ABSTRACT

An estimated 26% of potable water is lost due to leaks from the water distribution network in the City of Tshwane (formerly Pretoria), the capital of South Africa. Leaks are often difficult to detect, with the consequence that they are not fixed. A need therefore exists for a detection system that would indicate a water leak. The potential exists to bury a fibre optic cable in the same trench with the pipe when constructing new pipelines. The paper investigates the use of fibre optic temperature and strain measurement as a means of leak detection on pipelines buried in an unsaturated soil profile with a deep water table. For the system to be successful it is necessary that leakage-induced temperature and strain changes must be distinguishable from naturally occurring changes. Results from tests using discrete Fibre Bragg Grating Sensors to evaluate the performance of such a system suggests that successful leak detection will be possible under the soil conditions tested.