Watershed Management for Mitigation of Disasters Caused by Extreme Hydrologic and Tectonic Events in Taiwan

As a result of steep topography, young and weak geological formations, loose soils, disastrous floods, landslides and debris flows associated with extreme hydro-meteorological and tectonic events such as heavy typhoon rainfalls and earthquakes often cause significant losses of and damage to homes, human lives and property and pose serious challenges to the sustainable management of land and water resources in Taiwan. Considerable efforts are made for mitigation of these natural disasters, but most often in a crisis management manner that lacks a comprehensive and long-term perspective. Developing effective measures and responses to mitigate these natural disasters is compounded by difficulties in implementation of proper land use planning and regulation due to land scarcity, inadequate policies and lack of cooperation between people and institutions. Problems and solutions of disaster mitigation related to floods and debris flows are discussed in the context of sustainable land and water management in Taiwan. Engineering approaches to modify natural systems are contrasted with approaches that require changing human behavior. Watershed management practices include measures to change the natural system, human behavior, or both, for mitigating disasters related to debris flows and floods. The success of mitigation measures depends not only on characteristics and magnitudes of disasters but also on human responses related to socioeconomic, cultural and political factors.