Coastal modification due to human influence in south-western Taiwan

Abstract

The coastal zone of southwest Taiwan is characterised by muddy tidal flats, offshore bars, spits, lagoons and coastal sand dunes. These geomorphic features from an essential part of the natural defences against sea-level change and coastal erosion. Between 1955 and 1995 the area bounded by the Pei-Kang and Tseng-Wen rivers underwent considerable land use and topographic changes. Two examples were studied using time-series aerial photographs, remote sensing images and geomorphological field mapping. The result of this investigation demonstrates the influence of human activities and the importance of the natural coastal landscape in acting as a first-line of coastal defence and protection in Taiwan. Attention is drawn to: (1) inappropriately designed or misplaced coastal engineering structures which may destroy or reduce the effectiveness of neighbouring natural and engineered structures leading to storm damage, flooding and encroachment by the sea; (2) the need for a co-ordinated coastal management program to regulate on-shore activities, in particular the removal of ground water within the coastal zone. This research demonstrates that there is significant land subsidence and inland penetration of sea water into the ground water system in the coastal zone. Human activities also lead to considerable financial expenditure on the prevention of coastal erosion in Taiwan.