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close this bookShort-term training programme on GIS (Geographic Information System) for fisheries (1993)
View the document(introduction...)
View the documentObjective of the training programme
View the documentProgramme and Resource Persons
View the documentName of the Participants and their Organizations
View the documentInaugural Programme and Addresses
View the documentGIS for Fisheries - An introduction
View the documentFisheries Development Plan of Bangladesh
View the documentData Requirement for Inland Fisheries Planning and Development
View the documentPrinciples of Remote Sensing - Airborne and Satellite Remote Sensing
View the documentSatellite Data Processing and Image Analysis
View the documentFundamentals of GIS
View the documentApplication of Remote Sensing to Environment with Special Reference to Inland Fisheries and Aquaculture
View the documentApplication of Remote Sensing and GIS in Shrimp Farming Areas of Bangladesh
View the documentRemote Sensing Applications for Marine Fisheries Resources in Bangladesh
View the documentPond Concentration Studies in Bangladesh
View the documentInventory of Inland Waters (Based on Study of SPARRSO, 1984)
View the documentFormulation of Periodic Atlas of Structured Information of Fisheries Resources

Application of Remote Sensing to Environment with Special Reference to Inland Fisheries and Aquaculture

Dr. M.A. Shahid
Principal Scientific Officer Bangladesh Space Research and Remote Sensing Organization (SPARRSO)
Agargaon, Sher-E-Bangla Nagar, Dhaka

1. Introduction

Development activities as a result of increasing population and the natural phenomena are causing serious environmental changes. Population activities include widespread deforestation, industrial and other pollution, destruction of habitat etc. while the natural phenomena worth mentioning are: floods, cyclones, storm surges, droughts etc. The current and accurate data of these environmental changes are essential for national planning and sustainable development.

The current and accurate information on spatial location, quality, quantity and their environment are essential for proper planning and sustainable management of these water areas. The traditional methods to collect these information is time consuming and require more manpower. One possible solution is the utilization of remote sensing techniques to identify and locate the fisheries resources and assess their environmental conditions.

The principle of remote sensing technology is to look down to the earth from space platforms (satellites, aircrafts, space stations etc.) to regularly monitor the earth resources and its environment. It can be applied in the field of inland fisheries and aquaculture to identify and locate the fishery habitat and man’s activities is the environment to detect and predict the habitat qualities. This technique can also be used to locate and identify the different types of water bodies and to gather the information required for inland fisheries development and management (Welcome 1985). It is also possible to analyse the environmental conditions of the water areas from remote sensing data using keys from available information or existing/real time ground truths. The conventional field techniques are best suited when supplemented with remote sensing data. The surface water areas can easily be identified and categorized according to their optimum locations for inland aquaculture and culture-based fisheries using this technique in combination with the Geographical Information System (Travaglia and Klohn 1990, Meaden and Kapetsky 1991).

Realizing the importance of remote sensing technology, Bangladesh started putting emphasis on the development and use of space and remote sensing technology in the country, which ultimately resulted in the establishment of the Bangladesh Space Research and Remote Sensing Organization (SPARRSO) in 1980. SPARRSO is the national agency for application of space science and remote sensing technology in the country. It is a multi-disciplinary research and development organization involving national resource survey and environmental monitoring.

2. Objectives

Objectives of this presentation are to familiarize fishery scientists/decision makers with the capabilities of remote sensing techniques for inland fisheries development. Finally some of the application oriented activities of SPARRSO are also discussed. These will throw lights on how the remote sensing techniques are used in Bangladesh for fisheries resources inventory and environmental monitoring and ultimately helping planners and decision makers of the country.

3. General Remote Sensing Approach

Remote sensing is the science and art of acquiring information about material objects from a distance without coming into physical contact with the objects. It is a tool for the production of information presented in a statistical or cartographic form or combination of the both (Lantieri 1988). Remote sensing from satellite and airborne data provide authentic sources of information, which can be used for resources management and environmental monitoring in an effective way. One principal advantage of remote sensing is its ability to collect and analyse the multiband and multidate and/or multistage data. In a multistage sampling scheme, data are collected from different altitudes, usually at different scales and resolutions. More detailed information is obtained for progressively smaller areas as the altitude decreases with subsequent increases in the scale and resolution of the data. Interpretations and inferences can be verified in small subareas and then extrapolated to higher level of observation. Remotely sensed data collected at different dates can be used to monitor changes in dynamic natural resource features.

3.1 Data Acquisition

The selection of suitable remote sensing data is normally determined by the objectives of the study and data availability. There are two main kinds of methods to acquire remote sensing data.

3.1.1 Airborne

The data acquired from aircraft platform are known as airborne remote sensing data. Aerial photographs are the important examples of airborne remote sensing data. Advantages of using airborne remote sensing data include:

* provision of high scale,
* high flexibility for surveying an area at a precise time and at a designated scale
* possibility of flying below cloud level.

3.1.2 Satellite

Satellites are the most widely used and promising platforms for acquiring remote sensing data. These satellites are subdivided into two categories according to their altitude range and their rotation mode around the earth:

* the polar orbiting satellites (move north - south) and
* the geostationary satellites (move west - east).

Satellite based remote sensing data offer some unique advantages.

These include:

* good coverage of a larger area at a time,
* synoptic view of a given area,
* repetitive coverage of the same area at regular intervals.

Some of the important earth resources satellites with their dates for first launching are:

* The Landsat (U.S.A)

1972

* The SPOT (France)

1986

* The MOS (Japan)

1986

* The IRS (India)

1986

* The ERS (ESA)

1991

* The JERS (Japan)

1992

3.2 Data Interpretation

Interpretation of remote sensing data can be done either visually or digitally. Visual interpretation is normally based on the tone, colour, texture, pattern, size, shape and shadow of an image. On the other hand, digital image classification is a quantitative approach based on the brightness values of scene features and can be done with the help of a computer. Stereoscopic interpretation is another kind of photo interpretation technique and usually done with the help of stereoscopes on the photographs that can produce three dimensional views.

4. Remote Sensing Applications for Environment, Inland Fishery and Aquaculture Development

Remote sensing techniques can be applied for the development and management of inland fishery and aquaculture. Applications of this technique vary according to the degree of resolution of the remote sensing data available and also to the objectives of the study. The smallest element that can be easily identified from the remote sensing data is called its resolution. Thus satellite imagery serve primarily to obtain a broad impressions of an area, whereas various types of aerial photographs may be used for more detailed analysis of smaller areas. There is a close association between remote sensing and mapping. So, many of the applications are associated with inventory functions. On the other hand, maps tend to be fairly static documents, whereas the capacity to repeat surveys through time by remote sensing allows trends to be established and thereby they may be used for monitoring. The capabilities of remote sensing to collect information for environment, fisheries and aquaculture development may be summarized as follows:

4.1 Environmental Condition

Land use change of an area can affect the potential for inland fisheries of natural water bodies. Such activities as deforestation, irrigation, urbanization, dam construction etc. can produce radical changes within the water body which eventually affect the quality and quantity of water in the rivers and lakes. Monitoring of these changes provides information on the position of fisheries relative to other uses of the basin.

4.2 Survey of Geomorphology

The productivity of inland rivers and lakes is determined by several factors including the form of the landscape, drainage system, vegetation covers etc. The type of landscape is readily determined from Landsat imagery. It is also possible to collect information on spatial and temporal changes such as the alteration in course of river or the siltation of a series of floodplain.

4.3 Soils

Soil types can be inferred from remote sensing images both directly and indirectly. Since natural vegetation types correlate strongly with soils, hence the various vegetation categories will give a clue to the suitability of soils for pond construction or other fisheries development.

4.4 Inventory of Surface Water Bodies

Remote sensing techniques are being applied effectively for inventorying and determining the distribution and magnitude of inland waters to assess inland fishery resources. This is specially useful in areas where the number of water bodies are sufficiently large as in Bangladesh. It is also a practical method of keeping track of the number of man-made water bodies such as dams or fish ponds. Calculation of dimensions (length, breadth, shoreline, limits of seasonal fluctuation) of rivers, reservoirs, swamps, flood-plains of large river systems etc. may also be done using remote sensing data.

4.5 Productivity and Water Quality

Remote sensing data can be directly applied for productivity estimation. The chlorophyll content and temperature of water bodies are being measured from satellite data that can give immediate information on the primary productivity of a water body.

4.6 Suitable Site Selection

Site for inland fishery development should satisfy a location that is suitable for fish production. Remote sensing in combination with ground truth data and geographical information system can provide important tool for identifying potential sites for development of new aquaculture installations.

4.7 Survey Design

The first stage in the design of a survey is the establishment of a sampling frame. The frame is usually designed so as to group geomorphologically and sociologically similar units within which more detailed sampling activities can be generalized. The frame also requires the identification of specific sampling points which are often determined by accessibility. Maps and remote sensing imagery are the most useful means for establishing this frame.

There are some other production functions which can also be inferred from satellite imagery. These may include determination of water depth, identification of shelter for cage culture, estimation of temperature and sediment concentration of water, monitoring of vegetation levels or biomass estimation in inland water, existence of coastal flora or habital types such as mangroves etc.

5. Remote Sensing Activities of SPARRSO Related to Inland Fishery and Aquaculture

SPARRSO has conducted a number of studies in the field of fisheries. Some of the studies are briefly presented below:

5.1 Fishery Resources Survey

Satellite imagery and aerial photographs were used to collect information on available water bodies for fish production in the country. Methodologies used for the work included visual interpretation of Landsat imagery and stereoscopic interpretation of aerial photographs. Maps at the scale of 1:50,000 of 40 selected thanas for small water bodies (>25 ha) and whole of the country for large water bodies (<25 ha) were produced. These maps showed the location of water bodies including their communication facilities and physical situations. The results of this study were supplied to Fisheries Department of Bangladesh for their development planning and management purposes.

5.2 Standing Water Bodies Survey

Landsat imagery (dry season) and colour infrared aerial photographs were visually interpreted to identify and locate the latest position of standing water bodies of the country. Stereoscopes were used as and when needed to interpret these water bodies. Maps of the whole of Bangladesh at a scale of 1:250,000 were prepared in four parts (north-east, north-west, south-east and south west) showing the catchmentwise locations of the standing water bodies. The areas of the these water were measured and estimated to be 1922 sq. km (Table 1)

Table 1. Areas of Standing Water Bodies

Location

Area (sq. km)

A. North-West Region

334.14

B. North-East Region

748.02

C. South-West Region

140.37

D. South-East Region

699.14

Total

1922.14

(Source: SPARRSO Report, 1985)

5.3 Hail Haor Fishery Resources Survey

Fishery resources of Hail Haor were identified and mapped using aerial photographs taken during 1952, 1963, 1975 and 1982 and Landsat imagery of 1980. Total number of ponds were counted and total area of different water bodies in the haor zone was identified and their area was measured from the map. The data of this study were found to be very useful for fishery development and management of that haor.

5.4 Kaptai Lake Study

Remote sensing data were used to study the water condition of the Kaptai Lake in different seasons. The surface area of water of that lake was found to be 74,000 ha during full inundation (October), 57,000 ha during mid-dry season (March) and 26,000 ha during peak of the dry season (May). These information are found to be useful for fish resources development and management of that lake.

5.5 Study on Seasonal Fluctuation of Water Bodies

A sectoral study was conducted under UNDP supported project to monitor seasonal fluctuations in the area of inland water by water type between the period January/February and August/October using Landsat TM and SPOT HRV data. The objectives of these study were to:

- monitor seasonal fluctuation in the area of inland water,
- show the potential capability of digital image processing of Landsat data,
- apply GIS for development and management of inland fisheries.

Visual interpretation and digital classification methods supported by ground truth information were used for this study. Unfortunately, it was found during the study that the determination of fluctuations in the area of inland water was almost impossible, as good remote sensing data for wet season could not be available because of cloud cover. However, an indirect approach of seasonal fluctuations was used for this study. Kurigram, Kishorgonj and Sunamganj districts were selected for this study. The output of this sectoral study was surface water inventory maps at the scale of 1:100,000.

5.5.1 Interpretation and Mapping

Visual interpretation of Landsat TM imagery were done on the basis of their colour, texture, pattern, size, shape etc. PROCOM-2 was used to maintain the scale of the maps. Due attention was also given on drainage patterns, landscape, vegetation cover etc. during the identification of water bodies of an area. Colour composites of Landsat TM bands 4, 5 & 7 were found most suitable for separation of water bodies from other surface features.

ERDAS image processing system of SPARRSO was used for digital classification of Landsat data, for this study. Different water bodies, vegetation, bare land, settlement area etc. were classified using maximum likelihood supervised classification method. The classified image was converted to ERDAS GIS format for using in ARC/INFO GIS application.

5.5.2 Application of GIS (ARC/INFO)

The objective of this application is to demonstrate the use of GIS technique for proper planning and development of inland fisheries and aquaculture. Part of Kurigram district was selected for this purpose. Nine layers were chosen from the final map of this area. Surface water layers allow users to select suitable water bodies according to their water type (permanent, seasonal, closed, etc). Road layers show the transportation suitability of the water bodies. Town/village layers indicate the potential markets for selling the products.

Roads, main cities/towns, permanent closed water bodies and river system were separately buffered with distance of 1 km, 5 km, 1 km and 1 km respectively. The potential ponds were determined with the spatial relationship among the permanent water bodies (as water source), roads (as availability of transportation) cities/towns (as source of manpower and potential markets) buffers. Those areas fall on the buffer of roads and permanent water bodies and that of roads and rivers are considered as the potential areas where new ponds could be constructed for fish culture. The suitable sites for new ice plants were also analyzed on the ARC/INFO system considering the spatial relationship among roads and permanent water bodies.

5.5.3 Estimation of Chlorophyll Content of Water Bodies

Phytoplankton concentration is normally determined by their green pigment (i.e. chlorophyll). The increasing quantities of chlorophyll cause water colour to change from blue to green. Presence of phytoplankton can be considered as an index of biological productivity and it can be related to fish production. The spectral reflectance of chlorophyll is quite distinctive in near infrared range. Landsat MSS and TM data along with field sampling data allow for the calibration of chlorophyll concentrations and estimation of algal front movement. An attempt was, therefore, made to find out the potential capability of digital image processing of Landsat data for estimation of chlorophyll content of water bodies. Water area of Tanguar haor in Sunamganj was selected for a case study. Unfortunately, there were no real-time in-situ data of chlorophyll-concentration for the area; as such it was not possible to make correlation between them. However, this technique can be used in Bangladesh situation if sufficient real-time data are available for water bodies like the Kaptai lake.

6. Conclusion

Remote sensing techniques can be used to obtain up-to-date, and cost and time effective information for inland fishery management and aquacultural development. The combination of satellite imagery, aerial photographs and conventional method as well as ground truth information provide one of the best ways to survey and monitor the fisheries resources in Bangladesh. These techniques in combination with Geographical Information System (GIS) can provide a unique tool for aquacultural site selection.

7. References

Department of Fisheries, 1987-88. Fish Catch Statistics of Bangladesh, Government of the People’s Republic of Bangladesh, Dhaka, 26p.

Food and Agriculture Organization (FAO) of the United Nations, 1980. Twenty Year Fishery Development Plan for Bangladesh. Prepared by John C. Marr Associates of U.S.A for the People’s Republic of Bangladesh, pp. 8-22.

Lantieri, D. 1988. Introduction to Remote Sensing. Food and Agriculture Organization of the United Nations, RSC Series No. 48, 49p.

Meaden, G.J. and J.M. Kapetsky, 1991. Geographical Information Systems and Remote Sensing in Inland Fisheries and Aquaculture. FAO Fisheries Technical Paper, No. 318, Rome, FAO, 991, 262p.

SPARRSO Report, 1985. Report on Standing Water Bodies of Bangladesh. Prepared by SPARRSO for Master Plan Organization (MPO), Dhaka, 83p.

Travaglia, C. and W. Klohn, 1990. Application of Remote Sensing to Water Resources Assessment and Management in Developing Countries: The Experience of FAO, In: Pro. of the Conference on Remote Sensing and Water Resources, 1990, Enschede, The Netherlands.

Welcome, R.L., 1985. Application of Remote Sensing to Fisheries and Aquaculture. In: Proc. Ninth UN/FAO International Training Courses in Co-operation with the Government of Italy on Application of Remote Sensing to Aquaculture and Inland Fisheries, Food and Agriculture Organization of the United Nations, Rome, Italy, 10-28 Sept. 1984, pp. 23-25.