Home Articles Mapping of land use/cover in developing a catchment management for Perlis, Malaysia

Mapping of land use/cover in developing a catchment management for Perlis, Malaysia

Basharudin Abdul Hadi
University Teknologi MARA Perlis
Malaysia
Email: [email protected]

Kamaruzaman Hj. Wan Yusof
University Teknologi MARA Perlis
Malaysia

Che Senu Salleh
University Teknologi MARA Perlis
Malaysia

ABSTRACT
The objective of catchment management is to maximise the net socio-economic benefit of land use activities in the catchment area. In Malaysia, catchment management problems are associated with river pollution from untreated industrial wastes in urban areas (Low, 1993), with water shortages due to the uneven distribution of rainfall throughout the country and with high erosion rates due to deforestation for agricultural and urban expansion (JICA, 1982). The objective of this project research is to produce a digital map of land use/cover for Perlis using the spatial analysis technique of remote sensing and the geographical information system (GIS).

1.0 Introduction
The objective of catchment management is to maximise the net socio-economic benefit of land use activities in the catchment area. In Malaysia, catchment management problems are associated with river pollution from untreated industrial wastes in urban areas (Low, 1993), with water shortages due to the uneven distribution of rainfall throughout the country and with high erosion rates due to deforestation for agricultural and urban expansion (JICA, 1982). The objective of this project research is to produce a digital map of land use/cover for Perlis using the spatial analysis technique of remote sensing and the geographical information system (GIS).

2.0 Use of Computer Technology
In the past, conventional data collection was done mainly by ground surveys. This method has proved to be accurate but it has several drawbacks. The method is very time-consuming and costly. It is also subject to site accessibility and reliability depends very much on human capabilities. With the advance of computer technology, a revolution in gathering and analysing large data sets has been achieved. This new methodological approach including remote sensing and GIS has been used to address the problem of catchment-based management systems such as water availability. Databases have been collected in a digital format and updated frequently using remote sensing. These data can then be stored in a GIS, which can be used to compile, combine and analyse the data in order to simulate and evaluate management strategies dealing with various problems within the catchment. Based on this information, decision makers could, for example, decide on targeting their limited financial resources to those areas, which contribute most to the problem, or to identify those areas where development can proceed with appropriate control measures (Baban, 1998).

2.0 The Study Area
Perlis is situated in the northern Peninsular Malaysia, with neighbouring borders of Thailand in the north and Kedah in the south. It has an area of 795 sq. km. It has a tropical monsoon with “winter wind” (northerly wind from Siamese Bay), with temperatures between 21-23 degrees Celcius having a dry season of January to April and rainy season of May to December.

3.0 Research Methods
The research methods can be summarised as follow:

  1. An analysis of the ground based data and secondary data in providing direct quantitative information about the nature, structure, composition and the aerial extent of all relevant attributes (eg. Land use/cover types, soil types etc.)
  2. Employing Landsat imagery (Satellite image) to extract aerial information
  3. Employing GIS techniques to analyse the information.

A LANDSAT digital spectral data taken on 13 March 1997 (path/row 128/55) for northern Perlis region was used and analysed using IDRISI, a raster-based GIS software program. The image was atmospherically corrected using the darkest pixel approach and geocorrected with a residual mean square (RMS) error of less than half a pixel. Using IDRISI with a composite image of the bands TM3, TM4 and TM5, an unsupervised classification of land use/cover was performed on the basis of spectral signature for nine clustering areas. Available secondary data to support this work consisted of a 1987 topographic map at scale 1:50 000 issued by the Department of Survey and Maps, Malaysia, a 1996 land use map at scale 1:50 000 obtain from the Ministry of Agriculture, Malaysia.

The following land use/cover types were selected as representative classes in a supervised classification; inland forest, rubber, paddy fields, reserved forest, sugarcane, grassland, urban areas and water bodies. A minimum of 30 pixels were selected in the training areas for each class. The training areas were selected on the basis of the unsupervised classified image, primary field data and the secondary data. Using IDRISI the polygons around each training area were digitised and assigned a unique identifier for each cover type (Eastman 1997); a spectral signature file for each class was subsequently created. These signature files were used to categorise the continuum of spectral data in the entire image by using a maximum likelihood classifier involving bands TM3, TM4 and TM5. All relevant TM bands had been examined for autocorrelation and bands TM3, TM4 and TM5 emerged as having the least similarity in terms of information content. These bands were consequently used in the classification process.

5.0 Results
Figure 1.0 shows the image for the clustering image of TM band 354 combination. Figure 2.0 shows the unsupervised classification image while Figure 3. 0 shows the supervised classification image.

Figure 1.0 Image for CLUSTER TM band 354 combination

Figure 2.0 Unsupervised Classification image

Figure 3. 0 Supervised Classification image

6.0 Discussion And Further Work
The landuse/cover for the areas are classified as waterbody, inland forest, rubber, paddy, urban areas, sugarcane, reserved forest. Overall, most of the classes were easily separated and mapped due to their distinctive spectral reflectance signatures within the TM bands used.

During field survey, it was evident that topography was the main influence on the distribution of landuse/cover on the area. Low-lying areas of alluvium with plentiful amount of fresh water are dominated by paddy fields. The lowlands also contain sugarcane and urban settlements. Rubber seems to exist on the hills and hillsides whilst the highlands are mainly occupied by inland forest.However, there were some difficulties in the identification of urban areas. This may be due to their existence in small spatial units produces mixed class covers with the rubber and paddy units, which exist nearby. Rubber and paddy classes were also difficult to separate in a few locations.

Further work will be to justify the landuse/cover mapped using the GIS technique to be justified on the ground. Once the boundaries of the mapped landuse/cover are within the acceptable range of errors, the digital map is now available for further or future research involving catchment management resources.

7.0 Conclusion
In this preliminary study, the results suggest that the main factor controlling landuse/cover distribution on the area is topography. Low areas are dominated by paddy fields, sugarcane and urban settlement, hills and hill slopes are covered by rubber, and higher grounds are occupied by reserved forest.

These preliminary results clearly suggest that the spectral and spatial characteristics of Landsat TM data could serve to identify and map landuse/cover types in the northern of Perlis. The results also suggest that a raster-based GIS can facilitate the necessary digital analysis and manipulation. This includes data integration, geocorrections and handling the classification.

In conclusion, satellite remote sensing and GIS can be used to generate the necessary dynamic information for surveying and monitoring landuse/cover in northern Perlis.

References:

  • Baban, S.M.J. and Flannagan J. (1998). Developing and implementing GIS- assisted constraints criteria for planning landfill sites in the UK. Planning Practice & Research, 13, 139-151.
  • Eastman, J. R. (1997). User’s Guide in Idrisi for Windows, version 2.0. Clark Labs for Cartographic Technology and Geographic Analysis, Clark University, Worcester, MA, USA, pp Chapter 18 p 67.
  • JICA. (1982). Water resources development and use plan. National Water Resources Study, Malaysia. Main report. Government of Malaysia. Japan International Cooperation Agency. Kuala Lumpur, Malaysia, Volume 2, pp 183.
  • Low, K. S. (1993). Urban water resources in the Humid Tropics : An overview of the ASEAN Region. In M.Bonell, M. M. Hufschmidt and J. S. Gladwell (eds.), Hydrology and Water Management in the Humid Tropics: Hydrological Research Issues and Strategies for Water Management. International Hydrology Series. Cambridge Universtiy Press, United Kingdom, 526-534.