Author(s): Yu Guo-An; Wang Zhao-Yin; Duan Xuehua; Zhang Kang
Linked Author(s): Zhaoyin Wang
Keywords: Rtificial step-pool system; Debris-flow ravine; Ecological restoration 1
Abstract: A field experiment using an artificial step-pool system for ecological restoration was carried out on the Diaoga River, a debris-flow ravine on the Yunnan-Guizhou Plateau of Southwest China. The Diaoga River is seriously incised which caused extensive negative impacts on and even damages to human structures and aquatic eco-systems, and no natural step-pool system developed. Fifteen artificial steps, which were designed to mimic the natural step-pools developing in a neighboring ravine, were constructed on a stretch of about 150m in the middle-reach of the Diaoga River. Stones were laid out overlapping with each other to ensure the stability of the step structure. The artificial step-pool system increases the flow resistance and controls channel incision effectively. Two debris flows occurred in the river this year and has reduced to hyper-concentrated flows when passing through the experiment section, the hazards were greatly mitigated. The artificial step-pool system increases the water surface area, expands the range of water depth and flow velocity, and changes the streambed substrate, thus creates diversified habitats and the habitat diversity index has been doubled with the artificial step-pool system. The improvement of habitat creates a favourable aquatic environment, thus promotes the development of aquatic bio-community. The benthic macro-invertebrates are used as indicator species to evaluate the ecology of the stream. The number density of individual benthic invertebrate and taxa richness (number of benthic invertebrate species) both rise with the increase of habitat diversity, and many species, which were never found in the stream before have being attracted to colonize in the habitat. The artificial step-pool system is an effective strategy for aquatic ecology restoration of debris-flow ravine.