Author: Chris McDonough, Insight Extension for Agriculture
Research Team: Scott Gillett1, Phil Marks2, Tony Randall3.
1Wisdom Data and Mapping, 2Balanced Ag Consulting, 3 Natural Resources SAMDB
Funded By: Natural Resources SAMDB (Project 1557C)
Project Title: Use of Normalised Difference Vegetation Index (NDVI) to Manage Seeps
Peer Review: Tanja Morgan (Tanja Morgan Project Services)
- The NDVI images from both UAV and satellites can be effectively used for the identification of potential seep areas, as well as indicating areas of poor crop growth that may be contributing recharge and should be targeted for strategic high-water use management options.
- Clearest indications were provided by late season UAV flights (mid-October in SA Mallee in 2017), while satellite images taken slightly later (mid-November 2017) appeared to provide a strong identification of potential seep areas at some sites.
- While many of these areas showed obvious physical signs of excess water accumulation throughout the season, the NDVI imaging often revealed a much larger area that was under threat, which was subsequently verified by soil testing post-harvest.
- Ground-truthing the images, proved vital in understanding and interpreting the information, taking into account other landscape issues, such as the proximity to deep sandy areas, as there were often other causes of similar seep related image features.
- The use of early (pre-2015) satellite NDVI imagery had poor resolution and was unhelpful in identifying the formation of seep areas. However, more recent NDVI satellite imaging has improved with pictures that are reasonably comparable to the more defined UAV NDVI maps.
- Cloud cover can compromise satellite image quality, but there are regular flights (fortnightly) that are accessible via the internet, which creates large advantages to its potential application.
- Further work is required to develop the practical application of this technology.