:::

Sitemap

Lastest News

Effectiveness Evaluation and Improvement of the River Restoration Plan

2017-03-31

    Water resources have been vital for the survival of human life. Since the ancient times, people have gathered around rivers, developing into villages with dense populations (as shown in Fig. 1). Considering safety issues and the demand of water resources usage, there have been more and more public construction projects.
相關圖片
• Fig. 1 Human settlements have been developed around river beaches. In the picture, it is the Song He Tribe located along the shore of Dajia River, Heping District, Taichung City. Many check dams have been built by the slopes and streams. (Photo captured from Google Earth on October 14, 2015)

    Since 2001, the Public Construction Commission, Executive Yuan has been sponsoring the Public Construction Golden Quality Award contest in order to honor institutions, manufacturers, and individuals in public constructions to promote quality of public construction projects. Improving the living environment, it helps promote benign competition among manufacturers.
    The Public Construction Golden Quality Award includes four major categories of civil engineering, water conservation, architecture, and facilities. Their evaluation is conducted with seven indicators: quality control, progress control, quality durability and maintenance management, energy saving and carbon reduction, disaster prevention and safety, environmental conservation, and innovative technology. The execution of public construction projects are evaluated and marked with these indicators to award the excellent performers. From 2001 to 2015, it has awarded 57 supreme quality awards and 148 good quality awards.
    As people begin to concern more on the quality of living environment, and the promotion of the concept of ecological conservation and engineering technology, river restoration projects with different goals, including flood prevention, ecological conservation, landscape, water quality, and more, in hydraulic engineering have been increased year by year. As mentioned earlier, the Public Construction Golden Quality Award that is sponsored annually includes 12 Supreme Quality Awards and 26 Good Quality Awards. Among them, there are various cases related to river restoration and regulation projects. However, after the execution of river restoration and regulation projects, how did they accomplish their project goals? How were their accomplishments? As the environments of rivers and streams changed over past years, did the results of river restoration sustain? If they do not sustain, how should we improve the deterioration of the results of river restoration and regulation projects? How should we evaluate, maintain, and improve them? This essay will discuss related issues in the following.
    According to Downs and Kondolf, American scholars, mentioned the method of evaluating river restoration project – Post-project Appraisals, PPAs in their publication dated 2002. It mainly aims to utilize the experiences of existing river restoration projects to provide suggestions in the design of related plans in the future. With reference to their thinking of evaluation proposed in their research, this essay proposes the method – “Overall Effectiveness Evaluation of River Restoration and Regulation Projects” the evaluation of data collection of restoration projects, assistance in investigation and process of analysis, accomplishment of project goals, and model learning to understand the results and current conditions of the execution of the river restoration projects and the possibilities of using related cases as examples for learning. With the evaluation results, suggestions for the improvement of river restoration projects will be proposed. The process of the evaluation projects is shown in Fig. 2.
相關圖片
相關圖片
• Source: Su Yu-wen, 2016 Flow chart of Overall Effectiveness Evaluation of River Restoration and Regulation Projects

    “The restoration project of Zhonghe Bridge at the downstream of Chotengkeng Creek”, a Good Quality Award project in the sustaining project category of the Public Construction Golden Quality Award is used as example in this essay. Data was collected on related restoration projects, and the details of the restoration plans, including design charts and drafts and interviews, are obtained from the sponsor Taichung Branch, Soil and Water Conservation Bureau, Council of Agriculture, Executive Yuan and the supervisory unit De Zhong Engineering Consultants Ltd. By executing on-site investigations and measurements of river cross-sections, necessary information required to the evaluation of goals achievement were obtained. The completeness of documents on and records of the restoration plans were also evaluated for model learning.
    The evaluation result discovered that the goals of the restoration plan were flood control and habitat construction. The flood control adopted the standard of 50-year recurrence interval of no overbank flooding. The accomplishment standard of the water habitat construction was not recorded accurately. Regarding the investigation of basic data, design thinking, and design charts and drafts (Fig. 3), they were completely recorded. At the early stage of the completion of the engineering project, it was inspected and accepted at passed level. There is not any investigation records. Although Taichung City Government announced that since October 24, 2006, the river conservation policy would be implemented for three years, with the assistance of local residents in patrolling, there was not any monitoring plan for the accomplishments of the restoration project. There were only a few follow up plans to conduct investigation on ecology and water quality. It renders certain difficulties to conducting long-term follow-up.

相關圖片
Source: Taichung Branch, Soil and Water Conservation Bureau, 2006 Fig.3. Cross section of related configurations of pond construction at the downstream of ground sill

    In sum, the documents of this restoration project with the possibilities of providing model learning is evaluated as “good.” If we intend to promote the possibilities of model learning, we should design the accomplishment standard appropriate for the plan, regarding the project goals and considering the phase changes of the river. In addition, the management policy at the water collection zones by government institutions should be consulted together. Moreover, we can also cooperate with local groups to design long-term monitoring plans in order to create river restoration monitoring records.
    Regarding the evaluation of goals’ accomplishment, as the project goals include flood control and water habitat construction, this essay inspected and surveyed the site many times between 2010 and 2013, and conducted habitat investigation on 2013 and river cross-section measurement 2 times from 2012 to 2013. Analyzing the results of the surveys, it indicates that the goals of flood control is accomplished (consult Fig. 4 for river path environment), and the water habitat construction is partly completed. Their project goals accomplishments are evaluated as “good.” If we intend to promote the degree of goal accomplishment, it is suggested to review the setup of project goals. It is because the section of river restoration is a creek on a slope, with bigger changes on the sediments on the river bed. It is expected that it may be inappropriate to construct the water habitat with the regulation construction structures. Perhaps it may be highly effective in a short time after the completion of the construction project. However, with the changes of the river path, those achievements may disappear after a flood during a typhoon.
    Generally speaking, by applying the evaluation method discussed in this essay, it can provide experience for references derived from existing restoration projects for the design of related plans in the future. Regarding the improvement of existing restoration plans, it can also provide guidelines and suggestions for further references. It may be helpful for the enhancement and improvement for existing river restoration plans to promote the efficiency of river restoration.
相關圖片
相關圖片

• Source: Photo by Su Yu-wen. Fig. 4 Current conditions of the river section around Zhonghe Bridge at the downstream of Chotengkeng Creek. From the picture, there was no significant changes in the overall environmental changes between 2010 and 2013. The significant change was the increase of vegetation on the river path. It can provide references for the review of the design of flood-control capacity.

 


References
1.  (Construction completion graphs of the river regulation around Zhonghe Bridge at the downstream of Chotengkeng Creek, Taichung Branch, Soil and Water Conservation Bureau, Council of Agriculture, Executive Yuan)

2. Public Construction Golden Quality Award , Public Construction Committee, Executive Yuan, http://cloudweb.pcc.gov.tw/quality/2015quality/index_news.html#.V7p5_E197q4,2016。
3. (Public Construction Committee, Executive Yuan Homepage>Quality control>Public construction golden quality award) http://www.pcc.gov.tw/pccap2/BIZSfront/MenuContent.do?site=002&bid=BIZS_C09904125,2016。
4. Su, Yu-wen, Evaluation of Objective Achievement and Learning Opportunity in River Restoration Projects - Case Studies in Taiwan. Ph.D. Dissertation, Department of Hydraulic and Oceanic Engineering, National Cheng Kung University, 2016

5.Downs, P. W. and Kondolf, G. M. Post-project appraisals in adaptive management of river channel restoration. Environmental Management. Vol. 29. No. 4. P.477~496. 2002. 
Bio
Name: Su Yu-wen
Experience: Water and Soil Conservation and Ecological Engineering Research Center; Project engineer, Water Resource Planning Institute, Water Resources Agency, Co-Principal Investigator, Ministry of Economic Affairs; Taiwan River Restoration Network Maintenance Project
Specialties: River restoration, river water quality, water and soil conservation

 

Pictrue

  • 01