Research On Water Level And Flow Detection In Urban Rain And Sewage Drainage System

Nowdays, water environmental issues have widely been concerned by all walks of society. Researches of water level and flow detection in urban drainage system, not only have important significance for integrating water resources plans and preservation, but also play a huge role in solving environmental pollution of city. This task is from the State water pollution control and management of major projects"high sewage-interception rate of urban storm sewer network construction, alteration and operation control key technology research and engineering demonstration" (2008ZX07317-001). This paper focuses on the detection of the physical quantities relevant to the task. The main work has been accomplished as follows:Firstly, water level detection. Water level is one of the indicators of water safety problem; water-line detection is an important measure to ensure water safety. At present in the water level detection the water gauge widely used is still traditional, and its scale is usually masked with Arabic numbers. However, a small information amount of the number grapyeme makes it difficult to distinction accurately among some figures, and the calculate course is complex; the recognition rate is also not high, resulting in inaccurate measurements. To solve this problem, this paper proposes a water gauge of the new type, and on this basis, combining image processing technology to detect automatically the water level. This technology not only enriches the contents of image processing, but also gives a novel method of detecting water level.With a CCD vidicon over the riverway pillar and a lamp below it, images with water gauge are gained, and then collected water gauge image is preprocessed, namely, by means of gray processing, histogram equalization, median filtering, canny edge detection and morphological processing, image noise is decreased. Secondly, image is segmented by Otsu method and further extracted key features for recognition.Secondly, flow measurement. For this phenomenon that mixed rain water has a negative impact on the city, this paper presents a rain sewage water flow measurement method based on Doppler Ultrasonic combining characteristics of the rain-sewage flow.The paper briefly introduces basic principle and realizing method of the Doppler Ultrasonic flow measurement technology. On the basis of absorbing and referring to the domestic and foreign advanced ultrasonic flow measurement technology, the system hardware is designed and the idea of the system software is given. The core of the hardware is chip of R5F212A7SNFA, including generating and amplifying of ultrasonie, receiving and amplification of signal, data acquisition, memory and display. By the Doppler Effect principle, flow velocity is worked out; and then combined with other data, fluid flow is obtained further.The proposed water level auto-detection technology based on the new water gauge and image processing overcomes the problem of high error rate of traditional digital. Results from the recognition view shows that the new "field" type of water gauge has marked improved in recognition, and the correct recognition rate reaches to 100%, which significantly improved the detection accuracy.The designed rain-sewage flow measurement system is practical and convenient. This system can transmits and receives the ultrasonic wave, the results of practical measurement and experiment show that the scheme has basically reached the requisition. Because of the restriction of experimental conditions, the specific indicators have not been measured. Finally this paper makes the prospect.