Airborne water leak detection using an innovative ‘Triangle method’
This year is on course to be one of the hottest since measurements began and Europe saw its joint second warmest June on record. While the global soaring temperature is heavily impacting water resources, it is crucial to address the leakages in pipes and transmission mains. In some European countries almost half of the channelled water is lost before it reaches the tap. A high share of the losses happen in large diameter mains crossing rural areas, where companies have trouble monitoring them due to traditional field surveys being costly and time consuming. European researchers have therefore developed a surveillance service using planes – to survey wide areas – and drones – for sites difficult to access – equipped with multispectral and infrared cameras. To analyse the data, they used the so called Triangle method. It is quite a pioneering approach to detecting water leaks, which combines surface temperature measures and a vegetation index. It is based on the fact that leaks lead to lower surface temperatures, which can be detected by a thermal infrared camera. However the thermal response of vegetated soils is different from the bare ones, making it difficult to obtain an unequivocal answer in terms of moisture content and potential water loss. The researchers therefore added a parameter measuring the vegetation cover fraction, which is inferred by hyperspectral cameras, to get a temperature-dependent humidity scale which varies according to the vegetation. The system has been developed under the EU project WADI, coordinated by youris.com. Its executive director Elena Gaboardi shares the most important final results of the study. Why is this technology financially competitive? Limiting water leaks curbs the operational costs of the utilities, including the energy costs for pumping water, while increasing the amount of water that can be sold. This, in turn, limits the risk of raising prices for the customers. Compared to competing technologies, the WADI system’s economic benefit lies in the efficiency of operations: it can monitor complex networks and long pipes (50 to 90 km/h depending on the use of drones or planes) and, as it’s airborne, can reach inaccessible or secluded locations with all kind of terrain. Moreover, the cost of conventional ground detection techniques ranges from 1,000 to 5,000 euro per kilometre, while the airborne technology ranges from 50 to 200 euro per kilometre. What are the main advantages for the environment? Besides the savings in power consumption for water extraction and distribution, the identification of water leaks would obviously lead to more available water resources. Ultimately the amount of chemicals used in water treatment plants for human water delivery would also be lower. In this context, we applied an environmental and economic life cycle assessment and compared the results with the mainstream technology, which is the acoustic method. We took into account, for instance, the fuel consumed during the aircraft flights (MAV), the impact of manufacturing planes on some indicators such as freshwater eutrophication [as a consequence of the release of industrial wastewater, ed. note] and water depletion, the human toxicity indicator related to the mercury contained in the infrared detector of the cameras. For the drone flights (UAV), we focused on the impact of batteries on the ozone, metal resources and human health. In particular, we considered the electricity consumption to charge them and the need to replace them during the drone’s lifetime. It was estimated that applying the WADI techniques (both technologies (MAV and UAV)) to 5% of European water distribution systems could potentially reduce 166.5 million kg of CO2/year, by cutting the energy consumption for the water supplying. Read the full article here: http://www.waditech.eu/newsevents/airborne-water-leak-detection-using-an-innovative-triangle-method-.kl
Keywords
planes and drones, water losses, leakages in pipes, triangle method, energy costs, pumping water, environment