特集: 東アジア太平洋地域の河川復元に向けて FEATURE: Toward river restoration in East Asia-Pacific Region
CASE STUDY CASE STUDY

Application of GIS and Remote Sensing for measuring and evaluating land-use changes and its impact on water quality in the Pinang River watershed

Ahmad Jailani Muhamed YUNUS^1)*, Nobukazu NAKAGOSHI¹⁾ and Ab Latif IBRAHIM²⁾: Ecol. Civil. Eng. 6(1), 97-110, 2003.

1) Graduate School for International Development and Cooperation, Hiroshima University, 1-5-1 Kagamiyama, Higashi-Hiroshima, 739-8529 Japan
2) School of Humanities, University of Science Malaysia, Minden, 11800 Penang, Malaysia

Abstract:Human activities in the Pinang River watershed have dramatically changed land-use and land cover characteristics, and have subsequently altered hydrological and watershed processes. Pinang River water quality in downstream areas is badly polluted, based on the Malaysian Department of Environment-Water quality index (DOE-WQI) classification. In order to assess the past and present water quality and the possible uses of the Pinang River, a water quality index was applied to a data set collected for this study, which is based on the Malaysia DOE-WQI standards. This study investigated the land-use and land cover changes, which are the main contributors to the water quality and hydrological problems in this watershed. With some information derived from Landsat images, Geographic Information System (GIS) application and land-use/land cover map, we identified the land-use changes and landscape patterns in the Pinang River watershed. The results showed that forested and scrub areas decreased rapidly within the sub-watersheds as well as the entire watershed, in contrast to the urban or built-up areas. Statistical analysis indicates that impervious land parcels are increasing, which contribute to water pollution and watershed degradation. Based on land-use fragmentation and diversity indices, it was revealed that these indices are reliable tools for measuring and evaluating land-use and land cover changes for the general guideline for watershed management. This study revealed that integration of GIS and remote sensing (RS) data to quantify landscape structure is a feasible and efficient method for evaluating the temporal effect of land-use activities in the river basin for watershed planning and future development.

Key words: Department of Environment-Water Quality Index (DOE-WQI), Geographic Information System (GIS), Landsat TM, Land-use change, Watershed

摘要

マレーシアのピナン川流域において，人間活動による土地利用形態の変化は，特に下流域の河川水質を悪化させつつある．本研究では，ピナン川流域における土地利用変化を明らかにした上で，それが河川の水質に与えた影響を評価した．1992年，1996年，および2000年の土地利用の被覆状況をランドサットの画像データから地図化し，その経年変化をGISを用いて把握した．そして，４つの小流域および全流域を対象に経時観測されている水質データ，およびそれをもとに算出される指標値（DOE-WQI）の経年変化を土地利用変化とあわせて検討した．なお，DOE-WQIは，マレーシア環境省によって採用されているものである．
　森林や低木林の面積は経年的に急速に減少する一方，都市面積（人工造成地）が増加していること，そして，景観が分断化されてきていることが判明した．小流域および全流域のDOE-WQIの値は，それぞれの流域に含まれる森林面積と正の相関を，都市面積と負の相関を持っていた．このようなことから，流域の土地利用計画や開発計画に，リモートセンシングやGIS技術を用いることが有効であることが確認された．

Recieved 7 October 2002; Accepted 14 July 2003
* e-mail: jailaniyunus@yahoo.com