Karst water studies and environment in West Malaysia
The overall aim of the study is to investigate the environmental characteristics and karst water properties of selected limestone outcrops in Selangor, the Kinta Valley and the North-west region, West Malaysia. The meso-topography, soil and vegetation cover of 13 plots, which encompass the range of weathering environments observed in the limestone hills, are described. Reports are also given on regular measurements of throughfall, litterfall, throughflow, subcutaneous flow, soil moisture, soil carbon dioxide and karst water properties made over a one-year period. Five main conclusions result from the investigation. First, the surface of the limestone hills comprises a mosaic of weathering environments, determined principally by topographic position and rock purity. Each is distinguished by the nature and depth of soil cover, by the characteristics of the vegetation canopy, and by its meso-relief. Secondly, rapid cycling of nutrients, especially potassium and calcium, takes place within the soil/ vegetation system. Thirdly, marked systematic, spatial and temporal variations occur in karst water properties. The most important distinction is between groundwaters, which characteristically display only narrow hardness and temperature fluctuations, and surface waters, which exhibit much greater variability. Fourthly, a high proportion of solution occurs near the surface, and much secondary deposition takes place within the outcrops, especially where, as in the tower karst hills, groundwater flow is generally of low velocity. Variations in net denudation rates, which range from 38.4 to 81.0 mm/1000 yrs, are largely determined by differences in effective rainfall. Finally, detailed comparisons of the hydrological and denudational processes operative within the contrasted outcrops of the Setul Boundary Range and the tower karst hills suggest that whilst karstification processes under humid tropical conditions seem particularly favourable for the formation and preservation of tower karst hills, dominant vertical and subvertical fractures are normally prerequisite for their development.