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Land use / Land Cover Study of North West Part of Pune Metropolis, India, for Urban Planning and Sustainable Development of Resources through RS-GIS



Iyer Uma Chandrasekharan
Research Student
Department of Geology
University of Pune
India
uciyer@gmail.com/bnumrikar@unipune.ernet.in


Bhavana Umrikar
Senior Lecturer
Department of Geology
University of Pune
India

Introduction:

Change is inevitable in the process of urbanization. But its impact should be least in deteriorating environment. The development of any country largely depends on the natural resources and the manner in which they are exploited. The over exploitation and mismanagement of these resources are exerting detrimental impact on geo-environment, the results of which are seen in the form of land degradation, soil erosion, loss of fertility, uneven developmental growth, problems of water logging, depletion of water resources, etc. To preserve and enhance the available natural resource base of the country, it becomes essential to consider the geo-environmental parameters; i.e.; studying and understanding the systems of air, water, soil and biomass while developmental activities are taken up. Awareness about Environmental Impact Assessment (EIA) is therefore on rise. The first and most important aspect of EIA is to collect base-line data and use it not only for future comparison but also for offering necessary inputs right from the planning to implementation stages. Such a data often help policy makers, planners and implementing authorities to take timely measures for sustainable development of land and its resources. Management and planning of urban space requires spatially accurate and timely information on land use/ land cover set-up of an area and their changing pattern. Monitoring of land use/ land cover set-up of an area requires the support of two parameters; spatial resolution and temporal frequencies, which are provided by remotely sensed data and GIS based data.

This paper presents the impact of haphazard urbanization on geo-environment and aims to suggest ways to develop land and its resources in a sustainable manner by providing geo-technical inputs with the use of Remote Sensing and GIS techniques. For this purpose, two watersheds, namely, Ramnadi and Uraode, with different levels of urbanization, in NW part of Pune Metropolis (India) have been chosen.

Study Area:

Ramnadi and Uraode are tributaries of river Mula. The areal extent of Ramnadi watershed is 50.35 sq km and has an elevation ranging from 560 m to 800 m above mean sea level. It lies between 18o 28 00 and 18o 34 00 North latitude and between 73o 42 00 and 73o 49 15 East longitude. The areal extent of Uraode watershed is 54.45 sq km and has an elevation ranging from 560 m to 1100 m above mean sea level. It lies between 18 o 27 00 and 18 o 32 00 North latitude and 73 o 37 00 and 73 o 42 00 East longitudes The watersheds are included in the Survey of India toposheet nos. 47 F/10, 47 F/11, 47 F/14 and 47 F/15 on 1: 50,000 scale. The area constitutes a part of Haveli, Maval and Mulshi talukas of Pune district (fig.1), is approachable by National Highway No. 4 and well connected with a network of metalled road.

Owing to the geographical conditions within the district, the rainfall is unevenly distributed (Indian Meteorological Department, and Ministry of Agriculture, State of Maharashtra). The Western part of the district adjacent to the West coast is hilly area having forest cover, due to which the rainfall intensity is more in this area as compared to the eastern parts. While areas falling in Mulshi and Maval talukas fall in the high intensity rainfall zone, areas falling in Haveli taluka and Pune city area fall in moderate intensity rainfall zone.

The area is covered by basaltic flows, which are commonly referred to as Deccan Traps (Geological Survey of India). The flows are mostly horizontally disposed. The basaltic flows are of two types, viz, Pahoehoe flows and Aa flows. Amphitheatre-like geo-morphological features,valleys with broad bottoms are common. Major geomorphic units demarcated are valley/ valley fill, weathered lava plateau and dissected lava plateau. The drainage pattern observed is dendritic to sub-dendritic.

Natural hazards threaten sustainable economic development worldwide. Pune has recently been upgraded to lie in the zone IV, which is the second most dangerous seismic zone in India (Geological Survey of India). The area under study falls under the zone III, which is moderate damage risk zone. The areas are floodprone with river Mula causing floods in Pune city area and eight major rivers draining other talukas of Pune district. Due to heavy rainfall in the rainy season, landslides occur, with Mulshi taluka being the most affected (Indian Meteorological Department and Ministry of Agriculture, State of Maharashtra).

Figure 1 shows the location map of study area. Forest cover in Ramnadi watershed is around Pashan lake and is under Ministry of Defense since 1961. There are two forests in Uraode watershed, near Pirungut (Unclass forest, 23.55 hectare) and near Ambegaon (Reserved forest, 120.31 hectare) with a combined area of 144 hectares. Pirungut area falls in zone D or the Industrial zone and is rapidly undergoing urbanization.


Figure 1: Location map of study area (a)Ramnadi (b) Uraode



Figure.(a)




Fig.(b)

Materials and Methods:

Survey of India toposheets (1971) on 1: 50,000 scale were scanned and geo-referenced using ArcGis software. The contours and drainage were digitized using ArcMap to generate database on drainage network, contour, Digital Elevation Model (DEM), Slope, Aspect. Database on village locations, settlement boundary, area boundary etc. were also generated. Basin analysis of Ramnadi and Uraode watersheds were carried out using morphometric analysis (Hortons Method, 1945). Buffering was created around the river channel to delineate the flood plain area (flood prone area). To detect and analyze the changes that have taken place in the land use/land cover and geo-environmental set-up of the area, satellite data of Landsat ETM of 1999, LISS III image of 2006 and Google Earth image of 2008 were used. Using the satellite data, the area was divided into urban region (including settlement, asphalt and concrete road), green cover (including forest, agricultural land, orchards), water body (rivers, lakes), and barren/waste land (JongGyu Han, 2006). Using ERDAS 9.1 software, Supervised Classification was performed to classify the land cover based on the satellite images. Google Images were geo-referenced and digitised using ArcMap. The layers generated from toposheet were superimposed on the satellite images and the Google image to study the changes. Forest cover data was obtained from the Ministry of Forest, State of Maharashtra and agriculture data was obtained from Ministry of Agriculture, State of Maharashtra to study the area covered by these resources and density of urbanization around these resources. Figure 2 shows the slope of study area.


Figure 2: Slope of Study Area (a)Ramnadi (b) Uraode

Results and Discussion:

Case Study 1: Ramnadi Watershed

The morphometric analysis of Ramnadi watershed (Table 2) shows that the first order streams constitute 76.56%, the second order streams constitute 19.27%, third order streams 3.64 % and the main river channel constitutes a mere 0.52% of the total flow of water of the river. The drainage density and stream frequency are high indicating a structurally and topographically controlled occurrence, which is evidenced by the high relief (weathered and dissected lava plateaus). The high bifurcation ratio is also indicative of structurally controlled drainage (Thornbury W.D.) The increase in the area of water body from 1999 to 2006(Table 2), is due to construction of minor irrigation tank at Bhugaon. From the satellite images (Figure 3 and Figure 4) and Google image it can be observed that unplanned urbanization has resulted in loss of lower order streams (the first and second order streams are no longer present due to leveling of the slopes). According to Pune Municipal Corporation control rule, no construction is allowed within 30 meters of a river. A survey undertaken jointly by the District Collectorate and the Pune Municipal Corporation shows that 48 meter wide riverbed has been reduced to 8-20 meters due to encroachments at Pashan and Sutarwadi. The survey was conducted following the record 95.2 mm rainfall in the area in 2007 which led to flooding in low-lying areas like Baner, Pashan, Sutarwadi, Someshwarwadi. At Pashan and Sutarwadi the direction of Ramnadi has been changed drastically. The width of the river channel is found to vary from 26 meters to less than 5 meters at places like Bhavdhan and Bhugaon. At Baner housing projects are being developed right inside the river bed. Over 52 % of the 20 km stretch of the tributary has been destroyed by rampant construction. Out of the 52% urbanization, 40% is in the area below 650 meters elevation, while nearly 12% is on the hillslopes at 650 to 800 meters, with restaurants and other commercial establishments. Most of the land area along the main river channel has been used for construction purposes and disposal of waste which has narrowed down the width of the channel thus leading to problem of floods in the nearby areas. The catchment area of the river is full of construction blocking the flow of water. Though the area is conducive for construction purposes as the topography is flat and hard, care should have been taken to see that the natural flow of the water is not blocked and land area constituting the floodplain of the river be avoided from construction and disposal of waste. The high relief areas like Bhavdhan, Sutarwadi and Bhugaon or areas with steep slopes( more than 10 degrees) should not have been considered for commissioning activities as they lead to plugging of lower order streams which also cause problems of landslides and floods in other areas due to change in direction of stream course. Urbanization in and around the flood plain has led to drastic change in the drainage pattern. Soil cover is negligible or completely absent in the area. Dense urbanization in the area has rendered the soil impervious. The satellite images show a small stretch of land near Pashan lake which is devoid of urbanization. Constructions should be avoided near the lake and because of proximity to water body, the land can be developed as agricultural or fruit orchard area without disturbing the natural setup. Forest cover around the lake should also be protected by creating buffers. Land use classification (Table 1) shows increase in barren or waste land area in the watershed from 1999 to 2006. The slope (Figure 2) of the area covered by barren land is gentle and is therefore ideal for developing commercial and residential establishments. Places like Warpewadi, Khatpewadi, Ahlewadi, Angarwadi fall in gently sloping topography, and hence, are suitable for construction activities, but care should be taken to avoid encroachments on lower order steams.

Case Study 2: Uraode Watershed

The morphometric analysis of Uraode watershed (Table 3) shows that the first order streams constitute 67.2 % , second order streams constitute 24.8 % , third order streams constitute 5.6 % , fourth order streams constitute 1.6 % , while the main river channel constitutes a mere 0.8 % of the total flow of water in the watershed. The drainage density and the stream frequency of the first order streams are very high as compared to other higher order streams. It indicates a structurally and topographically controlled occurrence, which is evidenced by the high relief. The high bifurcation ratio between the second-third order streams and the third-fourth order streams is also indicative of topographically controlled drainage in the area. From the slope map of the area (Figure 2) it can be seen that there is wide variance in the slope of the area. From the satellite data (Figure 5 and Figure 6) and the Google Earth image it can be seen that developmental activities have begun around the main river channel with 15 sq km area already urbanized. Figure 3 & Figure 4 show Area covered by different classes. Though the terrain is flat around the main river channel and is favorable for developmental activities, it can be seen that almost 20% of lower order streams are lost because of settlements and road construction. The flood plain area of the river channel is rapidly coming under developmental activities. Since the drainage density in the area is very high, loss of lower order streams and reduction in width of river channel due to unmonitored urbanization can lead to flash floods in the area. It is therefore suggested that developmental activities in areas like Kalbhorwadi, Chorgewadi, Dhongarwadi, Botarwadi should be restricted where the slope is more than 10 degrees as these areas are prone to landslides and mass wasting and lead to loss in soil cover and fertility of soil making them impervious. Since groundwater is the major source of water in Uraode, development should also be restricted in and around the flood plain area of the river as floodplains serve as good groundwater recharge zones. Land around the main river can be developed as agricultural or fruit orchards. Plantation on slopes can be carried out to avoid loss in soil cover and improve soil fertility. Buffering should be created around agricultural and forest land to avoid encroachments in these areas.

Table 1: Area covered by different classes in Ramandi and Uraode watershed in 1999 and 2006.






Legend Legend
Water body Water body
Barren/Waste Land Barren/Waste Land
Urban Region Urban Region
Green Cover Green Cover



Table 2: Morphometric Analysis of Ramnadi Watershed using Hortons Method (1945)




Table 3: Morphometric Analysis of Uraode Watershed using Hortons Method (1945)

Conclusion:

Lack of proper monitoring system has led to unplanned development in the Ramnadi watershed area with encroachments on river bed and flood plains which have reduced the width of the main river channel causing blockage of the natural flow of water and resulting in hazards like floods. Haphazard urbanization on hill slopes in the area has triggered problems like rock falls and creep and has resulted in loss in soil cover. Debris generated at construction sites are abandoned near water bodies or thrown into it causing danger to the environment and pollutes water. Urbanization in places like Baner, Sutarwadi, Pashan and Bhavdhan is found to be dense and chaotic making it difficult to implement sustainable measures to protect the natural resources. Places like Warpewadi, Khatpewadi, Ahlewadi, Angarwadi are suitable for construction activities as the slope in these areas in flat to gentle, but care should be taken to avoid encroachments on lower order steams. In Uraode watershed, dense urbanization is found at Uroade and Pirangut areas. Developmental activities at places like Kalbhorwadi, Chorgewadi, Dhongarwadi, Botarwadi should be restricted where the slope is more than 10 degrees as these areas are prone to landslides and mass wasting and lead to loss in soil cover and fertility of soil making them impervious. This can be done only by creating buffer zones around the natural reserves like forests, agriculture, river and hill slopes to avoid encroachments in these areas. Engineering techniques like constructing terraces, retaining walls and fences or plantation of trees and grasses on the hill slopes and river banks can help in preserving the soil cover and soil fertility and serve as good preventive measure during natural hazards like landslides and floods. Barren land around a water body can be developed as an agricultural or green cover area.

References:

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