased magnitudes caused spatial shifts in habitat distribution. Due to fish preferences for specific hydrodynamic conditions, diverse sensitivities to streamflow regulation were observed. Across all regulatory scenarios, the weighted useable area for Schizothorax prenanti consistently surpassed that of Schizothorax davidi. These findings, clarifying the mechanistic ecohydrological implications and elucidating the quality of fish habitats under varied flow regulations, hold paramount significance for river managers endeavoring to counterbalance alterations in flow regimes and safeguard ecological integrity.

Flood impact on men's mental health: evidence from flood-prone areas of Bangladesh

Disasters can pose significant risks to mental health, often resulting in both temporary and long-lasting psychological distress. This study explores the impact of floods on mental health. A survey was conducted shortly after the 2022 flash flood, in which 452 male participants from the Ajmiriganj and Dharmapasha Upazilas in Bangladesh were surveyed. Mental health was assessed using the DASS-21 instrument, and we examined the variables associated with mental health issues. Descriptive statistics and multiple linear regression analysis were employed. Around 47% of participants reported severe or extremely severe depression, 41% reported severe or extremely severe anxiety, and 36% reported severe or extremely severe stress. Factors such as age, marital status, type of home, occupation, flood safety rating, and property loss during the 2022 flood were all found to be associated with depression. Anxiety was linked to flood safety, occupation, housing type, education level, and marital status. Additionally, all anxiety-related variables were also associated with stress. Mental health issues were more prevalent among older, married, illiterate participants living in kacha (temporary) housing, as well as among agricultural workers and fishers with low safety ratings. Psychological interventions and disaster risk reduction strategies could help mitigate the mental health impact of floods. The findings of this study have important implications for global disaster management and public health.

Response of bacterial communities and soil chemistry to flood durations and recovery phases

Flooding profoundly impacts soil bacterial communities; however, the underlying mechanisms remain poorly understood. This study investigated how flooding (3, 8, and 16 days) and post-flooding (immediately and 2, 5, and 30 days) durations affect soil physicochemical properties, bacterial communities, and their interactions-crucial factors in floodplain nutrient and carbon cycling. The results showed that bacteria constituted 99.9% of the total microbial composition, while archaea, contributing only 0.1%, had a negligible impact on soil traits. At 2-5 days after flooding (DAF), elevated soil electrical conductivity (EC) and pH enhanced soil bacterial abundance and activity, leading to increased water-extractable dissolved organic carbon (DOC), water-extractable total dissolved nitrogen, and biological production (BIX), accompanied by the degradation of soil organic matter (SOM) and aromatic compounds (SUVA254). These changes indicated robust interactions between soil bacterial communities and physicochemical properties affected by flooding events. However, these relationships weakened at 30 DAF, suggesting potential transitions from anaerobic to aerobic conditions in post-flooding soils after 5 DAF. Structural equation modelling indicated that an extended post-flooding duration increased BIX, accompanied by SOM and DOC degradation, providing nutrients and energy to soil microbes and consequently leading to increased bacterial diversity. This study underscores the significant impact of flooding and post-flooding durations on soil bacterial community composition and diversity, mediated by changes in EC, pH, SOM, and DOM, potentially influencing nutrient cycling in floodplains.

The impacts of climate change, early agriculture and internal fluvial dynamics on paleo-flooding episodes in Central China

Floods clustered in episodes are the most prevalent natural disaster worldwide, causing substantial economic and human losses. Although these events are often linked to time-periods of extreme rainstorms and unique atmospheric circulation patterns, the river basin characteristics affected by anthropogenic land use changes could exert a strong influence. However, the way and extent of how land use changes across different time scales affect flooding periods are still unclear, especially considering the historical land use changes. This study uses the Landlab landscape evolution model, coupled with an evapotranspiration model, to investigate the forcing factors for the paleo-flooding trends in the Wei River catchment over the last 5000 years. The results indicate that the flooding period from 4400 to 4000 BP was caused by an increase of 28 % in antecedent moisture content as well as a decrease of 28 % in its spatial variability, which are primarily due to climate change, and that the contribution of land-use change is less than 5 %. The increases of about 14 % and 8 % in main channel sedimentation rate play a leading role in flood generation during the time periods from 3400 to 2800 BP and 2000-1400 BP, respectively. These two periods of increased flooding are primarily caused by the erosional effects of increasing anthropogenic land use, whose contributions range from 33 % to 64 %. Furthermore, based on our modelling results, we suggest that the downstream propagation of the main flooding locations, from the Wei River to the lower reaches of the Yellow River, can be explained by the downstream migrating sediment wave. In conclusion, our simulation results give new insights into the causes of Holocene flooding periods in the middle Yellow River from the perspective of dynamic changes in catchment characteristics, which is helpful to improve regional flood risk management under future climate change and anthropogenic activities.

Advances in the integration of microalgal communities for biomonitoring of metal pollution in aquatic ecosystems of sub-Saharan Africa

This review elucidated the recent advances in integrating microalgal communities in monitoring metal pollution in aquatic ecosystems of sub-Saharan Africa (SSA). It also highlighted the potential of incorporating microalgae as bioindicators in emerging technologies, identified research gaps, and suggested directions for further research in biomonitoring of metal pollution. Reputable online scholarly databases were used to identify research articles published between January 2000 and June 2023 for synthesis. Results indicated that microalgae were integrated either individually or combined with other bioindicators, mainly macroinvertebrates, macrophytes, and fish, alongside physicochemical monitoring. There was a significantly low level of integration (< 1%) of microalgae for biomonitoring aquatic metal pollution in SSA compared to other geographical regions. Microalgal communities were employed to assess compliance (76%), in diagnosis (38%), and as early-warning systems (38%) of aquatic ecological health status. About 14% of biomonitoring studies integrated microalgal eDNA, while other technologies, such as remote sensing, artificial intelligence, and biosensors, are yet to be significantly incorporated. Nevertheless, there is potential for the aforementioned emerging technologies for monitoring aquatic metal pollution in SSA. Future monitoring in the region should also consider the standardisation and synchronisation of integrative biomonitoring and embrace the "Citizen Science" concept at national and regional scales.

Dam inundation reduces ecosystem multifunctionality following riparian afforestation in the Three Gorges Reservoir Region

Afforestation is an acknowledged method for rehabilitating deteriorated riparian ecosystems, presenting multiple functions to alleviate the repercussions of river damming and climate change. However, how ecosystem multifunctionality (EMF) responds to inundation in riparian afforestation ecosystems remains relatively unexplored. Thus, this article aimed to disclose how EMF alters with varying inundation intensities and to elucidate the key drivers of this variation based on riparian reforestation experiments in the Three Gorges Reservoir Region in China. Our EMF analysis encompassed wood production, carbon storage, nutrient cycling, decomposition, and water regulation under different inundation intensities. We examined their correlation with soil properties and microbial diversity. The results indicated a substantial reduction in EMF with heightened inundation intensity, which was primarily due to the decline in most individual functions. Notably, soil bacterial diversity (23.02%), soil properties such as oxidation-reduction potential (ORP, 11.75%), and temperature (5.85%) emerged as pivotal variables elucidating EMF changes under varying inundation intensities. Soil bacterial diversity and ORP declined as inundation intensified but were positively associated with EMF. In contrast, soil temperature rose with increased inundation intensity and exhibited a negative correlation with EMF. Further insights gleaned from structural equation modeling revealed that inundation reduced EMF directly and indirectly by reducing soil ORP and bacterial diversity and increasing soil temperature. This work underscores the adverse effects of dam inundation on riparian EMF and the crucial role soil characteristics and microbial diversity play in mediating EMF in response to inundation. These insights are pivotal for the conservation of biodiversity and functioning following afforestation in dam-induced riparian habitats.

Community stability of free-living and particle-attached bacteria in a subtropical reservoir with salinity fluctuations over 3 years

Changes in salinity have a profound influence on ecological services and functions of inland freshwater ecosystems, as well as on the shaping of microbial communities. Bacterioplankton, generally classified into free-living (FL) and particle-attached (PA) forms, are main components of freshwater ecosystems and play key functional roles for biogeochemical cycling and ecological stability. However, there is limited knowledge about the responses of community stability of both FL and PA bacteria to salinity fluctuations. Here, we systematically explored changes in community stability of both forms of bacteria based on high-frequency sampling in a shallow urban reservoir (Xinglinwan Reservoir) in subtropical China for 3 years. Our results indicated that (1) salinity was the strongest environmental factor determining FL and PA bacterial community compositions - rising salinity increased the compositional stability of both bacterial communities but decreased their α-diversity. (2) The community stability of PA bacteria was significantly higher than that of FL at high salinity level with low salinity variance scenarios, while the opposite was found for FL bacteria, i.e., their stability was higher than PA bacteria at low salinity level with high variance scenarios. (3) Both bacterial traits (e.g., bacterial genome size and interaction strength of rare taxa) and precipitation-induced factors (e.g., changes in salinity and particle) likely contributed collectively to differences in community stability of FL and PA bacteria under different salinity scenarios. Our study provides additional scientific basis for ecological management, protection and restoration of urban reservoirs under changing climatic and environmental conditions.

A large flood resets riverine morphology, improves connectivity and enhances habitats of a regulated river

Flow regulation in gravel-bed rivers impacts the hydrology, sediments and morphology, riparian vegetation, and vertical connectivity with the hyporheic zone. In this context, previous works have suggested that flood events may have riverine morphological and ecological benefits. In a Mediterranean-climate river system, we analyzed the impact of a 18-year return period flood on river morphology, riparian vegetation, fish aquatic habitat quality, and hyporheic exchange in a dam-regulated gravel-bed river, Serpis River (Spain). We collected pre- and post-flood riparian vegetation distributions and bathymetries, which were used to develop two-dimensional surface and three-dimensional subsurface numerical models to map surface and hyporheic hydraulics. Results show that the large flood removed the invasive giant reed from large areas, reshaped the in-channel morphology by forming new bars and pools, and enhanced the complexity of the flow field and the hydro-morphological diversity. The habitat availability for the endemic Eastern Iberian chub (Squalius valentinus) and invasive bleak (Alburnus alburnus) increased. Hyporheic exchange showed limited change under losing conditions, but noticeable under neutral ambient groundwater condition. This study corroborates the beneficial effects that flood events or high flow releases may have on regulated streams and the potential use of high flow pulse as a restoration tool.

Science of forests and floods: The quantum leap forward needed, literally and metaphorically

A century of research has generated considerable disagreement on the effect of forests on floods. Here we call for a causal inference framework to advance the science and management of the effect of any forest or its removal on flood severity and frequency. The causes of floods are multiple and chancy and, hence, can only be investigated via a probabilistic approach. We use the stochastic hydrology literature to infer a blueprint framework which could guide future research on the understanding and prediction of the effects of forests on floods in environments where rain is the dominant form of precipitation. Drawing parallels from other disciplines, we show that the introduction of probability in forest hydrology could stimulate a gestalt switch in the science of forests and floods. In light of increasing flood risk caused by climate change, this probabilistic framework can help policymakers develop robust forest and water management plans based on a defensible and clear understanding of floods.

A synthesis of anthropogenic stress effects on emergence-mediated aquatic-terrestrial linkages and riparian food webs

Anthropogenic stress alters the linkage between aquatic and terrestrial ecosystems in various ways. Here, we review the contemporary literature on how alterations in aquatic systems through environmental pollution, invasive species and hydromorphological changes carry-over to terrestrial ecosystems and the food webs therein. We consider both the aquatic insect emergence and flooding as pathways through which stressors can propagate from the aquatic to the terrestrial system. We specifically synthesize and contextualize results on the roles of pollutants in the emergence pathway and their top-down consequences. Our review revealed that the emergence and flooding pathway are only considered in isolation and that the overall effects of invasive species or pollutants on food webs at the water-land interface require further attention. While very few recent studies looked at invasive species, a larger number of studies focused on metal transfer compared to pesticides, pharmaceuticals or PCBs, and multiple stress studies up to now left aquatic-terrestrial linkages unconsidered. Recent research on pollutants and emergence used aquatic-terrestrial mesocosms to elucidate the effects of aquatic stressors such as the mosquito control agent Bti, metals or pesticides to understand the effects on riparian spiders. Quality parameters, such as the structural and functional composition of emergent insect communities, the fatty acid profiles, yet also the composition of pollutants transferred to land prove to be important for the effects on riparian spiders. Process-based models including quality of emergence are useful to predict the resulting top-down directed food web effects in the terrestrial recipient ecosystem. In conclusion, we present and recommend a combination of empirical and modelling approaches in order to understand the complexity of aquatic-terrestrial stressor propagation and its spatial and temporal variation.

Assessing the Human Health Benefits of Climate Mitigation, Pollution Prevention, and Biodiversity Preservation

Background

Since the Industrial Revolution, humanity has amassed great wealth and achieved unprecedented material prosperity. These advances have come, however, at great cost to the planet. They are guided by an economic model that focuses almost exclusively on short-term gain, while ignoring natural capital and human capital. They have relied on the combustion of vast quantities of fossil fuels, massive consumption of the earth's resources, and production and environmental release of enormous quantities of chemicals, pesticides, fertilizers, and plastics. They have caused climate change, pollution, and biodiversity loss, the "Triple Planetary Crisis". They are responsible for more than 9 million premature deaths per year and for widespread disease - impacts that fall disproportionately upon the poor and the vulnerable.

Goals

To map the human health impacts of climate change, pollution, and biodiversity loss. To outline a framework for assessing the health benefits of interventions against these threats.

Findings

Actions taken by national governments and international agencies to mitigate climate change, pollution, and biodiversity loss can improve health, prevent disease, save lives, and enhance human well-being. Yet assessment of health benefits is largely absent from evaluations of environmental remediation programs. This represents a lost opportunity to quantify the full benefits of environmental remediation and to educate policy makers and the public.

Recommendations

We recommend that national governments and international agencies implementing interventions against climate change, pollution, and biodiversity loss develop metrics and strategies for quantifying the health benefits of these interventions. We recommend that they deploy these tools in parallel with assessments of ecologic and economic benefits. Health metrics developed by the Global Burden of Disease (GBD) study may provide a useful starting point.Incorporation of health metrics into assessments of environmental restoration will require building transdisciplinary collaborations. Environmental scientists and engineers will need to work with health scientists to establish evaluation systems that link environmental and economic data with health data. Such systems will assist international agencies as well as national and local governments in prioritizing environmental interventions.

Characterizing the level of urban Flood vulnerability using the social-ecological-technological systems framework, the case of Adama city, Ethiopia

This study characterizes the flood vulnerability of Adama City, Ethiopia, where the city faces high flood vulnerability due to its unplanned urbanization in low-lying floodplain areas surrounding deforested mountains and ridges. The study applied an interlinked Social-Ecological-Technological-Systems (SETS) vulnerability framework using a GIS-based Multi-Criteria Decision-Making and Analytical Hierarchy Process (MCDM-AHP). The framework analyzed exposure, sensitivity, and adaptive capacity to flooding for each of the three SETS domains. The study analyzed 18 variables at the city level within each SETS domain. The result revealed that clusters of flood-vulnerable areas were identified by each SETS domain showing the concentration of flood vulnerability in the study area and the need to consider prompt adaptive mechanisms to severe and recurring flooding. The finding has significant implications for holistic approaches to sustainable cities. Moreover, the reduction of complex urban flood vulnerabilities according to their priority as individual or combined solutions for decision-makers and professionals in early warning and flood management systems is the other contribution of the study.

Long-term environmental stability does not erode plasticity in nest building responses to changing ambient conditions

The primary function of animal nests is to protect developing offspring from hostile and fluctuating environments. Animal builders have been shown to adjust nest construction in response to changes in their environment. However, the extent of this plasticity, and its dependence on an evolutionary history of environmental variability, is not well understood. To test whether an evolutionary history with flowing water impacts male ability to adjust nests in response to flow regime, we collected three-spined sticklebacks (Gasterosteus aculeatus) from three lakes and three rivers, and brought them into reproductive condition in controlled laboratory aquaria. Males were then allowed to nest under both flowing and static conditions. Nest building behaviour, nest structure and nest composition were all recorded. In comparison to males building nests under static conditions, males building in flowing water took longer to construct their nests and invested more in nesting behaviour. Moreover, nests built in flowing water contained less material, were smaller, more compact, neater and more elongated than nests built under static conditions. Whether males came from rivers or lakes had little impact on nesting activities, or male capacity to adjust behaviours in response to flow treatment. Our findings suggest that aquatic animals which have experienced a stable environment over a long period of time retain plasticity in nest-building behaviours that allow them to adjust nests to ambient flow conditions. This ability may prove crucial in coping with the increasingly unpredictable flow regimes found in anthropogenically altered waterways and those resulting from global climate change. This article is part of the theme issue 'The evolutionary ecology of nests: a cross-taxon approach'.

Disentangling direct and indirect effects of extreme events on coastal wetland communities

One of the primary ways in which climate change will impact coastal freshwater wetlands is through changes in the frequency, intensity, timing and distribution of extreme weather events. Disentangling the direct and indirect mechanisms of population- and community-level responses to extreme events is vital to predicting how species composition of coastal wetlands will change under future conditions. We extended static structural equation modelling approaches to incorporate system dynamics in a multi-year multispecies occupancy model to quantify the effects of extreme weather events on a coastal freshwater wetland system. We used data from an 8-year study (2009-2016) on St. Marks National Wildlife Refuge in Florida, USA, to quantify species-specific and community-level changes in amphibian and fish occupancy associated with two flooding events in 2012 and 2013. We examine how physical changes to the landscape, including potential changes in salinity and increased wetland connectivity, may have contributed to or exacerbated the effects of these extreme weather events on the biota of isolated coastal wetlands. We provide evidence that the primary effects of flooding on the amphibian community were through indirect mechanisms via changes in the composition of the sympatric fish community that may have had lethal (i.e. through direct predation) or non-lethal (i.e. through direct or indirect competitive interactions) effects. In addition, we have shown that amphibian species differed in their sensitivity to direct flooding effects and indirect changes in the fish community and wetland-specific conductance, which led to variable responses across the community. These effects led to the overall decline in amphibian species richness from 2009 to 2016, suggesting that wetland-breeding amphibian communities on St. Marks National Wildlife Refuge may not be resilient to predicted changes in coastal disturbance regimes because of climate change. Understanding both direct and indirect effects, as well as species interactions, is important for predicting the effects of a changing climate on individual species, communities and ecosystems.

Integrating optimization and damage estimation to increase economic benefit and ensure food security under seasonal land variability

Rapidly increasing population and rising food demand necessitates expansion of agricultural mainland. However, with accelerated urbanization, agricultural land resources are difficult to expand. The riverine sandbars offer a vast fertile terrain that is conducive to agricultural food production and could support the global food demands despite urbanization. Nevertheless, hydroclimatic factors like streamflow and precipitation have an impact on the availability of agricultural land and potential crop damage in riverine ecosystems. The present study determines the agricultural economic benefits from cultivation in riverine sandbars through optimization framework under stochastic streamflow. A damage estimation model was developed to evaluate the economic losses an optimally planned riverine agricultural area would suffer, if the flow variation exceeds a certain threshold. The findings showed that economic benefit of ∼130 million rupees could be achieved with ∼22 million rupees of additional benefit from the proposed optimization approach. This additional benefit was in reference to the selective cropping approaches, which the farmers did not account. Furthermore, the damage estimation model could comprehend the losses under fluctuating streamflow in subsequent years that was found to vary between 5 and 34 percent. Therefore, this framework of integrating optimization and damage estimation approaches contribute to a better understanding of optimally utilizing the riverine sandbars, thereby improving the socio-economic status of marginalized communities and providing potential additional land resources to sustain food security and production. The study also highlighted the need of crop insurance facilities to assess and manage risks that could provide financial support to farmers, cover crop loss and damage arising from hydroclimatic variabilities.

Beneficial and pathogenic plant-microbe interactions during flooding stress

The number and intensity of flood events will likely increase in the future, raising the risk of flooding stress in terrestrial plants. Understanding flood effects on plant physiology and plant-associated microbes is key to alleviate flooding stress in sensitive species and ecosystems. Reduced oxygen supply is the main constrain to the plant and its associated microbiome. Hypoxic conditions hamper root aerobic respiration and, consequently, hydraulic conductance, nutrient uptake, and plant growth and development. Hypoxia favours the presence of anaerobic microbes in the rhizosphere and roots with potential negative effects to the plant due to their pathogenic behaviour or their soil denitrification ability. Moreover, plant physiological and metabolic changes induced by flooding stress may also cause dysbiotic changes in endosphere and rhizosphere microbial composition. The negative effects of flooding stress on the holobiont (i.e., the host plant and its associated microbiome) can be mitigated once the plant displays adaptive responses to increase oxygen uptake. Stress relief could also arise from the positive effect of certain beneficial microbes, such as mycorrhiza or dark septate endophytes. More research is needed to explore the spiralling, feedback flood responses of plant and microbes if we want to promote plant flood tolerance from a holobiont perspective.

Sub-Saharan Africa Freshwater Fisheries under Climate Change: A Review of Impacts, Adaptation, and Mitigation Measures

Sub-Saharan Africa’s freshwater fisheries contribute significantly to the livelihoods and food security of millions of people within the region. However, freshwater fisheries are experiencing multiple anthropogenic stressors such as overfishing, illegal fishing, pollution, and climate change. There is a substantial body of literature on the effects of climate change on freshwater fisheries in Sub-Saharan Africa. This study reviews the existing literature and highlights the effects of climate change on freshwater fisheries, the adaptation strategies of fishery-dependent households in response to the effects, and fisheries’ management and mitigation efforts in the face of climate change. The general effects of climate change on freshwater environments include warming water temperatures, increased stratification, modified hydrological processes, and increased pollutants. These effects adversely affect the physiological processes of fish and the overall wellbeing of fishery-dependent people. To cope with the effects of fluctuating fishery resources due to climate change, fishery-dependent people have adopted several adaptation strategies including livelihood diversification, changing their fishing gear, increasing their fishing efforts, and targeting new species. Several management attempts have been made to enhance the sustainability of fishery resources, from local to regional levels. This study recommends the participation of the resource users in the formulation of policies aimed at promoting climate change adaptation and the resilience of freshwater fisheries for sustainable development.

Flooding, Food Security and the Sustainable Development Goals in Nigeria: An Assemblage and Systems Thinking Approach

Food is connected to sustainable development goals in numerous ways, as food security is key to achieving sustainable development. The world is currently not on track to achieve the set sustainable development goals (SDGs). In Nigeria, flooding is a recurrent disaster and constitutes a setback to success with the SDGs and sustainable development. Flooding disasters are a threat to food security due to their impact on the food system. This study is an integrative review that explores the link between Nigeria’s flooding, food security, and the SDGs. It adopts an assemblage and systems thinking approach to analyze the impact of flooding on all components of food security. It finds that, despite the impact of flooding on food security, it is not recognized as a threat by policymakers, as evidenced by the lack of mention of disasters in the current Nigeria Agriculture Promotion Policy (APP). Attention is drawn to this oversight in this work by highlighting the interconnections between flooding, food security, and sustainable development. Recommendations on flood mitigation and adaptive practices that can alleviate the negative impact of flooding on food security to enhance the success rate of the SDGs are proffered. This work contributes to the literature by showcasing the impact of flooding on food security and its connection to sustainable development, which is an area that has not received adequate attention in research. The assemblage and system thinking approach adopted brings novelty and allows for a succinct understanding of how flooding impacts all four aspects of food security. This paper serves as the first time the problem has been explored in this manner.

Willingness to pay for the ecological restoration of an inland freshwater shallow lake: case of Lake Malombe, Malawi

Lake Malombe is ranked among the most vulnerable inland freshwater shallow lakes in Malawi. The lake has lost over US$79.83 million ecosystem service values from 1999 to 2019 due to rapid population growth, increased poverty, landscape transformation, and over exploitation-hampering the effort to achieve United Nations (UN) Sustainable Development Goals (SDGs), in particular, life underwater (SDG 14), life on land (SDG 15), climate action (SDG 13), and no poverty (SDG 1) and Aichi Biodiversity Targets. In line with the 2021–2030 United Nations' Declaration on massive upscaling of the ecosystems restoration effort, this study applied the contingent valuation method (CVM) and binary logistic regression model to determine the public's willingness to pay (WTP) for ecosystem restoration and the influencing factors. The aim was to integrate science into policy framework to achieve a sustainable flow of ecosystem services (ESs). Qualitative data were collected by employing focus group discussion, key informant interviews, and field observation. Quantitative data were collected using structured questionnaires covering 420 households. The results revealed that 56% of the respondents were willing to pay an average of US$28.42/household/year. These respondents believed that the initiative would improve lake ESs, fish biodiversity, income level, water quality and mitigate climate change impact. Age, gender, literacy, income, social trust, institutional trust, access to extension services, period stay in the area, household distance from the lake, lake ecological dynamics impact, having the hope of reviving the lake health ecological status, perception of having lake ecological restoration program, participation in lake restoration program, access to food from the lake, involved in fishing and Lake Malombe primary livelihood sources significantly (p < 0.05) influenced WTP. This study provides a reference point to policymakers to undertake cost-benefit analysis and develop a practical policy response framework to reverse the situation and achieve United Nations Sustainable Development Goals and Aichi Biodiversity Targets.

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420 WTP questionnaires were analyzed.

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Mean WTP was $28.42/yr.

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Many factors influenced WTP.

Plastic Pollution, Waste Management Issues, and Circular Economy Opportunities in Rural Communities

Rural areas are exposed to severe environmental pollution issues fed by industrial and agricultural activities combined with poor waste and sanitation management practices, struggling to achieve the United Nations’ Sustainable Development Goals (SDGs) in line with Agenda 2030. Rural communities are examined through a “dual approach” as both contributors and receivers of plastic pollution leakage into the natural environment (through the air–water–soil–biota nexus). Despite the emerging trend of plastic pollution research, in this paper, we identify few studies investigating rural communities. Therefore, proxy analysis of peer-reviewed literature is required to outline the significant gaps related to plastic pollution and plastic waste management issues in rural regions. This work focuses on key stages such as (i) plastic pollution effects on rural communities, (ii) plastic pollution generated by rural communities, (iii) the development of a rural waste management sector in low- and middle-income countries in line with the SDGs, and (iv) circular economy opportunities to reduce plastic pollution in rural areas. We conclude that rural communities must be involved in both future plastic pollution and circular economy research to help decision makers reduce environmental and public health threats, and to catalyze circular initiatives in rural areas around the world, including less developed communities.

Modeling, mapping and analysis of urban floods in India-a review on geospatial methodologies

An increasing trend of urban floods in India from past several years causes major damages on Indian cities. By 2050, more than half of the population in the developing countries like India are expected to migrate to urban regions. Urbanization is triggered in developing countries as people migrate to cities in search of employment opportunities resulting in formation of new slums. With high density of population concentration in cities, urban floods are triggered leading to a significant impact of human life and economy of the country. The review focuses on addressing the urban flood occurrence in India and its relationship with population growth climate change. The study also describes the impact of urban floods to the environment and integrated methodologies adopted over decades for the prediction and effective mitigation and management during a disaster event.

Application of Multi-Criteria Decision-Making Model and Expert Choice Software for Coastal City Vulnerability Evaluation

Climate change is regarded as a serious threat to both environment and humanity, and as a result, it has piqued worldwide attention in the twenty-first century. Natural hazards are expected to have major effects in the coastal cities of the globe. At the same time, about two-thirds of the world’s human population lives in the coastal margins. One of the fundamental issues for coastal city planners is the coastal cities’ environmental change. This paper presents the application of a model framework for the management and sustainable development of coastal cities under a changing climate in Kuala Terengganu Malaysia. The analytic hierarchy process (AHP) is performed in the Expert Choice software for coastal city hazard management. This approach enables decision-makers to evaluate and identify the relative priorities of vulnerability and hazard criteria and sub-criteria based on a set of preferences, criteria, and alternatives. This paper also presents a hierarchy erosion design applied in Kuala Terengganu to choose the important sustainable weights of criteria and sub-criteria as well as the zone as an alternative model.

Tracking Fecal Bacterial Dispersion from Municipal Wastewater to Peri-Urban Farms during Monsoon Rains in Hue City, Vietnam

Disease outbreaks attributed to monsoon flood-induced pathogen exposure are frequently reported, especially in developing cities with poor sanitation. Contamination levels have been monitored in past studies, yet the sources, routes, and extents of contamination are not always clear. We evaluated pollution from municipal wastewater (MWW) discharge and investigated fecal contamination by Escherichia coli (E. coli) in three agricultural fields on the outskirts of Hue City, Vietnam. After E. coli concentration was determined in irrigation water (IRW), MWW, soil, vegetables (VEG), and manure, its dispersion from MWW was tracked using multilocus sequence typing (MLST) and phylogenetic analyses during the wet and dry seasons. IRW was severely contaminated; 94% of the samples were positive with E. coli exceeding the stipulated standards, while VEG contamination was very low in both seasons. The confirmed total number of isolates was comparable between the seasons; however, results from MLST and phylogenetic clustering revealed more links between the sites and samples to MWW during the wet season. The wet season had four mixed clusters of E. coli isolates from multiple locations and samples linked to MWW, while only one mixed cluster also linking MWW to IRW was observed during the dry season. The most prevalent sequence type (ST) complex 10 and two others (40 and 155) have been associated with disease outbreaks, while other STs have links to major pathotypes. Irrigation canals are significant routes for E. coli dispersion through direct links to the urban drainage-infested river. This study clarified the genotype of E. coli in Hue city, and the numerous links between the samples and sites revealed MWW discharge as the source of E. coli contamination that was enhanced by flooding.

Integration of hard and soft supervised machine learning for flood susceptibility mapping

Flooding is a destructive natural phenomenon that causes many casualties and property losses in different parts of the world every year. Efficient flood susceptibility mapping (FSM) can reduce the risk of this hazard, and has become the main approach in flood risk management. In this study, we evaluated the prediction ability of artificial neural network (ANN) algorithms for hard and soft supervised machine learning classification in FSM by using three ANN algorithms (multi-layer perceptron (MLP), fuzzy adaptive resonance theory (FART), self-organizing map (SOM)) with different activation functions (sigmoidal (-S), linear (-L), commitment (-C), typicality (-T)). We used integration of these models for predicting the spatial expansion probability of flood events in the Ajichay river basin, northwest Iran. Inputs to the ANN were spatial data on 10 flood influencing factors (elevation, slope, aspect, curvature, stream power index, topographic wetness index, lithology, land use, rainfall, and distance to the river). The FSMs obtained as model outputs were trained and tested using flood inventory datasets earned based on previous records of flood damage in the region for the Ajichay river basin. Sensitivity analysis using one factor-at-a-time (OFAT) and all factors-at-a-time (AFAT) demonstrated that all influencing factors had a positive impact on modeling to generate FSM, with altitude having the greatest impact and curvature the least. Model validation was carried out using total operating characteristic (TOC) with an area under the curve (AUC). The highest success rate was found for MLP-S (92.1%) and the lowest for FART-T (75.8%). The projection rate in the validation of FSMs produced by MLP-S, MLP-L, FART-C, FART-T, SOM-C, and SOM-T was found to be 90.1%, 89.6%, 71.7%, 70.8%, 83.8%, and 81.1%, respectively. While integration of hard and soft supervised machine learning classification with activation functions of MLP-S and MLP-L showed a strong flood prediction capability for proper planning and management of flood hazards, MLP-S is a promising method for predicting the spatial expansion probability of flood events.

Nexus between Water Security Framework and Public Health: A Comprehensive Scientific Review

Water scarcity, together with the projected impacts of water stress worldwide, has led to a rapid increase in research on measuring water security. However, water security has been conceptualized under different perspectives, including various aspects and dimensions. Since public health is also an integral part of water security, it is necessary to understand how health has been incorporated as a dimension in the existing water security frameworks. While supply–demand and governance narratives dominated several popular water security frameworks, studies that are specifically designed for public health purposes are generally lacking. This research aims to address this gap, firstly by assessing the multiple thematic dimensions of water security frameworks in scientific disclosure; and secondly by looking into the public health dimensions and evaluating their importance and integration in the existing water security frameworks. For this, a systematic review of the Scopus database was undertaken using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A detailed review analysis of 77 relevant papers was performed. The result shows that 11 distinct dimensions have been used to design the existing water security framework. Although public health aspects were mentioned in 51% of the papers, direct health impacts were considered only by 18%, and indirect health impacts or mediators were considered by 33% of the papers. Among direct health impacts, diarrhea is the most prevalent one considered for developing a water security framework. Among different indirect or mediating factors, poor accessibility and availability of water resources in terms of time and distance is a big determinant for causing mental illnesses, such as stress or anxiety, which are being considered when framing water security framework, particularly in developing nations. Water quantity is more of a common issue for both developed and developing countries, water quality and mismanagement of water supply-related infrastructure is the main concern for developing nations, which proved to be the biggest hurdle for achieving water security. It is also necessary to consider how people treat and consume the water available to them. The result of this study sheds light on existing gaps for different water security frameworks and provides policy-relevant guidelines for its betterment. Also, it stressed that a more wide and holistic approach must be considered when framing a water security framework to result in sustainable water management and human well-being.

Gel-like carbon dots: A high-performance future photocatalyst

To protect water resources, halt waterborne diseases, and prevent future water crises, photocatalytic degradation of water pollutants arouse worldwide interest. However, considering the low degradation efficiency and risk of secondary pollution displayed by most metal-based photocatalysts, highly efficient and environmentally friendly photocatalysts with appropriate band gap, such as carbon dots (CDs), are in urgent demand. In this study, the photocatalytic activity of gel-like CDs (G-CDs) was studied using diverse water pollution models for photocatalytic degradation. The degradation rate constants demonstrated a remarkably enhanced photocatalytic activity of G-CDs compared with most known CD species and comparability to graphitic carbon nitride (g-C₃N₄). In addition, the rate constant was further improved by 1.4 times through the embedment of g-C₃N₄ in G-CDs to obtain CD-C₃N₄. Significantly, the rate constant was also higher than that of g-C₃N₄ alone, revealing a synergistic effect. Moreover, the use of diverse radical scavengers suggested that the main contributors to the photocatalytic degradation with G-CDs alone were superoxide radicals (O₂^-) and holes that were, however, substituted by O₂^- and hydroxyl radicals (OH) due to the addition of g-C₃N₄. Furthermore, the photocatalytic stabilities of G-CDs and CD-C₃N₄ turned out to be excellent after four cycles of dye degradation were performed continuously. Eventually, the nontoxicity and environmental friendliness of G-CDs and CD-C₃N₄ were displayed with sea urchin cytotoxicity tests. Hence, through various characterizations, photocatalytic degradation and cytotoxicity tests, G-CDs proved to be an environmentally friendly and highly efficient future photocatalyst.

Extreme events and conservation of subtidal habitats: Effects of a rainfall flood on coralligenous reefs

The increase of the intensity and frequency of rainfall-dominated flood is considered a main effect of climate change. The present study evaluated the effect of a rainfall flood event on coralligenous reefs. The flooded site was compared to three control sites using a Before/After-Control/Impact (BACI) design. Sites were sampled using the STAR (STAndaRdized coralligenous evaluation procedure) approach and three ecological indices (ESCA, COARSE and ISLA) were calculated. At the disturbed site the number of species per sample, beta diversity, sensitivity levels of assemblages and the values of the three indices were lower after the flooding event, while the same variables did not decrease at the control sites. Algal turf and Dictyotales increased at the disturbed sites after the flood event, while Udoteaceae, erect sponges, bryozoans and Corallium rubrum decreased. This study provides evidence for identifying floods as a further cause of degradation for the coralligenous reef assemblages.

Machine learning models for wetland habitat vulnerability in mature Ganges delta

The present study attempts to measure wetland habitat vulnerability (WHV) in the Indian part of mature Ganges delta. Predictive algorithms belonging to bivariate statistics and machine learning (ML) algorithms were applied for fulfilling the data mining and generating the models. Results show that 60% of the wetland areas are covered by moderate to very high WHV, out of which > 300 km² belong to very high WHV followed by a high vulnerability in almost 150 km². This areal coverage increases by 10-15% from phase II to phase III. On the other hand, a relatively safe situation is confined to < 200 km². The receiver operating characteristic curve, root-mean-square error, and correlation coefficient are used to assess the accuracy of these models and categorization of habitat vulnerability. Ensemble modeling is done using the individual models having a greater accuracy level in order to increase accuracy. A field-based model of the same is prepared by gathering information directly from the field which also exhibits similar results with the algorithm-based models. Analysis of residuals in standard regression strongly supports the relevance of the selected parameters and multi-parametric models.

Water Quality Pollution Control and Watershed Management Based on Community Participation in Maros City, South Sulawesi, Indonesia

Increases in the number of urban residents have significant impacts on spatial pressure, affecting the utilization of river basins. The purpose of this study is to analyze (1) the increase in population and changes in spatial use as determinants of the complexity of the watershed ecosystem; (2) the effect of housing development, urban activity systems, and land use changes on the degradation of the environmental quality of the watershed; and (3) the direct and indirect effects of changes in spatial use, land reclamation, and community behavior on water pollution and the sustainability of watershed management in Maros City. The research method used is a sequential explanatory design combining quantitative and qualitative research methods. Data were obtained through observation, in-depth interviews, surveys, and documentation. The study findings show that land use change, complexity of spatial use, and community behavior have a negative impact on the environmental quality of the watershed. Housing development, urban activity systems, and changes in land use had a significant effect on environmental quality degradation, with a coefficient of determination of 73.9%. Furthermore, the influence of spatial use, land reclamation, and community behavior on water pollution in the watershed was 72.82%. This study may serve to assist the decision-making of and policy formation by the Maros Regency Government in the framework of controlling the use of watersheds, working towards their social, economic, and environmental sustainability.

Small Floodplain Reservoirs in the Face of Climate Change—Sink or Source of Nutrients?

Despite various water protection measures, good water quality and reduction of nutrient loads seem very distant goals, largely due to limited knowledge of processes occurring in river valleys. Our study aimed at establishing the role of small floodplain reservoirs in the eutrophication processes, in the face of recent climate changes. The content of phosphorus and nitrogen compounds was determined in sediments and water of small floodplain reservoirs, (the Vistula River Valley, Poland) using spectrophotometric and Kjeldahl’s method. Nutrient loads in sediments were linked to the texture and total organic carbon content. Seasonal changes in water quality were strictly connected to changing weather conditions, flood and drought. The concentrations of PO43− and NO3− were found to rise after summer flooding. Increases in NH4+, total phosphorus (TP) and total nitrogen (TN) were correlated with the surface water area reduction in the reservoirs, which during the year of the study was on average 62%. Therefore, small floodplain reservoirs could be considered simultaneously as sinks and sources of nutrients. On the one hand, they accumulate P and N compounds carried by the river during the flood. On the other hand, climate change cause that small floodplain reservoirs may be responsible for enhanced biomass production.

Modelling water richness and habitat suitability of the wetlands and measuring their spatial linkages in mature Ganges delta of India

Present study has attempted to measure Water Richness (WR) and Wetland Habitat Suitability (WHS) in deltaic environment and assessed their spatial linkages. Water richness exhibits availability of water in wetland and its dynamicity, whereas wetland habitat suitability depicts physical habitat ambiance of a wetland toward vibrant ecosystem. Both the components are very essential and should be measured to explore ecosystem service and environmental heath of a region. For investigating water richness of the wetland six water availability indicating parameters have been chosen and for assessing wetland habitat suitability four additional parameters have been taken into consideration. Four widely used and recognised machine learning algorithms like Reduced Error Pruning (REP) tree, Random forest, Artificial Neural Network (ANN) and Support Vector Machine (SVM) have been employed here in order to develop suitable model at two phases. Results reveal that very high water rich zone is found over 200-215 km² wetland area followed by high water rich zone over 125-140 km² wetland area in both the phases. Wetland habitat suitability assessment shows only 100-150 km² of the wetland having very high suitability and 110-120 km² of wetland having high suitability. Field investigation and accuracy assessment support the validity and acceptability of the results. Spatial linkage between water richness and habitat suitability demonstrates that 30-40% very high water rich zone represents very high habitat suitability figuring out importance of both the models. Therefore, results recommend that only water richness of the wetlands of the wetlands is not enough to represent the habitat suitability in the densely populated riparian flood plain region.

River-floodplain restoration and hydrological effects on GHG emissions: Biogeochemical dynamics in the parafluvial zone

The parafluvial zone is frequently exposed to drying-rewetting cycles with critical consequences for the biogeochemistry of soil and sediment in river-floodplain landscapes. Upon restoration of the hydrological connectivity, substantial changes in biogeochemical processes are expected. The effects of water fluctuation on the magnitude of GHG emissions were investigated in the parafluvial zone of a restored river floodplain in Austria. Sediment composition, DOM quality and N₂O, CO₂, CH₄ fluxes were quantified during distinct hydrological periods (intermittent, desiccation and post flood) and along a hydrological gradient. The hydrological gradient ranged from non-flooded plots in the floodplain soil (used as reference plots after restoration), to rarely-flooded and frequently flooded sediment plots in the parafluvial zone. Enhanced biogeochemical turnover rates were identified during the intermittent period, when N₂O and CO₂ emissions peaked. In particular, the frequently flooded plots showed significantly higher CO₂ and CH₄ emissions compared to non-flooded and rarely-flooded plots. This indicates a strong effect of water level fluctuation on GHG emissions, with higher emissions occurring during transitional stages of drying and rewetting. Strong positive relationships were found between individual GHG fluxes, suggesting a tight link between C and N cycles. Both the C and N cycles are dependent on similar substrate characteristics that are governed by the quality of the DOM pool. Interestingly, drier sediments in the rarely-flooded plots were also active areas for emissions. This highlights the importance to include dry phases and sites in the overall C and N emission estimates of riverine landscapes. From the restoration point of view, N₂O emissions in the parafluvial zone did not differ significantly from the emissions in the reference plots, whereas CO₂ and CH₄ fluxes did. When making management decisions to restore connectivity, one needs to carefully consider the interplay between nutrient removal from water versus GHG emissions, to reach maximum environmental benefits.

Effects of water levels on species diversity of silica-scaled chrysophytes in large tributaries of Lake Baikal

Large tributaries of Lake Baikal considered as a “hotspot” for silica-scaled chrysophytes diversity. Here we presented the updated species composition of silica-scaled chrysophytes and ecological parameters of their habitat in the Barguzin and Selenga River tributaries and delta in a high water level period. The number of registered taxa was significantly lower compared to the low water conditions (23 versus 66 species) and included the following genera with a given number of species: Chrysosphaerella – 1; Paraphysomonas – 2; Clathromonas – 1; Spiniferomonas – 3; Mallomonas – 9; Synura – 7. Mallomonas guttata and Synura borealis were identified in Russian waters for the first time. Thus, the corrected total list of silica-scaled chrysophytes in the Baikal Region includes 79 taxa. Though, the high water level reduced the total number of silica-scaled chrysophyte taxa, it made the water ecosystem more dynamic by enriching it with the entirely new species for this region.

Changes in riparian hydrology and biogeochemistry following storm events at a restored agricultural stream

Quantifying changes in riparian biogeochemistry following rainfall events is critical for watershed management. Following storms, changes in riparian hydrology can lead to high rates of nutrient processing and export and greenhouse gas (GHG) release. We assessed shifts in hydrology and biogeochemistry 24 and 72 hours post-rainfall following storms of three different magnitudes in an agricultural riparian zone influenced by stream restoration in the Piedmont region of North Carolina, USA. Post-storm changes in water table height, soil moisture, groundwater flow, and lateral hydraulic gradient were related to biogeochemical processing. Though near-field nitrate (NO3-) concentrations were elevated (median: 13 mg nitrogen (N) L-1 across storms), substantial riparian NO3- removal occurred (89-96%). High N removal throughout the study occurred concurrently with release of dissolved solutes (e.g., soluble reactive phosphorus [SRP]) and fluxes of gases (carbon dioxide [CO2], nitrous oxide [N2O], and methane [CH4]), based on storm timing, magnitude, and intensity. A high intensity, short duration storm of low magnitude lead to release of CO2 across the riparian zone and low SRP removal. A storm of intermediate duration/magnitude towards the beginning of the summer lead to mobilization of near-field NO3- and release of N2O in the upper riparian zone and SRP in the lower riparian zone. Finally, a larger storm of longer duration lead to pronounced near-stream release of CH4. Therefore, it is important to expand research of biogeochemical response to different types of storm events in restored riparian zones to better balance water quality goals with potential greenhouse gas emissions.