Rakesh Kumar Sarmah and Santanu Sarma
Abstract
Rapid urbanization targets in developing countries often underestimate the ecological balance between nature and humanity. Urban fringe or peri-urban landscapes need critical attention due to their increased vulnerability as areas for potential investments and rural-urban jurisdiction dichotomy. Through this study, an attempt has been made to assess the spatiotemporal landscape ecological risk associated with the south western fringe areas of Guwahati city using remote sensing and GIS technology. The Landsat satellite imagery from 1991 and 2011 is utilized to analyse the land use land cover (LULC) dynamics using random tree classifier technique. For accuracy enhancement, Normalized Difference Vegetation Index (NDVI) and the Normalized Difference Building index (NDBI) are incorporated. Standard formulae are used to determine the landscape ecological risk in a grid approach, and Bayesian kriging interpolation is adopted for the representation of the results. During this period the built-up area increased from 34.95 km2 to 74.72 km2. The increase in built-up areas is more prominent towards the north, adjacent to the Guwahati airport. 17.90% of cropland and 12.60% of sparse vegetation mainly contributed to this increment. The cropland area decreased from 121.87 km2 to 104.11 km2. The change in sparse vegetation is more compared to dense vegetation. The sparse vegetation patches are converted mainly into built-up, dense vegetation, and cropland. Sandbars, swamp/waterlogging, and waterbodies show a decrease in this period. The landscape ecological risk results show the concentration of high-risk areas in the central valley portion of the study area for 1991 covering 27.26%, which gradually shifted towards the south in 2011 with 15.11% area coverage. The subhigh-risk area also shows a significant increase in area coverage from 22.38% to 33.33%. The medium and sub-low-risk areas show a small increment from 21.56% to 23.92% and 18.41% to 19.13% respectively. The low-risk areas show a decrement from 10.39% to 8.52% during this time frame. The study will provide a sustainable framework integrating ecological values in urban planning and policy-making.