Flood Hazard Modelling in Upper Mandakini Basin of Uttarakhand

Floods in Himalayan region raise serious concerns regarding ongoing path of development as recent manifestations of catastrophic events establish link between climate changes and risk to anthropogenic activities in mountainous regions. Scientists predict frequent occurrence of such disasters wherein rapid glacial melting; incidents of glacial lake outburst and weather extremes may trigger floods in the Himalayan mountains. This paper examined flood risk in Upper Mandakini basin through GIS based flood simulationto highlight flood potential and risk associated with such hazard in the study area.It is observed that floods in study area display hazardous interplay of natural terrain gradient, high kinetic energy of streams, and intense rainfall. The upper sections of basin that includes Kali Ganga, Mandani Ganga, Madhyamaheshwar and Mandakini rivers shows high flood susceptibility with greatest risk in the latter. Such hazardousness is likely to be intensified by ongoing anthropogenic activities in the basin.

Reducing the Risk of Flood Disasters in Lamongan Regency Using the Geographic Information System (GIS)

Flood disasters cause negative impacts, such as damage to facilities to the onset of fatalities. Reducing the risk of flooding needs to be done to reduce the impact caused by this disaster. Lamongan Regency is one of the regencies in East Java affected by floods every year in most of its areas. This study aims to reduce the risk caused by flooding by using GIS (Geographic Information System). Mitigation is done by determining areas with a high potential risk of being affected by flooding. The study used spatial analysis functions in ArcGIS. Supporting variables used rainfall, land cover, slope, soil texture, and watershed area, and it becomes important in determining flood-prone areas. From the results, the largest soil classification is the Kpl soil type. Litosol Gray Grumosol, The wide distribution of rainfall from 1500-1750 mm has the widest distribution is 66,67 ha. The slope of 0-8% has the widest distribution of 92,257 ha, making Lamongan a very vulnerable high flood area. Laren District is the District with the greatest flood potential, and Irrigated Field is the dominant land cover type affected by the flood. With the flood disaster map generated from this research, local governments can seek prevention in areas with high flood potential. They can carry out socialization based on disaster mitigation, especially for districts with potential flooding.

Penerapan Algoritma K-Medoids dalam Menentukan Daerah Rawan Banjir di Kabupaten Karawang

Flood disasters often occur during the rainy season. Karawang is one area that is often flooded. Based on the risk index from BNPB, the flood disaster in Karawang affected 84% of the community, so efforts need to be made to reduce and overcome flood disasters. These problems are the beginning of efforts that need to be known which areas are prone to flooding. Therefore, this study aims to determine flood-prone areas in Karawang as an initial effort in tackling flood disasters. The research was conducted by classifying flood-prone areas using the k-medoids algorithm. K-Medoids uses the partition clustering method to group lists and objects into a number of clusters. This algorithm uses objects in a collection of objects that represent a cluster. The attributes used are flood-causing factors such as rainfall, elevation (soil height), population density, and distance to the river. The results of the study found three potential floods, namely low, medium, and high. There are 1 sub-district with low flood potential, 24 sub-districts with moderate flood potential, and 5 sub-districts with high flood potential. The test results using the silhouette coefficient get a value of 0.370.

Paleohydrological context for recent floods and droughts in the Fraser River Basin, British Columbia, Canada

The recent intensification of floods and droughts in the Fraser River Basin of British Columbia has had profound cultural, ecological, and economic impacts that are expected to be exacerbated further by anthropogenic climate change. In part due to short instrumental runoff records, the long-term stationarity of hydroclimatic extremes in this major North American watershed remains poorly understood, highlighting the need to use high-resolution paleoenvironmental proxies to inform on past streamflow. Here we use a network of tree-ring proxy records to develop 11 subbasin-scale, complementary flood- and drought-season reconstructions, the first of their kind. The reconstructions explicitly target management-relevant flood and drought seasons within each basin, and are examined in tandem to provide an expanded assessment of extreme events across the Fraser River Basin with immediate implications for water management. We find that past high flood-season flows have been of greater magnitude and occurred in more consecutive years than during the observational record alone. Early 20th century low flows in the drought season were especially severe in both duration and magnitude in some subbasins relative to recent dry periods. Our Fraser subbasin-scale reconstructions provide long-term benchmarks for the natural flood and drought variability prior to anthropogenic forcing. These reconstructions demonstrate that the instrumental streamflow records upon which current management is based likely underestimate the full natural magnitude, duration, and frequency of extreme seasonal flows in the Fraser River Basin, as well as the potential severity of future anthropogenically forced events.

Dynamic Assessment of the Flood Risk at Basin Scale under Simulation of Land-Use Scenarios and Spatialization Technology of Factor

Climate change, population increase, and urban expansion have increased the risk of flooding. Therefore, accurately identifying future changing patterns in the flood risk is essential. For this purpose, this study elaborated a new framework for a basin scale that employs a future land-use simulation model, a factor spatialization technique, and a novel hybrid model for scenario-based flood risk assessment in 2030 and 2050. Three land-use scenarios (i.e., natural growth scenario, cropland protection scenario, and ecological protection scenario) were set and applied in Jinjiang Basin to explore the changes in future flood risk under these scenarios. The results indicate the different degrees of increase in flood risk that will occur in the three scenarios. Under the natural growth (NG) scenario, the city will expand rapidly with the growth of population and economy, and the total area with high and very high flood risk will increase by 371.30 km2 by 2050, as compared to 2020. However, under the ecological protection (EP) scenario, woodlands will be protected, and the growth in population, economy, and built-up lands will slow down with slightly increased risk of flooding. In this scenario, the total area with high and very high flood risk will increase by 113.75 km2 by 2050. Under the cropland protection (CP) scenario, the loss of croplands will have been effectively stopped, and the flood risk will not show a significant increase under this scenario, with an increase by only 90.96 km2 by 2050, similar to the EP scenario. Spatially, these increased flood risks mainly locate at the periphery of existing built-up lands, and the high-flood-risk zones are mainly distributed in the southeast of the Jinjiang Basin. The information about increasing flood risk determined by the framework provides insight into the spatio-temporal characteristics of future flood-prone areas, which facilitates reasonable flood mitigation measures to be developed at the most critical locations in the region.

Distribution of coastal high water level during extreme events around the UK and Irish coasts

The interaction between waves, surges, and astronomical tides can lead to high coastal total water level (TWL), which can in turn trigger coastal flooding. Here, a high-resolution (1.5 km) simulation from a UK-focused regional coupled environmental prediction system is used to investigate the extreme events of winter 2013/4 around the UK and Irish coasts. The aim is to analyse the spatial distribution of coastal TWL and its components during this period by assessing (1) the relative contribution of different TWL components around the coast; (2) how extreme waves, surges, and tide interacted and if they occurred simultaneously; and (3) if this has implications in defining the severity of coastal hazard conditions. The TWL components' coastal distribution in winter 2013/4 was not constant in space, impacting differently over different regions. High (>90th percentile) waves and high surges occurred simultaneously at any tidal stage, including high tide (7.7 % of cases), but more often over the flood tide. During periods of high flood risk, a hazard proxy, defined as the sum of the sea surface height and half the significant wave height, at least doubled from average over three-quarters of the coast. These results have important implications for the risk management sector.

A Research by Design Strategy for Climate Adaptation Solutions: Implementation in the Low-Density, High Flood Risk Context of the Lake District, UK

The purpose of this paper is to propose a research by design strategy, focusing on the generation of innovative climate adaptation solutions by utilizing the Design Thinking Process. The proposed strategy has been developed and tested in a research and design studio, which took place in 2020 at a Master of Architecture degree program in the Netherlands. The studios focused on the sparsely populated, high flood risk region of the Lake District, UK. The Lake District faces urgent climate change challenges that demand effective solutions. On the other hand, the area is a UNESCO heritage site, characterized by massive tourism and tending towards museumification (sic). Three indicative design research projects were selected to illustrate the proposed research by design strategy. The results reveal that this strategy facilitates the iterative research by design process and hence offers a systematic approach to convert the threats of climate change into opportunities by unraveling the potentials of the study area. The findings lay the groundwork for more systematic studies on research by design as an effective strategy for climate change adaptation design. Beyond the local case, the results contribute to the critical theories on climate adaptation design and research by design methodologies.

Half a degree warming might cause doubled economic loss and intensified affected population of flood in China

Based on future scenario data and an improved quantitative assessment model of natural disaster risk, in this paper, we analyze the response of the characteristics of flooding events in China to 1.5 °C and 2 °C of global warming, quantitatively assess social and economic risks of the floods, and determine the integrated risk levels. The results indicate that for the RCP4.5 and RCP8.5 scenarios, the hazard and distribution area of the floods increase with increasing temperature and the influence range of floods in different levels expands more rapidly under RCP4.5 scenario. The floods mainly affect the social economy in the regions with lower altitudes and smaller slopes in eastern China. With intensification of temperature rise, the affected population and the direct economic losses would be aggravated. For 2 °C of global warming, under RCP8.5 scenario, affected population by floods would increase by 2 million and the economic risk would nearly double compared with 1.5 °C of global warming. The economic risk under RCP4.5 scenario would even reach three times that for 1.5 °C of global warming, but its proportion to GDP is lower than that of RCP8.5 scenario. Under both scenarios, the ranges of the medium-high flood risk zones would gradually expand westward and northward.

Flood exposure and poverty in 188 countries

Flooding is among the most prevalent natural hazards, with particularly disastrous impacts in poor countries. Presenting the first global estimates of the number of people exposed to high flood risks in interaction with poverty, this study finds that 1.81 billion people (23% of world population) are directly exposed to 1-in-100-year floods. Of these, 1.24 billion are located in South and East Asia, where China (395 million) and India (390 million) account for over one-third of global exposure. Low- and middle-income countries are home to 89% of the world’s flood-exposed people. Of the 170 million facing high flood risk and extreme poverty (living on under $1.90 per day), 44% are in Sub-Saharan Africa. Over 780 million of those living on under $5.50 per day face high flood risk. Using state-of-the-art poverty and flood data, our findings highlight the scale and priority regions for flood mitigation measures to support resilient development.