Fortescue Metals Group (FMG) is developing mines in the central Pilbara, Western Australia. The operations require ore to be mined from below the water table, so groundwater is abstracted and reinjected elsewhere. Reinjection of surplus water can result in water table rise (mounding) which has the potential to impact vegetation due to waterlogging. FMG has the objective of preventing adverse impact on the keystone tree species Mulga (Acacia aneura). However, very little is known about the depth and spread of the root system of Mulga and consequently also the vulnerability of this species to water table changes. In conjunction with monitoring, there was a need for development of robust, defensible management triggers for water table rise and fall beneath Mulga vegetation.
To address the objective, Astron implemented a monitoring program to assess the health of mulga in mounding areas. Health is monitored by a combination of qualitative visual assessment and quantitative measures including leaf water potential and projected foliar cover. In addition, so that Fortescue could develop defensible management triggers for water table rise and fall, Astron investigated the architecture of Mulga root systems at sites planned for clearing of vegetation.
The results of the Mulga root architecture investigation allowed FMG to develop scientifically based management triggers for water table rise and fall. The Mulga health monitoring program enables potential impacts to be detected in a timely manner. Astron has several PhD qualified scientists with strong plant science research backgrounds on topics including root system function and architecture, water relations, nutrition and ecophysiology.