Technology And Practice On The Safty Assessment Of City Water Supply Network

As the main part of city water supply system, water supply distribution network has such characteristics as foundation, complexity, openness which made it very difficult to manage and maintain. Guaranteeing the security of water supply distribution network is the foundation of basic life of citizen and city function to circulate normally. Whether safety guarantee system of water supply distribution network is perfect will directly affect economic development and construction of city. So the safety assessment system of the water supply network is established. It is of great significance for city planning and management of water supply system as well as rehabilitation-and-improvement plan of existing network.Not only various circumstance which influce on the water supply network, but also study present condition and the development direction of aftertime at home and abroad at present are analyzed completely. Carry on the analysis of system to the city water supply network, and research on dynamic management technology for it and engineering control technique. Considering the characteristics of base, complexity and the problem to manage and maintain difficultly of water supply system, a comprehensive safety assessment system is given according to system engineering principle and interrelated historical date. At the same time, a table of safety assessment rating is presented. The safety assessment rating that has been obtained can be classified as five levels, namely, unsafe, relatively unsafe, relatively safe, safe and very safe, and represented with V, IV, III, II and I respectively. Considering the characteristics of fuzziness in safety evaluation of water supply network, an approach of multi-layer fuzzy sets for complicated system is presented. The fuzzy pattern recognition model is combined with fuzzy overall assessment model to evaluate the safety of water supply network. In the model, adapted analytic hierarchy process (AHP) and relative membership functions are proposed to calculate respectively the weights of evaluation indexes. Finally, through two-level fuzzy synthesis evaluation, the proposed approach is successfully applied to assess a given water supply system in Qingdao area with MATLAB 7.1 program and a relative safety rating is given. Water distribution systems are inherently vulnerable to accidental or intentional water contamination, so applying early warning system is an important approach to guarantee water supply system security. A methodology is presented for finding the optimal layout of a given number of stations by 0-1 integer programming method. The objective is to detect all the likely external intrusions through nodes in the least time. The proposed approach is successfully applied to a given water supply system in Qingdao area, and it illustrates that the methodology is feasible to detect the external intrusions through nodes and it can help to identify the source-contaminated nodes.Finaly according to the complete analysis to the water supply distribution network, the emergency plan about water supply network are drawn up, at the same time, the appropriate safety prevention model are presented.