Machine learning methods for landslide susceptibility studies: A comparative overview of algorithm performance

Impact of urbanization on flooding: The Thirusoolam sub watershed – A case study

Surat city of India, situated 100 km downstream of Ukai Dam and 19.4 km upstream from the mouth of River Tapi, has experienced the largest flood in 2006. The peak discharge of about 25,770 m3 s−1 released from the Ukai Dam was responsible for a disaster. To assess the flood and find inundation in low-lying areas, simulation work is carried out under the 1D/2D couple hydrodynamic modeling. Two hundred ninety-nine cross sections, two hydraulic structures and five major bridges across the river are considered for 1D modeling, whereas a topographic map at 0.5 m contour interval was used to produce a 5 m grid, and SRTM (30 and 90 m) grid has been considered for Surat and the Lower Tapi Basin. The tidal level at the river mouth and the release from the Ukai Dam during 2006 flood are considered as the downstream and upstream boundaries, respectively. The model is simulated under the unsteady flow condition and validated for the year 2006. The simulated result shows that 9th August was the worst day in terms of flooding for Surat city and a maximum 75–77% area was under inundation. Out of seven zones, the west zone had the deepest flood and inundated under 4–5 m. Furthermore, inundation is simulated under the bank protection work (i.e., levees, retaining wall) constructed after the 2006 flood. The simulated results show that the major zones are safe against the inundation under 14,430 m3 s−1 water releases from Ukai Dam except for the west zone. The study shows the 2D capability of new HEC-RAS 5 for flood inundation mapping and management studies.

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Assessment of flood inundation mapping of Surat city by coupled 1D/2D hydrodynamic modeling: a case application of the new HEC-RAS 5

The process of urbanization has changed LULC patterns which have a strong influence on flood risk and resulting economic losses from flood events. This study intends to assess the flood risk in urban systems and governance in terms of the flood management plan for the Surat city, also called a part of the Lower Tapi Basin, Gujarat, India. Topographical maps of the year 1968 and a satellite image of Resources-1 for the year 2006 are used to analyze the study area. Based on the study, a change from low urbanization to a high urbanization pattern is the main driver for increasing the flood risk in the study area has been noted. These shows a lack of management of flood water in urban areas, which in turn led to increasing flood losses in the urban sprawl. The flood management maps have been made by using the spatial analysis tools of the Geographic Information System (GIS), which will be useful to reduce and transfer flood risk. It will enhance the flood resilience of the flood-prone region.

Flood risk assessment and resilience strategies for flood risk management: A case study of Surat City

Flooding in urban area is a major natural hazard causing loss of life and damage to property and infrastructure. The major causes of urban floods include increase in precipitation due to climate change effect, drastic change in land use–land cover (LULC) and related hydrological impacts. In this study, the change in LULC between the years 1966 and 2009 is estimated from the toposheets and satellite images for the catchment of Poisar River in Mumbai, India. The delineated catchment area of the Poisar River is 20.19 km2. For the study area, there is an increase in built-up area from 16.64 to 44.08% and reduction in open space from 43.09 to 7.38% with reference to total catchment area between the years 1966 and 2009. For the flood assessment, an integrated approach of Hydrological Engineering Centre-Hydrological Modeling System (HEC-HMS), HEC-GeoHMS and HEC-River analysis system (HEC-RAS) with HEC-GeoRAS has been used. These models are integrated with geographic information system (GIS) and remote sensing data to develop a regional model for the estimation of flood plain extent and flood hazard analysis. The impact of LULC change and effects of detention ponds on surface runoff as well as flood plain extent for different return periods have been analyzed, and flood plain maps are developed. From the analysis, it is observed that there is an increase in peak discharge from 2.6 to 20.9% for LULC change between the years 1966 and 2009 for the return periods of 200, 100, 50, 25, 10 and 2 years. For the LULC of year 2009, there is a decrease in peak discharge from 10.7% for 2-year return period to 34.5% for 200-year return period due to provision of detention ponds. There is also an increase in flood plain extent from 14.22 to 42.5% for return periods of 10, 25, 50 and 100 years for LULC change between the year 1966 and year 2009. There is decrease in flood extent from 4.5% for 25-year return period to 7.7% for 100-year return period and decrease in total flood hazard area by 14.9% due to provisions of detention pond for LULC of year 2009. The results indicate that for low return period rainfall events, the hydrological impacts are higher due to geographic characteristics of the region. The provision of detention ponds reduces the peak discharge as well as the extent of the flooded area, flood depth and flood hazard considerably. The flood plain maps and flood hazard maps generated in this study can be used by the Municipal Corporation for flood disaster and mitigation planning. The integration of available software models with GIS and remote sensing proves to be very effective for flood disaster and mitigation management planning and measures.

Hydrological impacts of land use–land cover change and detention basins on urban flood hazard: a case study of Poisar River basin, Mumbai, India

In this research, a methodology was applied to integrate hydraulic simulation model, HEC-RAS and GIS analysis for delineation of flood extents and depths within a selected reach of Zaremroud River in Iran Floodplain modeling is a recently new and applied method in river engineering discipline and is essential for prediction of flood hazards It is necessary to simulate complicated hydraulic behavior of the river in a more simple way, for the purpose of managing and performing all river training practices In this research, steady flow was simulated along 3 km end of Zaremroud River, upstream of the Tajan River in North of Iran Floodplain zonation maps were derived using integrating of HEC-RAS and GIS analysis Delineation of flood extents and depths within the floodplain were conducted in different return periods Critical flooding area along the river was distinguished based on the grid layer of flood depths The results indicated that hydraulic simulation by integrating with GIS analysis could be effective for various kinds of floodplain management and different scenarios for river training practices and flood mitigation planning

Floodplain Mapping Using Hydraulic Simulation Model in GIS

https://profdoc.um.ac.ir/articles/a/1015676.pdf

Comparison of Neural Network and K-Nearest Neighbor Methods in Daily Flow Forecasting

In this study, first by using Smirnov-Kolmogorov method, the consistency of data was applied in order to optimize the relationship between water and sediment discharge rates in Amameh indicator watershed of Iran. After the consistency and authenticity of data were confirmed, by means of daily mean discharge and a software called Technical Hydrology (TH), monthly hydrograph was sketched for total period of 1969-2000 in Kamarkhani station in Amameh watershed outlet. Then, different models were tested using the equation of sediment transport and considering hydrological, climatic and biological parameters such as hydrograph situation, classification of discharge rate and the time of flow measurement. In all models, the regression relationships between the rates of water and sediment discharges were established. To choose an optimized model, the sum of the error sum of squares index was used. According to the index, the least sum of squares shows the optimized model. The results showed that the common model in which only one equation is used as a sediment rating equation has the highest error in estimation of suspended sediment. But, a model in which the data are separated based on wet and dry months and classification of the discharge rates, has the lowest error sum of squares and is considered as the optimized model.

Mirkhalegh Z. Ahmadi

Papers

Floodplain Mapping Using Hydraulic Simulation Model in GIS

Comparison of Neural Network and K-Nearest Neighbor Methods in Daily Flow Forecasting

Optimization of the relationship between water and sediment discharge rates (case study; Amameh indicator watershed of Iran).