Monitoring Recharge in a Changing Climate
Perth is a groundwater city.
Groundwater fills our lakes, waters our gardens, and keeps the woodlands and forests green.
Surface - groundwater interactions in the streams feeding Mussel Pool at Whiteman Park.
Not all rain makes it to the groundwater. The amount that does - the recharge - varies a lot. What a warmer, drier, and more extreme future climate means for groundwater recharge, and how we can use groundwater sustainably, remains uncertain.
That's why the Thompson Lab at UWA is working with the Western Australian Department of Water and Environmental Regulation to create recharge observatories around Perth.
We started drilling earlier this month and have now installed equipment in bushland and pasture sites in beautiful Whiteman Park, and in a "wildings" environment in the former Gnangara Pines area. Gingin and Dandaragan sites yet to go in the north of Perth - with future sites to come south of the city near Myalup. It's a busy and exciting program - installing advanced tech from Sentek with expert drillers from Geosonic Drilling, running geophysics, and sampling for soil, water, and biological characterisation.
We are finding surprising things already.
Great variability in soil profiles over short distances - only the vegetation (we think) can be responsible.
Iron accretions well below the present water table in pasture sites - possibly marking the former (lower) water table height before the trees in the area were cleared?
We have a fun team to work with - Simone Gelsinari and myself, and Andrew Van De Ven from UWA. Expert on the Swan Coastal Plain, Richie Silberstein, who wears many hats (UWA, ECU and Hydro-Environmental Consulting). Joel Hall from DWER.
We're working with Geosonic Drilling, who run this lovely little rig. that sneaks in between the banksias and grasstrees with minimal disturbance. Rob, the lead driller, designed and built the rig, and has been navigating the technical challenges of flowing sands, iron accretions and chunky tree roots.
Lots of work left to do to get the sites up and running and characterised properly - but we're excited to get going, and feeling good.