Floodplain Research Articles

Distinct impact of land use and soil development processes on coupled biogeochemical cycling of C, N and P in a temperate hillslope-flood plain system

Abstract Understanding the biogeochemical cycling of phosphorus (P), particularly organic P (OP) in soils, under varying land use and soil development processes is essential for optimizing P usage under P fertilizer crisis. However, the complexity of OP impedes the mechanistic understanding. Therefore, by using well-documented organic carbon (OC) and total nitrogen (TN) cycling, we studied their stoichiometric correlation with P in soil fractions to indicate soil organic matter (SOM) and P turnover under two land uses (Cropland VS. Grassland) in Germany. Our results showed that grassland soils on the hillslope have higher OC and TN stocks than cropland soils. Total P (TP) stocks were unaffected by land use. However, grassland topsoil exhibited higher OP stocks and OP/TP proportions than cropland, with a constant IP stock throughout the soil profile, as this was determined by soil development processes in the subsoil. This proves that the flood plain soils are decoupled from hillslope soils due to different soil development processes. The stoichiometric assessment revealed a higher enrichment of OP in fine fractions of grassland soils, indicating stronger resistance to P loss by soil degradation. Mechanistic insights from OC:OP ratio of fine fractions indicate two potential OP cycling pathways: a ratio similar to microbial biomass C:P ratio suggesting a greater OP stabilization within microbial biomass/necromass; whereas a narrower ratio indicating more OP associated directly with mineral surfaces. This study illuminates the complex interplay between land use and soil development processes on OC, TN and P cycling, emphasizing the potential of stoichiometric assessment in soil fractions to understand OP biogeochemical cycling.

Risks of parasitic helminth disease outbreaks and influence of physico-chemical factors in flood prone areas of Yaoundé, Cameroon.

Urbanization coupled with poverty has promoted the exploitation of risk zones like flood-prone areas in the city of Yaoundé. The overcrowding and poor hygiene observed in these areas are responsible for the unsmiling variations in environmental cleanliness, exploitation of river water for domestic purposes thus putting them at risk for parasitic disease transmissions. This study was conducted in order to assess the risks of human helminthiases outbreaks in relation to water physico-chemical factors in the city of Yaoundé. Water samples were collected monthly from January to June 2022 in 12 stations from 4 rivers (Biyeme, Ebogo, Olezoa and Tongolo) situated in flood plains in the town of Yaoundé. Intestinal parasite resistant forms were identified using the basic sedimentation technique, while water parameters were assessed using standard procedures. Results indicated that rivers in flood-prone areas are highly contaminated with a 75% prevalence rate. In all, resistant forms of nine parasite species were recorded with the genus Toxocara being the most diversified with two species. Strongyloides stercoralis was the most prevalent (33.3%) and most abundant (1269) species followed by Toxocara canis (26.4%), Ascaris lumbricoides (25%), Toxocara leonina (20.8%), Hookworm (15.3%), Trichostrongylus sp. (11.1%), Diphyllobothrium latum (8.3%), Trichuris trichiura (2.8%) and Schistosoma intercalatum (1.4%). The least abundant species was Trichuris trichiura (33). Higher densities of parasite resistant forms were observed during the dry season. River Tongolo was the most contaminated with pathogenic forms. Water pH, orthophosphate, organic matter and alkalinity revealed negative corelations with the occurrence of Diphyllobotrium latum (r=-0.375, -0.253, -462, -0.448 respectively) while organic matter and pH showed positive correlations with the occurrence of Strongyloides stercoralis (r=0.378) and Trichostrongylus sp. (r=0.238) respectively. Flood areas constitute a potential risk zone for the maintenance and spread of human helminthiases. Maintaining proper personal cleanliness, environmental sanitation through the building of functional and accessible faecal disposal facilities and drainages and abstaining from using the rivers as waste dumps are essential in this area to prevent parasitic helminth disease outbreaks.

Spatiotemporal evolution and driving forces of landscape structure and habitat quality in river corridors with ceased flow: A case study of the Yongding River corridor in Beijing, China.

Flow cessation leads to severe degradation of river corridor landscape structure, habitat quality, and ecological functions. This study focuses on the representative river with ceased flow in northern China, the Yongding River plain section. Utilizing long-term, high-resolution satellite remote sensing imagery and the InVEST model, we analyzed the spatiotemporal evolution of landscape structure and habitat quality (HQ) before and after river corridor flow cessation over the past 50 years. The study further employs partial least squares regression (PLSR) to explore the impact of landscape structural changes on HQ and uses generalized additive models (GAMs) and geographical detector (GeoDetector) to quantitatively identify key factors affecting habitat degradation and their interactive effects. Results indicate that from 1967 to 2018, mid-channel bar, floodplain, and waterbody decreased sharply from 37.4% to 3.8%. The mean HQ value dropped from 0.58 to 0.34 after flow cessation. Although HQ slightly recovered post-2004, high-quality habitat areas remain absent. Different landscape structures significantly influence HQ, with increased size and area of the waterbody and forest patches positively contributing, while cultivated land, barren land, and built-up land generally have negative impacts. PLAND, LPI, MPS, and AWMPFD are key metrics for optimizing landscape structure and implementing habitat restoration in river management. Anthropogenic activities emerged as the primary driver of river corridor habitat degradation post-flow cessation. Different drivers exhibit complex linear and nonlinear effects on HQ. Based on these findings, we propose ecological management strategies for river corridors with ceased flow. This study is essential for a deeper understanding of river corridors' structural dynamics and degradation mechanisms, providing a scientific basis for effective ecological restoration and management.

Copula-based joint impact assessment of rainfall and tidal level on flood risk in tidal-influenced plain river network areas, Taihu Lake Basin

Copula-based joint impact assessment of rainfall and tidal level on flood risk in tidal-influenced plain river network areas, Taihu Lake Basin

CHEMICAL EVALUATION AND YIELD ESTIMATE OF ALLUVIAL SEDIMENTS OF FIVE MAJOR RIVERS IN SOUTHWESTERN NIGERIA FOR GLASS RAW MATERIALS

Alluvial sands are detrital materials which are transported by a river and deposited, usually temporarily, at points along the flood plain of the river. These sands are majorly consumed in construction industries, especially in developing countries like Nigeria. However, with value addition, it could have a high value-to-mass ratio. The alluvial sands of five major rivers in southwestern Nigeria were investigated. A total of 51 samples were collected along the channels of River Yewa, River Ogun, River Ona, River Osun, and River Shasha during the dry season in 2024. The objectives were to: assess the major chemical composition of alluvial sand vis-à-vis specification requirements for various glass industries; determine the beneficiation requirements where necessary for the silica sand to meet specification; and determine the tonnage of sediments and silica yields per year. The samples were analysed using (XRF) and XRD. The mean percentage of major oxides for the five rivers are SiO2 75.78%, TiO2 1.97%, Al2O3 8.96%, Fe2O3 4.45%, MnO 0.27%, MgO 1.25%, CaO 2.49%, Na2O 0.08%, P2O5 0.52%, Cr2O3 0.23%, and LOI 9.79%. Based on the chemical specification, it was found that the sands are not suitable for the production of first-quality glass materials. However, they are suitable for glass wool, optical glass, flat glass, glass ceramic, container glass etc. based on Best Available Techniques BAT, (2013). The Chemical Index of Alteration (CIA) was adopted to estimate the sediment yield of all the rivers. The average sediment yield of all the rivers was estimated at 2772.64t/km2/yr. Out of which...

Vertical and spatial differences in ozone formation sensitivities under different ozone pollution levels in eastern Chinese cities

Ozone is the primary air pollutant in eastern China during the warm season. Clarifying the differences in the spatio–temporal evolution of the ozone formation sensitivity between ozone polluted days and clean air days is key for the precise formulation of ozone prevention policies. By combining ground–and satellite–based remote sensing with ground station observations, we identified large spatio–temporal differences in the ozone formation sensitivity in eastern Chinese cities under different ozone pollution levels. Diurnally, the NO2 concentration was higher in the morning and lower at noon on the ozone exceedance days. The HCHO concentration was higher throughout the day, and the transition limited regime or NOx–limited regime contributed more to the ozone formation sensitivity on the ozone exceedance days. Vertically, the ratio of HCHO to NO2 (FNR) was higher on ozone exceedance days, and the contributions of NOx–limited regime at 0–2 km and the transition limited regime at 0–1 km on ozone exceedance days increased considerably. Spatially, HCHO in the North China Plain and middle–lower Yangtze River Plain was significantly increased on ozone exceedance days, while the NO2 concentration in the southeast hills was increased on ozone exceedance days. The difference in FNR values between northern and southern cities in eastern China on O3 exceedance days narrowed, and the ozone formation sensitivity in eastern China tended to be under a transition limited regime. The shifts in the ozone formation sensitivity under different ozone pollution levels implies that controlling only one of the precursors cannot achieve the best O3 prevention effect, and the most appropriate ratio of O3 precursor emission reductions should be designed according to ozone formation sensitivity in the different regions.

Evaluation of land ecological security and driving factors in the Lower Yellow River Flood Plain based on quality, structure and function

Land ecological security (LES) is crucial for human well-being and sustainable development, especially in areas like the Lower Yellow River Flood Plain (LYRFP), which faces flood threats, economic challenges, and ecological fragility. This study introduces a “Quality-Structure-Function” framework for evaluating LYRFP’s LES, incorporating ecological baselines and the impacts of land use changes on human well-being for a comprehensive assessment. Using the Optimal Parameter Geographic Detector (OPGD) model, we analyzed agricultural, industrial, and socio-economic factors as potential LES drivers. The findings indicate a gradual improvement in LES over the past two decades, with spatial variations—higher in upstream and estuarine areas and lower in the middle. Significant enhancements post-2010 were observed in Shandong Province, unlike the modest gains in Henan. Spatial heterogeneity in LES was evident across floodplain segments, with Jitai Beach witnessing the most decline, Dongying Beach the most improvement, and Zhengkai Beach the largest internal disparities. Economic growth and reduced agricultural activities positively impacted LES, while population growth-related human activities contributed to its decline. This study suggested land use safety improvements in LYRFP by considering spatiotemporal and influencing factors for regional ecological protection and development.

Zooplankton of small lowland rivers in the south of Western Siberia

In July 2022, the species composition of zooplankton was studied in seven small plain rivers of the Ob basin in the south of Western Siberia: Elbash, Chernaya, Nizhny Suzun, Upper Suzun, Pashenka, Bolshoy Barlak, Kirza, Chaus. 51 zooplankton species from three systematic groups were identified in the rivers: rotifers — 20 (39%), branched crustaceans — 23 (45%), oar-footed crustaceans — 8 (16%). The most common species of rotifers are A. priodonta and K. quadrata, branched crustaceans — D.longispina, C. reticulata, A. affinis, S. mucronata, C. sphaericus, paddlefoot crayfish — C. strenuus. Organisms belonging to different trophic groups have been noted in the zooplankton of small rivers. There are 20 saprobiont species in the zooplankton community of small rivers. An assessment of the quality of water purity showed that a fourth of the species belong to oligosaprobes, 40% to saprobiont species of mixed type, i.e. oligo–beta and beta-oligo-saprobes, 35% to mesosaprobes. In general, small rivers are rated as “moderately polluted”. Quantitative indicators of zooplankton in small rivers have a wide range of development: the number varied from 0.080 to 37.700 thousand specimens/m3, biomass — from 0.005 to 2.144 g/m3. The minimum values were observed in the Upper Suzun river, the maximum in the Elbash river. The copepodite type of development prevailed in the rivers: their share in the population ranged from 42 to 84%, in biomass — from 40 to 91%. Quantitative indicators of zooplankton have a positive dependence on the size of the catchment area. The correlation coefficient (r) with population is 0.5, with biomass — 0.1.

Urban rainstorm flood rapid simulation in plain river network area based on cellular automata

Urban rainstorm flood rapid simulation in plain river network area based on cellular automata

The Pannonian Stage: stratigraphy and geoenergy resources

The youngest regional chronostratigraphic unit of the Central Paratethys, the Pannonian Stage, is benchmarked by the deposits of Lake Pannon, containing a highly endemic, Caspian-type biota, and the sediments of adjacent deltas and fluvial plains. The Pannonian Stage also includes various freshwater lake deposits and vast volcanic formations, especially in the northern and eastern margins of the Pannonian Basin system. The Pannonian correlates with the Tortonian, Messinian, Zanclean and Piacenzian Stages, thus representing 9 Myr between 11.6 and 2.6 Ma. The Pannonian is divided into biochronostratigraphic units by the application of mollusc and dinoflagellate biochronozones in the Lake Pannon deposits and mammal biozones in the freshwater sediments. The Pannonian Stage is a leading geoenergy provider in terms of hydrocarbons and lignite. Prolific oil and gas reservoirs occur in both the deep-water and deltaic sand bodies in the central part of the Pannonian Basin, which is a highly mature exploration area. The practically inexhaustible lignite resource of the Pannonian Stage has been mined or is still being mined in the basin margins in all ten countries of the Pannonian Basin system.

Soil erosion assessment in the Ranganadi watershed of Lakhimpur district, Assam, using GIS techniques and Revised Universal Soil Loss Equation model

The loss of soil due to erosion is one of the most critical land degradation issues globally, representing a vital asset for both the economy and the environment. To effectively manage and regulate such a global issue, it is imperative to estimate the loss. With technological advancements, methodologies such as Geographic Information Systems (GIS) and Remote Sensing (RS) are crucial in addressing these difficulties. The primary objective of this study was to employ the Revised Universal Soil Loss Equation (RUSLE) model inside a GIS framework to quantify soil loss in the Ranganadi river basin of Assam, providing a more rapid and accurate estimate. Three distinct physiographic units, i.e., Piedmont Plain, Alluvial Plain, and Flood Plain, were delineated. Collected 60 GPS-based soil samples from distinct physiographic units were collected and analyzed for different soil physico-chemical properties, in addition to taking into account a variety of criteria, such as rainfall erosivity factor (R), soil erodibility factor (K), topography factor (LS), cover and management factor (C), and conservation practices factor (P), the RUSLE approach is based on the evaluation of soil loss per unit area. Five basic RUSLE factors, viz., R factor, K factor, LS factor, C factor, and P factor, were used to determine soil erosion. Further, erosion ratio, dispersion ratio, and erosion index are the basic examples of erodibility indicators that were taken into consideration while used to evaluating the erodibility of the soil. The anticipated soil erosion in the above-said area varied from minimal to severe, with values between 0.01 and 27.38 t ha-1 yr-1. Among the physiographic units, alluvial plain soils had the greatest mean soil erosion value of 8.52 t ha-1 yr-1, whereas floodplain landscapes indicated the lowest average value of 3.39 t ha-1 yr-1. The dispersion ratio varied between 0.08 and 0.33, with soils exhibiting a dispersion ratio exceeding 0.15, signifying their vulnerability to erosion. The erosion ratio varied between 0.04 and 0.61, whereas the erosion index fluctuated from 0.06 to 0.84. As a result, this model is particularly useful in anticipating soil loss in an area, allowing community members, legislatures, and other linked agencies to plan ahead of time for future efforts to mitigate the degradation.

Assessment of Soil Fertility of different Landform of Jiyadhol River basin in Dhemaji District, Assam

The current study was conducted to assess the soil fertility status of flood-prone soils in the Jiyadhol river basin in the Dhemaji district of Assam. Four landform units: Piedmont Plain, Upper Alluvial Plain, Lower Alluvial Plain and Flood Plain of the Jiyadhol river basin were delineated. 170 geo-tagged soil samples collected from different location of each landform and physico-chemical properties were analyzed. The results showed that the particle density, bulk density, porosity, field capacity, permanent wilting point and available water content varied from 2.17 to 2.48 g cm-3, 1.10 to 1.68 g cm-3, 33.6 to 55.2%, 2.0 to 28.6, 0.6 to 13.8, and 1.1 to 18.7 respectively, however, pH was extremely acidic to slightly acidic, electrical conductivity range from 0.01 to 0.15 dS m-1 which was almost negligible, soils were found to be moderate to high in organic carbon, cation exchange capacity of soils range from 3.2 to 13.6 cmol(p+) kg-1, base saturation range from 33.3 to 68.1 per cent, available nitrogen, phosphorus, potassium varied from low to high and exchange calcium and magnesium range from 0.90 to 4.30, 0.50 to 3.20, respectively.The soils in mountainous places have high organic carbon content due to the sluggish rate of mineralization caused by the lower temperature. The fertile soils of flood plain may be effectively utilized for crop diversification for attaining high productivity and profitability.

Flood Hazard Level Analysis of Kapuas Hulu Sub-watershed Using Geographic Information System

This article analyzes the flood hazard level in the Kapuas Hulu Sub-watershed using a Geographic Information System (GIS). The flood risk in this region is influenced by various factors such as soil types, land cover, elevation, slope, rainfall, and human activities. Ultisol (64.44%) significantly contributes to flood risk due to its low water permeability, leading to surface runoff during heavy rain. Inceptisol (31.73%) also plays a role in flood dynamics, with its water retention capacity dependent on vegetation. Smaller areas of Histosol (0.50%) and Spodosol (0.07%) pose localized flooding risks in lowland regions. The dominant land cover, primarily dryland forest, helps mitigate flooding, while settlements and agricultural zones increase vulnerability by reducing water absorption. Low-lying areas (50-100 meters) and steep slopes (25-45%) further exacerbate flood potential—areas receiving moderate to high rainfall increase surface runoff and flood risk. GIS-based analysis categorizes flood vulnerability into low, medium, and high levels, with 57.71% of the area classified as low vulnerability. Recommendations for flood risk mitigation include soil conservation, reforestation, sustainable land management, and drainage system improvements in vulnerable areas.

Turbulent anisotropy and coherent structures in flow through a symmetric compound channel with emergent floodplain vegetation

This experimental study advances understanding of the impact of homogeneous grass (HG), homogeneous shrub, and mixed (heterogeneous) vegetation (MV) on floodplains (FPs) and the flow dynamics within a symmetric compound channel. Velocity measurements were conducted using an Acoustic Doppler Vectrino Profiler in the main channel (MC), slope region (SR), and FP to compute depth-averaged mean streamwise velocity, Reynolds stress anisotropy tensors, and coherent structures. The analysis revealed a 54% increase in depth-averaged velocity at the MC centerline with MV compared to the no vegetation (NV) case, marking the highest increase observed among all vegetation scenarios. Reynolds stress anisotropy showed that streamwise turbulence anisotropy dominated in both the MC and SR, particularly with MV, reflecting enhanced momentum exchange due to vegetation. The anisotropic invariant map demonstrated a shift from one-dimensional to two-dimensional (2D) turbulence states and the formation of cigar-shaped turbulence structures, especially in the SR. This shift was attributed to increased momentum exchange and resistance. Quadrant analysis revealed that vegetation on the FP intensified bursting events, enhancing sediment transport in the near-bed region compared to the NV case. At the free surface, outward interactions were more frequent than inward interactions, indicating upward water movement. Higher vortex frequency and energy dissipation observed in the SR with vegetated FP confirmed the presence of quasi-2D coherent structures, facilitating the breakdown of larger vortices into smaller ones. These findings provide critical insights for river system management, emphasizing vegetation's role in altering flow dynamics and enhancing sediment transport.

Real‐Time Flood Inundation Modeling With Flow Resistance Parameter Learning

AbstractEmergency response to flood plain inundations requires real‐time forecasts of flow depth, velocity, and arrival time. Detailed and rapid flood inundation forecasts can be obtained from numerical solution of 2D unsteady flow equations based on high‐resolution topographic data and geomorphologically informed unstructured meshes. However, flow resistance parameters representing the effects of land surface topography unresolved by digital terrain model data remain uncertain. In the present study, flow resistance parameters representing the effects of roughness, vegetation, and buildings are determined hydraulically in real‐time using flow depth observations. A detailed numerical reproduction of a real flood has been largely corroborated by observations and subsequently used as a surrogate of the ground truth target. In synthetic numerical experiments, flow depth observations are obtained from a network of in‐situ flow depth sensors assigned to hydraulically relevant locations in the flood plain. Starting from a generic resistance parameter set, the capability of a tandem 2D surface flow model and Bayesian optimization technique to achieve convergence to the target resistance parameter set is tested. Convergence to the target resistance parameter set was obtained with 50 or fewer tandem flow + optimization iterations for each forecasting cycle in which the difference between simulated and observed flow depths is minimized. The flood arrival time errors across a 52 flood plain inundation area were reduced by 3.13 hr with respect to results obtained without optimization from a fixed range of flow resistance parameters. Performance metrics like critical success index and probability of detection reach values above 90% across the flood plain.

Forest‐Water Ecotones: Flooding Impacts on Ant Species Distribution

ABSTRACTNatural ecotones between forest and lake‐swamp succession impose severe environmental filters for ant fauna, compared to adjacent forest habitats. This filter effect may be more severe for soil than canopy fauna. We tested this hypothesis by investigating the patterns of species occurrence, richness and composition of soil and canopy ants in forest and lake‐swamp ecotones in a tropical river basin. We established two transects (250 m) at each site, one placed in the ecotone (i.e., flood zone) and the other inside the adjacent forest. Although upper and lower river basin had totally different ant species composition, the species occurrence, richness and composition distribution between habitats followed a similar pattern for both altitudes. Occurrence of soil ants and species richness was similar between interior and ecotone. The occurrence and species richness of canopy ants were both higher in the ecotones than in the forest interior. Ant species composition was similar between the ecotone and adjacent forest, for both soil and canopy fauna, and the ant species composition was different between seasons (dry and rainy) and between canopy and soil fauna. Most importantly, the environmental filter imposed by the ecotone and its unpredictable habitat conditions favoured fewer but opportunistic species, which drove the higher occurrence in these habitats. The years we studied were particularly dry and had a substantial decrease in lake depth. Hence, the abilities of species to best use unpredictable resources from the natural succession on the new dry grounds might have been defined by omnivorous, opportunistic and numerically dominant ants. The abiotic particularities of forest‐water ecotones are important in the temporal dynamics of ant species assemblages. Fluctuations in water dynamics can restrict soil assemblages, but subtle changes in soil flooding also affect canopy fauna and can have unpredictable effects due to intensified variations in seasonal dynamics.

Natural or man-made disaster? Lessons from the extreme rain and flood disaster in Zhengzhou, China on "2021.7.20"

Natural or man-made disaster? Lessons from the extreme rain and flood disaster in Zhengzhou, China on "2021.7.20"

An analysis of PFAS pollution and a comparison of potential treatment methods in the Middle Lower Yangtze Plain

PFAS pollution has become a significant and global problem, posing threat to human beings. The Yangtze River also suffers from a high amount of PFAS pollution. While textile industries and fluorochemical companies pollute the water with PFAS, no specific water stations designed to tackle the pollution exists in the Yangtze River Plain, the most PFAS-polluted region of the river basin. While a few PFAS-treatment methods exist in the waste water treatment industry, many have been considered impractical for the future due to their low removal efficiency or high costs, or other such reasons. However, a few methods have been proven reliable in recent research papers. The super-fine activated carbon method (SPAC), the plasma chamber method, as well as the electrochemical oxidation method will be discussed in the article in terms of there effectiveness and cost, as well as their applicability in the Yangtze River Plain Region.

Pengelompokkan Wilayah Banjir di Jawa Tengah untuk Mitigasi Banjir Menggunakan Pendekatan K-Medoids

Background: Flooding is a natural event that can occur at any time, often resulting in fatalities and significant material losses. Mapping flood zones in Central Java based on flood occurrences is crucial for optimizing disaster management. Clustering approaches are highly relevant and potential methods for tackling flood mitigation challenges in Central Java. Objective: To map flood zoning in Central Java using the optimal K-Medoids method based on the Silhouette Coefficient. Methods: This study uses the K-Medoids method for Clustering analysis because it is more resistant to outliers. Unlike K-Means, K-Medoids selects the medoid as the cluster center, making it more stable against extreme values. The data used was obtained from the Dinas PUSDATARU of Central Java Province regarding flood events in the region from October 1, 2022, to March 2023. Results: The K-Medoids method with k=2 produced the highest Silhouette Coefficient of 0.83748, Clustering 34 districts/cities with low flood occurrences and 1 district/city with high flood occurrences. This model evaluation supports the planning of disaster mitigation policies that focus more on flood-prone areas. Conclusion: There are two groups of districts/cities based on flood occurrence levels. The high Silhouette Coefficient value indicates a good cluster structure.

Pengelompokkan Wilayah Banjir di Jawa Tengah untuk Mitigasi Banjir Menggunakan Pendekatan K-Medoids

Background: Flooding is a natural event that can occur at any time, often resulting in fatalities and significant material losses. Mapping flood zones in Central Java based on flood occurrences is crucial for optimizing disaster management. Clustering approaches are highly relevant and potential methods for tackling flood mitigation challenges in Central Java. Objective: To map flood zoning in Central Java using the optimal K-Medoids method based on the Silhouette Coefficient. Methods: This study uses the K-Medoids method for Clustering analysis because it is more resistant to outliers. Unlike K-Means, K-Medoids selects the medoid as the cluster center, making it more stable against extreme values. The data used was obtained from the Dinas PUSDATARU of Central Java Province regarding flood events in the region from October 1, 2022, to March 2023. Results: The K-Medoids method with k=2 produced the highest Silhouette Coefficient of 0.83748, Clustering 34 districts/cities with low flood occurrences and 1 district/city with high flood occurrences. This model evaluation supports the planning of disaster mitigation policies that focus more on flood-prone areas. Conclusion: There are two groups of districts/cities based on flood occurrence levels. The high Silhouette Coefficient value indicates a good cluster structure.