Burnt Yambulla catchment 1979 - soon after the wildfire

Yambulla catchments


Steve Mackay Msc





After graduating in forestry, Steve worked for two years as a management forester before commencing a Masters program in Natural Resources and then specialising in forest hydrology research for the following 16 years.  During this period he managed the Yambulla Forest Hydrology Study located in native forest south of Eden NSW and published research papers on aspects of forest hydrology, water quality and erosion.


He also designed and managed the Tantawangalo Catchment Study from its inception in 1981 until 1990.  Steve was a member of the national Forest Hydrology Working Group from 1976 to 1990 and Secretary from 1984 to 1990.  He was also a member of the interdepartmental Tantawangalo Technical Committee 1987-90, which had oversight of the Tantawangalo study, and a referee for the First National Symposium on Forest Hydrology in 1982.


In June 1990, Steve joined the Sydney Water Board as Section Leader of the Urban Runoff Group in the Scientific Services Division.  He built and led a team of up to 40 science graduates who sampled, analysed and reported on water quality investigations for the Clean Waterways Program conducted by Sydney Water Corporation in the early nineties.  This included the Stormwater Monitoring Project that measured event and dry weather loads of nutrients, suspended solids and indicator bacteria at 24 sites across the Sydney/Illawarra Region.


Steve co-authored a paper – Sampling methodology for the assessment of nutrient and bacterial loads in stormwater presented at the Water Down Under Conference in 1994.  This study used data from the Stormwater Monitoring Project to compare flow proportional and composite sampling for load estimation of sediment and nutrients.  Steve also has experience in water quality modelling, commencing with his Masters program and later in an UWRAA study published in 1999 – Sediment, Nutrient and Heavy Metal Characteristics of Urban Stormwater Runoff.


In December 1995, Steve was appointed as a Project Director in the Environment and Science Division of Australian Water Technologies, a wholly subsidiary of Sydney Water Corporation.  In this role he managed a number of specialist teams – aquatic ecology, vegetation management, modelling, lake limnology, environmental microbiology and urban runoff – conducting a wide range of projects for clients in Sydney Water Corporation, Sydney Catchment Authority and various Local Government Councils.  Involvement in these studies as Project Director has provided broad knowledge and understanding of water and catchment management issues, as well as experience in the management of multi-disciplinary teams.


Since June 2001, Steve has operated as a self-employed environmental consultant on projects in Brisbane and Sydney.




Research experience in the SE Region


This is summarised in the first two paragraphs of the biography above.


Presentation title: Early hydrological, water quality and erosion studies in the forests of southeast NSW – an overview.



Scope of presentation


It is proposed that the presentation will encompass a broad, plain-English overview of the major hydrological, water quality and erosion studies conducted in the SE forests during the late nineteen seventies and eighties.


These studies were initiated by NSW State Government agency responsible for managing State Forests at the time – The Forestry Commission of NSW.  This was in recognition of the need to understand the impact of proposed woodchip and sawlog logging operations on runoff characteristics, water quality and erosion, and to develop expertise within the organisation on operational procedures to minimise any likely adverse impacts.


A paired catchment approach was adopted and resulted in the selection of five small catchments in the Yambulla State Forest, south of Eden (see attached map).  These were instrumented in 1977 for the measurement of runoff (using V-notch weirs, see attached photo) rainfall and water quality.  After an initial period of data collection in all catchments, a logging treatment was commenced in one catchment in May 1978.  The logging was incomplete when a wildfire swept through the area in January 1979, burning four of the five catchments, including the one being logged.  Fortuitously, one catchment remained unburnt, thus providing the opportunity to quantify the effects of wildfire on hydrology and water quality.


A sixth catchment was instrumented later in 1979 to pursue the original objectives of the study.


Salvage logging treatments were conducted in two of the bunt catchments and an erosion study was established in the catchment logged before the wildfire.


Scientists from CSIRO and the University of NSW (ADFA) were also involved in complementary research on the analysis and reporting of suspended sediment data from the catchments, detailed investigations of sediment production processes, hydrologic process studies and catchment modelling.  The catchments were also used for vegetation and wildlife studies.


Another paired catchment study was established by the Forestry Commission in the Tantawalgalo State Forest in the early nineteen eighties to assess the impact of possible logging on the water quality and yield because the catchment was used for part of the water regional water supply.



Perspectives on Science

These will be added later.



Erosion study measurement 1988







Yambulla catchment soon after the 1979 wildfireBurnt Yambulla catchment 1979 - soon after the wildfire

Some of the publications from early hydrological, water quality and erosion studies in SE NSW

Lane, P.N.J. and Mackay, S.M. (2001). Streamflow response of mixed-species eucalypt forests to patch cutting and thinning treatments. For. Ecol. Mgmt. 143 131-142.

Crapper, P.F., O’Loughlin, E.M. and Mackay, S.M. (1989). The hydrological effect of intensive logging operations on a small forested catchment near Eden, N.S.W. I.E. Aust.

Christchurch. Ryan, P.J., Williams, R.D., Mackay, S.M. (1988). Tantawangalo research catchments: variability of soil and vegetation in relation to terrain and comparison with Yambulla study area. Aust. For. Res.

Mackay, S.M. and Robinson, G. (1987). Effects of wildfire and logging on streamwater chemistry and cation exports of small forested catchments in southeastern New South Wales. Hydrol. Processes 1 (4) 359-384.

Moore, I.D., Mackay, S.M., Wallbrink, P.J., Burch, G.J. and O’Loughlin, E.M. (1985). Hydrologic characteristics and modelling of a small forested catchment in south-eastern New South Wales. Pre-logging condition. J. Hydrol. 83, 307-335.

Mackay, S.M., Long, A.C., Chalmers, R.W. (1985). Erosion pin estimates of soil movement after intensive logging and wildfire. In R.J. Loughran (ed). Drainage Basin Erosion and Sedimentation. Univ. of Newcastle. 15-22.

Mackay, S.M. and Cornish, P.M. (1982). Effects of wildfire and logging on the hydrology of small catchments near Eden, N.S.W. In E.M. O’Loughlin and L.J. bren (eds.). The First National Symposium on Forest Hydrology 1982. Melbourne 11-13 May. The Institution of Engineers, Australia. National Conference Publication No. 82/6. 111-117.

Mackay, S.M., Michell, P.A. and Young, P.C. (1980). Hydrologic changes after burning in small catchments near Eden, N.S.W. p. 149-155. I.E. Australia, Hydrology Water Resources Symp. Adelaide.