Taiwan - Development of flood detention space in the Xinji Industrial Park, Tainan City

Issues and Objectives

The Xinji Industrial Park is located at the border of Annan and Anding Districts in Tainan City. The park covers a total development area of ​​123.26 hectares, including approximately 74.23 hectares of industrial land (I), approximately 2.52 hectares of industrial land (II), and approximately 46.51 hectares of public facilities land. To meet the needs of industrial land use and support local industries, development work on the Xinji Industrial Park was restarted at the end of 2012. The land use plan was revised in March 2015, and construction began in November of the same year. The site plan of the Xinji Industrial Park is shown in Figure 1. The Xinji drainage system outside the industrial park flows into the Zengwen River. This area is characterized by flat terrain, slow-moving water, and a tendency for riverbed siltation. To prevent the development of the Xinji Industrial Park from burdening the existing Xinji drainage system, remediation work was carried out.

Figure 1. Site plan of Xinji Industrial Zone. Image source: Reference website.

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Improvement Measures Taken

Following the development of the Xinji Industrial Park, the total flood retention capacity provided, including the flood retention ponds within the industrial park, the intercepting ditches at the park boundaries, and the flood retention space provided by building and road land, is approximately 280,000 tons, higher than the 270,000 tons of flood retention capacity in the low-lying areas before development. Furthermore, to prevent the raised ground level from affecting the drainage system of this area, intercepting ditches are planned to be excavated around the green belt surrounding the industrial park to collect surface runoff from outside the park. This prevents external runoff from affecting the drainage within the park and creates a lower-lying area around the intercepting ditches, providing additional flood storage space and further reducing the risk of flooding in the surrounding area. The Xinji Industrial Park flood retention pond is shown in Figure 2. In conjunction with the development of the Xinji Industrial Park, the Tainan City Government Water Resources Bureau also invested approximately NT$64.95 million to improve the Xinji drainage system. Construction began in March 2018, and upon completion, it will enhance flood control and drainage capabilities, reduce flooding in the Tian Dong community of Annan District, and benefit the overall land use and development of the area.

Figure 2. Flood Detention Pool in Xinji Industrial Zone. Image source: Reference website.

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Results

On August 23, 2018, a tropical depression lingered, causing continuous heavy rain and flooding in many parts of Annan District. The 24-hour accumulated rainfall in various parts of Tainan City exceeded 600 mm. The flood retention pond in Xinji Industrial Park played its role in water storage and regulation, keeping the rainwater in the retention pond and not affecting the manufacturers in the area or increasing the burden on the downstream drainage system.

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Reference Websites

Xinji Industrial Zone - Official Website.https://www.sin-ji.com.tw/index.php

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