Impacts of Urbanization on Water Resources and Vegetation on the Delta Region of Tamilnadu Using Remote Sensing and GIS

摘要

Background: The fast urbanization and related anthropogenic activities has been devouring the adjacent natural resources leading to a greater decline of the complex ecosystem. This in turn leads to loss of habitat and decline in species associated with this ecosystem. The resulting loss is not only a burden on the environment but acts as an economic and social burden among the public whose lives are directly dependant on the natural resources. Therefore regular monitoring of the depletion of natural resources is a forefront task. The study areas Tiruchirapalli, Thanjavur, and Tiruvarur districts are located in the Cauvery delta region, with fertile soil and endowed with rich water resources. Agriculture is the chief occupation in these areas. The depletion of water resources affects the irrigation of the agricultural lands which in turn lowers the agricultural productivity. This increases the cost of agricultural production and also increases the economic burden on the poor. The inflation of costs of natural food resources and water is a result of such environmental damage. Therefore proper planning, monitoring and management of infrastructural development and urbanization in these areas become crucial.Objectives: The present study aims at assessing the depletion of natural resources such as water resources and vegetation in the delta region i.e., Tiruchirapalli, Thanjavur, and Tiruvarur using spatial technologies tools like remote sensing and Geographical Information System (GIS). GIS is an interactive computer based tool which has gained importance in recent decades to aid easy monitoring of natural resources.Data use and Methodology: The Survey of India toposheet of the year 1972 at the scale of 1:50000 for the study area were geo registered and projected using Universal Transverse Mercator projection. The administration boundaries of Tiruchirapalli, Thanjavur, and Tiruvarur were digitized including the vegetative area and water bodies. The recent satellite images (IRS, LISS III) of the study were extracted from ISRO Bhuvan (2009). The near infrared red and green bands were layer stacked to obtain a false color composite. The images were classified using supervised classification (maximum likelihood) in to four classes’ i.e., urban settlements, drainages, vegetation and water body. Change detection analysis was performed to detect the rates of depletion among water and vegetative resources.Results: A comparison of the areas estimated for urban, water bodies and vegetation was done to identify the land increase and decrease over a period of 37 years. The results show that the urban areas increased by421.61 km2 and the water bodies had drastically decreased by 107.844km2, and the land under vegetation had drastically decreased by 6075.78km2. This pattern was accounted as a total sum for the entire three districts. Conclusion: From the present study, it is revealed that the natural resource has greatly declined over the period of 37 years due to the urbanization activities. This value exceeds the naturally estimated declinefor the same region. Hence conservation measures have to be adopted for the optimal utilization of these resources without compromising the economic benefits and sustainability of these resources.