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Changes in Land Use Pattern at Chakaria Sundarbans Mangrove Forest in Bangladesh

Md. Razib Rahman
Soil Resource Development Institute, Farmgate, Dhaka, Bangladrsh

Md. Babul Hossain
Soil Resource Development Institute, Farmgate, Dhaka, Bangladrsh

Abstract/ Executive Summary:

A comparative study was made during January to July 2012 to assess changes in land capability class due to deforestation in six soil series of Chakaria Sundarbans mangrove forest over time. Primary data have been generated on land and soil of the area through semi-detailed soil survey, GIS techniques and soil chemical analysis. Review of secondary data on land and soil has been done and tertiary data have been generated. The primary, secondary and tertiary data have been carefully interpreted to determine the status of land capability classes. Time series land use maps, starting from the base year of 1974 to 2012 have been generated through field survey and interpretation of aerial photographs of 1974, 1984, 1994 and land sat image of 2012. Soil profiles are described in the field following USDA Soil Taxonomy. Soil physical and chemical analyses have been made following conventional soil analysis methods and as followed during Reconnaissance Soil Survey (RSS) carried out in 1973. Six identified soil series viz. Badarkhali, Barabakia, Chakaria, Cheringa, Kutubdia & Pahartali had been considered for the study. The most prominent and significant changes have been observed in land use. In 1974 the forest was almost virgin and there was no land under shrimp culture. It increased to about 26% of the study area in 1994 and slightly declined to 21% in 2012. Agricultural land shrunk from 36% in 1974 to 7% in 2012. Salt farming increased from 2% to 23% in 2012. Forest cover was almost cleared in 1994. Major changes in land use occurred during 1984 to 1994.

Keywords: Land Capability Class, Degradation of Soil, Six Soil Series and Chakaria Sundarbans Mangrove Forest.

Location: Chakaria Sundarbans, Cox`s Bazar district, Bangladesh.

Start Date: 00-01-2012

End Date: 00-07-2012

Program Area: Conservation and Biodiversity

Non-commodity: Remote sensing

Objectives:

Objective of this study was to study the changes in land use of the study area over time as affected by the deforestation.

Methodology:

The study has been conducted in Chakaria Sundarbans, a deforested area of Cox`s Bazar district of Bangladesh. It lies in the delta of Matamuhuri River of Cox’s Bazar district. Remote sensing technology has been used during survey. The basis of the soil survey was air photo interpretation supported by a planned program of field traverses, which has done in 1973 during reconnaissance soil survey of SRDI. The base material e.g. topographic map, Reconnaissance Soil Survey (RSS) maps and reports, aerial photographs, Upazila Land & Soil Resources Guide (Upazila Nirdeshika) and other related study reports have been collected. The data sources were social survey, field measurement, and topographic map and Land sat TM images. Stratified simple random sampling technique was used to select the features of the area from different predominant land cover areas (e.g. agricultural land, mangrove forest, reserve or hill forest, salt bed, shrimp pond, water bodies, settlement etc.). Current use patterns of the area were taken from topographic map and administrative map and updated with the interpretation of Land sat TM images. Geometric correction was performed with bilinear transformation (RSI, 2000a) and the root mean square error was (0.49) controlled within less than one pixel for 42 ground control points (GCPs). Ground data were obtained by field investigation. Additional data on land use and socio-economic are also important for the analysis. The other basis was laboratory analysis of representative soil samples of selected series that were collected from the same sites indicated in RSS report, 1973. All maps and images were transformed into Universal Transverse Mercator (UTM) projection. Meter was defined for the software system as unit of the scale and map. Remote sensing image analysis was used as ENVI (version 3.4) developed by Research Systems Inc, USA. Soil samples were collected from different locations on horizon basis and processed and analyzed for physical and chemical properties following standard procedures. The morphological properties of the soils were studied in the field following the methods of USDA as described in Soil Survey Manual. A net work of traverses was laid down so as to examine the landscape units differentiated by study of the air photos as before. Soils were examined as often as necessary along these traverses. Selected profiles were described from pits dug along traverses, supplemented by spot identification from auger holes. Routine traverse examinations were made to a depth of 120 cm and profile pits for detailed description and sampling of the representative soils were examined to a depth of about 180 cm or more. The nomenclature of FAO, as described in the booklet “Guideline for Soil Description” which is essentially derived from the USDA Handbook 18, the Soil Survey Manual has been followed. Color notation has described according to the Munsell Soil Color Chart (Munsell Color Company). The main soil unit recognized was the soil series during RSS done by SRDI. Wherever soils with similar properties occur in the survey area and elsewhere, they are called by the same name (SRDI, 1973).

Source of Information: BANGLADESH RESEARCH PUBLICATIONS JOURNAL, Volume: 11, Issue: 1, Page: 13-20, March - April, 2015; ISSN: 1998-2003

Article Link (Online Journal): http://www.bdresearchpublications.com/journal/containerAction.php?area=currentIssue

Funding Source:

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Remarkable changes in land use practices and soil characteristics were observed during the period, 1973-2012 due to deforestation of the mangrove. Soil management practices, however, have not kept pace with these changes especially in the point of agricultural production. During 1984 to 1994 major changes in land use occurred in the study area. As salt farming increased from 2% to 23% in 2012 it lead in Agricultural land shrunk from 36% in 1974 to 7% in 2012. On the other hand, forest cover was almost cleared in 1994. The change in land use negatively affects physical and chemical properties of soils of the study area. Clay migration from the top soil observed almost in every soil series. Salinity increases significantly. Exposure of jarosite was observed markedly. Abundance of sulphur, iron and boron increased in the soils over three and half decades. Organic matter, nitrogen, phosphorus, potassium, copper, manganese and zinc decreased markedly. Overall soil fertility depletion takes place due to deforestation and change in land use.

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