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Environ Earth Sci (2014) 72:407416 DOI 10.1007/s12665-013-2961-3
ORIGINAL ARTICLE
Differentiating tower karst (fenglin) and cockpit karst (fengcong) using DEM contour, slope, and centroid
Wei Huang Chengbin Deng Michael J. Day
Received: 5 July 2013 / Accepted: 13 November 2013 / Published online: 29 November 2013 Springer-Verlag Berlin Heidelberg 2013
Abstract The complex geometry of tropical karst land-forms poses particular challenges for morphometric analysis, morphological classication and evolutionary assessment. Detailed geomorphological studies of the two most spectacular formstower karst (fenglin) and cockpit karst (fengcong)have employed time consuming and labor intensive eld surveys, which have yielded inconclusive and ambiguous results. This paper tests a novel discriminatory approach utilizing contour, slope and centroid derived from the ASTER Global Digital Elevation Model to differentiate between cockpit and tower karst in the Guilin area of southern China. Morphological indices are calculated to compare and contrast geomorphic variations using Object-Based Image Analysis (OBIA). The results suggest that the method provides a feasible means of differentiating between tower and cockpit landforms, and that OBIA offers a fast and semi-automatic way to extract morphological parameters.
Keywords Tower karst (fenglin) Cockpit karst
(fengcong) Morphology Morphometry Contour
Slope Centroid Object-Based Image Analysis
Introduction
Tower karst (fenglin) is isolated limestone tower with vertical anks rising from alluvial plains (Zeng 1982; Day and Tang 2004). Cockpit karst (fengcong), on the other hand, involves similar dimension enclosed depressions surrounded by overlapping hills and ridges (Day 2004a; Day and Chenoweth 2004; Yuan 1984; Zhu et al. 2013). The two land forms are the two most spectacular and diagnostic landscape styles in tropical environment, where higher temperature and abundant precipitation provide favorable environment for rapid and prolonged corrosion. Typical examples can be found in Southeast Asia, Central America and the Caribbean, and the towers there are lower and rounded, being formed in Tertiary porous carbonate rocks (Troester 1992).
Studying the relationships between them hold the key to understanding tropical karst evolution (Sweeting 1972; Smart et al. 1986; Zhu 1988; Yuan 1991, 2004; Ford and Williams 2007; Waltham 2008). Jakucs (1977) proposed a four-phase genetic model (Fig. 1) to describe the erosion of karst surface: (1) soil and related waste are removed and accumulated in the karst depression, (2) tectonic uplift occurs as the karst plain becomes corroded with cockpit karst,...