Applications for Irrigation Engineers
- Surface water transport and storage efficiency improvements using HERBI,
- Soil moisture and salt migration mapping around irrigation infrastructure, and
- Recharge Infiltration and managed aquifer recharge and recovery design services.
HERBI lightweight seepage and saline inflow mapping and channel dimensions measurement apparatus.
Since 2002, Groundwater Imaging have refined a waterway geophysics solution while conducting the majority of seepage investigations of Australian Canals and Channels. We now offer the same solution developed and refined in Australia to overseas clients.
With our lightweight HERBI (Hydrographic Electrical Resistivity and Bathymetry Imager) we can survey about 10km of channel or other waterway per day on foot, or much more if there is continuous vehicular or boat access. HERBI images the substrate to reveal where seepage occurs and where it goes and thus from where it could be recovered. HERBI was a finalist in ‘The Australian Innovation Challenge 2012′. In drains and rivers, the reverse of seepage, that is baseflow (which usually increases waterway salinity) is imaged very clearly. HERBI also collects sonar bathymetry data, and optionally geodetic quality GPS position data and waterway width data (from rangefinders) resulting in cross section and gradient data along the full surveyed length of waterways (this is our current area of R&D). Such data can quickly be converted into simulated and calibrated 1D flow data plus surface area data for evaporation and water balance calculations.
Find where water escapes from DAMS using HERBI and at the same time measure dimensions and install a level gauge so losses can be measured over time. For examples click here.
Moisture Migration Mapping (MMM) :We can also create time-lapse tomographic images of subsurface moisture and salt migration around irrigation infrastructure such as drippers, sprinklers or ponds using specialised geo-electric equipment. Such imaging equipment may be equipped with GSM/GPRS telemetry for remote monitoring.
Managed Aquifer Recharge (MAR): Legislation is finally being prepared that facilitates continuity of ownership of surface water as it is intentionally recharged into the ground. In most Australian farming enterprises this technique of storing water is the biggest untapped opportunity we now have for water management improvement. Recharging water, in a measured and beneficial way, into un-confined aquifers however is not a simple process and a high degree of investigation and monitoring is appropriate. In agriculture, it is anticipated that the typical scheme will target permeable pathways from the near surface to deeper aquifers and our geophysics is ideal for mapping such pathways in 3D. A short duration surface water storage would be used to capture flood flows and hold them while they are fed into settling and filtration works and injection bores that inject into pre-prepared infiltration galleries connected to the tops of deeper natural infiltration pathways. Injection rate must be managed to avoid waterlogging and to control this we would install water level monitors in piezometers strategically placed using our geophysical imaging. The level monitors would be observed continuously and the injection rate adjusted in a ‘feedback loop’ manner to maintain appropriate groundwater levels in the infiltration area. This ‘agricultural’ type of MAR differs from that used for high value water in town and mine supplies in that it must cheaply inject huge volumes of water when the opportunity exists just after floods, and for such injection, unconsolidated aquifers are preferred due to the lower cost of setting up, and regularly de-clogging, injection/infiltration works near the ground surface as opposed to deep underground.
For unconsolidated shallow aquifer MAR we can image relevant aquifers and infiltration pathways in 3D detail sufficient to design infiltration works and surface water storages using AgTEM. (See ‘Land Based’ page). Once set up with telemetry based monitoring, we can image soil moisture differences around the infiltration galleries.