供水管網漏水管理之探討-以大台北供水區為例

Abstract

一個四周環海，年平均降雨量達2,510㎜為世界平均值2.6倍的寶島，依國際人口行動組織〔PAI〕統計，台灣被列為世界排名第18位的缺水國家，其原因包括：第1留不住水；第2存不住水；第3太浪費水；2010年亞洲綠色城市評比，台北市名列第二，僅次於新加坡。然而在評比報告中也指出，在水資源運用指標中，台北市僅呈現等同於整體的平均水準，其中以漏水率及每人每日用水量，均比亞洲參與評比城市之平均值高。依臺北自來水事業處資料，大台北地區之漏水率為21.60%(99年底)，以每年配水量9億噸計算，漏水量即達1億9千萬噸，相當於流失翡翠水庫一半之蓄水量，如此龐大之漏水，讓北水處想盡各種辦法要找回失去的水。為解決漏水問題，依據國際自來水協會(IWA)建議，為維持配、給水管網系統漏水不致惡化，其管線汰換年汰換率須達1.5%以上，因此北水處進行管網漏水控制及管理方式，推行小區計量工法，依循區塊規劃、裝表計量、管網改善及長期管理之系統化方式降低漏水率。 本研究統計北水處93年至99年間漏水原因及管種等資料，分析供水管網中之各種管種之漏水現象，並針對不同管種其管網汰換之管線長度與漏水件數之變化加以探討，找出最容易漏水之管種及地區，以利進行管線汰換，另依據國際自來水協會(IWA）所建議之漏水管理四大主軸：管線汰換、漏水檢測、修漏品質、水壓管理，對於管線汰換及漏水檢測兩項，利用小區計量加以結合，並以次分區、夜間最小流及巷弄直接法等方法，檢核管線汰換及漏水檢測之成效，並對修漏品質提出具體建議，以減少漏水復發，提出如何以有效之方法及可行之預算經費，可供北水處管控將大台北供水轄區之漏水率由21.6%降至目標值。

Taiwan, surrounding by oceans, its annual precipitation 2510mm is 2.6 times of average value worldwide. However, according to the report of Population Action International (PAI), Taiwan is ranked as the 18th water shortage country. The reasons inciude 1. its steep rivers barely holding rainfall, 2. lacking of enough reservoirs for preserving water, and 3. too much water been wasted. In 2010, “Asian Green City Index” has reported that Taipei was rated as the 2nd fine city following after Singapore, but one of the indexes, “Water”, performed nothing but ordinary, only to be weighed down by leakage rate & water consumption per capita per day which were higher than any other country in Asia.According to statistical yearbook of the Taipei Water Department (TWD), the leakage rate of the Great Taipei Area was 21.6% by the end of year 2010. Under such leakage rate, the annual water leakage volume of TWD is staggering 190 million m3 which is equivalent to half capacity of Feitsui reservoir. That is why TWD is always trying to control its leakage. In order to do it effectively, TWD has adopted the suggestion of International Water Association (IWA) who recommended that annual pipeline replacement rate must reach 1.5% to prevent the leakage of pipeline networks from deterioration. Therefore, TWD has implemented a project of pipeline replacement along with management measures for leakage control. The most important measure is District Metering Area (DMA) which includes 4 main steps of Zoning, Metering, Pipeline Replacement and Long-term Management. This research analyzed the leakage phenomenon of different kinds of pipeline in the networks from the leakage repair data of TWD during 2004 to 2010. By studying the relation of the leaking frequency, categories of pipe and lengths of pipe, we were able to find the very areas and pipes suffering from most serious leakage which are crucial for pipeline replacement project. The TWD is now adopting IWA’s multi-pronged approach named “4-major axes of leakage management” which combines pipeline replacement, active leakage inspection, quality of leakage repair and pressure management. This research suggests that using DMA for evaluating the results of pipeline replacement & leakage repair is necessary. And, the suggestions also comprise the strategies for increasing the quality of leakage repair to avoid the Leakage Recovery in the future. Furthermore, this research would be a good reference for the TWD and other utility companies who are fighting against the leakage problems.