Land Cover and Coastline Change Assessment of Nijhum Dwip, Bangladesh, using Geospatial Analysis

Mohoua Sobnam,Al Mamun

doi:10.34257/gjhssbvol21is2pg63

Abstract

Nijhum Dwip is a southern island of Bangladesh isolated from the mainland, in the convergence of the Meghna River and the Bay of Bengal. This island has studied through overlay analysis and supervised classification by geospatial and remote sensing technique, over 38 years (1980-2018) using multitemporal Landsat MSS, TM, OLI, and TIRS satellite images with identification of historical changes. This landform is facing frequent shifting of its coastline and leading to sequential changes on the land surface. Analysis revealed substantial growth of settlement and agricultural land whereas significant lessening on vegetation cover and open space. In 1990 agricultural land was 4.47 km2 (13.29%) and improved to 9.16 km2 (19.17%) in 2018. Similarly, settlement also increased from 1.92 km2 (4.79%) in 1999 to 5.72 km2 (11.97%) in 2018. Conversely, vegetation was primarily 8.02 km2 (27.71%), 18.70 km2 (55.61%), 20.97 km2 (52.29%), 18.47 km2 (36.28%) and 15.28 km2 (31.98%) in 1980,1990,1999, 2010 and 2018, indicating declination. As well, water bodies and open space also fluctuated through the period because of geomorphological processes and human intervention. Besides, the least and highest unstable char land was 1.15 km2 (3.42%) and 1.68 km2 (5.80%) in 1990 and 1980.

Highlights

Uddin, 2013; Sarwar and Woodroffe, 2013; Emran et al, 2016; Hossain et al, 2016; Kumara and Ghosh, 2012; Coastline and coastal areas of Bangladesh are neither uniform nor static, and dynamic (Brammer, 2014) due to shifting through the Rahman et al, 2017; Rahman et al, 2018)
This island has studied through overlay analysis and supervised classification by geospatial and remote sensing technique, over 38 years (1980-2018) using multitemporal Landsat Multispectral Scanner System (MSS), Thematic Mapper (TM), Operational Land Imager (OLI), and Thermal Infrared Sensor (TIRS) satellite images with identification of historical changes
Conversions of land like, from non-buildup barren open space or char land to settlement and farming; naturally vegetated area cleared for agricultural practice, etc. have resulted within the study area

Summary

STUDY AREA

For this study Nijhum Dwip (Silent Island) has selected as the study area, a mauza under Zahajmara Union of Hatiya Upazila of Noakhali district (PDO-ICZM, 2002) in Bangladesh It is an extreme southern isolated small island of Bangladesh separated by the Hatiya channel (Alam and Uddin, 2013), about 2.2 meters high from the sea level situated in the Meghna estuary, confluences of the Bay of Bengal and enclosed by the Bay of Bengal (South and West), Domar char and the Meghna River on the East and Hatiya Island on the North (Saha et al 2014). This island is divided into two parts by a canal, named Kamalarpur (Northern part) and Char Osman (Southern Part) that is mostly populated This mudflat land is still unstable because of erosion, deposition, storm surge, monsoon inundation, cyclone, etc. The population is increasing from 4372 to 7835 and 12796 in 1991, 2001 to 2011, along with the total number of households are 2464 (PDO-ICZM, 2002; BBS 2011)

MATERIALS AND METHODS

AND DISCUSSION

Findings

CONCLUSION