Use of Digital Elevation Model to compute Storm Water Drainage Network (original) (raw)
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International Journal of Innovations in Science and Technology, 2019
The rapid urbanization and the population growth, have increased the demands of fresh water to manage various tasks from domestic to industrial scales. Various man driven sectors such as agriculture, industry and water filtration plants, require fresh water to cater the need of increasing population. Therefore, the management of available fresh water reservoirs is of great importance to save water for a sustainable future “save water save life”. Digital elevation model (DEM) is efficient to extract the drainage network, basin boundaries and to evaluate the volume of fresh water available in study site. We used Arc hydro tools in Arc GIS interface for extraction of drainage network in the study site. Flow direction and accumulation were computed according to Z-value of individual pixel available in the raster grid. A total 127 streams were extracted against 127 catchments. We observed that the catchments bearing steep slopes were incised in comparison to gentle slopes which were most...
Water Science and Technology, 2023
In recent years, there has been severe flooding in urban areas as well as coastal and river flooding. Urban flooding is exacerbated by climate change, urbanization, growing population, and the increase of impervious surfaces in urban areas. Stormwater drainage systems that discharge stormwater to a safe location in urban areas are becoming increasingly important. The objective of this study is to analyze and calibrate the flood performance of stormwater drainage systems currently used in the central region of Malatya in a potential flood situation using geographic information systems and the InfoWorks ICM. The model was created using the land use type, buildings, and DEM, and the analysis was performed by exposing stormwater drainage systems to rainfall events of 5, 10, and 15 min of duration for return periods of 2, 5, and 10 years. The model was then validated using field-observed rainfall and flood data and its performance was evaluated using R 2 , NSE, RMSE, and MAE metrics. The results showed that the eight stormwater drainage systems currently in operation cannot fully convey stormwater and may pose a risk of loss of life and property in residential areas. In addition, the severity of the flooding was found to increase with an increasing return period.
Urban Drainage Network Generation with Geographic Information Systems Using Remotely Sensed Data
In Sri Lanka most of the existing urban drainage systems are not functioning properly. Establishing a proper drainage system in an urban area.is extremely important since it could avoid floods and inundation which causes damage to property and inconvenience to city dwellers; improve health conditions of the urban community by avoiding stagnant water; give an aesthetically pleasing environment, etc. Therefore, in Sri Lanka, establishing a proper drainage system and maintaining the same has become a major challenge in urban areas. Urban drainage network identification is a primary requirement for developing a proper drainage system. Urban drainage network identification is a tedious task, which is usually done through engineering surveys. The computer aided Geographical Information Systems (GIS) can be utilized to generate drainage network from the terrain data. The main objective of this work is the study of stream network generation in GIS using data extracted from aerial photographs, carryout accuracy comparison with surveyed drainage network and then to identify the parameters that affect the accuracy of generating streamlines. In this study, two urban watersheds from Colombo and one watershed from Moratuwa were studied to identify the stream network generation and associated terrain indicators using data extracted from aerial photographs. The data extraction for the study was done using three methods. Existing drainage network and watershed boundary were digitized from hard copy maps of Sri Lanka Land Reclamation and Development Corporation (SLLRDC). Contours, spot heights, buildings and road data in digital form were extracted from the digital archives of the National Survey Department (NSD). Some of the existing streamlines and culvert locations were surveyed specifically using GPS. Then the generation of the Triangulated Irregular Network (TIN) was carried out using the extracted contours and spot heights. Using the TIN, Digital Elevation Models (DEM) for spatial resolutions of 2m, 5m, 10m, 20m & 50m were generated. For each DEM, flow direction grids and flow accumulation grids were generated as components of stream network generation. Once the streamlines are generated from the flow accumulation grid, it is necessary to give a threshold value to separate the stream network. After comparing several vector and grid based methods, it was identified that Grid Based Comparative Squares (GBCS) method could be effectively used for comparing the accuracy of generated and extracted streamlines. In the GBCS method the streamlines generated and observed are matched for fitting only within identified square areas. In the squares, comparison is done using zones of distance from observed streamlines created using buffering capability of GIS, and giving an error code for the generated lines which fall into buffers that represent the deviation. Therefore, once the squares are selected spatially, then the degree of fitting of the computed and the observed streamline are compared with a system of buffers drawn to each observed streamline within a square. The squares and a buffer zoning of the extracted streams enable the identification of deviations of the generated streams from those of engineering survey sheets. Deviations were compared using RMSE (Root Mean Square Error) as the numerical indicator. The extracted stream network of catchments indicated a strong human influence in deviating the stream network and hence buildings were combined to the DEM to identify whether the results would show a difference. The same accuracy assessment method for five spatial resolutions was used for comparison of stream network. Also Flatness, Stream Order N. Attygalla and N. T. S. Wijesekera and Surface Slope based on streamline network of each watershed were computed for comparison.
IAEME, 2019
The frequent monsoon fluctuation in the coastal region of Thanjavur city of Tamil Nadu, which is known to be the rice bowl of southern India, has been imparting increasing insecurity in the yield of the crops, but even the very living conditions of the population, who are mostly dependent on agriculture. Road-expansion (NH-67) of the recent years involving mass-removal of thousands of trees located at the roadside have led to micro-climatic variation over the years. Since most of the agricultural land of the area depends on the irrigation as well as water from canals of Cauvery river, the precipitation (with respect to quantity, duration, and periodicity) has been the lifeline of progress and sustenance of this zone. To track the baseline morphological and lithological regimes of Thanjavur city of Tamil Nadu (India) precisely, which forms the heart of storm-water modeling, the present study was carried out. The digital elevation modeling (DEM) was developed, using the topsheet and satellite imageries so as to evaluate the basis for hydro-geological modeling.
Effect of Elevation Data Accuracy on Storm Drainage Schemes, Lagos, Nigeria
The check of elevation data is an essential step prior the start of any drainage study. An investigation for this concept was done in Lagos, Nigeria using two types of survey sources; a Digital Elevation Model (DEM) with a 15 m resolution produced from Russian Stereo Satellite images (RSS) and a LiDAR survey with a 5 m DEM resolution. A comparison between the RSS model survey and the LiDAR survey showed that LiDAR survey was more accurate than RSS survey and given high reliability. The study also showed that RSS survey could sometimes become misleading and could not assure reliability. A watershed modeling tool was used to analyze both surveys to produce the expected drainage streams. It was found that some locations using RSS had a false drainage direction when compared with higher accurate LiDAR surveys.
Numerical definition of drainage network and subcatchment areas from Digital Elevation Models
Computers & Geosciences, 1992
A set of ten algorithms to automate the determination of drainage network and subcatchment areas from Digital Elevation Models (DEMs) is presented. The algorithms perform such tasks as: DEM aggregation; depression identification and treatment; relief incrementation of fiat areas; flow vector determination; watershed boundary delineation; drainage network and subcatchment area definition and systematic indexing; tabulation of channel and subcatchment area properties; and evaluation of drainage network composition. A computer program (written in FORTRAN 77) that integrates these algorithms for a full DEM evaluation also is discussed. The primary purpose of the algorithms and computer program is to parameterize rapidly drainage network and subcatchment properties from widely available DEMs for subsequent use in hydrologic surface runoff models, watershed discretizations, or statistical and topological evaluation of drainage networks. Selected results of a DEM evaluation are presented for illustration purposes.
Journal of Geographic Information System, 2013
Digital Elevation Models (DEMs) are constructed using altitude point data and various interpolation techniques. The quality and accuracy of DEMs depend on data point density and the interpolation technique used. Usually however, altitude point data especially in plain areas do not provide realistic DEMs, mainly due to errors produced as a result of the interpolation technique, resulting in imprecise topographic representation of the landscape. Such inconsistencies, which are mainly in the form of surface depressions, are especially crucial when DEMs are used as input to hydrologic modeling for impact studies, as they have a negative impact on the model's performance. This study presents a Geographical Information System (GIS) tool, named LAN (Line Attribute Network), for the improvement of DEM construction techniques and their spatial accuracy, using drainage network attributes. The developed tool does not alter the interpolation technique, but provides higher point density in areas where most DEM problems occur, such as lowland areas or places where artificial topographic features exist. Application of the LAN tool in two test sites showed that it provides considerable DEM improvement. A. GEMITZI, O. CHRISTOU 330 Figure 7. Comparison of semi variograms produced with and without the use of LAN tool, to the semi variogram with measred altitude data. u
Road and urban storm water drainage network
2016
Urbanization along with its impermeable structures is the major causes of flooding in urban areas. Urban storm water influences the service life of urban infrastructures. The rainfall intensity and characteristics of catchment area are the major factors for designing urban storm water drainage facilities. These facilities have a paramount advantage to safely dispose the generated floods to ultimate receiving system. This study has assessed the integration of road and urban storm water drainage infrastructure with the help of topographic map and also the condition, pavement type and hierarchy of every road and drain were assessed in Addis Ketema Sub-city. This study area, particularly, is bounded in between Addis Ababa Municipality (East), Addis ‘Ketema ’ high school and General bus terminal (West), ‘Yohannes ’ Church (North-East) and Bethel high school (North-west). The objectives of this study includes: to identify sites most prone to flooding problems, to assess the existing condi...
Computers & Geosciences, 2007
A digital elevation model (DEM) of a watershed can be used to acquire various parameters such as basin-wide information about overland flow direction, flow accumulation and area contributing flow to any point. The resolution and quality of a DEM are important to achieve a significant level of accuracy in derived parameters. Inadequate elevation information exacerbated by applied interpolation methods, reduce DEM accuracy, resulting in pits and flat areas and makes flow tracing a difficult task. These types of problems are more prominent in cases of residual undulating terrains. In the present paper, an attempt has been made to review and suggest an improved method for the generation of a DEM from raster contour data. Further, a criteria-based region growing method (CBRGM) is presented for the extraction of discrete drainage network (cell size: 20 Â 20 m) of the watershed. Here, the flat area removal algorithm, with a variable increment, is used to generate the DEM. This induces a gradual slope even in the case of a large contour interval (20 m) extended over larger area, as is commonly available from a topographic map at a scale of 1:50,000. Further, in order to capture topographic information in flow tracing, the CBRGM is followed. The rasterised stream network from the same topographic sheet is used as ancillary data to make the concentrated flow lines to follow the channel. The methodology has been tested over Gandheshwari subwatershed under the lower part of Chhotanagpur Plateau in Eastern India. The DEM generated using this method gives a better representation of the terrain, which shows good agreement with the terrain information delineated by using the contour and channel information available in the topographic sheet. The drainage network derived shows additional extra-concentrated flow lines, many of which match the drainage network obtained from satellite imagery (cell size: 23.5 Â 23.5 m). The algorithm thus shows superiority over other available methods for the extraction of drainage networks.