Riparian land-use and land cover change analysis using GIS in Pinang river watershed, Malaysia

Abstract

This study was conducted to develop appropriate mapping and assessment techniques to quantify the nature and magnitude of riparian landscape structural changes along the Pinang River using remote sending data. Based on stream order land-use ranks classification, the stream ecosystem health can be determined. The lower rank stream order segment indicates that, the stream ecosystem is in good condition. Vegetation land-use changes from 1992 to 2000, within fixed 50-m width stream buffer, were identified using GIS and used to estimate the riparian zone and subsequently calculate the landscape patterns using Patch Analyst. Since the Pinang River watershed is the most urbanized, it experienced rapid development and land-use changes that deteriorated the watershed ecosystem. The riparian land-use patterns in 1992 and 2000 were studied by landscape metrics such as areal percentage, patch number per unit area, landscape diversity, evenness index, and mean fractal dimension. The results show that in vegetation areas have significantly decreased mainly due to conversion to urban and built-up, agricultural, and recreational land. Thus, riparian vegetation corridors have become more fragmented, isolated, and much smaller. The large proportion of deforested riparian areas within stream order segments raises serious questions about the watershed ecosystems health and the longer term possibility of river degradation by upland clearing. Furthermore, most of the agricultural land is being displaced to the hill slopes and hilly area (85% of first-order stream located), while urban and built-up developments are gradually replacing the original agricultural land. Based on landscape metrics, it has been revealed that landscape metrics indices are significant for evaluating the riparian land-use and land cover change, in addition integration of GIS and remote sensing to quantify landscape structure is a feasible and efficient way to evaluate the temporal effect of land-use activities on watersheds.