Map India 2000 - Poster Sessions

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Application of GPS and GIS for the detailed Development planning
C. Mohana Doss and K. Sunitha
Department of Geology, Anna University, Chennai - 25

Landslide is a common natural hazard that usually occurs in mountainous areas. They are the most devastating and frequently occurring environmental hazards landslide is a common term generally used for all forms of rapid mass environment.

In general landslide activity is related to the following factors. Slope, geology, structure, lineament, geomorphology, climate, rainfall and landuse. The principal factors that initiate landslides are heavy and prolonged rainfall, cutting and deep excavations on slopes for buildings, earthquake shocks and tremors widespread deforestation and population pressure.

In this paper an attempt has been made to prepare a land slide hazard zonation mass of Nilgiri districts covering far of Conoor and Kotagiri, Ooty taluks using GIS systems. A study has been made on the extent to which some important factors like slope land use lineament density rainfall and geomorphology exert this control over triggering of land slopes various thematic maps were prepared and these were ranked bases on frequently of occurrence of past landslides for the case of certain factor such as slope and lineament density the ranking does not appear to follow conventional geology, relatively low slope percentage were given like ranking, origin high lineament density regions were given low ranking become of frequency of past landslides. Therefore a second landslide zonation map was prepared by modifying the rank. High slopes were given a high rank. The same procedure was also followed into the case of lineament density map and drainage density map.

GIS is a very fast and accurate methods by which large volume of the integrating of various landslide triggering factors has resulted in a map which in a certain extent a is ale to predict the susceptibility of an area of landslides and a regional scale. The software IDRISI was used for the work.

Description of the Study Area
The study area is located in Nilgiri district a mountainous terrain in the NW part of Tamil Nadu state the study area covers part of Ooty Coonoor and Kotagiri taluks. The area is between 11 15' to 11 30' N latitude and 76 45' to 76 55' East. Longitude. The study area covers about 500 sq. kilometers. Physiographically the Nilgiri hills rise abruptly form the plains to an average elevation of 1370 m above MSL. Many of the hill peaks have steep rocky escarpment with or without soil cover around which radial drainage pattern are seen.

The Nilgiri ranges comprise archaen metamorphic rocks which include quartzite, biotite gneiss, magnetite quartzite, hornblende granulite, pegmatite, dolerite and quartz veins. Charnockite forms the bulk of the rock units in the study area.

The Nilgiri hills is a plateau sloping steeply into the Mysore plateau towards north and merging gradually with the western ghats in the NW west and SW. The plateau is divided into a highly dissected plateau and a less dissected undulating plateau.

Nilgiri plateau has been formed by three systems of faults along the peripherals namely a E-NE fault, a North-West fault and a third fault along the northern boundary of the platea. The regional foliation is towards E-NE. Most of the lineament may represent fractures along which there may or may not have been movement. Many of the lineaments represent faults.

The major area in the Nilgiri is either under vegetation or is used for plantation. The reserves forest area have over the years has reduced and more and more thick woods have turned into vegetated scrub lands.

Methodology
Various thematic maps like geology geomorphology, landuse, rainfall. Lineament density, drainage, soil and slope were prepared in the scale of 1:50, 000. Toposheets, satellite images and published maps were used to compile the themes. The maps were scanned and input into the system. Each map was geometrically corrected for latitude and longitude. The thematic maps were digitized and polygons and each feature in as there was given an identity. A sample of 25 landslides from the inventory map was taken and the number of landslides occurring in each feature of a thmatic map was counted.

The map layers were considered as separate entities and each feature in a map layer was ranked according to the frequency of occurrence of landslides. High the number of landslide occurs higher the rank. Thus, rank I indicates low susceptibility and rank 4 indicates a high susceptibility analysis was done by overlay. The eight thematic maps were overlaid on one another successively. The eight thematic maps were taken as 4 pairs and each pairs was overlaid were item successively overlaid.

Table I Landslide Susceptibility ranking
Landslide susceptibility value	Susceptibility rank
29-32	Very high
23-28	Moderate to high
17-22	Low to moderate
8-16	Very low

The maps thus devices the area in to form zones of varying slope stability. The map was used for analyses the control of slope land used geomorphology and lineament density in triggering slides.

The slope map, lineament density map and drainage density maps were also ranked according to expected occurrence of landslides to landslide susceptibility increases with increasing slope, lineament density and drainage density. Thus higher slope percentages were given a higher rank as they are usually more susceptible to sliding. Overlay of all the terms were done and a landslide hazard zonation map was prepared. This was compared with the landslide hazard zonation map based on past slides.

Analysis and Information
The landslide hazard zonation map for the study area covering 500 square kilometers clearly indicates that there are few zones of low susceptibility. Land slides acn occur through out major portion of the study area. Nearly 18% of the total study area falls in the very high susceptibility zone. Fifteen landslides from the landslide inventoys map were overlaidonn the mpa.Nine- lanslides fell in the highly susceptible zone, three in the moderately susceptible and two in the low to moderate zones are also susceptible areas and sliding may be triggered.

Recommendations
The following recommendations are given for landslides hazard mitigation based on the present work for the regions, where slope in the main triggering factor the upper parts of the slope can be unloaded or the lower slopes can be loaded. A general flattening of the slope can be achieved. Boulders on the upper slops can be removed to arrest their movement.

Rainfall is an important cause for landslides surface water should be deviated and not allowed to infiltrate in to the ground. Horizontal drains and drainage galleries can be made for the purpose. The run-off can be intercepted by cut-of drains or through the nearest culvert. The conduit of the culvert slopes should not be allowed to get choked up and proper care should be taken to remove the block periodically.

Retaining and strengthening structures like retaining walls and cribs can be used to protect unstable slopes. Hill slopes are cut at the toe and provide space for construction of building and rocks stability. Reinforced earth retaining walls are capable of strengthening slopes.

Afforestation ploys a key role in increasing the stability of the slopes. The barrier slops can be planked with tree a number of grasses like lemon grass have been known to protect slopes from sliding.

References

Gupta R. P, Joshi B. C. 1990. Landslide Hazard Zoning using GIS approach - a case study from the Ramganga catchment - Himalayas, Engineering Geology 28 119 - 131.
Hydro geological conditions in Nilgiri district 1984, Central Ground Water Board, Dept. of Irrigation Tamil Nadu India
Nilgiri landslide. 1982. Geological Survey of India Miscellaneous publications No 57.
Pachouri A. K , and Pant. M. 1992 Landslide hazard mapping base on geological attributes. Engineering Geology. 32, 81 - 100.
Report on the study of landslides of no Vol 993 in Nilgiri District 1993, The Geotechnical cell Coonoor.

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Valedictory

GIS in the Internet Era: Opportunities and Challenges for India
N. Vittal
Central Vigilance Commissioner

Geographic Information System (GIS) is the net result of two key technologies, the technology of satellite imagery and information technology, which is the synthesis of computers and communication. Both of them have certain common features. First is The pervasive impact of digital technology. Everything is reduced to binary digits zero and one. It is this technology, which has helped the growth of convergence of text, audio and video and a wide range of uses and means of communication. Today we can make computers talk to each other. We can cross the barriers of time and space thanks to the digital technology.

Digital technology is thus at the root of GIS consisting of satellite technology and information technology. There is another dimension again which bring satellite technology and information technology together. They have meant the death of distance. Barriers and national boundaries were common features in the last 300 years especially after the French Revolution where the nation state became the major reference point for organising countries and governance. It is out of national boundaries that the whole set of governance and administration came up. What information technology especially the Internet is doing is to remove this barrier. Thanks to the Internet, today it is possible for the citizen in even centrally controlled or totalitarian regimes to have information about what is happening in the rest of the world. Similarly, satellite imagery has also helped to cross national borders and access information. We in India are aware of the fact that while the Ministry of Defence may be considering a particular map to be a restricted map and make it difficult for the Indians to access it, the same way may be freely available through the United States or other countries, which have their satellite maps.

Apart from the common technology underlying GIS spanning satellite and information technologies, there is also this common feature of looking at the entire world as one unit-Vasudhika kutumbakam in a new sense.

What are the challenges and opportunities in this so far as India is concerned? The entire issue of GIS can perhaps be looked at from three angles. The first is purely the hardware aspect, the second is the content and the third, of course, is the policy framework which includes legal and administrative matters. So far as the hardware part is concerned, if GIS has to become an important feature in the knowledge economy of India then the simplest thing we would require is the capacity for making the GIS accessible to as many people as possible. Forums like the Maps 2000 are occasions where people in this sector come together and exchange ides about how we can increase the reach of the technology. An interesting feature of the modern technology whether it is space technology or information technology, is that the costs are coming down and there is a wide reach across national borders. When it comes to the last mile or making it available to the ultimate user, there are a lot of problems. It is on this last mile problem that attention has to be focussed. For India, the starting point would be the low computer density. However, one positive aspect is that Government seems to have realised the significance of information technology. Three reports of the National Task Force on Information Technology are before the Government. The first report has already been accepted. The recent budget of the Government also showed that the Government has a soft corner for the information technology. It is the responsibility of those who are in this sector to look at what specific measures are needed to see that the physical reach of GIS is enhanced by increasing computer density and also building in national information infrastructure.

The second and perhaps the most important part of the issue is creating content. It is here that many Indian companies are already doing the work for foreign countries in bringing GIS. For example, Intergraph is one company I recall which is specialising in this area. There may be other companies which are specialising in content. There has been a systematic effort made to see how quickly the content for the GIS can be enhanced. Andhra Pradesh has done a wonderful job in bringing GIS for their state and particularly in areas like highways and irrigation, I think contents created are so useful that the quality of governance of the state can easily go up because of clarity of thought and speedy action.

In the context of liberation and economic development, one of the issues that has been widely discussed is the need of upgrading the infrastructure GIS can play a crucial role in upgrading the infrastructure because practically, I think, no infrastructure project, be it a power project or roads or communication or even urban infrastructure like sewage or gas lines can be set up without proper GIS support. The challenge of designing the contents for the GIS to meet the demands of different sectors of the infrastructure projects which will be coming up in this decade has to be met on a priority basis.

We then come to the basic issue of creating this content as quickly as possible. I think the whole GIS movement will get a great boost if the fact that a lot of employment can be generated in creating content and also designing the different contents for specific users is properly projected. Bibliographic database alone according to Dr. Viswanathan, Director, INSDAC who made an assessment sometime back can create 3 lakh to 30 lakh jobs. Think of the jobs that can be created in GIS by different sector specific projects focussed content creation.

We then come to the third aspect of GIS namely the policy dimension. It is here, I think, the final battles have to be fought because when it comes to maps of Survey of India, still there are hitches about the security restricted maps and so on. We must be able to overcome this quickly so that national security is not compromised. The growth of GIS information and making optimum use of the potential of India is not adversely affected because of policy constraints.

The economic dimension of GIS is more than an opportunity than a challenge. The opportunities lies in the use of India's skill in GIS and its infrastructure through way of satellites which can help us to get a share of the global market. I understand that the satellite imagery maps SRO are much better than many of the competitors. We must be able to make use of the infrastructure already developed by us in terms of equipments and satellites on the one hand and more important the technical skills we have created on the other so that the GIS can become in the age of the internet a major source of foreign exchange earning for India.

We have looked the GIS angle but what about the Internet? Internet is only the new medium for commerce. E-commerce is not possible with out Internet. Once we have created the GIS content and the basic backbone in India for overcoming the last mile problem and the reach of the internet is extended widely in the country, then by making optimum use of the Internet is extended widely in the country, then by making optimum use of the internet we ensure that the value of the GIS is enhanced many-fold. Internet can be multiplier to see that the investments made in the India's GIS infrastructure both in terms of hardware, in terms of software and human skills gets the maximum returns.

Einstein supposed to have said that in times of challenge and crises, imagination is more important than knowledge. Perhaps when it comes to use of GIS by India in the age of Internet, we require a lot more imagination. There is no limit to what India can achieve in the age of the Internet using a technology like GIS.

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Valedictory

GIS in the Internet Era: Opportunities and Challenges for India
N. Vittal
Central Vigilance Commissioner

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Poster Sessions

Application of GPS and GIS for the detailed Development planning
K.Sukumar
Scientist Institute of Remote Sensing, Anna University, Chennai-25
E-Mail: Suku_irs@hotmail.com / Suguirs@yahoo.com

L.Subbaraj
Scientist Institute of Remote Sensing, Anna University, Chennai-25

Dr.A.R.Santhakumar
Director Institute of Remote Sensing, Anna University, Chennai-25

Abstract
Velachery is a small ward in the Chennai Corporation area. Part of the area is facing lot of environmental problem especially during the monsoon period and creating various health hazards. The Corporation find it very difficult to implement the developmental programme, in the absence of large scale base maps, to minimise the environmental problems.

The IRS-1C satellite data both PAN and LISS III data were merged. Based on the landuse information derived from the satellite merged data and using slope, soil and other attribute data, the GIS analysis were carried out to identify the problematic areas which requires immediate attention of the Corporation Engineers.

The Aerial photographs on 1:6000 scale have been used for preparing large scale maps for this problematic areas for creating the data base. The TRIMBLE GPS has been extensively used for carrying out the Ground Control Survey, and in addition Levelling survey was also conducted for establishing vertical control. The Ground Controls were established using GPS and the Digital Elevation Models were measured using Planicomp Instrument at an interval of 50m. The Orthophotos were generated on 1:1500 scale using Orthocomp equipment and contour maps with a contour interval of 20cm were also prepared. The Landuse information has been interpreted from the Orthophotos. The base maps in addition to Contour maps were very useful for various developmental activities like identifying the low lying areas, flooded zones, haphazard growth of slums unauthorised contructions and the location of various service lines like Water supply line, Sewage lines etc., and the Corporation has planned a suitable measures for the Storm water drains and management from the Remote Sensing outputs. The data base created using GPS and the Aerial Photographs were found to be very effective and economical in cost, time and reliability, for implementing various developmental measures.

Introduction
Chennai is one of the important Metropolitan cities in India, the India's fourth largest Urban agglomeration, having more than 6.5 million population. Because of the rapid industrialisation and population growth the city has faced several problems. Since the growth of Urban population is very fast it has become extremely difficult to keep pace with growing demand for infra structural facilities including basic necessities of shelters, leading to the establishment of slums, squattors and unauthorised Constructions. The other problems that has been associated with the City growth are related to traffic and transportation, increase in land values, short supply of developed plots.

The human impact on the landuse due to rapid industrialisation and urbanisation is found to be very high especially in the frings areas of Corporation limit. For proper planning and effective remedial measures the identification of problematic areas and their intensity are the concern of the Corporation Engineers. Large scale maps showing the present landuse, required for planning and development are not readily available. It would take very long time to prepare the maps by conventional methods. Aerial photographs taken during 1990 were used to generate the large scale Orthophotos on 1:1500 scale. In addition, Contours at 20m interval on 1:1500 scale were also prepared to help in planning of engineering structures required by Corporation Engineers. For Generating Orthophotos Controls were established using the Global Positioning Systems and the landuse details were updated using IRS-1C satellite data.

Objectives

Establishing Ground Controls by using GPS Insturment.
Identifying the problematic areas which requires immediate attention for the developmental work by integrating Satellite data and GIS technique.
Developing the data base by generating large scale Orthophotos on 1: 1500 scale with a contour interval of 20cm from the aerial photograph on 1:6000 scale.

Need for the Scheme
The Corporation of Chennai with an area of 170 sq km, has a population of 6.5 million. Urbanisation is at a rapid rate because of industrialisation and migration of population from rural area. The Corporation is find it very difficult to provide the basic utility services like water supply, sewage, waste disposal and other facilities in the absence of a large scale map. It is also very difficult to regulate the haphazard Urban development and managing the storm water drainage system especially during monsoon period.

In order to check and regulate the haphazard development, the Corporation has to prepare detailed development plans for these Velacery area to guide and Control the growth. There is an imperative need to prepare a large scale comprehensive landuse maps to guide and control the development and to effectively monitor the growth of these areas. For effective plan Corporation needs a large scale base maps and hence the work has been entrusted to IRS to prepare the Orthophotos with Contours for part of Corporation area of about 10 sq km.

Methodology
NRSA has already taken Aerial photographs for the entire Chennai Metropolitan area (1167 sq km) during 1990 at a scale of 1:6000 for the use of three Organisations namely the CMDA, CMWSSB (Metro Water) and the Corporation of Chennai for the preparation of Master plans.

The Corporation is interested in preparing the developmental plans for the Velachery area of about 10 sq km, situated on the south of Chennai city. Ground control survey were carried out using the Global Positioning System (GPS) and EDM, to establish the control points in the Project area and the same has been post pointed on the aerial photographs. The sophisticated equipments like Planicomp PHOCUS P3, Orthocomp Z2 equipments were used to generate DEMs and Orthophotos. These products served as a large scale base maps and helped the Corporation Engineers for preparing detailed development plans.

Ground Control Survey
The TRIMBLE 4000 SSE GPS has been used to traverse the area to determine the planimetric controls and levelling survey were also carried out for establishing the altimetric control. The Electronic Distance Meter SOKKIA is also used for connecting nearby GTS co-ordinates. Both the GPS and Levelling surveys were completed within 3 days. The WILD PUG5 instrument has been used for post pointing in the Aerial photographs. Models were established in the Analytical Stereo plotter Planicomp PHOCUS P3 and the model points including ground control and tie points were measured. Digital Elevation Models (DEM) were measured at an interval of 50m in order to prepare the Contrours at an interval of 20cm and also the input for the generation of Orthophotos. In addition the break lines and skeleton lines of the objects were also measured.
Satellite Data
The PAN and LISS III satellite digital data of IRS-1C satellite were extracted and both the data were merged. Based on the landuse information, extracted from the above merged and classified data and from the derived slope, soil and the morphological maps, the GIS technique has been used to identify the areas which are liable for flooding and areas which requires immediate storm water management (fig.1).
Orthophoto
Orthophoto maps on 1:1500 scale were generated using Orthocomp Z2 instrument for this area. The Orthophoto with superimposition of Contour line provides a very good data base for the developmental plans. The entire work of DEM measurement and generation of Orthophotos tllk only five days. The line maps prepared from mosaicing the Orthophotos is also super imposed on the merged satellite data (fig.2).

The above large scale information such as Orthophotos and contour maps have been extensively used for the detailed development plans for the Velachery area and the plans were effectively implemented by the Corporation authorities.

Conclusion
The merged satellite data products of IRS-1C (PAN & LISS III) provides a valuable data base in the extraction of landuse, soil and other resources. The data base is found to be very useful for the GIS analysis, for identifying the problematic areas which requires immediate attention, so as to prepare the large scale Orthophoto maps and Contour maps in these problematic areas for implementing the developmental plans.

The Orthophotos and the Contour maps on 1:1500 scale which have been prepared within a very short time and with a reasonable cost of Rs.1.08 lakhs after the ground control survey using GPS instruments, proved to be a effective tool in the storm water management and for implementing the Developmental plans by the Corporation Authorities. It also serves as a data base of various resources and can be updated periodically with the new data products.

Acknowledgement
The authors wish to thank to Deputy Commisioner (Works), Corporation of Chennai and the Officials of the Corporation for sponsoring the project. Thanks are due to Mrs.K.Vani and E.Singaravel for their help rendered in bringing out this paper.