Illicit discharge detection in stormwater drains using an Arduino-based low-cost sensor network

Abstract

Illicit discharges in urban stormwater drains are a major environmental concern that deteriorate downstream waterway health. Conventional detection methods such as stormwater drain visual inspection and dye testing all have their fundamental drawbacks and limitations which might not easily locate and eliminate illegal discharges in a catchment. We deployed 22 novel low-cost level, temperature and conductivity sensors across an urban catchment in Melbourne for a year to monitor the distributed drainage network, thereby detecting likely illicit discharges ranging from a transitory flow with less than 10 minutes to persistent flows lasting longer than 20 hours. We discuss rapid deployment methods, real-time data collection and online processing. The ensemble analysis of all dry weather flow data across all sites indicates that: (i) large uncertainties are associated with discharge frequency, duration, and variation in water quality within industrial and residential land uses; (ii) most dry weather discharges are intermittent and transient flows which are hard to be detected and not simply due to cross-connections with the sewerage network; (iii) detectable diurnal discharge patterns can support mitigation efforts, including policies and regulatory measures (e.g., enforcement or education) to protect receiving waterways; and, (iv) that it is possible to cost effectively isolate sources of dry weather pollution using a distributed sensor network.

Low-cost monitoring systems for urban water management: Lessons from the field

“…With more sensors, more water management systems can be monitored, which is particularly useful in regions where empirical data are still scarce ( Hamel and Tan, 2021 ). Hydrologic behaviour of complex catchments can also be better understood with more observations, with greater opportunities to track water flows spatially and temporally ( Shi et al, 2022 ). In addition, real-time communication opens the door to maintenance on demand, greater information sharing with a range of audiences (see Section 6 ), and optimisation through real-time control for centralised and decentralised systems.…”

A Low-Cost Radar-Based IoT Sensor for Noncontact Measurements of Water Surface Velocity and Depth

“…This can lead to additional costs, initially during installation and in maintenance over the lifetime of the sensor. For example, [ 24 ] outlines the severe challenges of operating an in-water sensor, including maintenance up to every two weeks, which is not logistically or economically possible when considering a dense network of sensors in a water catchment. Out-of-water and noncontact sensors promise to offer the same measurements, but without contact with the body of water being measured, hence alleviating these issues.…”