Daniel Penney

Daniel Penney

Daniel is a hydrologist from the Department for Environment and Water in South Australia, who commenced working in NRM with the South Australian Government in 2006. His technical skillsets include water allocation planning and hydrological catchment modelling. Recent projects include: •Low flow release modelling for catchments of the Mount Lofty Ranges, South Australia •Hydrological modelling of water supply catchments of the Western Mount Lofty Ranges, using the eWater Source model platform, and •Hydrological modelling to inform Basin Plan reporting and development of the Eastern Mount Lofty Ranges Water Resource Plan, using the WaterCress model platform.

Constructing Catchment Scale Rainfall-Runoff Models for Low Flow Release Modelling in the Mount Lofty Ranges, South Australia

Water resources of the Mount Lofty Ranges have been managed under water allocation plans (WAP) since 2013. Extraction or use limits defined in the WAPs aim to find balance between provision of water for both consumptive use and maintaining water dependent ecosystems at an acceptable level of risk (environmental targets). Earlier work to support regional water allocation planning (Vanlaarhoven and van der Wielen 2009; 2012) identified allocations could be improved and environmental targets met if low-flows were returned to streams around patterns of farm dam development. Ensuing work, conducted on small headwater catchments, indicated targets could also be met by returning low-flows via a low flow release (LFR) mechanism around various dam configurations (Alcorn et al. 2013, Savadamuthu et al. 2013). This work, to extend earlier efforts, describes the methodology for catchment scale rainfall-runoff modelling in the Mount Lofty Ranges and results of the ongoing investigations.

Development of catchment models in Source platform, with explicit representation of individual farm dams and watercourse extractions, enables assessment of the achievability of various LFR placement scenarios, in terms of the number required (cost) and environmental targets likely to be met (benefit). Scenario modelling considered how the scale and number of LFRs could be reduced while still achieving environmental targets. Options for exclusion of farm dams was based on their (i) relative location, (ii) size, (iii) use type or (iv) combination of the above. Scenarios were explored to also develop generic rules of thumb, which could be used to inform decision-making. Results confirm the earlier hypothesis that it is feasible to achieve WAP environmental targets with fewer LFRs, by strategically locating them across the landscape. Results also indicate the possibility of several suitable location strategies for a given area, and that a strategy suitable for one area might not necessarily be suitable for others.

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