Conserving Coastal Eco-System in Mumbai, India:
A Case for use of GIS.
Prakash M. Apte
Urban Development Consultant
Abstract : Mumbai, the financial capital of India, is an island city surrounded on three sides by Arabian sea. Made up of seven islands joined by causeways/land filling, it has many small seasonal rivers draining into the seas on the East and West. There are a number of creeks that are still used by small fishing boats for access to open seas. Over the years, increasing urbanization and consequent influx of population gave a spurt to the building activity. In the process, the natural course and the morphology of rivers and creeks and the extent of wet lands has undergone drastic changes endangering the fragile coastal eco- system of the city. The most glaring evidence is the destruction of mangroves along the creeks and changes in the tidal patterns along the open sea shores. Most slums have come up on the wet lands along the creeks and the seasonal water courses, resulting in pollution and heavy silting further affecting the tidal patterns. Despite well intentioned legislation for regulation of development in the coastal zones, but due to lack of effective and computerized data collection, referencing and analytical system; enforcement of regulation has had to depend on age old cartographic and hydrological manual mapping methods. To save the vital coastal eco- system we need to take recourse to a GIS to ensure quick decision making and enforcement of regulations to conserve the ecology in this city.
Introduction
Mumbai is the financial capital of India. It is an island city surrounded by sea on
all sides except on the north. It has therefore a very long coast line and a number of creeks penetrate the land mass. These creeks, over 100 years ago, were navigable and ships used to bring in materials and cargo.
Over the years, increasing urbanization and consequent influx of population gave a spurt to the building activity. In the process, the natural course, the morphology of the rivers and creeks and the extent of wet lands underwent drastic changes. The most glaring evidence is the destruction of mangroves along the creeks. Most slums have come up on the wet lands along the creeks and the seasonal water courses resulting in pollution and heavy silting further affecting the tidal patterns. The pressure of population which is today estimated at around 1.8 m. has resulted in indiscriminate reclamations and encroachments on wet lands and mangroves for building activity. The Government of India has in 1991 enacted regulations to conserve, protect and manage the coastal areas of the country.
Under these regulations, all the coastal states were asked to prepare Coastal Zone Management Plans and their stringent enforcement. A coastal Zone management Plan has been prepared for the State of Maharashtra and also the city of Mumbai. Regulations for classification and development of the coastal areas in Mumbai have been prescribed in the city’s Development Control Regulations that came into force in 1991.These are shown in the map above.
Map of Mumbai showing Creeks and wetlands
However, much before the regulations came into effect and even after that, encroachments and illegal reclamations and filling up of creeks continued unabated because of ineffective regulating and policing and also pressures of the “builders” lobby, the bureaucrats and the covert help from politicians of all hues!
The map of Mumbai above shows the creeks (light blue ) and the wetlands where mangroves existed (deep blue). Much of these wet lands have been filled up and there is a constant struggle between the environmentalists and the people on one side and the builder lobby on the other over this issue. The problem is the lack of authentic base maps clearly showing the existing situation and the historical records of these lands. Despite well intentioned legislation for regulation of development in the coastal zones, lack of effective computerized data collection, referencing and analytical system; enforcement of regulation has had to depend on age old cartographic and hydrological manual mapping methods. If we are to save the city and its vital coastal eco system we need to take recourse to a Geographical Information System to ensure quick decision making and enforcement of regulations to conserve the ecology in this city.
What is GIS?
It is an information system that is designed to work with data referenced by
spatial or geographic coordinates. It is a computer system capable of capturing, storing, checking, integrating, manipulating, analyzing and displaying geographically referenced information; that is, data identified according to location.
The usefulness of a GIS is its ability in relating information from different sources in a spatial context so as to help reach a conclusion about this relationship. Most of the information we have about our regions and cities contains a location reference, placing that information at some point on the land. When tidal information along a sea coast is collected, it is important to know the extent and location of its effect with reference to the land formation. This is done by using a location reference system. Comparing this information with other information, such as the location of mangroves along the coastline, may indicate the health of these mangroves. This can help us make the most appropriate decisions about how human settlements should interact with the mangroves. A GIS, therefore, can lead to better decision making.
A GIS can also convert existing digital information, which may not yet be in map form, into forms it can recognize and use. For example, digital satellite images can be analyzed to produce a map of digital information about land use and land formation. Had we created a record of the creeks and the abutting wet lands in the city of Mumbai by converting the satellite images into digital maps, it should have been possible to detect any change in the extent of the wet lands and the mangroves. Unfortunately there was no such data base available.
"Every object present on the Earth can be geo-referenced", is the fundamental key of associating any database to GIS. 'Database' is a collection of information about things and their relationship to each othe, and 'geo-referencing' refers to the location defined by the co-ordinate referencing system.
Evolution of GIS has transformed and revolutionized the ways in which planners, engineers, managers etc. can conduct the database management and analysis.
GIS is both a database system with specific capabilities for spatially referenced data as well as a set of operations for working with the data. It may also be considered as a higher order map. GIS technology integrates common database operations such as statistical analysis with the visualization and geographic analysis benefits offered by maps. These abilities distinguish GIS from other information systems and make it valuable for explaining events, predicting outcomes, and planning strategies. As almost 70% of the data has geographical reference as it's denominator, the importance of a system which can represent the given data geographically can be well appreciated.
Essentially therefore, a geographic information system (GIS) is a computer-based tool for mapping and analyzing things that exist and events that happen on Earth and as a tool to assist in decision-making and management of attributes that need to be analyzed spatially. The Geographic Information System can be a very effective tool for implementation and monitoring of municipal lands, open spaces infrastructure, natural features, settlement patterns, hydrography of an area and the ecosystem in a city like Mumbai.
GIS Applications:
The GIS technology is rapidly becoming a standard tool for management of natural resources. The effective use of large spatial data volumes is dependent upon the existence of an efficient geographic handling and processing system to transform this data into usable information. The GIS technology is used to assist decision-makers by indicating various alternatives in development and conservation planning and by modeling the potential outcomes of a series of scenarios as in:
Physical planning (Urban planning, housing, transportation planning, architectural conservation, urban design, landscape. Zoning, sub-division plans review, land acquisition, environment impact analysis, nature quality management and maintenance etc)
Street Network(vehicle routing and scheduling, location and site selection and disaster planning.)
Natural Resource Management (Management and environmental impact analysis of wild and scenic recreational resources, flood plains, wetlands, aquifers, forests, ground water modeling, Wild life habitat study)
Physical Infrastructure(locate underground pipes and cables for maintenance, planning, tracking.)
By using GIS technology, it is possible to combine human settlement records (particularly slum settlements) with hydrographic data to determine which streams will carry certain levels of sewage runoff. Settlement records can indicate how much untreated sewage runoff is taking place from a parcel of land. By locating these parcels and intersecting them with streams, the GIS can predict the amount harmful runoff in each stream. Then as streams converge, the total loads can be calculated downstream where the stream enters the sea.
A GIS can be used to emphasize the spatial relationships among the objects being mapped. While a computer-aided mapping system may represent a road simply as a line, a GIS may also recognize that road as the boundary between wetland and urban development. Data capture—putting the information into the system—involves identifying the objects on the map, their absolute location on the Earth's surface, and their spatial relationships. Software tools that automatically extract features from satellite images or aerial photographs are gradually replacing what has traditionally been a time-consuming capture process. Objects are identified in a series of attribute tables—the "information" part of a GIS. Spatial relationships, are the key to all GIS-based analysis.
Conclusion:
If the data to be used are not already in digital form (as is the case in Mumbai and may be in many other less developed states) that the computer can recognize, various techniques can capture the information. Maps can be digitized by hand-tracing, or on a digitizing tablet to collect the coordinates of features. Electronic scanners can also convert maps to digits. Coordinates from Global Positioning System (GPS) receivers can also be uploaded into a GIS
An advantage of a GIS is its ability to produce graphics on the screen or on paper to convey the results of analyses to the people who make decisions about resources. Wall maps, Internet-ready maps, interactive maps, and other graphics can be generated, allowing the decision makers to visualize and thereby understand the results of analyses or simulations of potential events. GIS technology has enhanced the efficiency and analytical power of traditional cartography. As the scientific community recognizes the environmental consequences of human activity, GIS technology is becoming an essential tool in the effort to understand the process of global change. Map and satellite information sources can be combined in models that simulate the interactions of complex natural systems
It is high time that GIS is immediately put to use in a city like Mumbai to ensure protection of its natural environment and the fragile Coastal Eco- System.
Prakash M. Apte
Tel: 91-22-26311241 302-E Gurudarshan, 7 Samarthanagar, Andheri W. Mumbai 400 053 India.
References:
1Development Control Regulations Mumbai, 1991
2Water (Prevention & Control of Pollution) Act 1974
3Development Plan of Mumbai: Municipal Corporation of Greater Mumbai
4Coastal Regulation Zone Notification of 19th February 1991: Ministry of Environment and Forests: Government of India
5Regional Development Plan for Mumbai Metropolitan Region: Mumbai Metropolitan Region Development Authority
6GIS for Coastal Zone Management: Edited by Darius Bartlett
7Wetland Landscape Characterization: GIS, Remote Sensing and Image Analysis by J.G. Lyon
8Geographical Information Systems: An Introduction by Tor Bernhardsen
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