Article Channel Planform Dynamics Monitoring and Channel Stability Assessment in Two Sediment-Rich Rivers in Taiwan Cheng-Wei Kuo 1,*, Chi-Farn Chen 2, Su-Chin Chen 1, Tun-Chi Yang 3 and Chun-Wei Chen 2 1 Department of Soil and Water Conservation, National Chung Hsing University, 145 Xingda Rd., South Dist., Taichung, 402, Taiwan;
[email protected] (S.-C.C.) 2 Center for Space and Remote Sensing Research, National Central University, 300 Jhongda Rd., Jhongli Dist., Taoyuan, 32001, Taiwan;
[email protected] (C.-F.C.);
[email protected] (C.- W.C.) 3 Water Administration Division, Water Resources Agency, Ministry of Economic Affairs, 501,Sec. 2, Liming Rd., Nantun Dist., Taichung 408, Taiwan;
[email protected] (T.-C.Y.) * Correspondence:
[email protected]; Tel.: +886-4-22840238; Fax: +886-22853967 Academic Editor: Peggy A. Johnson Received: 30 November 2016; Accepted: 25 January 2017; Published: 30 January 2017 Abstract: Recurrent flood events induced by typhoons are powerful agents to modify channel morphology in Taiwan’s rivers. Frequent channel migrations reflect highly sensitive valley floors and increase the risk to infrastructure and residents along rivers. Therefore, monitoring channel planforms is essential for analyzing channel stability as well as improving river management. This study analyzed annual channel changes along two sediment-rich rivers, the Zhuoshui River and the Gaoping River, from 2008 to 2015 based on satellite images of FORMOSAT-2. Channel areas were digitized from mid-catchment to river mouth (~90 km). Channel stability for reaches was assessed through analyzing the changes of river indices including braid index, active channel width, and channel activity.