Remote sensing is the quick technique of obtaining information about objects on the surface of the earth without physically coming into contact with them. This process involves making observations using sensors mounted on platforms (aircraft and satellites), which are at a considerable height from the earth surface and recording the observations on a suitable medium. Remote sensing data have been used for wide range of applications in Bangladesh, although in limited institutions, partly due to lack of expertise and financial support to obtain updated image and logistics. Bangladesh Space Research and Remote Sensing Organization -SPARRSO, is responsible for research, development and operational activities in space science and remote sensing technology in Bangladesh. This multi-sectoral programme involves several government departments and agencies. A National Space Research and Remote sensing committee decide the policy matter of the programme and also do the inter-ministrial co-ordination.
One of the most popular applications of remote sensing data is environmental sector in Bangladesh. Several Government and Non government organizations such as LGED, SPARSO, WARPO, SRDI, BRAC, SOB, GSB, and CEGIS are included in the study of the environment.
Flood monitoring: CEGIS has initiated using RADARSAT Imagery for flood monitoring during wet seasons. Mapping flood and damage extent has also been done by SPARSO and others using NOAA-AVHHR.
River Bank Erosion: Riverbank line and bank erosion are relatively easier in detection, identification, and monitoring with remote sensing data and can easily be vecorized in GIS format.
Charland Monitoring: Distribution of Jamuna charlands and Meghna estuary charland shifting tendency have been studied using remote sensed data.
River Morphology: Satellite images like SPOT and Landsat TM are being used for identifying the bank line shifting tendency and erosion and siltation behavior of rivers in Bangladesh.
Coastal Zone Monitoring: Estuarine bio-geomorphology, ecology, land degradation due to shrimp farming, salt manufacturing and water logging and coastal change detection are some of the recent issues covered using high resolution remote sensing data in Bangladesh, particularly IRS-LISS, SPOT, Landsat TM and IKONOS.
Drought Stress: Thermal infrared data were applied in the barind tract in the north-western part of Bangladesh for mapping and monitoring drought porn areas.
Wetland Monitoring: Basin wise wetland monitoring with remote sensing have been attempted in Bangladesh.
Salinity/ Water logging: CEGIS (2002) has initiated a study called Khulna-Jashore Drainage Rehabilitation Project wherein Landsat TM and IRS ID LISS images have been used for identifying changes in the land cover of the area.
Urban land use and land cover information on a regular basis are crucially important for map updating and planning for development initiatives. High resolution Landsat ETM, IRS, QUICK bird, IKONOS, SPOT is found to be extremely useful in urban land cover mapping. One of the limitations of these satellite images in Bangladesh is their prohibitive cost.
Agricultural application of remote sensing in Bangladesh mainly focused on mapping shrimp farm area and estimation of boro paddy area. Other crop inventorying through remote sensing has been attempted sporadically but has not progressed much.
Forestry applications include Monitoring of forest area mapping, identifications of actual forest cover extent, preparation of forest working plan, identification of vulnerable sites of forest encroachment, mapping extent of jhum cultivation sites, state of coastal forest, identification of new plantation sites and monitoring forestation program.
Geological applications of remote sensing data mainly limited to the identification of lineaments, fault line and brad landforms. The geological survey of Bangladesh has been using remote sensing data on selected fields of research.
The shrimp farming and mangrove forest areas are identified and located by remote sensing techniques. The Landsat (MSS & TM) data are used to delineate the surface feature of the coastal area. Infrared colour (IRC) aerial photographs provided most revealing information. Sequential aerial photographs provided information on change in time and places. This study reveals that the shrimp farming areas are expanding through destruction of the mangrove forest of Chokoria Sundarban and agricultural land of Rampai and Paikgachha area. For scientific development of the coastal area intensive shrimp culture methods are to be encouraged rather than horizontal expansion.
The remote sensing data are using to estimate the surface water in Bangladesh. Estimation of precipitation is very essential for its various important features such as flood and drought which are very common natural disasters in Bangladesh (88.05°-92.74°E and 20.67°-26.63°N). Precipitation is invaluable as a source of renewable fresh water and the importance is much more realistic in a region like Bangladesh which suffers from excessive rate of Arsenic in her ground water. At present, low-dense rain-gauge network over Bangladesh is only the tool to measure rainfall. The information from low-dense rain-gauge network sometimes is not sufficient for quantification of exact amount of precipitation and for monitoring flood situations. In order to gain the precise distribution of rainfall radar data available for 2000 from the Bangladesh Meteorological Department (BMD) are employed as the first research work in Bangladesh.
Remote sensing is the most valuable technology used in various kinds of sectors. Remote sensing data have been used for wide range of applications in Bangladesh, although in limited institutions, partly due to lack of expertise and financial support to obtain updated image and logistics.
(Shishir Reza is an Environmental Analyst & Associate Member, Bangladesh Economic Association).
