Overview

This project aims to better understand how to manage urban development in high groundwater impacted environments (that is, where the water table is within 4 m of the natural ground surface).

Stage 1 was a scoping study to evaluate academic and non-academic research and 'grey' literature from Australian and international sources, and define the state of knowledge for urban development in areas of high groundwater. GHD, Water Technology and the University of Western Australia conducted the scoping study, which included structured interviews with more than 20 practitioners, regulators, researchers and academics located in Australia and overseas.

The study identified 27 contested knowledge areas and six unknown knowledge areas, clustered around the broader knowledge areas of pre- and post-development water balance, particularly infiltration and recharge rates; evapotranspiration rates; groundwater fluxes; and groundwater levels.

Stage 2 commenced in September 2019, to address these fundamental water balance and water quality gaps, using case studies, expert knowledge and new data and information.

Stage 2 comprises three work packages.

Work Packages

Work package 1: Expert Panel review

The Expert Panel has:

formulated guidance for a process and methodology for urban water management in developments impacted by high groundwater, drawing on the experience and knowledge of practitioners and researchers working in the region
reviewed several case studies to identify the technical and/or process barriers that must be overcome and the level of certainty behind the selection of modelling assumptions that needed to be made to support modelling and design parameters today. Key assumptions considered included annual and event-based runoff rates and recharge rates at different scales, evapotranspiration rates and their application in water balance modelling, and stormwater management system (including groundwater impacts) modelling.
recommended a way forward in research, particularly field-based monitoring, to validate assumptions made to reduce uncertainty in our urban water balance predictions.

The Panel consisted of Associate Professor Dr Sally Thompson from the University of Western Australia (UWA), Dr Margaret Shanafield from the National Centre for Groundwater Research and Training (Flinders University), and Greg Claydon (Chair, CRCWSC Board Director), and assisted by Research Associate, Dr Ana Mareno-Ruiz (UWA).

Work packages 2 and 3: Establishment of field validation catchment and development of validation datasets

In this phase, the Project Team will work to fill the existing fundamental science gap. They will work directly with the Expert Panel and Project Steering Committee, to design a field program to test the assumptions highlighted in the Panel's Guidance Note. This work will establish at least one field validation catchment, to determine how unsaturated zone dynamics control recharge, in urban areas impacted by high groundwater. In particular, the team will monitor key groundwater characteristics, to determine how urban development changes soil water storage and interflow dynamics, and thus recharge to, and discharge from, groundwater.