Managing our floodplains using the latest technology

Historically it has been difficult to accurately and reliably measure floodplain flows captured through the practice of floodplain harvesting.

Whilst many water entitlements take water from a direct point such as a river pump, floodplain harvesting is captured through multiple points and via numerous mechanisms. In addition to this complexity, floodplain harvesting may also mix with water taken under other entitlements, from previous floodplain take events, irrigation tailwater returns and agricultural runoff.

As part of the NSW Healthy Floodplains Project, there has been significant investment in data, satellite imagery and modelling over 7 years to more accurately understand what happens to floodplain flows that do not return to a river. Using the latest technology, the department is being able to calculate with greater accuracy historical and legitimate floodplain harvesting practices and take in the northern Basin. Public confidence in this process has been bolstered through the Independent Peer Review PDF, 1419.81 KB and the NSW Floodplain Harvesting Action Plan PDF, 421.67 KB.

Better data from better measurements

The department is using high-resolution light-detection-and-ranging (LiDAR) and remote-sensing technology to construct 3D images. Along with traditional 2D satellite imagery, this technology enables accurate measurement of floodplain storage capacities. People have used LiDAR for many years to construct models that predict how water moves across floodplains. However, this is the first time it has been used to establish the location, capacity and relative height of each storage on the floodplain. Using LiDAR, detailed storage curves have been developed for all storages on the floodplain. These detailed storage curves convert water-level data for each on-farm storage into water volumes.

Read about the development and application of storage curves.

LiDAR has also been used to assess the effect ‘first flush’ rainfall and runoff events have on floodplain harvesting and overall storage volumes. This first flush assessment has resulted in a thorough and reliable assessment of floodplain harvesting volumes.

Read about the Assessment of take and protection during first flush flows in the northern basin PDF, 1495.35 KB

Digital data loggers and telemetry equipment will send data securely to the department’s data acquisition service. This will enable the landowner, Natural Resources Access Regulator (NRAR), WaterNSW and the department to monitor water volumes in a transparent way. This accurate data will allow any compliance and enforcement, billing and other water-management activities to be done quickly.