基於模式率定需求之自來水監測站址優選模式

Abstract

一個經過嚴謹率定且能描述實際狀況的管網模式對於自來水系統的管理、操作、維護、設計甚為重要。而自動監測站之設置若能考量模式率定之需求，選擇較佳的位置設置監測站，將有利於管網模式之率定，本研究因而結合模擬模式、敏感度分析、叢集方法及優選模式發展了一套基於模式率定需求的監測站網選址模式與程序。首先發展一個介面程式，結合GRG2及EPANET2 建立非線性優選模式，以尋求符合監測站實測水頭壓力之最佳粗糙度係數組合。監測站選址乃是基於敏感度分析而訂定，主要以二種方式進行。第一個方式為選擇對已設監測站點影響較小(新站點對既設點敏感度低)的站址，以期新設監測站能擴大監測所代表性涵蓋範圍；第二個方式為選擇在改變水頭壓力之重新率定結果下，令粗糙度修正值較多(新站點對目前率定結果敏感度高)的站址，以選擇能改善目前率定誤差最多的站址。新站點之選擇則採用叢集方法，將空間中之候選節點分成數個叢集，並由所有叢集中選擇一組較佳的站址組合，以滿足涵蓋範圍最大之設置原則，並以新選的組合重複上述步驟進行選址，直到滿足需求或達到站址數限制。本研究以一個假想案例，以分析上述程序之適用性，分別說明敏感度分析結果、站址篩選結果、叢集分區結果、選站結果、率定結果，綜合結果發現，監測站設置考量敏感度分析與叢集分析，可增加率定所涵蓋之範圍，以增進率定優選模式之準確性，達到自來水管網模式率定之目標。

A hydraulic model is important for the design, management, and operation of a water distribution network. The hydraulic model must be well calibrated to approximate the real flow pattern in the network. If monitoring stations are placed at locations that can provide appropriate data, they should be able to facilitate the model calibration. Therefore, this study integrates a simulation model, sensitivity analyses, a clustering approach, and an optimization model to propose a calibration-based monitoring station siting procedure. A computer program is developed to serve as the interface between GRG2 and EPANET2 for establishing a nonlinear optimization model to seek the best roughness set to fit observed head pressures. Two sensitivity-based criteria are applied for siting monitoring stations: (1) low roughness sensitivity after calibration for head pressures at desired locations; and (2) high roughness sensitivity after calibration for a specified head pressure change at a desired location. A clustering method is used to divide candidate locations into a desired number of groups and one is selected from each group to effectively expand the monitoring coverage. Repeat the above procedure until a specified number of locations are selected. A hypothetical case is applied to illustrate the applicability of the proposed procedure. The monitoring network obtained by the procedure can effectively increase the coverage and also the quality of the hydraulic simulation model calibration.