scholarly journals INTEGRATING DIGITAL ELEVATION MODEL, LANDUSE/LANDCOVER AND FLOOD FREQUENCY ANALYSIS: A DETERMINISTIC APPROACH TO FLOOD INUNDATION AND RISK MODELING OF MAKURDI ALONG ITS RIVER BENUE REACH

2021 ◽  
Vol 5 (1) ◽  
pp. 477-489
Author(s):  
Kehinde T. Oyatayo ◽  
C. Ndabula ◽  
D. N. Jeb ◽  
G. K. Adamu ◽  
G. G. Jidauna

The study applied GIS techniques to integrate Digital Elevation Model (DEM), Landuse/Landcover (LULC) and flood frequency analyses to determine extent of flood hazard inundation of Makurdi town along its River Benue reach following extreme discharges and stage levels. Annual maximum stage and discharge data from 1914 to 2015 was analyzed using Gumbel’s distribution to predict flood flow for different return periods (T): 5, 10, 25, 50, 75, and 100. A goodness of fit test was conducted using Chi square statistics, which was insignificant indicating that River Benue at Makurdi flood flow fits the Gumbel distribution. Combining this result with DEM and classified LULC data, the GIS spatial analyst tool was used to estimate the areal extent of landuse that will be inundated per return period. The result shows extent of flood inundation based on current landuse pattern for the respective return periods of predicted extreme stage / discharge likely due to climate change to be as follows: bareland (1.69, 1.74, 1.78, 1.84, 1.83, 1.89 km2); settlement/built-up (5.38, 5.50, 5.63, 5.76, 5.76, 6.02 km2); farmlands (272.27, 283.59, 295.10, 306.43, 306.43,and 317.49 km2); Vegetation (91.56, 95.26, 98.78, 102.45, 102.48, and 105.95 km2); water bodies (0.21,0.21, 0.22,0.22,0.22, and 0.22 km2) and Wetlands (44.14,  45.80, 47.48, 30.36,49.42 and 50.78 km2). This reveals a general increase in the extent of flood inundation at progressive recurrence interval, and predicted rising extreme river stage heights / discharge except for the flood with 50 year recurrence interval. The study recommends that NEMA and Benue State Urban Development Board

2020 ◽  
Vol 3 (1) ◽  
pp. 58-68
Author(s):  
D. Nagesh Kumar ◽  
Apoorva R. Shastry ◽  
K. Srinivasa Raju

Abstract The modified topographic index () based on digital elevation models (DEMs) was employed to delineate flood-prone areas in Mahanadi basin, India. and flood inundation maps were compared to obtain the threshold () beyond which the area is assumed to be inundated by flood and the exponent of the . Scale dependence was also investigated to evaluate the sensitiveness of spatial resolution of the DEMs. DEMs of five resolutions, namely, ASTER global, SRTM, GMTED2010 (30 arc-seconds), GMTED 2010 (15 arc-seconds), and GMTED 2010 (7.5 arc-seconds), were used and ASTER global was preferred due to its low error compared to the remainder. Flood frequency analysis was conducted to obtain the relationship between flood-prone areas and flood magnitude. It was observed that (i) the exponent in the showed little variation, (ii) is reduced with reducing spatial resolution of the DEM, and (iii) error is also reduced as the DEMs' resolution is reduced.


Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 486
Author(s):  
Hongping Zhang ◽  
Xinwen Cheng ◽  
Lei Jin ◽  
Dong Zhao ◽  
Tianjing Feng ◽  
...  

Watershed delimitation is very important in flood control management. The traditional sub-watersheds delimitated by a filling digital elevation model (DEM) may change the real sink area, such that it may not be the best choice in studies sensitive to sub-watershed storage. This paper proposes a dynamical watershed delimitation method using a no-fill DEM and precipitation. It considers a closed sink area containing cells that fully flow into a large special cell, which can flow out when its water level is “higher than outlet”. We took Wuhan City as a study area and defined the precipitation in return periods of 1, 5, 20, or 100 years to derive the sub-watersheds. It is found that, in the four delimitations, the ratio of isolated basic units which could not flow outside were 27%, 9%, 5%, and 1%, respectively, as the precipitation increased. The results show that the provided method satisfies the assumption that the sink area might overflow with increased precipitation. The sub-watershed delimitated by the proposed method has higher correlation with the distribution of waterlogging points than those delimitated according to the D8 algorithm. These findings indicate that the proposed method can derive reasonable sub-watershed delimitation and that it may be helpful in the practice of urban flood control management.


2021 ◽  
Author(s):  
Shobhit Singh ◽  
Somil Swarnkar ◽  
Rajiv Sinha

<p>Floods are one of the worst natural hazards around the globe and around 40% of all losses worldwide due to natural hazard have been caused by floods since 1980s. In India, more than 40 million hectares of area are affected by floods annually which makes it one of the worst affected country in the world. In particular, the Ganga river basin in northern India which hosts nearly half a billion people, is one of the worst floods affected regions in the country. The Ghaghra river is one of the highest discharge-carrying tributaries of the Ganga river, which originates from High Himalaya. Despite severally affected by floods each year, flood frequencies of the Ghaghra river are poorly understood, making it one of the least studied river basins in the Ganga basin. It is important to note that, like several other rivers in India, the Ghaghra also has several hydrological stations where only stage data is available, and therefore traditional flood frequency analysis using discharge data becomes difficult. In this work, we have performed flood frequency analysis using both stage and discharge dataset at three different gauge stations in the Ghaghra river basin to compare the results using statistical methods. The L-moment analysis is applied to assess the probability distribution for the flood frequency analysis. Further, we have used the TanDEM-x 90m digital elevation model (DEM) to map the flood inundation regions. Our results suggest the Weibull is statistically significant distribution for the discharge dataset. However, stage above danger level (SADL) follows General Pareto (GP3) and Generalized Extreme Value (GEV) distributions. The quantile-quantile plot analysis suggests that the SADL probability distributions (GP3 and GEV) are closely following the theoretical probability distributions. However, the discharge distribution (Weibull) is showing a relatively weak corelation with the theoretical probability distribution. We further used the probability distribution to assess the SADL frequencies at 5-, 10-, 20-, 50- and 100-year return periods. The magnitudes of SADL at different return periods were then used to map the water inundation areas around different gauging stations. These inundation maps were cross-validated with the globally available flooding extent maps provided by Dartmouth flood observatory. Overall, this work exhibits a simple and novel technique to generate inundation maps around the gauging locations without using any sophisticated hydraulics models.</p>


2021 ◽  
Vol 328 ◽  
pp. 10003
Author(s):  
Ichsan Rauf ◽  
Imran ◽  
Idhar Sahdar

This study aims to map the distribution of floods that occurred due to the overflow of the Amasing Kali River on Bacan Island, South Halmahera. The magnitude of the flood as an input in the Watershed (DAS) system was analyzed using the Nakayasu unit synthetic hydrograph (HSS) method, while the morphometric characteristics of the watershed were analyzed by extracting digital elevation model data (Digital Elevation Model, DEM) using a Geographic Information System (GIS) application. The simulation of flood distribution with return periods of 2, 5, 10 and 25 years was carried out by applying the HecRAS 2D application. The mapping of the analysis and simulation results of this study shows that the potential flood-affected areas are on the north and south sides of Amasing Kali village with inundation heights varying between 0.50 m – 1.50 m.


Author(s):  
C. M. Bhatt ◽  
G. S. Rao ◽  
B. Patro

Conventional method of identifying areas to be inundated for issuing flood alert require inputs like discharge data, fine resolution digital elevation model (DEM), software for modelling and technically trained manpower to interpret the results meaningfully. Due to poor availability of these inputs, including good network of historical hydrological observations and limitation of time, quick flood early warning becomes a difficult task. Presently, based on the daily river water level and forecasted water level for major river systems in India, flood alerts are provided which are non-spatial in nature and does not help in understanding the inundation (spatial dimension) which may be caused at various water levels. In the present paper a concept for developing a series of flood-inundation map libraries two approaches are adopted one by correlating inundation extent derived from historical satellite data analysis with the corresponding water level recorded by the gauge station and the other simulation of inundation using digital elevation model (DEM's) is demonstrated for a part of Godavari Basin. The approach explained can be one of quick and cost-effective method for building a library of flood inundation extents, which can be utilized during flood disaster for alerting population and taking the relief and rescue operations. This layer can be visualized from a spatial dimension together with other spatial information like administrative boundaries, transport network, land use and land cover, digital elevation data and satellite images for better understanding and visualization of areas to be inundated spatially on free web based earth visualization portals like ISRO's Bhuvan portal (<a href="http://http://bhuvan.nrsc.gov.in" target="_blank">http://bhuvan.nrsc.gov.in</a>). This can help decision makers in taking quick appropriate measures for warning, planning relief and rescue operations for the population to get affected under that river stage.


2022 ◽  
Vol 28 (3) ◽  
pp. 371-380
Author(s):  
Asril Zevri

Abstrak Kota Meulaboh adalah salah satu daerah di provinsi Nanggroe Aceh Darussalam yang berada di wilayah perairan Lautan Samudra Hindia sebagai sarana Pelabuhan. Pelabuhan Meulaboh sangat berperan penting dalam meningkatkan perekonomian dan memenuhi kebutuhan masyarakat khususnya di Wilayah Kabupaten Aceh Barat. Daerah perairan pantai sangat rentan terhadap banjir pasang (rob) akibat fluktuasi muka air laut dengan kejadian pasang tertinggi (Highest Water Level) yang berpotensi mengakibatkan daerah genangan banjir di sekitar wilayah pemukiman penduduk. Studi penelitian dilakukan untuk menganalisis pemetaan potensi daerah genangan banjir pasang (rob) menggunakan Sistem Informasi Geografis (SIG). Elevasi tinggi pasang surut dianalisis dengan metode Admiralty, penggambaran elevasi kontur permukaan tanah dan banjir pasang (rob) dianalisis berdasarkan data Digital Elevation Model (DEM), dan pemetaan potensi daerah genangan banjir antara elevasi permukaan banjir pasang (rob) dengan peta administratif Kota Meulaboh dilakukan dengan Sistem Informasi Geografis (SIG) yang menggunakan software Arcgis. Hasil penelitian menunjukan elevasi muka air banjir pasang (rob) tertinggi berada di ketinggian 0.78 m di atas permukaan laut rata-rata (MSL) dan mengakibatkan potensi luas daerah genangan banjir mencapai 18.18 Km2. Luas daerah genangan banjir mengakibatkan 11 desa terkena dampak dan mengakibatkan kerugian bagi masyarakat khususnya di wilayah Desa Kampung Pasir, Suak Indrapuri, Suak Raya, dan Suak Nie. Kata-kata Kunci: Meulaboh, pasang surut, admiralty, dan sistem informasi geografis. Abstract Meulaboh City is one of the regions in the province of Nanggroe Aceh Darussalam in the territorial waters Indian Ocean as a port. Meulaboh Port is very important in improving the economy and meeting the needs of the community, especially in the District of West Aceh. Coastal waters are very susceptible to tidal flooding (rob) due to sea level fluctuations with the highest water level which has the potential to cause flooding areas around residential areas. The research study was conducted to analyze the mapping of potential tidal flood areas (rob) using Geographic Information Systems (GIS). Tidal height analysis is carried out using the Admiralty method, depiction of ground surface contour elevation and tidal flooding (rob) is analyzed based on Digital Elevation Model (DEM) data, and mapping of potential inundation areas between tidal flood surface elevations (ROB) with administrative maps of Meulaboh City carried out with a Geographic Information System (GIS) that uses Arcgis software. The results showed that the highest tidal flood water level (rob) was at an altitude of 0.78 m above the mean sea level (MSL) and resulted in the potential area of ​​flood inundation areas reaching 18.18 Km2. The total of ​​flood inundation area affected 11 villages and caused losses to the community, especially in the villages of Kampung Pasir, Suak Indrapuri, Suak Raya, and Suak Nie. Keywords: Meulaboh, tides, admiralty, and geographic information systems.


2018 ◽  
Vol 12 (5-6) ◽  
pp. 50-57 ◽  
Author(s):  
I. S. Voskresensky ◽  
A. A. Suchilin ◽  
L. A. Ushakova ◽  
V. M. Shaforostov ◽  
A. L. Entin ◽  
...  

To use unmanned aerial vehicles (UAVs) for obtaining digital elevation models (DEM) and digital terrain models (DTM) is currently actively practiced in scientific and practical purposes. This technology has many advantages: efficiency, ease of use, and the possibility of application on relatively small area. This allows us to perform qualitative and quantitative studies of the progress of dangerous relief-forming processes and to assess their consequences quickly. In this paper, we describe the process of obtaining a digital elevation model (DEM) of the relief of the slope located on the bank of the Protva River (Satino training site of the Faculty of Geography, Lomonosov Moscow State University). To obtain the digital elevation model, we created a temporary geodetic network. The coordinates of the points were measured by the satellite positioning method using a highprecision mobile complex. The aerial survey was carried out using an unmanned aerial vehicle from a low altitude (about 40–45 m). The processing of survey materials was performed via automatic photogrammetry (Structure-from-Motion method), and the digital elevation model of the landslide surface on the Protva River valley section was created. Remote sensing was supplemented by studying archival materials of aerial photography, as well as field survey conducted immediately after the landslide. The total amount of research results made it possible to establish the causes and character of the landslide process on the study site. According to the geomorphological conditions of formation, the landslide refers to a variety of landslideslides, which are formed when water is saturated with loose deposits. The landslide body was formed with the "collapse" of the blocks of turf and deluvial loams and their "destruction" as they shifted and accumulated at the foot of the slope.


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