V. Kandasamy, S. Jayaseelan, K. Venugopal
Institute of Remote Sensing Anna University
Chennai-600 025, India
The Nilgiris is one of the important hilly areas in the South India and lying in the junction of eastern and western ghats of India. Nilgiris is one of the smallest districts in Tamilnadu, with the geographical area of 2544 km2. Nature manifests itself in the form of Forests, Grass lands and Tea estates over here. This study has been under taken to create Cadastral Level Resources Information System using Remote Sensing, Geographical Information System and Global Positioning System.
Objectives of the study
The main objectives of the study are as follows,
- Creation of cadastral level Resources information system for sustainable watershed development
- To identify the improper landuse practice areas with the combination of slope and soil type
- To evolve and arrive at local-specific cadastral boundary level development action plan considering land and forest resources for optimal utilization and to address the remedial developmental measures for Neeralipallam (Kb3) micro watershed on a sustainable basis.
Neeralipallam (Kb3) micro watershed lies in the Nilgiris district of Tamilnadu with a geographical area of 12 sq.km and is bounded by 76° 35′ 30″ and 76° 37′ 30″ longitudes and 11° 14′ 15″ and 11° 16′ 15″ latitude.
Nilgiris is a hilly district located on the fragile environment of Western Ghats with an elevation ranging from 300 m in the Moyar gorge to 2634 m above MSL at Doddabetta peak.
Major part of the Nilgiris ie.56% is under forest cover and about 20% of the district is under plantation crops such as Tea, Coffee, Arecanut etc.Out of which Tea plantation dominates and is found at all slopes. Net area under agriculture including plantation crop is around 29% Paddy, Potato, Cabbage, Carrot and other vegetables are the important crops grown in this district. Grasslands and sholas are seen throughout the district. Extensive wattle, euccalyptus, pine and other forest plantation are also seen.
Varying altitudes, high rain fall, varying temperature regimes have endowed the Nilgiris with a diverse natural heritage. It has a unique ecosystem with different types of vegetation and great diversity of plant communities. Improper landuse practices are leading to the degradation of fragile ecosystem.
- Climate and Rainfall
Nilgiris district of Tmilnadu experiences diverse climatic conditions due to large variations in altitude varying from 300-2634 m above MSL. The microclimatic conditions also vary due to variation in 1) degree of slope (2) aspect (3) vegetation conditions and soil conditions. The region is influenced by both SouthWest and NorthEast monsoons. The annual rainfall is nearly 1300-2000 mm
The mean monthly temperature generally varies with the altitude. The maximum temperature in the summer season is 24.3° C and the minimum temperature observed in the winter season 2.0° C. The humidity is about 89% and it is generally higher in the months of July, October and November.
Nilgiris district is located in the plateau region. Structurally, the Nilgiris plateau belongs to continental block of peninsular India and the mountain ranges comprises of archean metamorphic rocks like Charnochite, Biotite gneiss, Magnetic quartzite, Hornblend granite along with some intrusive bodies like pegmatite, dolerite and quartz veins.
Laterites are found in large quantities in the district. The laterite found over the charnochites is hard. Bauxite is the other mineral found in the district.
Structurally the area is highly disturbed and is subjected to faulting. The major rivers in the district flow along the prominent fractures. The prominent fractures in the district are trending East-North, East and North-North West.
Data source and methodology
Aerial photographs on 1:8000 scale taken during 1996, IRS IC LISS III, PAN data, the corresponding SOI topographical maps of the area and other collateral data have been used in this study.
The methodology used consists of the following types
- Ground Control Survey using GPS and generation of orthophotos on 1: 5000 scale, DEM and contour maps at 5m contour interval.
- Visual Interpretation of Orthophots, Satellite data and preparation of various thematic maps, collection of cadastral maps and bringing it to 1: 5000 scale. Generating digital database from thematic maps and integration and preparing action plans.
- Landuse map
- Annual crop
- Tea/ Coffee
- Evergreen / Semi evergreen / Shola forest
- Degraded forest
- Forest plantation
- Land with or without scrub
- Barren rocky / out crops
- Grass land
- Slope map
- 0 – 10% Nearly level to moderately sloping
- 10 – 33% Moderately to steep sloping
- > 33% Very Steep sloping
- Soil Map
Landuse / Landcover map for the area has been prepared using 1:5000 scale orthophotos and IRS 1C PAN data.
Following categories of landuse classes were identified.
Slope map was prepared using ArcView 3D Analyst from 5 m interval contours derived by photogrammetry techniques. Originally nine groups were identified and the same were regrouped as given below.
The soil map also has been prepared using the Orthophotos and updated using IRS1-C LISS III satellite data based on the tone, texture and pattern.
Soil survey method include (i) Identification of kind of Soil (ii) Description of kind of soil (iii) Classification of the same (iv) mapping their extent and distribution on the standard scale base map.
- Cadastral map
- Data Integration
- Action plan
- Slope class – 1 (0-10%) suitable for annual crops
- Slope class – 2 (10-33%) suitable for tea/agricultural plantations
- Slope class – 3 (>33%) suitable for forest /grassland / permanent tree cover.
- Areas whose landuse practices are in tune with the slope and thus need not be altered
- Areas to be conserved / preserved
- Areas whose landuse practices are not in tune with slope and need to be altered/modified suitability.
Cadastral maps on 1:7920 scale showing individual parcel boundary are available with Survey and Land records department. They are collected and converted to 1:5000 scale and digitized using PC based Arc/Info GIS. Further all the attribute data such as owners name, survey number, soil quality etc had also been stored into the system.
All the above thematic maps were digitized using PC based Arc/Info GIS software. The thematic maps pertaining to the watersheds were registered and labelled and after assigning suitable rank and weightage, overlay analysis were carried out and the action plans for land resources were generated. Cadastral maps showing the parcel boundaries were superimposed on the thematic maps.
The spatial data for the watershed were integrated based on the decision rules incorporating the landuse, soil and slope. Due to the hilly terrain, slope plays a major role for all activities. Based on the different slope classes, the land suitability are classified as follows:
Decision rules for each landuse category with respect to the corresponding slope class, rank and weightages were assigned. After assigning suitable ranks and weightage, overlay analysis was carried out using Arc/Info GIS software for action plan generation. The analysis clearly brought out the following.
Attribute data like population (male/female), SC/ST population, literacy level, cattle population, location of primary health center, veterinary Dispensary, educational institutions etc were also included in the database.
The study has shown that fragile eco-system of the Nilgiris district is under threat due to improper land use practices, human activities, land slides and environment of forest. The analysis has brought out the areas whose landuse practices are in tune with the slope and thus need not be altered, area to be altered and area to be preserved.
The cadastral database created in user friendly and interactive. The Remote Sensing , GIS and GPS have been found to be very effective and economical tool for resources management.
The authors wish to acknowledge the help and encouragement of the Vice Chancellor, Anna University and the Project Director, Hill Area Development Programme, Ooty for sponsoring the project.
- Bitter -P., 1997, Application of GIS and Remote Sensing in planning for mountain agriculture and landuse management Vol.5 Project manual, Kathmondu. ICIMOD.
- Storns, D.M and Estes U.E.,1993, A Remote Sensing Research Agenda for mapping and monitoring Bio-diversity, International Journal of Remote Sensing 1993, Vol – 14 No-10, PP 1839-1860
- A report on assessment of Eco-Degradation in the Nilgiris of Western Ghats 1986, By Institute of Remote Sensing, Anna University, Chennai.
- V. Kandasamy 1986, Hydrological study of Watersheds in Nilgiris district, Institute of Remote Sensing, Anna University, Chennai.