Melatonin Priming Promotes Crop Seed Germination and Seedling Establishment Under Flooding Stress by Mediating ABA, GA, and ROS Cascades.

Both seed germination and subsequent seedling establishment are key checkpoints during the life cycle of seed plants, yet flooding stress markedly inhibits both processes, leading to economic losses from agricultural production. Here, we report that melatonin (MT) seed priming treatment enhances the performance of seeds from several crops, including soybean, wheat, maize, and alfalfa, under flooding stress. Transcriptome analysis revealed that MT priming promotes seed germination and seedling establishment associated with changes in abscisic acid (ABA), gibberellin (GA), and reactive oxygen species (ROS) biosynthesis and signaling pathways. Real-time quantitative RT-PCR (qRT-PCR) analysis confirmed that MT priming increases the expression levels of GA biosynthesis genes, ABA catabolism genes, and ROS biosynthesis genes while decreasing the expression of positive ABA regulatory genes. Further, measurements of ABA and GA concentrations are consistent with these trends. Following MT priming, quantification of ROS metabolism-related enzyme activities and the concentrations of H2O2 and superoxide anions (O2 -) after MT priming were consistent with the results of transcriptome analysis and qRT-PCR. Finally, exogenous application of GA, fluridone (an ABA biosynthesis inhibitor), or H2O2 partially rescued the poor germination of non-primed seeds under flooding stress. Collectively, this study uncovers the application and molecular mechanisms underlying MT priming in modulating crop seed vigor under flooding stress.

Assessing the district-level flood vulnerability in Bihar, eastern India: an integrated socioeconomic and environmental approach.

States of India like Bihar, Uttar Pradesh, and West Bengal along the Ganga River, endure natural disasters periodically, resulting in repeated trends of economic loss and damages. Especially, most of the districts of Bihar, India, are prone to floods. Based on this background, this study aims to assess the flood vulnerabilities across districts of Bihar, India, employing data from the Central Water Commission from 1953 to 2020. Further, we explore trends and patterns of loss and damage due to flood risks in Bihar. Using the flood vulnerability integrated method and the principal component analysis, the index is constructed by incorporating the three major indicators: exposure, sensitivity, and adaptive capacity. This study is unique, and advances from previous studies in using a greater number of variables in exposure indicator. The proxy variable for each indicator is identified through both inductive and deductive approaches, and the composite index is constructed using all three indicators. Also, we identify the districts with high level of education and per capita income are less likely to expose flood vulnerability. The comparison of the districts reflects wide range of variation in terms of flood vulnerability as per their adaptive capacity and sensitivity. Specifically, these findings align with Target Sustainable Development Goal 11.5. This study addresses the policy for disaster prevention, risk reduction, and mitigation measures, as well as the enhancement of the capability of adaptation to floods by the affected community.

Sustainable flood control strategies under extreme rainfall: Allocation of flood drainage rights in the middle and lower reaches of the yellow river based on a new decision-making framework.

Climate change has exacerbated the frequency and magnitude of extreme rainfall, which has led to the perpetuation of flooding as a hazard to humans and society. China has begun to consider introducing Flood drainage rights (FDR), a sustainable flood control measure, into non-engineering measures as a complement to engineering measures for flood control. FDR represent the right of regions to discharge regional floodwaters caused by extreme rainfall into the river, and are the primary means of controlling the amount of floodwaters from regions when regional flood capacity is exceeded. However, existing studies on quantitative FDR allocation still have limitations, and some previous methods have resulted in allocation schemes that are not entirely reasonable and fair because they do not comprehensively consider the influencing factors of FDR or the allocation method is unreasonable. This paper explores the impact of flooding on rural and agricultural areas. We incorporate the factors of agricultural economy and security and construct a system of the allocation indicators of FDR composed of five principles: Natural Environmental Endowment, General Economic and Social Development, Agricultural Economy and Security, Macro policy regulation, and Respect for Historical Background. Second, considering the influence of expert judgment and data of different time nodes on the allocation of FDR, we introduce the concepts of expert weight and time weight into the allocation model of FDR, and construct a new set of framework for the allocation of FDR, i.e., "[(expert weight + subjective weight)+(time weight + objective weight)]+decision making model ". To reduce the loss of information during the transformation of subjective judgments, we also introduced triangular fuzzy numbers for the transformation between expert judgments and numbers. Finally, we take the five provinces in the middle and lower reaches of the Yellow River as an example. Using the data from 2010 to 2021, we obtain the final allocation scheme (proportion) of FDR as Henan (33.26%) > Shaanxi (23.08%) > Inner Mongolia (21.31%) > Shanxi (14.44%) > Shandong (7.91%). On this basis, this paper utilizes sensitivity analysis and comparative validation to demonstrate the rationality and effectiveness of the method, and identifies several indicators that have a greater impact on the results of the allocation of FDR. FDR can form part of a set of integrated flood management system together with flood control projects, which greatly alleviates the drainage conflicts arising from flooding caused by extreme precipitation. Under extreme rainfall conditions, FDR improves drainage efficiency and minimizes the overall damage caused by flooding in the watershed. This study can contribute to the sustainable development of the watershed and provide a reference for the promotion and utilization of sustainable flood control measures.

Impact of Flooding and Drought Risks on the Cost of Bond Financing for Water Utilities.

The global water cycle has experienced significant changes due to the interplay of climate shifts and human activities, resulting in more frequent and severe droughts and floods. These shifts have started to impact the operational efficiency of water treatment and delivery systems. This, in turn, has implications for the economic performance of these assets and the climate-impacted cost of their financing through the issuing of municipal bonds. Analyzing a decade of water bond data (2009-2019), this study offers empirical evidence for the impact of flood and drought risks on bond investor demand to offset water risks. The results reveal that bond markets factored in coastal flood risks between 2013 and 2019, adjusting by 3-6 basis points (bps) per risk score unit, and riverine flood risks from 2009 to 2013, with a 5-11 basis points increase per risk score unit. These effects were primarily driven by bonds issued in the Pacific Coast and Great Plains regions, respectively. In contrast, the pricing of drought risks in the bond market followed a more nuanced pattern. Additionally, we show the channeling effects of water consumption and investor perceptions of climate change on water risk pricing in the bond market. These findings have significant implications for water risk management in the public sector as regions with heightened water risk exposure are perceived as riskier by market participants, leading to a higher cost of capital for municipalities and water agencies.

Water level regime variation is a crucial driver for taxonomic, functional, and phylogenetic diversity in seasonally flooded tropical forests.

Floodplains contribute significantly to terrestrial ecosystem service provision but are also among the most vulnerable and degraded ecosystems worldwide. Heterogeneity in floodplain properties arises from variations in river-specific flood regimes, watershed characteristics, and valley morphology, influencing seasonally flooded forests' taxonomic, functional, and phylogenetic diversity. This study addresses persisting knowledge gaps in floodplain ecology, focusing on the seasonally dry tropics. We explore the relationships between flood regime, environmental conditions, vegetation composition, functional and phylogenetic diversity, and the impact of environmental variables on above-ground biomass (AGB) and ecological strategies. The study spans six rivers in southeastern Brazil's main river basins: Rio Grande and São Francisco. We identified five eco-units in each floodplain based on flooding regimes and surveyed six plots per eco-unit. We measured trees with DBH > 5 cm and collected functional traits, along with detailed soil, climate, and water level data. We calculated plot-level floristic composition, taxonomic, functional, and phylogenetic diversity, wood density, and AGB. Functional and phylogenetic dissimilarity were analyzed, and the effects of climate, soil, and hydrological variables were quantified using generalized linear mixed models. We show how flood frequency and duration affect floristic composition across the floodplains. Taxonomic and phylogenetic diversity responded to climate, soil, and hydrological variables, while functional diversity responded primarily to hydrological variables, emphasizing the role of environmental filtering. Hydrological seasonality, soil fertility, and flood regime emerged as key factors shaping community structure and ecological strategies in the studied seasonally flooded tropical forests. Plot-level AGB responded to phosphorus but not to climate or hydrological variables. The study also highlights functional and phylogenetic dissimilarities among eco-units and basins, indicating potential climate change impacts.

Effect of local and regional factors on the structure of the fish communities associated with aquatic macrophyte stands in oxbow lakes on the Amazon floodplain.

The Amazon floodplain is home to an extremely high diversity of fish, with lakes playing an important role in the establishment of this biological richness. These lacustrine environments are subject to constant fluctuations caused by the annual flood pulse, with local factors and other regional patterns also contributing to the variation in fish community structure. The present study verified how local (depth and transparency of the water, the size and species composition of the macrophyte stands) and regional factors (spatial distribution of the stands and the hydrological phase) influence the structure of the fish community of the floodplain lakes of the Môa River, in northern Brazil. Fish species richness was influenced by the depth of the water and the spatial distribution of the macrophyte stands. Fish species composition was influenced by local environmental variables, spatial structure, and the hydrological phase. However, variation partitioning indicated that only the hydrological phase explained the variation in fish composition. These findings indicate that the local environment, the spatial structure, and the hydrological phase drive changes in the structure of the fish communities associated with aquatic macrophytes in the floodplain lakes of the Amazon basin.

From phenotyping to genetic mapping: identifying water-stress adaptations in legume root traits.

BACKGROUND: Climate change induces perturbation in the global water cycle, profoundly impacting water availability for agriculture and therefore global food security. Water stress encompasses both drought (i.e. water scarcity) that causes the drying of soil and subsequent plant desiccation, and flooding, which results in excess soil water and hypoxia for plant roots. Terrestrial plants have evolved diverse mechanisms to cope with soil water stress, with the root system serving as the first line of defense. The responses of roots to water stress can involve both structural and physiological changes, and their plasticity is a vital feature of these adaptations. Genetic methodologies have been extensively employed to identify numerous genetic loci linked to water stress-responsive root traits. This knowledge is immensely important for developing crops with optimal root systems that enhance yield and guarantee food security under water stress conditions. RESULTS: This review focused on the latest insights into modifications in the root system architecture and anatomical features of legume roots in response to drought and flooding stresses. Special attention was given to recent breakthroughs in understanding the genetic underpinnings of legume root development under water stress. The review also described various root phenotyping techniques and examples of their applications in different legume species. Finally, the prevailing challenges and prospective research avenues in this dynamic field as well as the potential for using root system architecture as a breeding target are discussed. CONCLUSIONS: This review integrated the latest knowledge of the genetic components governing the adaptability of legume roots to water stress, providing a reference for using root traits as the new crop breeding targets.

Urban flood-bearing vulnerability evaluation based on the moment estimate weighting and improved gray target model.

Increasingly severe flooding seriously threatens urban safety. A scientific urban flood-bearing vulnerability assessment model is significant to improve urban risk management capacity. The gray target model (GTM) has advantages in urban flood-bearing vulnerability assessment. However, indicator correlation and single bull's-eye are commonly neglected, leading to defective evaluation results. By integrating the four base weights, an improved weighting method based on the moment estimate was proposed. Then, the marginal distance was used to quantify the indicator correlation, and the TOPSIS model was introduced to define the relative bull's-eye distance. Thus, an improved gray target evaluation method was established. Finally, an urban flood-bearing vulnerability evaluation model was presented based on the moment estimate weighting-improved GTM. In this study, Zhengzhou City, China, was taken as an example. The spatial and temporal changing characteristics of the flood-bearing vulnerability of Zhengzhou from 2006 to 2020 were investigated. The results show that: (1) On the temporal scale, the disaster-bearing vulnerability of Zhengzhou City showed an upward trend during the 15 years; (2) On the spatial scale, Guancheng District of Zhengzhou City had the relatively highest vulnerability to urban flooding. This study is expected to provide a scientific reference for urban flood risk management.

The association of adverse birth outcomes with flood exposure before and during pregnancy in Australia: a cohort study.

BACKGROUND: Exposure to floods might increase the risks of adverse birth outcomes. However, the current evidence is scarce, inconsistent, and has knowledge gaps. This study aims to estimate the associations of flood exposure before and during pregnancy with adverse birth outcomes and to identify susceptible exposure windows and effect modifiers. METHODS: In this cohort study, we obtained all the birth records occurring in Greater Sydney, Australia, from Jan 1, 2001, to Dec 31, 2020, from the New South Wales Midwives Data Collection and in the Brisbane metropolitan region, Australia, from Jan 1, 1995, to Dec 31, 2014, from the Queensland Health Perinatal Data Collection. For each birth, residential address and historical flood information from the Dartmouth Flood Observatory were used to estimate the numbers of days with floods during five exposure windows (Pre-1 was defined as 13-24 weeks before the last menstrual period [LMP], Pre-2 was 0-12 weeks before the LMP, trimester 1 [Tri-1] was 0-12 weeks after the LMP, trimester 2 [Tri-2] was 13-28 weeks after the LMP, and trimester 3 [Tri-3] was ≥29 weeks after the LMP). We estimated the hazard ratios (HRs) of adverse birth outcomes (preterm births, stillbirths, term low birthweight [TLBW], and small for gestational age [SGA]) associated with flood exposures in the five exposure windows using Cox proportional hazards regression models. FINDINGS: 1 338 314 birth records were included in our analyses, which included 91 851 (6·9%) preterm births, 9831 (0·7%) stillbirths, 25 567 (1·9%) TLBW, and 108 658 (8·1%) SGA. Flood exposure in Pre-1 was associated with increased risks of TLBW (HR 1·06 [95% CI 1·01-1·12]) and SGA (1·04 [1·01-1·06]); flood exposure during Tri-1 was associated with increased risks of preterm births (1·03 [1·002-1·05]), stillbirth (1·11 [1·03-1·20]), and SGA (1·03 [1·01-1·06]). In contrast, flood exposures during Pre-2 and Tri-3 were associated with reduced risks. INTERPRETATION: Exposures to floods in Pre-1 and Tri-1 are both associated with increased risks of adverse birth outcomes, and the risks increase with a higher exposure. Upon planning for conception and prenatal care, individuals and health practitioners should raise awareness of the increased risks of adverse birth outcomes after experiencing floods. FUNDING: The Australian Research Council and the Australian National Health and Medical Research Council.

"What influences how well householders living in previously flooded communities feel they are protected or could recover from future flooding?: Results of a survey".

In England, the Environment Agency (EA) estimates that over 3 million properties in England are at risk of surface water flooding. Heavy and prolonged rainfall that drives surface water flooding is projected to increase in the future due to climate change. This paper presents a quantitative secondary analysis of a cross-sectional household flood survey in a disadvantaged city in England heavily impacted by surface water flooding in 2007 and at severe risk of flooding in the future. The aim of this study was to examine how previous experience of flooding, demographic factors, and behaviours impact on feelings of protection against flooding and perceived ability to recover from flooding. Survey data were collected from residents in Hull in northern England in 2018, in areas impacted by major floods in 2007 when over 8,600 households were flooded. Valid responses were received from 453 households, of whom 37.3% were flooded or flooding damaged their house (n = 169), 14.6% had been disrupted by flooding (n = 66), 9.3% had been exposed to flooding (n = 42) and 176 (38.9%) had not experienced flooding. Over 22% felt they had very low protection against flooding, and over 25% would make a very slow recovery if they were flooded. Associations were found between gender and both low levels of protection against flooding. Females were less likely to feel confident in their recovery from flooding than males (OR 0.551). The findings support a need to focus on women's perceptions of flood vulnerability and capacity to cope and recover from flooding in flood and disaster management policy and practice, including providing effective support before, during and after flooding.

Freshwater wetlands for flood control: How manipulating the hydroperiod affects plant and invertebrate communities.

Thoughtfully managed hydroperiods in natural and artificial wetlands could potentially provide a combination of desirable flood control services and high ecological functions. To explore how managed freshwater wetlands typical of the Houston, Texas area would respond to different hydrological regimes that might occur if wetlands were drained in anticipation of a heavy rain that did not materialize, we conducted a mesocosm experiment with six flooding depths and seven drought durations, followed by seven months of recovery. We found that the speed in which mesocosms dried out was a function of initial water depth, with mesocosms initially set with greater water depths (30 cm) taking ~ 38 days to dry out versus zero days for wetlands that were completely drained. Individual plant species (14 species planted; 8 species common at the end of the recovery period) were affected by drought length, flooding depth, or their interaction, although details of these responses varied among the species. The composition of the plant community at the end of the drought period was strongly affected by drought length, and the effect of the drought length treatment persisted through seven months of post-drought recovery, with the 80- and 160-day drought treatments diverging most strongly from shorter drought treatments. Above- and below-ground biomass of plants was not affected by the treatments, but above-ground dead biomass (litter) decreased with increasing drought length. Densities of mosquito larvae, snails and tadpoles were temporally variable, and were affected more during the treatment period and early in recovery than after a disturbance event late in recovery. Our results indicate that managed wetlands in southeast Texas would be quite resilient to dry periods of up to 40 days in duration, especially if water was not completely drained at the beginning of the drought. In addition, many species would persist in managed wetlands even with droughts of up to 160 days. This indicates considerable potential for managing the hydroperiods of artificial detention ponds by retaining water longer to increase ecological function, with little to no loss of flood control services, and for managing the hydroperiods of natural wetlands by draining them in advance of anticipated rains to increase flood control services, with little to no loss of ecological function.

Global insights from local actions: a case study on enhancing flood disaster management efficiency in China's Greater Bay Area.

This study examines the flood disaster management network within the Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 2015 to 2021, identifying government department involvement and influence shifts. Key findings indicate a decrease in the centrality of the Public Security Office and Department of Transportation, suggesting a strategic shift toward more specialized, technology-driven disaster management. Conversely, the Science Bureau's increased engagement, from 8.43% to 12.84%, highlights a policy shift toward scientific research and technological innovation in managing flood risks. The analysis reveals underutilized communication between the Central Committee, the Poverty Alleviation Office, and the Publicity Department, highlighting opportunities for improved integration in disaster management and public communication strategies. To address these issues, the study suggests strengthening inter-departmental collaboration to leverage technological advancements in disaster management. It also recommends integrating flood disaster management with poverty alleviation initiatives to support affected populations comprehensively. Increasing the involvement of the Publicity Department is crucial for improving timely and transparent communication of flood-related data to the public. The conclusions advocate for an adaptive, strategically planned network approach to flood disaster management in the GBA, aiming to bolster responsiveness and preparedness for future flood events.

Examining direct and indirect flood damages in residential and business sectors through an empirical lens.

Investment to reduce flood risk for social and economic wellbeing requires quantitative evidence to guide decisions. Direct and indirect flood damages at individual household and business building levels were assessed in this study using multivariate analysis with three groups of flood damage attributes, i.e., flood characteristics, socioeconomic conditions, and building types. A total of 172 and 45 respondents from residential and commercial buildings were gathered through door-to-door interviews at areas in Peninsular Malaysia that were pre-identified to have frequently flooded. Two main findings can be drawn from this study. First, flood damage is greatly contributed by high-income households and businesses, despite them being less exposed to floods than low-income earners. This supports the current use of mean economic damage in engineering-based flood intervention analysis. Second, indirect damages increase with the increase in family size, indicating the importance of strengthening preparedness and social support to those with great social responsibility. Overall, the study highlights the importance of holistic flood management accounting for both direct and indirect losses.

Integrated modeling of urban mobility, flood inundation, and sewer hydrodynamics processes to support resilience assessment of urban drainage systems.

With the increasing frequency of extreme weather events and a deepening understanding of disasters, resilience has received widespread attention in urban drainage systems. The studies on the resilience assessment of urban drainage systems are mostly indirect assessments that did not simulate human behavior affected by rainfall or semi-quantitative assessments that did not build simulation models, but few research characterizes the processes between people and infrastructure to assess resilience directly. Our study developed a dynamic model that integrates urban mobility, flood inundation, and sewer hydrodynamics processes. The model can simulate the impact of rainfall on people's mobility behavior and the full process including runoff generation, runoff entering pipes, node overflow, flood migration, urban mobility, and residential water usage. Then, we assessed the resilience of the urban drainage system under rainfall events from the perspectives of property loss and urban mobility. The study found that the average percentage increase in commuting time under different return periods of rainfall ranged from 6.4 to 203.9%. Calculating the annual expectation of property loss and traffic obstruction, the study found that the annual expectation loss in urban mobility is 9.1% of the annual expectation of property loss if the rainfall is near the morning commuting peak.

The impact of flooding from the Minjiang River on the succession of harmful algal blooms (HABs) caused by diatoms in China's offshore waters.

This study examines diatom assemblages in the Matsu Archipelago, an area influenced by Minjiang River runoff. It focuses on harmful algal blooms (HABs) that occurred between August 2021 and July 2022. Utilizing 18S rRNA metabarcoding and microscopic analysis, we observed a significant diatom bloom during early summer runoff, peaking at 5 × 105 cells L-1. The research reveals dynamic community changes during the runoff season, with dominant genera including Pseudo-nitzschia, Chaetoceros, and Skeletonema. Skeletonema cell density correlated with NO3 levels, Chaetoceros had a slight PO4 affinity, and Pseudo-nitzschia showed a negative correlation with Skeletonema. Pseudo-nitzschia, which prefers high light and pH conditions, had notably high concentrations in the flood season and in the autumn. In both, it was dominated by potential toxin-producing species - P. multistriata and P. pungens during the flooding, and P. cuspidate in the autumn. These findings highlight the intricate relationship between diatom dynamics and environmental factors, providing essential insights for managing HABs, especially Pseudo-nitzschia species, amidst environmental changes.

Variation of 137Cs activity concentration in flood and pore water in paddy fields and its transfer to rice.

Caesium-137 (137Cs) is a major anthropogenic radionuclide released into the environment as a result of the TEPCO Fukushima Daiichi Nuclear Reactor Station accident (occurring on March 11, 2011). Rice, being a staple food in Asian countries, including Japan, and is predominantly cultivated in paddy fields. Consequently, 137Cs present in rice is absorbed from both soil and irrigation water, making it the most important crop for estimating internal radiation doses. In this study, over the 2018-2022 cultivation periods, flood water and pore water samples were collected biweekly from paddy fields. These samples were analyzed to measure the 137Cs activity concentration, as well as the potassium (K+) and ammonium (NH4+) concentrations. Under anaerobic conditions, the 137Cs + activity concentration in pore water increased markedly to reach a value 20-fold higher than that in flood water, correlating with NH4+ concentration. However, despite the release of 137Cs + caused by increased NH4+ concentrations in pore water due to reduction processes, the 137Cs+/K+ ratio did not increase, which was attributed to the simultaneous release of K+. The competition between 137Cs+ and K+ uptake by plants indicates that rice uptake of 137Cs is not necessarily enhanced during the waterlogging period.

Transformation and environmental risk of 90Sr and 137Cs under extreme rainstorm at a proposed nuclear facility site in China.

This paper explores the environmental hazards associated with nuclear facilities in arid regions, focusing on the rapid migration of radionuclides facilitated by flood runoff resulting from extreme rainstorms. Through a case study of a proposed nuclear facility site in China, the study developed a comprehensive model to calculate the transformation of 90Sr and 137Cs in flood and subsurface water during accidents. The methodology employs a combination of field tests, radionuclide adsorption tests, the SWAT model, and the HGS model to create a fully integrated model. This approach allows for the several complex couplings (radionuclide-flood runoff-subsurface water) that have not been previously examined in the reactive solute transport. The findings reveal that despite groundwater movement being relatively sluggish, 90Sr and 137Cs migrate downstream rapidly due to their transportation by floods, which permeate the Upper Pleistocene gravel aquifer along the route. The study underscores the importance of considering the migration of radionuclides carried by floods generated by extreme rainstorms, as it poses a significant risk that cannot be ignored.

Sources of nutrients fuelling post-flood phytoplankton biomass in a subtropical bay.

Extreme rainfall from an ex-tropical cyclone caused a major flood event in the Logan River system in southeast Queensland, Australia. This resulted in a significant flood plume, containing nutrients and sediment, being discharged into the adjacent estuary/Bay system. The spatial extent of higher phytoplankton biomass (Chl a) matched the distribution of higher nutrient and sediment concentrations post-flood, suggesting nutrients fuelled phytoplankton production. Particulate nitrogen (PN) constituted over 50 % of total nitrogen in floodwaters, with lower proportions of dissolved inorganic nitrogen (DIN) and phosphate (PO4-P). Phytoplankton utilised DIN rapidly but may have maintained growth due to the release of ammonia from suspended sediments and microbial mineralisation of particulate organic nitrogen. Ammonia release from intertidal sediments contributed minimally (0.85 %) to daily phytoplankton nitrogen demands. Our study highlights the need to understand the fate of particulate nitrogen in coastal systems and its role in stimulating phytoplankton growth.