Progress
The project has achieved all
milestones to date and is making excellent progress. The team
has completed three major tasks. These include the first
major task of completing broad-scale soil and drainage works to
complete the fully operational Lime Assisted Tidal Exchange
management system. This has involved the design and fitting
of new technology floodgates, constructed to allow for controlled
exchange of tidal waters into the wetland drainage system.
The research team have undertaken a
major field study of site characteristics including geomorphology,
soils, micro-topography, drainage patterns, tidal exchange / liming
regime and existing monitoring equipment installations to identify
suitable locations for more detailed investigations. EM
survey highlighted ideal locations to monitor soil remediation at
the fringe of the current tidal inundation. EM38 data
demonstrated varied degrees of sub-surface lateral seepage of
marine solutes (up to ~15 m) adjacent to existing drainage systems.
The extent of lateral saline seepage into the soil profile adjacent
drains appears strongly related to their relative elevation and the
tidal range in adjacent drains and suggests strong relationships
between geomorphic units (a major control on topography) and site
specific hydrological behaviour. This has important
implications for sub-surface transport of acidic and alkaline
solutes.
The field data has been
complemented by a substantive review and analysis of archived
baseline soil and water quality data, collected over the past 6
years by QDNRW. The archived data encompass preliminary
short-term trials of Lime Assisted Tidal Exchange technology.
Preliminary results of our analysis are highly promising. It
appears that less acidity is being exported via waterways and soil
geochemistry is changing in favour of reduction and acid consuming
geochemical processes during the trail periods.
These preliminary results are being
prepared for publication.
