AbstractFlooding remains one of the most destructive natural disasters, posing significant risks to both human lives and infrastructure. In India, where a large area is susceptible to flood hazards, the importance of accurate flood frequency analysis (FFA) and flood susceptibility mapping cannot be overstated. This study focuses on the Haora River basin in Tripura, a region prone to frequent flooding due to a combination of natural and anthropogenic factors. This study evaluates the suitability of the Log‐Pearson Type III (LP‐III) and Gumbel Extreme Value‐1 (EV‐1) distributions for estimating peak discharges and delineates flood‐susceptible zones in the Haora River basin, Tripura. Using 40 years of peak discharge data (1984–2023), the LP‐III distribution was identified as the most appropriate model based on goodness‐of‐fit tests. Flood susceptibility mapping, integrating 16 thematic layers through the Analytical Hierarchy Process, identified 8%, 64%, and 26% of the area as high, moderate, and low susceptibility zones, respectively, with a model success rate of 0.81. The findings highlight the need for improved flood management strategies, such as enhancing river capacity and constructing flood spill channels. These insights are critical for designing targeted flood mitigation measures in the Haora basin and other flood‐prone regions.
AbstractFacing climate change and rapid urbanization, urban flooding has exposed human and properties to increasing disaster risks. The attention from researchers and decision‐makers to understand the key role of flood regulation service (FRS) in flood management has arisen. However, the mechanism of FRS supply–demand is little known from landscape scale. The FRS assessment methodology considering interacts between source, sink, and flow landscape was proposed in this study. The spatial distributions of surface runoff generation, runoff reduction capacity, and flood inundation were mapped using one‐dimensional rainfall–runoff method SCS‐CN and two‐dimensional flood propagation model CADDIES. Four 3‐hour designed rainfall scenarios ranging from nuisance to extreme events (3a, 11a, 56a, and 100a) were simulated. The Liuyang River Watershed in Changsha Municipality, China was selected for case study. The results showed that, the differences of runoff reduction coefficient and runoff generation volume between vegetation and built‐up landscape have shortened. The peak flood depth, extent of flood inundation, and peak flood velocity have increased continuously with the growing rainfall intensity. The number of source–sink mismatch catchment was the highest under 56 and 100a, and the most of source‐sink match catchments were observed under 3a. Under four rainfall scenarios, the changes of source–sink relationships were witnessed and the potentials of flow zone in source–sink mismatch catchments have increased. The FRS management framework concerning supply–demand connections has been proposed based on source–sink–flow analysis. These findings could provide a scientific basis for sustainable urban flood management and disaster risk mitigation.
Stanimir Kostadinov, Sonja Braunović, Slavoljub Dragićević
et al.
The aim of this research was to analyse the changes in the soil erosion intensity caused by erosion control works (ECW) in Grdelica Gorge (The South Morava River) in the period between 1953 and 2016. For the purpose of quantifying the erosion intensity changes, the erosion potential model (EPM) was used to calculate the annual gross erosion (W), sediment transport (G), and erosion coefficient (Z) in the study area. As a result of the performed technical and biotechnical erosion control works, there was a general decreasing trend in the intensity of soil erosion processes in the last 63 years. The specific annual gross erosion in Grdelica Gorge was 1920.34 m3/km−2/year−1 in 1953, while in 2016 it was 492.42 m3/km−2/year−1. The specific sediment transport was 1421.05 m3/km−2/year−1 in 1953 and 364.39 m3/km−2/year−1 in 2016. Due to the changes in the intensity of erosion processes, the specific annual gross erosion in the study area decreased by 1427.92 m3/km−2/year−1 and the specific sediment transport by 1056.66 m3/km−2/year−1. The value of the erosion coefficient was reduced from Z = 0.84 in 1953 to Z = 0.32 in 2016. The results show that there is a significant correlation between the soil erosion intensity (erosion coefficient) and ECW (biotechnical works) performed in Grdelica Gorge. The permanent control of erosion processes in Grdelica Gorge is very important for torrential flood prevention and protection of two very important traffic routes (Belgrade-Skopje-Athens railway and motorway—Corridor X), as well as settlements, local roads, and other facilities in this area. Furthermore, these results are the basis for future water management projects, soil and environmental protection, spatial planning, agriculture, and other human activities.
In the Polish part of the Carpathians there are 14 retention reservoirs that accumulate around 1200 million m3 of water. The last larger hydrotechnical structure is the Świnna Poręba reservoir, capacity: 160 million m3, built on the Skawa river. The reservoir has a very varied coastline, within which there are many landslide areas (including the Ostałowa landslide region). Hydropower disasters are known from the history of hydrotechnical objects, the reason for which was the insufficient identification of the geological structure of the reservoir bowl. Documentation of landslide in such areas is therefore an issue of great importance for the safety of not only the hydrotechnical object itself, but also people inhabiting the area of the water reservoir. At particular stages of documenting landslide areas, it is important to: recognize the mechanism that activates the landslide, assess the possibility of securing a slope or escarpment, indicate the optimal method of stabilizing the landslide, determine the geotechnical parameters necessary to develop a landslide protection project and its monitoring. In the article, the key elements of the documentation for the protection of the Ostałowa region were presented against the background of the legal regulations in Poland. The content of landslide document sheets, the scope of the geological work project and the scope of geological engineering documentation for the landslide protection project were characterized. The key elements of the geotechnical design are presented, including slope stability calculations and the proposed protections are presented. Surveying monitoring of the Ostałowa area constituting a continuation of geological works is carried out on a network of sixteen benchmarks controlled in relation to four benchmarks of the reference network. This monitoring should also be continued after the protection of the landslide, as it is the basic measurable way of determining land displacements. Measurement results indicating soil displacement are the basis for possible prevention actions.
Abstract Floods often occur in Padang City, mainly in the areas of Pasia Nan Tigo Village and Lubuk Buaya Village, caused by the overflow of Batang Kandis when heavy rains occur (intensity of rainfall >15mm/hours). To decrease the river overflow an artificial canal with 300 m long and 50 m wide (floodway) was constructed to bypassing the river flow from the Batang Kandis River to the ocean. In order to find out the effects of the floodway, four scenarios are performed the scenario 1 and 2 were the simulation condition of Batang Kandis River before and after the construction of floodway. While to increase the effectiveness of floodway, simulations 3 and 4 were carried out. Scenario 3 was the combination of floodway with normalization and embankment. To prevent the entry of seawater into the Batang Kandis River, because the floodway is affected by the tide of the sea, then 3-door motion weir was simulated namely scenario 4. Scenario 4 was the combination of floodway normalization, embankment, and a 3 door motion weir. From the simulations, we found that the floodway was effective to decrease the water surface level up to 15 m and 20 m during 10 years and 25 year return period of discharge respectively. From the scenario 3, we found that the embankment with 1.5 m and 2 m was effective to prevent overflow by 10-year and 25-year return period of discharge respectively. While for scenario 4 the water level rises 0.5 m due to motion weir So, that it is needed to extend the embankment with 0,5m high.
Márta Koczka Bara, Y. Velísková, R. Dulovičová
et al.
Abstract The spatial and temporal patterns of surface water (SW) - groundwater (GW) exchange are significantly affected by riverbed silting, clogging or erosion processes, by altering the thickness and hydraulic conductivity of riverbed sediments. The duration of SW-GW exchange is controlled by the drainage and infiltration resistance of river bottom sediments (e.g. Andrássy et al., 2012). Generally, these two parameters primarily depend on the hydraulic conductivity and on the thickness of clogged layer. In this study the flow processes between GW and SW were modeled by model TRIWACO for different infiltration resistance and drainage resistance of riverbed sediments. The model area is situated on the Rye Island, which is a lowland area with very low slope. In this area a channel network was built up, where the flow conditions are controlled by water-gates. Because of the low slope and the system of water gates built on the channels, the riverbeds are influenced by intensive clogging processes. First, the applicability of model TRIWACO in the study area was tested by modelling the response of GW on SW level fluctuation. It was simulated, how the regulation of water level and flow direction in the channels influence the GW level, especially in extreme hydrological conditions (drought/flood), and if the GW flow direction and GW level change as it was expected. Next, the influence of channel network silting up on GW-SW interaction was modeled. The thickness of riverbed sediments was measured and their hydraulic conductivity from disturbed sediment samples was evaluated. The assessed hydraulic conductivity was used to calculate the infiltration resistance and the drainage resistance of riverbed sediments in the study area. Then, the GW level and flow direction was simulated for different infiltration resistance and drainage resistance of sediments.
This article proposes the development of a rainfall-runoff model in order to simulate the hydrologic behavior of the Djerem sub-basin at Mbakaou in the Sanaga basin in Cameroon. We suggest a solution based on a spatial conceptual modeling, then a restriction to a finite number of parameters judged applicable for the different choices of models. The approach relies on the hydrologic system HEC-HMS whose interest is not only it's adaptability to the tropical and equatorial climate, but also and especially to the acceptable results that it provides for a very weak quantity of data. In this work, we take into consideration the different aspects of modeling such as: surface flow, underground flows, direct runoffs, losses, as well as interactions between the surface and the base-flow of rivers. The results obtained allows the planning of the Mbakaou dam, consequently to increase the hydroelectric production on one hand and on the other hand, provide some exploitable information for dimensions of hydrologic works, protective against floods or for hydrologic management and ecology of the Djerem basin at Mbakaou. To validate our model, a comparison of the simulated flow-rate and the observed flow-rate was carried out using historic data with the Nash-Sutcliffe Criterion and we obtained an efficiency of 0.862, meaning that the simulation was good.