This Project investigates the physical properties and ecological features of rivers, and reviews case studies of the reestablishment of habitat for fish abroad and the design using eco-engineering method for Fa-Tzu Creek and Beinan River, a central government administered stream in Taiwan. It is understood that constructions employing eco-engineering method for river improvements and preservation or restoration of ecosystems should be performed under circumstances of safety assurance of flood control and thorough understanding of ecosystems. Making good use of models for analysis purpose may increase the chances for the project planning in question to become feasible. As for construction technology, this Project collects information on the recent failures of river bank protection works and flow control structures in Taiwan and investigates the design criteria of the failed structures. It is found that most designs follow analysis methodologies frequently employed abroad. Main reasons for the failures of hydraulic structures in Taiwan include drastic scour and deposition in river channels, severe scour of foundations and negligence of river characteristics in planning layouts.
This Project, following the design criteria for eco-engineering method -- taking appropriate measures in accordance with local conditions and acquiring necessary materials locally, develops a model analyzing the stability of river bank with vegetative protection and collects information on species and characteristics of plants suitable for growing in the middle and lower reaches of rivers in Taiwan. It is aimed to provide useful references for bank stability analysis and plants selection in river improvements using eco-engineering method. Models for stability analysis of river channel are also investigated regarding their individual functional applications and their aids in design.
Work items completed in the fiscal year of 2005 are as follows.
1. Completed the task of "Importance of Pre-engineering Planning", including preliminary study on contents and items of pre-engineering planning, and drawup of selection of eco-engineering method and flowchart of layout.
2. Proposed an approach for investigation of river environment suitable for river improvements using eco-engineering method.
3. Completed "Design Essentialities for Eco-engineering Method for River Improvements", including design criteria determination and design essentialities for eco-engineering method taking into account of flow discharges and relevant empirical formulas. Each eco-engineering method was presented with check formula and point of emphasis for ecosystems to be considered in design.