Recurrent Floods Research Articles

Analysis of Flood Risk in the Lower Hydrographic Basin of the Río Negro (Argentina)

The recurrent floods in the lower hydrographic basin of the Río Negro (RN), documented since 1899, have caused significant damage to the resident population settled in flood-prone areas, whose socioeconomic condition is unfavorable. The aim of this study was to analyze the risk associated with flood occurrences in this area by integrating the flood susceptibility level (hazard) of the study area and the vulnerability of the population. The risk analysis was derived from the algebraic overlay of hazard and vulnerability maps, developed according to criteria published by Renda et al. (2017). In the study area, floods are primarily caused by intense rainfall and winds, upstream water discharges from the Limay and Neuquén rivers, and interactions between increased upstream flow from the lower hydrographic basin of the RN and extreme meteorological events known as Sudestadas. Every certain period, such as every 2 years for winds exceeding 75 km/h and precipitation exceeding 37 mm in 24 hours, as well as every 100 years for flows exceeding 4,000 , the occurrence of floods in the lower basin of the RN is expected to be derived from these events. Based on terrain characteristics and topography, 41.7% of the lower RN basin area showed moderate to high susceptibility to flooding. INDEC data (2010) indicated that 51.0% of the population in the study area was vulnerable to floods due to unfavorable socioeconomic conditions. According to hazard and vulnerability analyses, 43.2% of residents in the lower RN basin lived in high-risk areas, with homes located near the riverbank and on the outskirts of the Viedma-Carmen de Patagones urban conglomerate, hence being the most vulnerable. The results obtained in this research showed the influence of the natural and anthropogenic factors on the occurrence of flood-related disasters in the lower hydrographic basin of the RN. In addition, they served as a preliminary study that will enable decision-makers to create better prevention and mitigation plans contributing to improving the quality of life of its inhabitants.

Flood-induced mobility in rural and urban coastal jurisdictions: a homeowner’s perspective

AbstractCoastal flooding often exceeds homeowners’ capacity to cope with repetitive damages and profoundly disrupts their livelihoods. Permanent relocation has been proposed as a solution for some coastal areas experiencing recurrent flooding and anticipating acceleration of impacts. However, it is unclear if homeowners living in such areas would support this strategy, where they would choose to go, and why. This study evaluates the willingness to relocate and the reasoning behind it among rural and urban homeowners residing in coastal high-risk areas. The rural versus urban comparison explores how attitudes toward relocation differ between these settings with distinct sociodemographic, economic, and cultural profiles. A mail survey administered on the Eastern Shore, Maryland, and in the Hampton Roads metropolitan area, Virginia, measured how willingness to relocate differs across the socioeconomic spectrum, prior flood exposure, concerns with flood impacts, and preferences for relocation destination. The survey responses were analyzed using descriptive and inferential statistics. The results show that more than one-third of respondents would consider relocating. The willingness to relocate was marginally influenced by socioeconomic factors and flood experiences and instead was significantly correlated with the risk of disastrous flooding, inadequate insurance compensation, and worsening crime. However, data show a clear shift in relocation support and the distance of the preferred destination from minor to significant flooding. Rural respondents are slightly less likely to relocate than urban ones. Descriptive statistics indicate nuanced differences in flood experiences, reasons to relocate, and preferences for a new destination between rural and urban populations.

Recurrent Flooding and Household Food Access in Central Java, Indonesia.

It is unknown how recurring flooding impacts household diet in Central Java. We aimed to assess how recurrent flooding influenced household food access over 22 years in Central Java by linking the Global Surface Water dataset (GSW) to the Indonesian Family Life Survey. We examined linear and nonlinear relationships and joint effects with indicators of adaptive capacity. We measured recurrent flooding as the fraction of district raster cells with episodic flooding from 1984-2015 using GSW. Food access outcomes were household food expenditure share (FES) and dietary diversity score (DDS). We fit generalized linear mixed models and random forest regression models. We detected joint effects with flooding and adaptive capacity. Wealth and access to credit were associated with improved FES and DDS. The effect of wealth on FES was stronger in households in more flood-affected districts, while access to credit was associated with reduced odds of DDS in more flood-affected districts. Flooding had more predictive importance for FES than for DDS. Access to credit, a factor that ordinarily improves food access, may not be effective in flood-prone areas. Wealthier households may be better able to adapt in terms of food access. Future research should incorporate land use data to understand how different locales are affected and further understand the complexity of these relationships.

Development and validation of a novel tool: The family resilience assessment scale for flood-affected families (FRAS-FAF)

Family resilience is critical in coping with disasters such as floods, yet there is a lack of tools specifically designed to assess family resilience in flood-prone regions. This study aimed to develop and validate the Family Resilience Assessment Scale for Flood-Affected Families (FRAS-FAF), a culturally sensitive tool tailored to families impacted by recurrent flooding in Pakistan. A mixed-methods study design was employed in two phases. In Phase I, qualitative data were collected through in-depth interviews with heads of flood-affected families in the Nowshera district of Pakistan, revealing key themes related to family resilience. These insights informed the creation of 54 initial items for the FRAS-FAF. In Phase II, the psychometric properties of the tool were assessed using factor analysis with 400 participants, allocated for Exploratory Factor Analysis (EFA) 200 and the remaining 200 for Confirmatory Factor Analysis (CFA). The final version of the scale retained 52 items across five factors: Family Culture, Family Structure, Family Spirituality, Family Resources, and Environment. EFA and CFA confirmed a strong five-factor structure, with model fit indices demonstrating adequate construct validity (χ2 ​= ​1551/df ​= ​936, CFI ​= ​.91, TLI ​= ​.89, SRMR ​= ​.075, RMSEA ​= ​.057). Internal consistency was high for all factors, with Cronbach's alpha values ranging from .85 to .96. FRAS-FAF is a reliable and valid tool for assessing family resilience in flood-affected families. It provides a framework for practitioners and policymakers to identify areas of strength and vulnerability, informing the development of targeted interventions aimed at enhancing family resilience in flood-prone regions. The tool's culturally sensitive design ensures its relevance for flood-affected families in Pakistan and offers the potential for adaptation in other disaster-prone areas.

A synergic approach using the model and remote sensing data for flood monitoring in under-observed transboundary rivers

ABSTRACT The southern plain of Nepal recognized as the ‘granary of Nepal’, confronts recurrent monsoon-induced flooding, posing a substantial threat to its pivotal role as a major agricultural contributor to the national economy. As an analysis, this study employs advanced satellite imagery to delineate historical floods in nine flood-prone transboundary basins and compares the rainfall-induced model-based inundation in the West Rapti Basin (WRB) to validate the result. The extent of flooding was mapped between 2015 and 2022 using Sentinel-1 Synthetic Aperture Radar data processed on Google Earth Engine. Hydrodynamic modelling centred on the WRB, incorporated daily measured precipitation data with varying return periods over a 10 m resolution digital elevation model generated through an in situ survey. The model was calibrated for the August 2017 flood event with Nash–Sutcliffe efficiency greater than 70% and validation reasonably with satellite-derived flood maps with Cohen's Kappa value of 0.58 and an overall accuracy metric of 0.84. This synergic approach integrates climatology, remote sensing data, and hydraulics to monitor transboundary river floods in Nepal where precise hydro-meteorological data are limited, thus, offering continuous all-weather monitoring.

Social dimensions of climate‐induced flooding in Jakarta (Indonesia): The role of non‐point source pollution

AbstractBecause of its low‐lying location, urbanization, and inadequate infrastructure, Jakarta (Indonesia) has experienced an increase in annual flooding events, rising from an average of five significant floods per year in the 1990s to over 20 annually (2010–2020). With climate change exacerbating extreme weather events, Jakarta encounters escalating risks of flooding. Although the recurrent flooding is exacerbated by non‐point source (NPS) of pollution such as urban runoff and agricultural discharge that contribute to 40% of total pollutants leading to flood‐related issues in Jakarta, none has investigated this research gap. To reflect its novelty, this work explores the implications of climate change on the annual flooding in Jakarta by focusing on NPS and analyzes their impacts from social perspectives. This work also underscores the implications of flooding on livelihoods, health, and social cohesion in Jakarta. Focus group discussion with affected residents was used to shed light on the coping strategies employed in response to recurrent floods, ranging from community‐based initiatives to reliance on informal networks. The empirical findings show that the implications of flooding extend beyond physical damages. Displacement of communities, loss of livelihoods, disruption of essential services, and increased health risks are among the social impacts experienced by local residents. Vulnerable populations, including low‐income communities residing in informal settlements, bear their consequences. Economic losses from flooding amount to USD 500 million annually, impacting over 1 million residents. However, recent interventions have led to a 15% reduction in peak flood levels and a 20% reduction in flood duration in affected areas. Community resilience has also improved, with a 25% increase in flood insurance coverage and a 20% rise in community response initiatives. Overall, this study highlights that climate change exacerbates annual flooding in Jakarta, significantly impacting vulnerable communities through NPS pollution. Addressing the challenges requires integrated approaches combining effective pollution control, resilient infrastructure, and community engagement to mitigate social and long‐term environmental impacts.Practitioner Points Climate‐induced flooding disproportionately affects vulnerable communities in Jakarta. Non‐point source pollution from urban runoff contributes to the severity of flooding in Jakarta. Waterborne diseases, disruption of livelihoods, and reduced access to clean water are major concerns identified in the study. The study highlights the importance of community‐based adaptation strategies to mitigate the impact of flooding and pollution.

A Comparative Study on 2015 and 2023 Chennai Flooding: A Multifactorial Perspective

Floods are highly destructive natural disasters. Climate change and urbanization greatly impact their severity and frequency. Understanding flood causes in urban areas is essential due to significant economic and social impacts. Hydrological data and satellite imagery are critical for assessing and managing flood effects. This study uses satellite images, climate anomalies, reservoir data, and cyclonic activity to examine the 2015 and 2023 floods in Chennai, Kanchipuram, and Thiruvallur districts, Tamil Nadu. Synthetic-aperture radar (SAR) satellite data were used to delineate flood extents, and this information was integrated with reservoir data to understand the hydrological dynamics of floods. The classification and regression tree (CART) model delineates flood zones in Chennai, Kanchipuram, and Thiruvallur during the flood years. The study region is highly susceptible to climatic events such as monsoons and cyclones, leading to recurrent flooding. The region’s reservoirs discharged floodwaters exceeding 35,000 cubic meters per second in 2015 and 15,000 cubic meters per second in 2023. Further, the study examines the roles of the Indian Ocean Dipole (IOD), which reached its peak values of 0.33 and 3.96 (positive IOD), and El Niño in causing floods here. The complex network of waterways and large reservoirs poses challenges for flood management. This research offers valuable insights for improving the region’s flood preparedness, response strategies, and overall disaster management.

Towards a Community-Based Framework for Flood Risk Management in Woodlands Park, Gweru

AbstractUrban flood risks in Zimbabwe emanate from the twin challenges of rapid urbanisation and climate change. Most urban settlements have become increasingly anchorages, which require increased adaptation through the sustainable management of urban storm water. Building on the Woodlands Park case in Gweru, this paper locates the problem of recurrent floods to the impasse between residents and council authorities on the one hand, and climatic risks reinforcing underlying rapid urbanisation challenges on the other hand. The purpose of the study was to gather the views of residents and their role in seeking solutions to the storm water management challenges. Utilising a mixed methodology, insights were drawn from field observations and purposive selection of 50 household representatives, triangulated with the views of officials from Gweru City Council (GCC). Data were obtained through in-depth interviews using semi-structured questions and analysed using thematic content analysis where participants’ views were grouped into themes according to their resemblance. By utilising Vensim PLE 7.3 Software, we applied systems thinking theory to reveal the interconnectedness of the factors leading to heightened storm water challenges. The findings showed that Woodlands Park lacks proper drainage installations that meet the standards of GCC. Some residents use personal resources to make storm drains on their yards but with differing structural dimensions. The local drainage system gets choked by silt and illegally dumped litter. Municipal authorities do not undertake routine annual drain reticulation operations, exposing houses to flooding. We argue that municipal authorities, land developers and the residents have not equitably collated their efforts to create bargained storm water management initiatives. The study proposes a community-based, low-cost flood resilience framework that engages residents with technical guidance from municipal staff.

Investigation of the recurrent flash flood events in the Far-North Region of Cameroon

Investigation of the recurrent flash flood events in the Far-North Region of Cameroon

The Nexus of Climate Change, Food Insecurity, and Conflict in Somalia: A Comprehensive Analysis of Multifaceted Challenges and Resilience Strategies

Climate change poses a significant threat to Somalia’s food security and stability. This review examines the complex interplay between climate change impacts, food insecurity, and conflict in Somalia. Recent climate data and forecasts paint a concerning picture: the rainfall probabilistic forecast for April- June 2024 indicates a high likelihood of above-normal rainfall across much of Somalia, thus increasing the flood risks. Concurrently, temperature forecasts project above-normal temperatures, potentially exacerbating drought conditions between the rainy seasons. Historical climatology data reveal Somalia’s vulnerability, with average temperatures ranging from 25°C to 30°C and significant seasonal variations affecting agriculture and water resources. These climate trends, combined with ongoing political instability and weak governance, have created a storm of challenges. This perspective explores how recurrent droughts and floods disrupt agricultural production, decimate livestock, and displace vulnerable populations, particularly those affecting rural and nomadic communities. It also examines how environmental stress exacerbates poverty and conflict, thereby creating a vicious cycle of vulnerability. This analysis draws on recent data on poverty rates, food expenditure patterns, and climate-related displacement, to illustrate the multifaceted nature of the crisis. Finally, this perspective proposed recommendations for building climate resilience, enhancing food security, and promoting sustainable development in Somalia, emphasizing the need for integrated approaches that combine immediate humanitarian assistance with long-term adaptation strategies.

Assessing livelihood vulnerability of rural communities in the wake of recurrent tropical flood hazards in India

Assessing livelihood vulnerability of rural communities in the wake of recurrent tropical flood hazards in India

Quantifying future climate extreme indices: implications for sustainable urban development in West Africa, with a focus on the greater Accra region

Climate change leading to Climate extremes in the twenty-first century is more evident in megacities across the world, especially in West Africa. The Greater Accra region is one of the most populated regions in West Africa. As a result, the region has become more susceptible to climate extremes such as floods, heatwaves, and droughts. The study employed the Coupled Model Intercomparison Project 6 models in simulating climate extreme indices under the Shared Socioeconomic Pathway scenarios (SSPs) over West Africa between 1979 and 2059 as exemplified by the Greater Accra region. The study observed a generally weak drought in the historical period and expected to intensify especially under SSP585 in Greater Accra. For instance, continuous dry days (CDD) reveal an increasing trend under the SSPs. Similarly, the overall projected trend of CDD over West Africa reveals an increase signifying a more frequent and longer drought in the future. The flood indices revealed a surge in the intensity and duration of extreme precipitation events under the SSPs in the region. For instance, R99pTOT and Rx5days are expected to significantly increase under the SSPs with intensification under the SSP245, SSP370, and SSP585. A similar trend has been projected across West Africa, especially along the Guinean coast. The study foresees a gradual and intensifying rise in heatwave indices over the Greater Accra region. The warming and cooling indices reveal an increasing and decreasing trend respectively in the historical period as well as under the SSPs particularly within urban centers like Accra and Tema. Most West African countries are projected to observe more frequent warm days and nights with cold nights and days becoming less frequent. Expected effects of future climate extreme indices pose potential threats to the water, food, and energy systems as well as trigger recurrent floods and droughts over Greater Accra. The findings of the study are expected to inform climate policies and the nationally determined contribution of the Paris Agreement as well as address the sustainable development goal 11 (Sustainable cities) and 13 (Climate action) in West Africa.

Revisiting the Causes and Effects of Recurrent Floods in the Haor Region of Sunamganj, Bangladesh: Evidence from the 2022 Flash Flood

Bangladesh, particularly the Haor region, is well-known for its susceptibility to natural disasters. Haor locals suffer more from floods than other regional individuals. Sunamganj district, predominantly a Haor region adjacent to India’s Meghalaya, was devastated by the 2022 flood. This unprecedented and catastrophic flood has broken nearly all previous flash flood records. The prime objective of this study is to explore the underlying factors and effects of recurrent flash floods in the Haor region, with a specific focus on Sunamganj, by examining the 2022 flash flood. The study employed a descriptive qualitative research approach to meet its objectives. Data was collected from 30 target individuals from diverse stakeholders based on specific inclusion criteria. An open-ended, non-structured questionnaire is used to conduct interviews with selected respondents. Riverbed siltation, heavy rainfalls, excessive water flow from upstream, and mismanagement of River and Haor, among others, are revealed as significant causes of the 2022 flash flood. On the other hand, the consequences of the flood include loss of life and property, damage to infrastructure, and adverse effects on education and social life. The study concluded by making some proposals that policymakers could consider while developing strategies to reduce losses and safeguard the Haor region from future flash floods.

A Nationwide Flood Forecasting System for Saudi Arabia: Insights from the Jeddah 2022 Event

Saudi Arabia is threatened by recurrent flash floods caused by extreme precipitation events. To mitigate the risks associated with these natural disasters, we implemented an advanced nationwide flash flood forecast system, boosting disaster preparedness and response. A noteworthy feature of this system is its national-scale operational approach, providing comprehensive coverage across the entire country. Using cutting-edge technology, the setup incorporates a state-of-the-art, three-component system that couples an atmospheric model with hydrological and hydrodynamic models to enable the prediction of precipitation patterns and their potential impacts on local communities. This paper showcases the system’s effectiveness during an extreme precipitation event that struck Jeddah on 24 November 2022. The event, recorded as the heaviest rainfall in the region’s history, led to widespread flash floods, highlighting the critical need for accurate and timely forecasting. The flash flood forecast system proved to be an effective tool, enabling authorities to issue warnings well before the flooding, allowing residents to take precautionary measures, and allowing emergency responders to mobilize resources effectively.

Impact of recurrent intermittent flooding on the yield and growth of Elaeis guineensis

AbstractIncreased frequency and severity of flooding are linked to global warming. Flooding stress can severely affect crop yields and plant survival, and therefore the livelihoods of farmers. An oil palm breeding trial plot consisting of six progenies in Terengganu, Malaysia, happened to be inundated with flooding within a year after planting and annually for 2 years thereafter. Flooding recurred at the 8th year of planting and several times after that within the 14‐year period of monitoring. Due to the uneven terrain in this trial, palms were exposed to various flood levels and were categorized into two flooding groups. Yields and survivability of the palms were not affected by low‐flood levels, in contrast to the palms in lower areas that experienced higher flood levels. Compared to neighbouring non‐flooded trials, palms exposed to high floodwaters generally experienced lower fruit yields, and reduced vertical growth with poorer canopy cover. However, one of the progenies that exhibited a moderate survival rate in high‐flooded areas outperformed the other progenies in terms of yield in these areas. Generally, young oil palms exposed to low floods were able to survive and produce yields that were comparable to palms in non‐flooded areas, though 10%–20% of the low‐flooded palms produced poor yields in the first 3–5 years. In high‐flooded areas however, oil palm survivability ranged from 45% to 73% during the early 3 years and 46%–89% thereafter. Hence, young palms exposed to recurrent flooding of approximately more than 1 m during their early years are likely to become poor yielders with poor survival rates. Observations from this study may assist oil palm farmers in the management of this crop in the event of unexpected flooding.

The heterogeneity of human flood adaptation characteristics in Central Asia based on human-flood distance

The Central Asian region is subject to frequent seasonal floods, resulting in substantial losses. These recurrent floods have induced certain changes in human flood adaptation characteristics in Central Asia, an area that is currently under-researched. This study, grounded in meticulously simulated flood inundation outcomes, multisource population distribution data, and flood protection infrastructure data, introduces an improved approach to calculating the distance between human and flood (HFD) and investigates human flood adaptation characteristics in Central Asia. Our findings indicate that residents in Central Asia get close to flood-prone areas from 1970 to 2007, with the exceptions of Turkmenistan (TKM) and Kyrgyzstan (KGZ). Notably, this trend is particularly pronounced in regions such as Xinjiang, China, and Tajikistan (TJK). An intricate exponential increase is observed in the population exposed to floods as the HFD decreases. Under future scenarios, KGZ exhibits the most significant trend of staying away from flood-prone areas, while TJK presents the opposite trend, and TKM experiences minimal changes. Additionally, compared with urban areas, rural areas of Central Asia exhibit a trend towards approaching floods. This study underscores the optimum nature of human flood adaptation when the HFD reaches 4.23 km, showing the potential for substantial benefits by implementing population evacuation within this threshold buffer zone. These insights highlight the complex interplay between human behaviours and floods and can inform the formulation of effective flood risk mitigation strategies.

Distribution and dynamics ofAnopheles gambiaes.l. larval habitats in threeSenegalesecities with high urban malaria incidence.

Urban malaria has become a challenge for most African countries due to urbanization, with increasing population sizes, overcrowding, and movement into cities from rural localities. The rapid expansion of cities with inappropriate water drainage systems, abundance of water storage habitats, coupled with recurrent flooding represents a concern for water-associated vector borne diseases, including malaria. This situation could threaten progress made towards malaria elimination in sub-Saharan countries, including Senegal, where urban malaria has presented as a threat to national elimination gains. To assess drivers of urban malaria in Senegal, a 5-month study was carried out from August to December 2019 in three major urban areas and hotspots for malaria incidence (Diourbel, Touba, and Kaolack) including the rainy season (August-October) and partly dry season (November-December). The aim was to characterize malaria vector larval habitats, vector dynamics across both seasons, and to identify the primary eco- environmental entomological factors contributing to observed urban malaria transmission. A total of 145 Anopheles larval habitats were found, mapped, and monitored monthly. This included 32 in Diourbel, 83 in Touba, and 30 in Kaolack. The number of larval habitats fluctuated seasonally, with a decrease during the dry season. In Diourbel, 22 of the 32 monitored larval habitats (68.75%) were dried out by December and considered temporary, while the remaining 10 (31.25%) were classified as permanent. In the city of Touba 28 (33.73%) were temporary habitats, and of those 57%, 71% and 100% dried up respectively by October, November, and December. However, 55 (66.27%) habitats were permanent water storage basins which persisted throughout the study. In Kaolack, 12 (40%) permanent and 18 (60%) temporary Anopheles larval habitats were found and monitored during the study. Three malaria vectors (An. arabiensis, An. pharoensis and An. funestus s.l.) were found across the surveyed larval habitats, and An. arabiensis was found in all three cities and was the only species found in the city of Diourbel, while An. arabiensis, An. pharoensis, and An. funestus s.l. were detected in the cities of Touba and Kaolack. The spatiotemporal observations of immature malaria vectors in Senegal provide evidence of permanent productive malaria vector larval habitats year-round in three major urban centers in Senegal, which may be driving high urban malaria incidence. This study aimed to assess the presence and type of anopheline larvae habitats in urban areas. The preliminary data will better inform subsequent detailed additional studies and seasonally appropriate, cost-effective, and sustainable larval source management (LSM) strategies by the National Malaria Control Programme (NMCP).

Hydrogeomorphological approach for flood analyses at high- detailed scale: Narrow rivers with broad complex alluvial plains

Fluvial flood risk management requires precise knowledge of flooding processes; thus, there is a need to carry out a detailed hydrological, hydraulic, and geomorphologic analysis to understand floods and the factors that influence them. Although the integration of geomorphological methods and hydrological-hydraulic modelling is known to be crucial for flood risk analysis, it remains a challenge to apply these approaches to the understanding of floods in small and medium-sized catchments, focusing on complex fluvial systems that have been highly modified. In this work, a hydrogeomorphological methodology was developed to analyse fluvial floods in narrow rivers with broad complex alluvial plains. The procedure comprises different phases that combine hydrologic-hydraulic modelling and a geomorphological break-down. Critically, this allows for a detailed analysis of existing relationships among erosional and depositional fluvial landforms and hydraulic parameters, comprising geometric sections, discharges, depths, flood extents and, therefore, flood hazards. The approach involves the analysis of specific flood events beforehand and the study of fluvial floods associated with different probabilities of occurrence afterwards. The information employed in the present study incorporates high- detailed inputs comprising hourly time series of hydrometeorological data, LiDAR data to extract high-precision terrain information, fluvial geomorphic maps and flood event extents based on Sentinel-2 imagery. We demonstrate this methodology in the Carrión River, located in the province of Palencia, Spain, whose characteristics include a wide complex alluvial plain, reaches highly modified by anthropic interventions and recurrent flood episodes. This hydrogeomorphological approach allowed the integration of geomorphological knowledge and hydrologic-hydraulic modelling in flood analysis. As a result, it led to a deeper comprehension of the processes of inundation, which would be challenging to thoroughly understand without incorporating a holistic method, an essential factor for defining effective flood management strategies.

Ciujung river basin flood risk assessment due to climate change and its countermeasure

Ciujung River is experiencing recurrent flooding, which was caused by climate change factor and extensive land use change. Therefore, this study carried out risk assessment in this basin area. First, hydrology analysis was carried out using HEC-HMS software to obtain flood discharge hydrograph, with obtained peak discharge of 3534.3 m3/s for 25-year return period. This hydrograph was then modeled into an inundation map using HEC-RAS two-dimensional model to calculate hazard index. Meanwhile, the vulnerability and capacity index were calculate using the demographic data. Finally, the risk index was calculated by combining hazard, vulnerability, and capacity index using raster calculator on Arc-GIS. Overall, the flood risk analysis shows a medium level. The results shown that hazard index is the most contributing factor in causing a high risk index. Thus, in this study we proposed a structural approach to reduce the hazard index. An embankment with a length of 50.37 km was applied and remodeled to analyze its effectiveness. The modeling results show high effectiveness with a significant reduction in inundation area. The reduction of inundated area reached 39.6%, while the reduction of affected buildings reached 49.9%. Hopefully, the result of this study can provide theoretical support and recommendations for future development.

Sub1 QTL confers submergence tolerance in rice through nitro-oxidative regulation and phytohormonal signaling

Constant change in global climate has become the most important limiting factor to crop productivity. Asymmetrical precipitations are causing recurrent flood events around the world. Submergence is one of the most detrimental abiotic stresses for sustainable rice production in the rainfed ecosystems of Southeast Asia. Therefore, the development of submergence-tolerant rice is an essential requirement to encounter food security. Submergence tolerance in rice is governed by the major quantitative trait locus (QTL) designated as Submergence1 (Sub1) near the centromere of chromosome 9. The introduction of the Sub1 in high-yielding rice varieties producing near-isogenic lines (NILs) has shown extreme submergence tolerance. The present study aimed to understand the responses of rice genotype IR64 and its Sub1 NIL IR64 Sub1 following one week of complete submergence treatment. Submergence imposed severe nitro-oxidative stress in both the rice genotypes, consequently disrupting the cellular redox homeostasis. In this study, IR64 exhibited higher NADPH oxidase activity accompanied by increased reactive oxygen species, reactive nitrogen species, and malondialdehyde buildups and cell death under submergence. Higher accumulations of 1-Aminocyclopropane-1-carboxylic acid, gibberellic acid, and Indole-3-acetic acid were also observed in IR64 which accelerated the plant growth and root cortical aerenchyma development following submergence. In contrast, IR64 Sub1 had enhanced submergence tolerance associated with an improved antioxidant defense system with sustainable morpho-physiological activities and restricted root aerenchyma formation. The comprehensive analyses of the responses of rice genotypes with contrasting submergence tolerance may demonstrate the intricacies of rice under complete submergence and may potentially contribute to improving stress resilience by advancing our understanding of the mechanisms of submergence tolerance in rice.