Conservation policies of four development plan areas of Bangladesh: a study on present status and future trend

Abstract

Conservation areas, as defined in this research, are those land use zones of the existing four development plans, i.e., DMDP, CMMP, KMMP and RMDP, of Bangladesh that are restricted to be changed from their original use. Included in these areas are agricultural lands, flood flow zones, water bodies, water retention areas, hilly areas, etc. A set of policies has been stated for each category of the conservation areas in the development plans. Though all these development plans are gazette documents, there are evidences of encroachment of these designated conservation areas during the process of urban development. However, due to the lack of academic researches, the concerned authority as well as the people in general is oblivious of how much conservation area is still intact and how much has already been lost due to development. In such a backdrop, this research is aimed to study the trend of land use change in four development plan areas along with the conservation area therein. In order to determine the trend, this research employed remote sensing analysis. Three broad land covers, namely, vegetation, wetland and built-up area were extracted from satellite images of five years, i.e., 1995, 2000, 2006, 2011 and 2015, using relevant indices. Both Landsat-5 TM and Landsat-8 OLI images were collected for all four development plan areas. Trend analysis revealed a comparative scenario among four development plans. In the entire DMDP area, the vegetation and wetland decreased at an average rate of respectively 5659.57 acre and 1433 acre per year from 1995 to 2015, while the built-up area increased at 2958.94 acre per year. During this timeline, the vegetation and wetland, only in the conservation area, decreased by 429.72 acre and 437.27 acre per year respectively, and built-up area increased more than 16 times. From 1995 to 2015, vegetation and wetland covers of CMMP area also decreased at the rate of 2391.11 acre/year and 193.66 acre/year and built-up area increased at 276.39 acre/year. Inside the conservation area of CMMP, vegetation and wetland declined by 18.18 acre and 4.11 acre per year respectively, whereas, built-up area increased more than 6.5 times. Over the last twenty years, the built-up area of KMMP increased by 33.89 acre/year, vegetation decreased by 975.47 acre/year and wetlands increased by 330.13 acre/year. Since the inception of KMMP, vegetation covers inside conservation area decreased by 55.37 acre/year, wetland increased by 54.34 acre/year and built-up area increased by 2.56 acre/year. Similarly, the built-up area of entire RMDP increased at an average rate of 56.13 acre per year. The vegetation covers decreased by 149.23 acre/year and wetlands increased by 117 acre/year. Since the inception of RMDP, vegetation cover of the conservation area increased by 104.4 acre/year, wetland decreased by 105.02 acre/year and built-up area increased by 46 acre/year. After the land use change trend analysis, this research also attempted to predict the future urban growth in both four development plans and particularly for the conservation areas up to the year of 2035. The prediction is accomplished by SLEUTH simulation. For SLEUTH modeling, five inputs, namely, slope, exclusion area, urban extent, road network and hillshade, were prepared for all four study areas. SLEUTH model ran through three calibration phases – coarse, fine and final, and an additional calibration was run to generate the forecasting coefficients. After the calibration phase, best fit coefficient values were determined to run the prediction mode. Upon the completion of the prediction, output images were generated for each of the development plan areas, where area with more than 90% probability of future urban growth in 2035 was rendered. SLEUTH prediction disclosed that, the built-up area of DMDP will increase by 158.66% from 2015 to 2035, and only 69.76% of the conservation area will remain intact in 2035. In case of CMMP, 96.90% of the conservation area will remain intact and in KMMP, 95.02% conservation area will be in its original use in 2035. On the other hand, the built-up area of RMDP will increase the least among the others, accounted for 96.08%. Also, 95.62% conservation area of RMDP will be left in its original use by 2035. After the trend analysis and SLEUTH prediction, a comparative scenario of the compliance of conservation policies among four development plans is illustrated. It is found that, none of the conservation policies of four development plans is in 100% compliance. The conservation policies of CMMP, KMMP and RMDP are in 90% to less than 100% compliance. DMDP is found out to be in the worst shape, as most of the conservation policies of DMDP are in less than 80% compliance. Based on these findings this research recommended that, during the preparation of next Dhaka and Chittagong development plans, there should be on-site delimitation of the conservation area. Besides, more stringent policies and enforcement of penalty are recommended. The KDA and RDA authority should also discontinue any development project that is going on the conservation area. Besides, this study also recommended other relevant acts to be enforced more strictly.