Essay: The approach to manage Storm Water in Visakhapatnam

CHAPTER 1
INTRODUCTION
1. INTRODUCTION
This project generally develops approach to manage Storm Water in Visakhapatnam and to protect all low-lying areas using Geographical Information System. It is important to identify all low-lying areas and protect flood vulnerable areas so that measures can be taken for each location. Conventionally, all flood subjected areas have been plotted on Toposheets. However in recent years, software applications incorporating Geographical Information System (GIS) have been developed in many fields.
In addition to permitting linkage between various types of data and maps, GIS is able to manipulate and visually display numerous types of data for easy comprehension. The ultimate goal of this research is to establish an GIS-based system to analyse factors contributing to Storm Water Management.
1.1 BACKGROUND STUDY
The growth of any country depends upon its Urban Hydrology network, comprising of drainage systems and water bodies connectivity. A good network of system is important as it provides connectivity between different areas of urban areas. Along with this, storm water storage is an equally important aspect. All water bodies of Visakhapatnam is to be identified and low-lying areas are marked. Then, the requisite measures are to be taken for Storm Water Management.
1.2 PROBLEM IDENTIFICATION
The current system that is adopted in Visakhapatnam is combined sewer systems, so that Storm Water is wasted. This project will give new methods of Storm Water Management in Visakhapatnam so that water scarcity can be reduced.
1.3 OVERVIEW OF VISAKHAPATNAM CITY
Visakhapatnam is among the most populated cities in India. As mentioned earlier, Visakhapatnam is located in Andhra Pradesh state, in the eastern part of India. Visakhapatnam is also rapidly growing in city in terms of population growth and urban physical growth.
There is an authority which governs the city of Visakhapatnam. It is Greater Visakhapatnam Municipal Corporation which governs 72 wards comes under six zones is shown in figure 1.1. Visakhapatnam is one of the major cities on the East Coast of India connected by NH5, a major highway and a part of the Golden Quadrilateral System of Indian Highways.
1.4 OBJECTIVES OF STUDY
The objective of the study is to make a base map for storage and supply Storm water for the public.
‘ To collect storm water and store it in requisite forms which is to be supplied to the public (Visakhapatnam) for sustainable management of natural resources.
‘ Creation of GIS Database for Stormwater Management which includes water bodies, Storm sewers, topography, and other features to better understand the complex relationship of all features within Visakhapatnam drainage system.
1.5 LOCATION OF STUDY AREA
The study is covered in 65 O/5 of Survey of India Toposheets on 1:50,000 scale bounded by 17083′ and 17066′ Northern Latitude and 83017′ and 83o42’ eastern longitude.
1.6 PHYSIOGRAPHY
Physiographically, the study area may be divided into two parts- Hill ranges and plains with valleys. The hill ranges are in North and Southern areas, where ad plains are located in the centre of these two hill ranges. The Bay of Bengal is located in the east of the city. Kailasha hill range has a height of about 484 metres above mean sea level whereas on the southern side hilly range namely are located.
1.7 METHODOLOGY
‘ Pre-field work
‘ Field work
‘ Post-field work
1.7.1 Pre-field work
‘ SOI Toposheet collection
‘ Preparation of base map
I. Rectification
II. Sub setting of images
III. Mosaic of images for study area
IV. Delineation
‘ Digitization of drainage network
‘ Preparation of drainage map
‘ Preparation of low-lying areas
1.7.2 Field work
‘ Data collection.
‘ Identify existing sewer and pipe-line system.
1.7.3 Post-Field work
‘ Scanning, Rectification, digitization of images.
‘ Create Digital Elevation Model for terrain evaluation.
‘ Design criteria for pipe lines.
‘ Analysis of pipe layer system.
‘ Connection of existing pipe lines to the recently designed.
‘ Implementation.
‘ Identify low-lying areas
‘ Methods for Storm Water Management
CHAPTER 2
LITERATURE REVIEW
2. LITERATURE REVIEW
Growing populations and migration towards built areas is driving land use change in the form of urbanization across the globe and by 2050 some 70% of the world’s population are expected to live in urban areas (UN, 2008). The current population of Visakhapatnam is 15lakhs which is going to be increased rapidly within next few years. The loss in pervious surfaces reduces the infiltration into soils, while the introduction of artificial drainage replaces natural pathways. This combination is generally considered to have considerable effect on the hydrological response of an area to rainfall, such as: greater magnitude of river flow, higher recurrence of small floods, faster response , reduced base flow and groundwater recharge. Urbanization brings with it a range of environmental challenges for both the local, regional and wider environment as a direct result of the biochemical and physical changes to hydrological systems. The reality is often further complicated by the installation of storm water retention systems, and the import/export of water to and from a catchment.
A storm drain system is designed to prevent the accumulation retention of urban stormwater runoff on city surfaces and discharge the accumulated waters into receiving waters. On dry-weather days, however, non-stormwater discharges also find their way into stormwater drainage systems, contributing significant pollutant loadings to receiving waters and even resulting in severe foul stench phenomenon.
Brown et al. (2004) proposed the piecewise observation methods in rainwater pipes to isolate the illicit discharge between two storm drains. In China, several storm drainage systems in Shanghai were assessed from 2006 to 2010, by employing flow meters to measure the flow rates of inappropriate sources and further develop understanding of the status of the storm drainage network.
(Field et al., 1994; Pitt et al., 1993), researchers have used direct discharge surveys to determine the dry-weather flow of their storm drainage systems.
Musolff et al. (2010) presented an entry-exit balance approach to quantifying major water flow within sewers. It has the advantage of describing the process concisely, with moderate input; however, the process described is not appropriate for those within the storm drains receiving inappropriate dry-weather flows. It is therefore necessary to develop a method of estimation that can be used to generate well-resolved information about flows from non-stormwater sources entering storm drains with moderate work input as well.
2.1 SUMMARY OF LITERATURE AND SCOPE OF WORK
The overall goal of this study is to establish a methodology to estimate the quantities of non-stormwater sources flowing into storm drains. On this basis, necessary pollution control activities to minimize or eliminate dry-weather damage to the environment via the storm drains.
‘ To collect storm water and store it in requisite forms which is to be supplied to the public (Visakhapatnam) for sustainable management of natural resources.
‘ Creation of GIS Database for Stormwater Management which includes water bodies, Storm sewers, topography, and other features to better understand the complex relationship of all features within Visakhapatnam drainage system.
‘ The drainage system in Visakhapatnam of GVMC is combined system for both storm water and sewerage.
‘ In order to arrest the inundation of low lying areas in the city, GVMC has undertaken massive exercises. However, only 20km long storm water drain has been concretely built so far and the rest 82km is yet to be completed.
‘ A stormwater drainage system is proposed in the city which consists of Storm water tank and a treatment plant.
CHAPTER 3
REMOTE SENSING’
3. REMOTE SENSING
3.1 INTRODUCTION
Remote Sensing technology was developed to assess accurate information on natural resources, which is a pre-requisite for optimal utilization and effective management. The space technology was used since long, however the aerial photography was used during the World War I and II, to recognize the enemy troops and their locations. SPUTNIK-L the first artificial satellite was launched by the American Space Agency in 1957 to study the atmosphere and several topographic conditions. The first remote sensing satellite LANDSAT-I was launched by NASA(National American Space Agency) in 1972 with this achievement the United States of America occupies the first position in the field of remote sensing. It has launched various remote sensing satellites and collects the data through a network of satellite receiving stations all over the world.
India has established DOS (Department of Space) in the year 1972 with a view to harness the space technology. There after several experimental satellites were launched from India and Abroad. India occupies fifth position in the field of remote sensing. The first Indian Satellite Aryabhatta was sent to space in 1975.An indigenous IRS (Indian Remote Sensing Satellite) program has finalized to support the national economy in the areas of ‘agriculture water resources forestry and ecology, watershed, marine fisheries and coastal management.’ Data of IRS satellites received and disseminated by several countries all over the world. The high-resolution satellites enable us in the areas of urban sprawl. Infrastructure planning and other large-scale applications. The potential applications now cover diverse fields such as crop acreage and yield estimation, drought warning and assessment flood control and damage assessment, land use/land cover information. Agro-climatic planning waste land management, water resources management, ground water exploration, prediction of snow-melt runoff, management of water sheds and command areas, fisheries development, mineral prospecting, forest resources, survey etc. Active involvement of the user ministries/departments has ensured in an effective harnessing of the potential of space-based remote sensing.
3.1.1 How Remote Sensing works
Remote Sensing is the science and art of obtaining information about an object, area or phenomenon through the analysis of data acquired by a device that is not in contact with the object, area or phenomenon under investigation. A comprehensive definition of remote sensing is the non-contact recording of information about the earth surface, from the ultraviolet, visible, infrared and microwave regions of the electro-magnetic spectrum. Image by means of scanners, cameras located on mobile platforms such as aircraft or spacecraft and the analysis of acquired information by means of photo interpretive techniques, image interpretation and image processing. Different objects of the earth surface return different amounts of reflected/emitted energy in different wavelengths of the electromagnetic spectrum and this reflectance/emittance from each object depends on the wavelength of radiation, the molecular structure of the object and its surface conditions. Detection and measurement of these spectral signatures enable identification of surface objects both the from airborne and space borne platforms. The objective of image interpretation and processing in the present investigations are as follows.
I. To understand the visual image characteristics of different litho-units, landforms, lineaments and structures etc., which are important to understand the terrain character of the area.
II. To enhance lineaments pattern in different directions and to find out their impact on the urbanization.
III. To understand land use/land cover studies for urban change in the area.
3.2 ELECTROMAGNETIC RADIATION
Electromagnetic waves are energy transported through space in the form of periodic disturbances of electric and magnetic fields. All electromagnetic waves travel through space at the same speed, C=2.99792458 x 108 m/s, commonly known as the speed of light. Electromagnetic wave is characterized by a frequency and a wavelength. These two quantities are related to the speed of light by the equation, Speed of light= frequency x wave length is shown in figure 3.2 . The frequency of an electro-magnetic wave depends on its source. There is a wide range of frequency encountered in our physical world, ranging from the low frequency of the electric waves generated by the power transmission lines to the very high frequency of the gamma rays originating from the atomic nuclei. This wide frequency range of electro-magnetic waves constitute the Electromagnetic Spectrum which is shown in figure 3.1.
Fig. 3.1 Electromagnetic Radiation Spectrum
Different satellite remote sensing data have been used for the generation of themes such geomorphology lineament pattern, and land use/ land covers are some of the approaches. Digital Elevation Model of the area has been generated with a view to study the slope and drainage conditions of the area.
Fig. 3.2 Direction of Electric field
Now-a-days the field of Remote Sensing and GIS has become exciting and glamorous with rapidly expanding opportunities. Many organizations spend large amounts of money on these fields. Here the question arises why these fields are so important in recent years. Two main reasons are there behind this.
1) Now-a-days scientists, researchers, students and even common people are showing great interest for better understanding of our environment. By environment we mean the geographic space of their study area and the events that take place there. In other words, we have come to realize that geographic space along with the data describing it is part of our everyday world, almost every decision we take is influenced or dictated by some fact of geography.
2) Advancement in sophisticated space technology which can provide large volumes of spatial data. Along with declining costs of computer hardware and software which can handle there data has made Remote Sensing and GIS affordable to not only complex environmental / spatial situation but also affordable to an increasingly wider audience.
3.3 REMOTE SENSING
Literally Remote Sensing means obtaining information about an object, area or phenomenon without coming in direct contact with it. If we go by this meaning of Remote Sensing , then a number of things would be coming under Remote Sensor, e.g. Seismographs, fathometer etc. Without coming in direct contact with the focus of earthquake, seismograph can measure the intensity of earthquake. Likewise without coming in contact with the ocean floor, fathometer can measure its depth. However, modern Remote Sensing means acquiring information also earths land and water surfaces by using reflected or emitted electromagnetic energy. Remote Sensing then in the widest sense is concerned with detecting and recording electromagnetic radiation from the target areas in the field of view of the sensor instrument.
This radiation may have originated directly from separate components of the target area, it may be solar energy reflected from them; or it may be reflections of energy transmitted to the target area from the sensor itself. Remote Sensing is the practice of deriving information about the earth’s land and water surfaces using images acquired from an overhead perspective, using electromagnetic radiation in one or more regions of the electromagnetic spectrum, reflected or emitted from the earth’s surface. So the stages of Remote Sensing include.
3.4 REMOTE SENSORS
Remote Sensors are the instruments which detect various objects on the earth’s surface by measuring electromagnetic energy reflected or emitted from them. The sensors are mounted on the platforms discussed above. Different sensors record different wavelengths bands of electromagnetic energy coming from the earth’s surface. As for example, an ordinary camera the most familiar type of remote sensor which uses visible portion of electromagnetic radiation.
3.4.1 CLASSIFICATION OF SENSORS
On the Basis of Source of Energy used: On the basis of Source of Energy used by the sensors. They can be classified into two types ‘ Active sensors and Passive sensors.
Active Sensors: Active Sensors use their own source of energy and earth surface is illuminated by this energy. Then a part of this energy is reflected back which is received the sensor to gather information about the earth’s surface. When photographic camera uses its flash, it acts as an active sensor. Radar and laser altimeter are active sensors.
Passive Sensors: Passive sensors do not have their own source of energy. The earth surface is illuminated by sun/solar energy. The reflected solar energy from the earth surface or the emitted electromagnetic energy by the earth surface itself is received by the sensor. Photographic camera is a passive sensor when it is used in sun light, without using its flash.
CHAPTER 4
GIS APPLICATIONS IN URBAN HYDROLOGY
4. GIS APPLICATIONS IN URBAN HYDROLOGY
4.1 INTRODUCTION
This paper presents an integrated system to support the urban storm water runoff estimation by using remote sensing and GIS technology with a distributed hydrologic simulation. The integration framework is discussed first, then a real application is introduced. High resolution GIS data, as well as three different remote sensing data were used to study the impact of remote sensing data to urban storm water runoff estimation. The results show the advantages of the integration of RS and GIS with hydrologic simulation to improve the urban hydrology. One conclusion from this research is that RS and GIS complement each other; the high quality RS data is necessary in addition to high resolution GIS data for modeling a residential area mixed with some commercial and industrial uses.
4.1.1 Recent development in the integration of remote sensing and GIS with hydrology
Many types of hydrological analysis are limited by a lack of spatial data, since traditionally hydrological data are point measurements. Remote sensing data are fundamentally different, they incorporate spatial information. The rapidly developing GIS technology is a powerful tool to organize, process and visualize spatial data. Thus, RS and GIS can complement each other and enable hydrological models to be more physically based and more efficient. It is only during the last five years that an integration of RS and GIS with hydrological models became technically feasible. For hydrological modeling, the integration of RS and GIS was weak. However, in 1998 ESRI and ERDAS together released the Image Analysis tool for ArcView GIS, which directly linked some basic functions in RS and GIS.
GIS has provided a new environment to develop distributed hydrological models. These models take into account and predict the values of the studied phenomena at any point within the watershed. RS and GIS have become increasingly important in hydrology. However, the current use of RS information in the field of planning, design and operation of water resources systems still falls far below its potential. GIS technologies are relatively new and still near the lower end of the growth curve in terms of applications. Valuable urban spaces and resources require precise storm water management and flood control. Stormwater runoff estimation is a fundamental problem for both urban planning and urban water resource management.
4.2. An attempt to integrate RS and GIS with urban storm water management
In 1997, an attempt to integrate RS and GIS with urban storm water management was made by a research group in The University of Arizona. Its area is about 6.69 square kilometres and is predominantly mixed residential with some industrial and commercial areas. The remote sensing data consisted of images from aerial photography. The high-resolution (1ft grid size) digital elevation map (DEM) was acquired from the field survey. The GIS database included the data for streets, underground pipes, flow paths, soils, etc.. This integrated system provided a new environment for both research and application.
4.2.1 Processing Remotely Sensed Data
Three remotely sensed images were processed by supervised classification, then geo-registered and rectified with reference to aerial photography and street map. The identified categories were residential buildings, industrial buildings, asphalt, concrete, trees, grass, bare soil, water, and agriculture land. The processed images were spot-checked by the field observation in an adaptive sampling approach. Since its sensor has best spectral resolution and highest spatial resolution of those three systems. Landsat has a more accurate classification of the paved area than SPOT, due to its higher spectral resolution. The impact of RS data resolution to hydrologic simulation were investigated in detail, the results will be introduced later.
4.2.2 Digital Elevation Modeling the Urban Watershed
A high-resolution DEM with 1-foot grid size was provided by the City of Scottsdale, together with a basin boundary map. The research team made field surveys to improve the GIS database, especially with regard to data on channels and flow paths. The field surveys showed that, in this area, it is necessary to model walled boundaries to delineate the sub-basins, since a mile-long wall can physically change flow direction. These walls could not be identified from the three RS images, and it was not in DEM either. Field investigations of flow paths were performed on some streets and large parking lots that were relatively flat, the flow paths were field investigated. Data were also collected along the channels. Data for detention ponds were collected in industrial areas. These field data greatly improved the GIS data quality. Using these data, the basin was partitioned by GIS hydrologic functions, based on pre-selected outlet points.
4.2.3 Hydrologic Parameterization by RS and GIS
Each processed image was converted to a grid. The spatial land use information was organized and processed with GIS tools. Using a rule base, the GIS determined the pixel hydrologic parameters based on the surface feature (soil type, vegetation type,…) combined with other GIS data (natural channel, residential area, …). For modeling flow routing along a channel or pipe, the GIS provided cross-section data, roughness and slope. Figure 4.1 shows the geo-reference connected RS and GIS with hydrologic parameterization together.
Figure 4.1. Geo-referencing Connects RS and GIS with Hydrologic Parameters
In summary, GIS tools played a central role for parameterization. Geo-referencing connected Remote Sensing and GIS with hydrologic parameterization together. Here, the parameters were directly observed and then automatically derived from each pixel, which is significantly different from the traditional approach where the parameters were interpolated from the point measurements. It would be very difficult to apply the traditional interpolation approach in the highly developed urban area, where land use conditions change rapidly.
‘
CHAPTER 5
GIS ANALYSIS
5. GIS ANALYSIS
GIS is a Geographical Information System that supports the display and analysis of spatial data. GIS has its strength in providing capabilities to model the physical proximity of spatial features. The powerful aspect of GIS is the flexibility in modelling spatial objects to suit particular application requirement. It provides capability to store and maintain large data sets.
It provides link between different streams of drainage data. It provides facilities to understand one to many, many to many and many to one relation-ship, which exists in spatial data.
5.1 Digitization
Digitizing is the process of converting analog information into a digital information. It regards to spatial information one application of this is the process of creating a vector digital database by creating point, line and polygon objects. Scanning a map can also be considered digitizing turning colours into shades on the map into digital values, but for this class when we refer to digitizing this for the most part refers to creating vector datasets. We are going to follow a process of making digital versions of objects that will have an attribute table associated with them. Our primary goal will be digitizing the road network, water bodies and drainage network. By digitizing these features you make them available for mapping once you have added the tabular data to the attribute table. The digitizing process is started by creating new layers in Arc Catalog and then adding features to them in Arc Map.
5.2 Types of Digitizing
5.2.1. Manual Digitizing
In this method the digitizer uses a digitizing tablet to trace the points, lines and polygons of a hardcopy map. This is done using Special Magnetic pen or stylus that feeds information into a computer to create an identical digital map.
5.2.2. Heads-up-digitizing
This method involves scanning a map or image into a computer. The digitizer then traces the points, lines and polygons using digitizing software. This method of digitizing has been named ‘heads-up’ digitizing because the focus of the user is up on the screen, rather than down on a digitizing tablet.
5.3 ANALYSIS
5.3.1 Conversion of DXF file to COVERAGE file
1. Open a drawing file in AUTO-CAD.
2. Make sure only contours with proper corners are present.
3. Type DXFOUT in the Command block as shown in figure 5.1.
Fig. 5.1 How to open a DXF file
4. Save as Files of type ‘AUTOCAD R12/LT2dxf’.
5. Go to START MENU ARC.
6. Type ‘cw (space) Path of file(eg. E:)’
‘w (space)path of file’
‘arctools (space)edit’.
7.’EDIT TOOLS’ folder and ‘ARCEDIT’ folder will be opened.
8. Go to ‘EDIT TOOLS’ folder TOOLS ‘COMMAND TOOLS’.
9.In ‘COMMAND TOOLS ‘ folder ‘CONVERSION’ ‘TO ARC ‘ ‘TO DXF TO ARC’ is shown in figure 5.2.
Fig. 5.2 DXF conversion
10. A folder named ‘DXF CONVERSION’ is opened.
11. Right click on ‘INPUT DXF FILE’ is shown in figure 5.3.
Fig.5.3 How to input a DXF file
12. Click on the requisite file (ex:6505secn.dxf).
Then, the path is shown in ‘DXF FILE CONVERSION’.
Below that, a symbol representing ‘LAYERS’ is to be clicked is shown in figure 5.4.
Fig. 5.4 Conversion of DXF file
All LAYERS are opened.
13. Click on every ‘LEVEL’ and Click on ‘ALL’ under ‘INCLUDE LAYER ENTITIES’ .
14. Give a FILE NAME in ‘OUTPUT COVERAGE’.
15. Click on ‘APPLY’.
16. After the application process is done, click on ‘CANCEL’.
17. Click on ‘ARC TOOLS ‘ in ‘EDIT TOOLS’ folder ‘QUIT’.
18. Type ‘QUIT’ in ‘ARC’ folder as shown in figure 5.5.
Fig. 5.5 Closing of ARC folder
5.3.2 Applying TIC-IDs to the images
1. Go to ‘START menu’ ‘ARC’ .
2. Type ‘cw(space)Path of file(eg. E:)’
‘w(space)path of file’
‘arctools(space)edit
3. Click on EDIT TOOLS FILE OPEN Click on the respective file (ne_6502) ARC OK.
4. Click on EDIT TOOLS FILE OPEN TIC OK.
5. EDIT TOOLS DISPLAY DRAW ENV. GENERAL TIC IDS APPLY DISMISS.
Fig. 5.6 Application of TIC-IDs
6. Take a note of all latitude and longitude values of four TIC-IDs as shown in figure 5.7.
Fig. 5.7 Input of Latitude and Longitude values
7. Initially, we need to drag the TICs to the exact four corners of the respective image.
Use Feature selection folder select which is used to select TIC of a corner. Type 9 to deselect the option.
8. In order to zoom to the required area, type ‘CTRL+E’.
To drag the TIC, go to EDIT TICS and select DRAG as shown in figure 5.8.
9. Save the file after the four TICs are placed at the corners of the image.
Fig. 5.8 Geo-referencing TIC-IDs
5.3.3 APPLYING LAT/LONG VALUES TO TIC-IDs
1. GOTO START MENU ARC.
2. First turn on CAPS LOCK.
3. Type CLEAN(space)FILE NAME(space)NEW FILE NAME as shown in figure 5.9.
(Process undergoes)
Fig.5.9 Input a new file name
4. Type ARC: BUILD (space) NEW FILE NAME
ARC: INFO
ENTER USER NAME: ARC
ENTER COMMAND: UPDATE PROMPT
ENTER COMMAND: SELECT (space) NEW FILE NAME.TIC
(4 recs selected)
ENTER COMMAND: LIST
Fig. 5.10 Entering of TIC-IDs
ENTER COMMAND: UPDATE PROMPT
RECORD :1
ID TIC:5
.
.
.(continues to all four corners).
ENTER COMMAND: Q(space) STOP.
ARC: TRANSFORM(space) TEST1(space)TEST2.
5. Open the file and check whether LAT/LONG values are applied.
5.3.4 APPLYING CONTOUR INTERVALS
1. Go to ‘START menu’ ‘ ARC’ .
2.Type ‘cw(space)Path of file(eg. E:)’
‘w(space)path of file’
‘arctools(space)edit’.
3.Click on ‘FILE’ in the ‘EDIT TOOLS’ Click on the above obtained respective file.
4.Go to ‘DISPLAY’ in the ‘EDIT TOOLS’ Click on ‘DRAW ENV: GENERAL
‘ ARC IDS ON.
5.Then Click on ‘APPLY’ ‘DISMISS’.
Fig. 5.11 Editing contours
6.We can observe that the ARC IDS are applied to the contours.
7.Now, GO TO ‘TOOLS’ in ‘EDIT TOOLS’.
8. Scroll down to ‘LABEL CONTOUR LINES’ as shown in figure 5.12.
Fig. 5.12 Input of contour interval
9. Now, Select the Start Value of a particular contour for which a value is to be assigned.
Check whether the value is to be increased or decreased and click accordingly. Click on ‘APPLY’.
10. Click at the centre from where the contour value is to be applied.
Press ‘2’ for the initiation and then drag the cursor till where the contour value is to applied as shown below as shown in figure 5.13.
Fig. 5.13 Assigning Contour intervals
11. Finally, the contour value is applied as shown in figure 5.14.
Fig. 5.14 Application of contour interval
5.3.5 CREATION OF Digital Elevation Model (DEM)
1. DEM can be used to create elevation contours.
‘ Lines that indicate constant elevation values
‘ Used to create a sense of topography on maps
‘ Usually a vector data structure
2. User will need to select an interval and a starting elevation.
Advantages of DEM
‘ accept data direct from digital altitude matrices
‘ must be re-sampled if irregular data used
‘ may miss complex topographic features
‘ may include redundant data in low relief areas
‘ less complex and CPU intensive.
Fig. 5.15 DEM in ERDAS viewer
Fig 5.17 DEM of Visakhapatnam
5.3.6 EDGE MATCHING
1. GOTO START ARCMAP FILE NEW.
2. Then, Click on ‘ADD DATA’ to add the required files for Edge-Matching as shown in figure 5.18.
Fig. 5.18 Adding files to ARC-GIS
3. Scroll down to the required folder and to the file.
4. Double click on the file name and click on ‘ARC’ click on ‘ADD’ as shown in figure 5.19.
Fig. 5.19 Adding ARC files
5. Similarly, all the other files are to be added as shown in figure 5.20.
6. Convert to SHAPE FILE:
Right click on file name Data Export Data for all the files.
Fig. 5.20 Addition of all files
To start editing, click on ‘START EDITING’ as shown in figure 5.21.
Fig. 5.21 Editing of a file
7.’START EDITOR’ > SNAPPING > Click on VERTEX, END for respective images as shown in figure 5.22.
Fig. 5.22 Snapping
8. Select the lines or any polygon to merge. Select ‘MERGE’ in ‘EDIT TOOLS’ which merges both the lines.
9. Once editing is done ,click on ‘SAVE EDITS’ in ‘EDITOR’.
10.The required image and its changes will be automatically saved.
5.3.7 CREATION OF SLOPE MAP
1. Goto START menu > ARCMAP > Open DEM image.
2. Click on ‘SPATIAL ANALYST’ in ARCMAP .
3. Scroll down to ‘ SURFACE ANALYSIS’ > ‘SLOPE’ as shown in figure 5.23.
Fig. 5.23 Applying surface analysis
4. An image showing Slopes of Visakhapatnam Area is obtained as shown in figure 5.24.
Fig. 5.24 SLOPE MAP
5. Click on ‘ADD DATA’ and add the required Drainage map of Visakhapatnam Area which will be overlaid on the DEM image.
6. Mark all the areas which are very low-lying areas as shown in figure 5.25.
7. An icon is to be used to mark the points for further analysis.
Fig. 5.25 Marking of low-lying areas
8. Similarly all the low-lying points having less slope are to be marked as shown in figure 5.26.
Fig. 5.26 Plotting of all low-lying areas
These are the areas of slopes less then 0.5,0.8,1.0,1.15 and so on.
5.3.8 CREATION OF ATTRIBUTES
1.To the above obtained slope map, rainfall data is to be attached.
2.Right click on drainage file name > open attribute table > Create different columns according to the data as shown in figure 5.27.
Fig. 5.27 Creation of attributes
5.3.9 INTERSECTION OF DRAINAGE SYSTEM, SLOPE MAP AND RAINFALL DATA
1. Open the above saved image in ARC MAP.
2. Click on ‘SELECTION’ > Scroll down to ‘select by location’ as shown in figure 5.28.
-Fig. 5.28 Analysis by selecting location
3. Click on ‘select features from’ > ‘intersect’.
4. Select the required files that are to be intersected with each other. Click on ‘APPLY’ > ‘OK’ as shown in figure 5.29.
Fig. 5.29 Intersection of drainage system, slope map and rainfall data
5.Varying slopes are already found, now drainage line at a distance of respective slopes are exported and intersected.
CHAPTER 6
METHODS FOR STORM WATER MANAGEMENT
6. METHODS FOR STORM WATER MANAGEMENT
6.1 STORM WATER STORAGE TANK WITH TREATMENT PLANT
6.1.1 STUDY AREA
Floods still a threat in low-lying areas of Visakhapatnam
‘ In order to arrest the inundation of low lying areas in the city, GVMC has undertaken massive exercises. However, only 20km long storm water drain has been concretely built so far and the rest 82km is yet to be completed.
‘ The new city has been developed adjacent to the hillocks and even a light rain causes water to reach the old town area. As 80 percent of the city has been concreted, the rain water automatically floods the low lying areas.
‘ To curb the problem, storm water drains have been concreted at most affected areas like Gnanapuram, Lakshmi talkies and Convent Junction area.
Though entire Visakhapatnam is digitized, but the methods are implemented only for Zone-IV which is very low-lying area compared to the entire city.
The drainage pattern of ZONE-IV is shown in figure 6.1.
Fig.6.1 Drainage pattern of Visakhapatnam
The slope map of entire Visakhapatnam city is shown in figure 6.2.
Fig.6.2 Slope map of Visakhapatnam
From the above drainage map and slope map we can conclude where the storm water drainage system is to be constructed for Stormwater management. Here is the intersection of Drainage map of zone-IV as in fig. 5.26, Rainfall data and slope map as shown in figure 6.3.
Fig.6.3 Intersection of drainage system, slope map and rainfall data
From the above obtained GIS image, all low-lying areas and flood inundating areas are found where traps are to be placed for collection of Stormwater.
The Study area i.e. ZONE-IV is plotted as shown in figure 6.4.
Fig.6.4 ZONE-IV in VISAKHAPATNAM
‘ The Gnanapuram area consists of Sea-horse junction where a Stromwater tank which is proposed to be constructed as shown in figure 6.5.
Fig.6.5 Location of Stormwater tank
‘ The Drainage pattern is proposed from Sea-horse junction, Gnanapuram area and 75feet road near Kotha road is shown in figure 6.6.
Fig.6.6 Drainage pattern of Storm Water Drains
6.1.2 GUTTER TRAPS to be placed in Visakhapatnam city
‘ JAGADAMBA AREA
‘ PURNA MARKET
‘ KOTHA ROAD(75ft ROAD)
‘ Low-lying areas as plotted in Arc-GIS.
6.1.3 LOCATION OF STORM WATER TANK
6.1.3.1 Storm Drains in Visakhapatnam
‘ The storm water drain that originates at the AU Engineering hostels runs parallel to the National Highway, close to Pithapuram Colony.
‘ Total annual Precipitation averages 955 mm (37.6 inches) which is equivalent to 955 Litres/m�� .
‘ The city has storm water drains criss-crossing for a total of 108 km.
‘ On the three works so far Rs.78 crore has been spent and that includes lining for 12 km.
‘ Lining for the entire length has been proposed at a whopping Rs.1,400 crore but major parts of the city can be covered with a cost of Rs.200 crore.
Stormwater tank is to be located at Sea-horse junction as it is GVMC land which is best suited as shown in figure 6.7. This place is located near 75feet Kotha road which is economically constructed.
Fig. 6.7(i) Location of STORM WATER TANK
Fig. 6.7(ii) Location of STORM WATER TANK
6.1.4 METHODOLOGY FOR TREATMENT PLANT
6.1.4.1 CONTINOUS DEFLECTION SYSTEM (CDS)
The CDS is a swirl concentrator hybrid technology that provides patented continuous deflective separation ‘ a combination of swirl concentration and patented indirect screening to screen, separate and trap debris, sediment, and hydrocarbons from storm water runoff as shown in figure 6.8. The indirect screening capability of the system allows for 100% removal of floatables and neutrally buoyant material debris 2.4mm or larger, without binding. CDS retains all captured pollutants, even at high flow rates, and provides easy access for maintenance.
CDS is used to meet trash Total Maximum Daily Load (TMDL) requirements, for storm water quality control, inlet and outlet pollution control, and as pretreatment for filtration, detention/infiltration, bio retention, rainwater harvesting systems, and Low Impact Development designs as shown in figure 6.9.
Fig. 6.8 Direct and Indirect Screening of CDS system
Fig.6.9 CDS system
6.1.4.2 How CDS Treats Stormwater
‘ Stormwater enters the CDS through one or multiple inlets and/or a grate inlet.
‘ The inlet flume guides the treatment flow into the separation chamber where water velocities within the chamber create a swirling vortex.
‘ Water velocities in the swirl chamber continually shear debris off the patented treatment screen, making it the only non-blocking screening technology available in a hydrodynamic separation system.
‘ The combination of swirl concentration and indirect screening force floatables and solids to the centre of the separation chamber trapping 100% of floatables and neutrally buoyant debris larger than the screen aperture.
‘ Sediment settles into an isolated sump while floatables and neutrally buoyant pollutants are captured in the separation cylinder. All pollutants remain in these sections of the unit until they are removed during maintenance.
‘ Stormwater then moves under the hydrocarbon baffle, and the treated water exits the system. The baffle acts as a wall for hydrocarbon containment. It contains previously captured hydrocarbons and prevents the agitation of hydrocarbons when high-flows spill over the diversion weir as shown in figure 6.10.
Fig.6.10 Mechanism of CDS system
‘ During high-intensity events, the internal diversion weir directs a portion of flows greater than the design storm around the treatment chamber and over an internal bypass weir.
‘ Treated storm water exits the CDS via the outlet pipe.
6.1.4.3 CDS Features and Benefits
Table 6.1 CDS features and benefits
Features Benefits
1. Patented screen technology 1. Captures and retains 100% of floatables and neutrally buoyant debris 2.4mm or larger
2. Self-cleaning screen 2. Ease of maintenance
3. Isolated storage sump eliminates scour potential 3. Excellent pollutant retention
4. Internal bypass 4. Eliminates the need for additional structures
6.1.4.4 CDS Configurations
‘ Inline, offline, grate inlet, and drop inlet configurations available
‘ Internal and external peak bypass options available
6.1.4.5 CDS Approvals
CDS has been verified by some of the most stringent storm water technology evaluation Organizations in North America, including:
‘ Washington State Department of Ecology
‘ New Jersey Department of Environmental Protection
6.1.4.6 CDS Applications
CDS is commonly used in the following storm water applications:
‘ Stormwater quality control ‘ trash, debris, sediment, and hydrocarbon removal
‘ Urban retrofit and redevelopment
‘ Inlet and outlet protection
‘ Pretreatment for filtration, detention/infiltration, bio retention, rainwater harvesting systems, and Low Impact Development designs.
6.1.4.7 CDS Maintenance
Maintaining a CDS is a simple process that can be accomplished in less than 30 minutes for most installations using a vacuum truck, with no requirement to enter the unit as shown in table 6.2.
Table 6.2 CDS MODEL DIMENSIONS
CDS MODEL DIAMETER DISTANCE FROM WATER SURFACE TO TOP OF SEDIMENT PILE SEDIMENT STORAGE CAPACITY
ft. m ft. m Yd3 M3
CDS2015-4 4 1.2 3 0.9 0.5 0.4
CDS2015 5 1.5 3 0.9 1.3 1.0
CDS2020 5 1.5 3.5 1.1 1.3 1.0
CDS2025 5 1.5 4 1.2 1.3 1.0
CDS3020 6 1.8 4 1.2 2.1 1.6
CDS3030 6 1.8 4.6 1.4 2.1 1.6
CDS3035 6 1.8 5 1.5 2.1 1.6
CDS4030 8 2.4 4.6 1.4 5.6 4.3
CDS4040 8 2.4 5.7 1.7 5.6 4.3
CDS4045 8 2.4 4.2 1.9 5.6 4.3
6.1.5 IMPLEMENTATION OF CDS SYSTEM
‘ CDS system is used to completely purify and reuse storm water and supply to the public for their daily needs.
‘ Storm water is collected from different traps placed at different places in Visakhapatnam city which is led to a Storm water tank.
Fig.6.11 Gutter traps
‘ Storm water collected from gutter traps are to be led to CDS system which purifies storm water and supplied to the public as shown in figure 6.12.
Fig.6.12 Collection of water from storm drains
6.1.6 LAYOUT OF TREATMENT PLANT AT SITE
Initially, rain water passes from different parts of the city to gutter traps excluding debris as most part of the city is urbanized as shown in figure 6.13.
Fig.6.13 Gutter traps at low-lying areas
Storm water which passes through the gutter traps is being collected by the storm drains which are concreted under the ground as shown in figure 6.14.
Fig.6.14 Storm water drains
Storm water tank is constructed at the site where water is collected at that place. Storm water from different locations of zone-IV is collected to a point where treatment of water is to be done. Then, CDS system is connected to the location point and further to the storm water tank as shown in figure 6.15 which is then supplied to the public through the water supply system.
Fig.6.15 STORM WATER TANK
The layout of treatment plant at site location is being shown below in figure 6.16. The storm water system is very useful for the public as water scarcity is being increasing day by day. The water collected and reused through the water supply system may reduce the scarcity to some extent.
Fig.6.16 Layout of Treatment plant at site
6.2 RAINWATER HARVESTING
Rainwater Harvesting is the collection of rainwater that falls onto your roof and rather than being wasted down the drain, the rainwater passes through a filter (to remove leaves and debris) and is then directed to a storage tank. This harvested rainwater is pumped into the house to be used for non-consumptive applications such as toilet flushing and washing machines. Outdoor taps can also be connected to this storage tank. Rainwater harvesting systems can be installed to new or existing dwellings. Now with the introduction of water metering, it might be wise to consider rainwater harvesting, which can save you up to 50% of your potential water bill.
6.2.1 WHAT IS INVOLVED?
The rainwater that falls onto the building’s roof is channelled through standard gutters and pipes to the storage tanks. Rainwater storage tanks and fittings are required to store and filter the captured water, which can be located either above or below the ground. Above ground tanks provide the quickest and simplest facility for storing harvested rainwater. Below ground tanks are more commonly used for water storage as they are more discreet with the tank and piping hidden underground. There are a number of different systems available, such as the Gravity System (which involves a header tank in the attic supplying the appliances) and the Direct System (which feeds each of the appliances directly). If the harvested rainwater runs low, these systems automatically switch to the mains water, thereby ensuring that a constant water supply is maintained without intervention from the user. On the other hand to prevent the storage tank overflowing an overflow pipe is directed to a soak away or surface water drain. The rainwater that falls onto the building’s roof is channelled through standard gutters and pipes to the storage tanks. It would be advisable to discuss the installation procedures and system types with a reputable company to see which option is most favourable to your dwelling, refer to our directory.
Fig.6.17 Recharge through abandoned dug well
Due to deforestation and the consequent ecological imbalance, the water level beneath the ground is being depleted day by day. As known to all, the constant rising demand of water supply, especially from the urban areas does not match with the surface water sources, as a result of which the water reserves beneath the ground level are overexploited. This consequently results in the water level depletion. Thanks to the selfless endeavour and untiring efforts made by the scientists in the field of hydrogeology, special techniques for recharging ground water level have been developed recently.
Fig.6.18 Rain water harvesting
Water harvesting, apart from recharging the ground water level, increases the availability of water at a given place at a given point of time. It also reduces the power consumption as 1 m rise in water level results in saving of 0.4 KWH of electricity (as per recent finding). It further reduces the run off which chokes the storm water drains, reduces flooding of water on the roads, improves the quality of water and reduces the chances of soil erosion.
6.2.2 What are the Rain Water Harvesting techniques for urban areas?
‘ Suitable for buildings having roof area of 100 square meters
‘ Constructed for recharging shallow aquifers
‘ Pit width 1 to 2 meter, depth 2 to 3 meter
‘ Pits to be backfilled with
‘ boulders at bottom 5 to 20 cm size,
‘ gravel in between 5-10 mm size and
‘ coarse sand at the top 1.5 to 2 mm size in graded form.
‘ Mesh to be provided at top to prevent leaves etc. from falling & choking.
‘ Top sand to be cleaned periodically.
‘ Bye-pass arrangements to be provided before collection chamber to reject first showers.
Fig.6.19 Recharge through hand pump and ground water recharge
Subsequent rain water taken through T to online PVC pipe filter
‘ 1 to 1.2 meter long,
— 15 to 20 cm diameter.
— has 3 compartments,
first one filled up with 6-10 mm size gravel,
middle one with 12-20 mm pebbles and
the last one with 20-40 mm size pebbles.
Fig.6.20 Rain water harvesting in urban cities
6.3 GROUNDWATER RECHARGE
6.3.1 AVAILABILITY OF RAINWATER THROUGH ROOF TOP
‘ Rain water can be conserved from roof tops which is to be led to the nearby ground surface. So that the ground water can be increased.
‘ Rain water is to be collected from roof tops by providing traps which excludes debris and to be passed to nearby earth’s surface as shown in figure 6.21.
‘ Storm water also helps in increasing in ground water levels by providing traps in highways which recharges ground water as shown in figure 6.21.
Fig.6.21 Ground water recharge
Table 6.3 Availability of rainwater through roof top rainwater harvesting
RAINFALL(mm) 100 200 300 400 500 600 800 1000 1200 1400 1600 1800 2000
ROOF TOP AREA(sq.m)
HARVESTED WATER FROM ROOF TOP (cu.m.)
20 1.6 3.2 4.8 6.4 8 9.6 12.8 16 19.2 22.4 25.6 28.8 32
30 2.4 4.8 7.2 9.6 12 14.4 19.2 24 28.8 33.6 38.4 43.2 48
40 3.2 6.4 9.6 12.8 16 19.2 25.6 32 38.4 44.8 51.2 57.6 64
50 4 8 12 16 20 24 32 40 48 56 64 72 80
60 4.8 9.6 14.4 19.2 24 28.8 38.4 48 57.6 67.2 76.8 86.4 96
70 5.6 11.2 16.8 22.4 28 33.6 44.8 56 67.2 78.4 89.6 100.8 112
80 6.4 12.8 19.2 25.6 32 38.4 51.2 64 78.8 89.6 102.4 115.2 128
90 7.2 14.4 21.6 28.8 36 43.2 57.6 72 86.4 400.8 115.2 129.6 144
100 8 16 24 32 40 48 64 80 96 112 128 144 160
150 12 24 36 48 60 72 96 120 144 168 192 216 240
200 16 32 48 64 80 96 128 160 192 224 256 288 320
250 20 40 60 80 100 120 160 200 240 280 320 360 400
300 24 49 72 96 120 144 192 240 288 336 384 432 480
400 32 64 96 128 160 192 256 320 384 448 512 576 640
500 40 80 120 160 200 240 320 400 480 560 640 720 800
1000 80 160 240 320 400 480 640 800 960 1120 1280 1440 1600
2000 160 320 480 640 800 960 1280 1600 1920 2240 2560 288 3200
3000 240 480 720 960 1200 1440 1920 2400 2880 3360 3840 4320 4800
CONCLUSIONS
CONCLUSIONS
The storm water drains which is proposed by GVMC has come to a pause due to several issues. I have planned Storm water Management in Zone-IV of Visakhapatnam which would be very useful for the public needs.
‘ The low-lying and flood inundating areas are plotted out using the slope map which are Jagadamba area which consist of slope less than 5% , Kotha road area consists of slope 2% to 4%, Convent Junction, Chinna Waltair and Gnanapuram area consists of slope less than 5% which are near to Coast line.
‘ Gutter taps are provided at different junctions in low-lying areas for collection of storm water which is led to the underground concreted storm drains. Gutter traps are placed at Jagadamba area, Kotha road, Gnanapuram area, 75 feet road near Kotha road, Convent Junction, Chinna Waltair, near Andhra University out gate, Siripuram area.
‘ Storm Water drain is proposed to be constructed from Gnanapuram junction to Sea-Horses Junction through 75feet Kotha road.
‘ Storm water tank is also proposed to be constructed near Sea-Horses Junction moving towards Gnanapuram Railway station.
‘ Storm water tank which includes treatment plant which purifies water using Continuous Deflection System.
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