2.1.5.3 Gaps

Some knowledge gaps in the existing datasets that have been identified so far include:

There is a general lack of groundwater monitoring bores in the Richmond and Clarence river basins. This means that hydraulic gradients between streams and aquifers are often only inferred through interpolation of widely spaced data which significantly reduces the accuracy at which the riparian hydrological requirements and responses can be determined.
Improving identification of gaining and losing reaches (where threatened by mining activity/modification of hydrology) is important in assessing risk to aquatic and hyporheic systems. Using EC as an indicator of baseflow to streams is more difficult in areas of low groundwater ECs such as the Richmond river basin and Clarence river basin due to the smaller contrast in EC during periods of low flow and high flow. This limitation can be mitigated through the assessment of additional chemical parameters and groundwater age tracers along stream transects. Tracers such as ²²²Rn and groundwater age tracers could further help with the identification of gaining reaches.
Lidar data are available for part of the bioregion, but have not been acquired to date due to the substantial cost. Lidar data would improve the accuracy of topographic representations. This would further help to determine the hydraulic relationships between creeks or rivers and the underlying aquifers, in particular in low-relief/low-lying areas such as in the floodplains of the Bremer River, Richmond River and Clarence River. In particular, lidar data would help to assess whether the creeks or rivers are incised deeply enough to intersect the basal coarser-grained alluvial sediments (i.e. sands and gravel). However, the usefulness of lidar data for assessment of surface water – groundwater interaction is limited in areas where only few monitoring bores exist.
There is a lack of long-term surface water chemistry monitoring data in most areas.
Stream-gauging stations are often not located in areas where stream-aquifer connectivity can be inferred (i.e. they are not close to existing groundwater monitoring network transects). As a result, hydraulic gradients between streams and aquifers can often only be inferred through interpolation of widely spaced data.
In many parts of the bioregion, many wetlands are likely to be related to either upwelling of deep groundwater at the down-gradient end of flow paths within the basin or to faults where aquifers and aquitards are juxtaposed. However, there is a general lack of nested groundwater monitoring bore sites where stacked bedrock aquifers are screened. Having more nested bore sites would provide an improved understanding of vertical gradients between aquifers and therefore help with the identification of bedrock discharge areas.

Last updated:

8 January 2018

Product Finalisation date

Numbered headings

ASSESSMENT

PRODUCT DATA