Hancock Watch Home

Water falling in a catchment can evaporate, flow overland or seep underground. The relative proportions of each component vary enourmously depending on the nature of the catchment and the precipitation. In addition, different amounts of water are used by different vegetation types growing in the catchment. This water use is called evapotranspiration, and is a combination of transpiration and interception by vegetation, and evaporation from the vegetation and soil. Cornish (1989) provides a detailed discussion of the water use components in relation to forests.

In any one catchment the surface runoff or yield, is a balance of precipitation, evapotranspiration, groundwater input and distribution of vegetation across the landscape. As a general rule, forests have higher evapotranspiration than pastures. Higher water use is expected from forests as compared to pastured catchments. As a consequence water flow is related to the amount and type of forest cover in any given catchment...

Experimentation is difficult to conduct and problematic in relation to water yield and the alterations in vegetation cover as a result of forestry operations (Doeg and Koehn 1990)...

Some general rules of thumb can however be accumulated from similar forest types from various sources outside Tasmania. In general some aspects of water yields can be summarised:

water yields are higher from pasture than eucalypt catchments (Holmes and Sinclair, 1986)
water yields are proportional to the percentage of the catchment afforested (Cornish, 1989)
water yields are lower for pine than eucalypt plantations because of greater canopy interception of pines (Cornish 1989)
there is no evidence for a difference in water yield between native eucalypt forest and plantation eucalypt at same age and density
water yield increases immediately following clearfelling and then decreases as regeneration appears (Nandakumar and Mein 1993)
water yields are lower for actively transpiring regrowing forests than mature forests (Kuczera 1985)
where silvicultural thinning favours increased growth rates resulting in higher canopy interception and evapotranspiration, water yield is likely to decrease...

Forestry and water quality

...Erosion and Sediments

Roading and forestry snig tracks are considerd to be potential major contributors to increased sediment loads in streams and resultant decline in water quality (Doeg and Koehn 1990, King 1988). One storm event can wash out a culvert and supply a large sediment load into a stream. Road crossings have been known to contribute large amounts of sediment 30 - 50 years after construction (Davies and Nelson 1993)...

Sediment fluxes in streams have been known to take 5 years for return to normal levels following logging (Davies and Nelson 1993). This study also found that ephemeral headwater streams on steep slopes have a significant role in the export of fine sediments from logged coupes...

Chemicals and fertilizers

Chemicals usage in forestry is mainly associatwed with plantations. Application of herbicides and insecticides are made through aerial spraying or ground based methods ... Forestry Tasmania has not used chlorinated Triazine herbicides (Atrazine, Simazine) for the last two years, nor Amitrole for the last four years (Brian Hodgson, Forestry Tasmania, pers. comm).

Herbicide usage in forestry has been common with establishment of plantations, and is usually applied in winter as a single spray event. This contrasts with agricultural applications of similar herbicides in spring and early summer, often as annual events...

Chemicals in waterways can affect invertebrates and vertebrates, and is of concern for domestic usage. Detectable levels of atrazine have been measured in Tasmanian streams draining forestry plantations (Davies et al. 1994). The same study recorded low levels of atrazine persisting up to 16 months following an isolated single spray event. The concentrations were likely to cause significant short term but infrequent impacts on the stream biota...

Whenever chemicals are used in any field based applications the possibility exists for inadvertent contamination. Spray drift and surface run-off can carry contaminants into streams. The provision of stream buffer zones minimises such additions. Worst case scenarios such as Olivers Creek at Lorinna where chemicals were applied late in the season and the Cascade River at Derby where unintentional over spraying of an upper drainage line highlight the need to take precautions with pesticide use. Application techniques in forestry are being constantly refined with chemical use being minimised and broadcast techniques being replaced with strip and spot spraying.

No spray zones or buffers adjacent to streams are important measures to reduce contamination by herbicides and insecticides in forestry operations (Barton and Davies 1993). Tasmanian research indicates that at least 30 metres is needed for the aerial application of Atrazine and 50 metres for pyrethroid insecticides. (Barton and Davies 1993). Interestingly the study found that width was more important than quality of buffers...

Insecticide usage is irregular in Eucalypt plantations, and is usually times with outbreaks of insect pests. Both synthetic compounds (eg. pyrethroids) and natural compunds (eg. Bacillus type) compounds are used. The aerial application of pyrethoids where buffer zones fell below 50m have been associated with short term responses in invertebrate drift (Barton and Davies 1993).

Fertilizers can be applied by aerial application in plantations. When required the application of Nitrogen is generally more frequent than Phosphorus. Fertilizer application directly to streams or as high concentration runoff could raise stream nutrient levels leading to significant effects on stream ecosystems (King 1988). Adherence to buffer zone distances will reduce the possibility of water contamination.

THE EFFECTS OF RADIATA PINE PLANTATION ESTABLISHMENT AND MANAGEMENT ON WATER YIELDS AND WATER QUALITY - A REVIEW

BY P.M. CORNISH
FORESTRY COMMISSION OF NEW SOUTH WALES
TECHNICAL PAPER NO. 49

CONCLUSIONS

1. Water Use and Water Yield

(a) The principal processes that determine variations in water use between different types of vegetation are transpiration, canopy interception, energy input, and possibly, growth rate.

(b) Under similar conditions tree species such as pine and eucalypt transpire at about the same overall rate, and at a greater rate than more shallow rooted species such as unirrigated grasses subject to seasonal dormancy.

(c) Tree species intercept much more precipitation than pasture species because of greater interception capacities and higher rates of evaporation from wetted surfaces.

(d) P. radiata intercepts more precipitation than eucalypt species because of a different canopy architecture, the overall difference being up to 10% of annual rainfall.

(e) Forests receive more energy for the evaporation process than grassland, and this process in forests is itself more efficient.

(f) Land cleared of eucalypt forest and planted to P. radiata is likely to suffer a long-term reduction in water yield up to about 10% of annual precipitation.

(g) The complete afforestation of a cleared pasture catchment in Australia by P. radiata is likely to result in maximum reductions in water yield in excess of 400mm per annum where precipitation exceeds 1,300 mm annually. While actual annual reductions will depend on the precipitation received, such an overall change would be major, at least at the local level.

(h) The actual decrease in water yield resulting from afforestation of grassland by P.radiata will depend on a combination of the following factors, each having an important bearing on the final outcome:-

(i) Water yield changes will be in direct proportion to the percentage of the catchment afforested.
(ii) Until maximum water use is established at about age of maximum growth rate, water yields in a P. radiata plantation will decrease before increasing. Plantation water yields overall will therefore depend on the particular age classes present and the relative proporation of each.
(iii) As thinning a plantation reduces canopy interception and changes growth rates, water yields will increase following each thinning operation, with first thinning possibly reponsible for a yield increase in excess of 100mm in the following year.
(iv) Water yield decreases in plantations also depend on the amount and nature of the precipitation received, greater decreases occurring when annual precipitation is greater and average rainfall intensities lower.

(i) Afforestation of grassland by P. radiata results in additional hydrologic consequences in the catchment which may be summarized as follows:-

(i) Peak streamflows during storms may be reduced.
(ii) Streams may take longer to rise following rainfall.
(iii) Baseflow in streams during dry weather may decline.
(iv) Periods of dry-weather flow in ephemeral streams may become shorter, and some perennial streams may become ephemeral.

(j) Overall biomass production on an equivalent site will be similar for pine and eucalypt, although biomass production rates are strongly influenced by site conditions and vary with the age of the stand. Maximum production rates occur at different ages in different species. Although little data are available (and more research is required), transpiration efficiencies are probably similar in pine and eucalypt. Maximum transpiration rates for any species may occur at the age of maximum biomass production possibly leading to a specific species (and site) pattern of water yield change during the rotation.

(k) Fertilization of pine plantations may result in site dependent decreases in water yield of 50-100mm or more per year in comparison with an equivalent unfertilized stand.

(l) The dependence of water use on growth rate is not well understood for P. radiata and a systematic examination of relevant factors needs to be undertaken in a lengthy study of growth rates and water use to refine predictions of P.radiata water use with age.

(m) Dryland salinity is unlikely to be present in pasture catchments in moderate - high rainfall areas suitable for afforestation by P. radiata in N.S.W.

2. Water Quality

(a) Suspended sediment and turbidity are the most widespread pollutants of streamwater in P. radiata plantations.

(b) Principal factors likely to be responsible for increased turbidity levels in plantation streams include:-

(i) A high roading density, particularly in older plantations.

(ii) The frequent occurrence of streamside roading networks.

(iv) General reliance on wheeled harvesting equipment and downhill extraction patterns.

(v) Harvesting throughout the year, notwithstanding the fact that P.radiata areas in southern Australia experience a wet winter when soils frequently remain near saturation for long periods.

(vi) Lack of suitable machinery that would allow the complete introduction of some practices such as contour ploughing that are universally accepted as less likely to result in increased erosion.

(vii) Streamside buffer strips, if present, may be ineffective at certain times depending on their management, their composition and their treatment during the re-establishment of the plantation.

(c) Areas in catchments that wet up first and remain wet for longer periods are likely to be more prominent in the supply of suspended sediment and turbidity to streams following disturbance by machinery, and therefore require more sensitive management if water quality problems are to be avoided.

(d) While the imposition of logging and planning controls such as erosion mitigation measures, wet weather closures and the seasonal planning of logging areas in plantations are designed to reduce the impact of streamwater from suspended sediment, and turbidity, these measures appear less successful in pine plantations than in hardwood forests. Factors responsible for this include the greater roading density and intensity of operations in pine, the winter rainfall maximum and year-round logging.

(e) Afforestation of grassland by P. radiata should generally increase slope stability. Steep P. radiata areas are likely to suffer some loss of stability following each thinning operation, with the possibility of a greater reduction in stability occurring after clearfalling.

(f) Grassland areas with a long history of grazing since clearing may have developed lower hydraluic conductivity values over time. Afforestation of such areas may present a higher erosion risk at establishment than equivalent recently cleared eucalypt land because of increased and more frequent surface runoff.

(g) Cleared pastoral areas suffer widespread soil erosion problems in Australia. Afforestation of pasture lands generally may therefore result in a reduction in soil erosion overall, and improved quality during much of the rotation.

(h) Slash burning during re-establishment of the plantation may result in increased raindrop impact and surface runoff, particularly if the fire is hot and the soil hydrophobic, leaving the area vulnerable to erosion until the adequate surface revegetation occurs.

(i) Fire, particularly a hot fire, has the potential to consume ground cover and litter in unprotected streamside buffer strips thereby considerably reducing their effectiveness as an erosion mitigation measure.

(j) Any elevated streamwater nitrogen and phosphorus levels in pasture catchments resulting from a history of fertilizer application or introduced legumes are likely to decline gradually when afforested by P. radiata.

(k) Hot slash burning, and windrow burning, may result in increased concentrations and fluxes of ions such as nitrate and potassium in streamwater, the increases disappearing after a few years.

(l) Windrow burning in streams and drainage lines is likely to allow considerable quantities of ash to be washed into streams during rain, resulting in possible short term eutrophication of the stream and in a permanent loss of nutrient capital from the site.

(m) Broadcast, rather than spot, applications of nitrogenous fertilizers to P. radiata plantations may reduce the likelihood of leaching losses to streams, at least in sandy soils such as in South Australia where surface runoff is minimal.

(n) The aerial application of herbicides and pesticides to plantations of P. radiata is unlikely to effect streamwater quality if streams, streamside buffers and major drainage lines all remain unsprayed. This requires proper control over droplet size and the avoidance of windy days.

(o) Recreational activities and the associated provision of sewage disposal facilities are the greatest potential threats to the pollution of streamwater from elevated bacteria levels in forested catchments.

(p) While the disposal of sewage sludge and effluent in forests generally does not effect streamwater quality, care must be taken in planning to tailor disposal rates to the hydrologic characteristics of the particular site.

Forests: the argue goes to water

The Weekend Australian Financial Review - November 9-10, 2002.

P24: Forests: the argument goes to water

Tree plantations are thirsty water consumers, but it seems the growers are never the ones who pay.

Story Julie Macken

As this once-in-a-century drought tightens its grip on Australia, farmers face escalating feed bills and irrigators are seeing their water allocations slashed by up to 90 per cent. Those who can afford to are paying up to $500 a megalitre for water, with this basic commodity fast becoming a new currency.

There is, however, one sector of agriculture that can afford to ignore the escalating crisis: forestry.

Plantation owners across Australia are using water worth $6.75 billion a year. Australian tree plantations consume 13.5 million megalitres of water a year - and if the Federal Government realizes its vision of trebling the size of plantations by 2020, that figure will blow out to 45 million megalitres a year. All of this, and the industry does not pay a cent for the water.

The reasons for this situation are historical and cultural. Until very recently, state and federal governments have considered the water that falls upon the Earth to be free and abundant. While irrigation and commercial water use have attracted fees since the 1940s, non-irrigated agriculture has not. The thinking was simple: forestry does not dam rivers or require irrigation, it just uses the water that falls as rain to grow its product.

That product now covers more than 1.5 million hectares of Australia. Because most of it is grown for commercial use, and therefore requires fast growth times, it is generally grown in high rainfall areas - that is, areas with annual rainfall of more than 1,000 millimetres. It is increasingly being grown on land that has been clearfelled of old growth or native forest and areas traditionally used for pasture.

�Land use change of this kind and on this scale is like introducing a permanent drought,� says Mike Young director of economic and social research at the CSIRO and a member of the Wentworth Group of scientists.

�At the moment we don�t have any systems in place to account for these changes. In the interest of managing risk, it is incumbent on government to tell downstream water users what impact forestry will have on future water availability, because it will be a big one.�

An example of that impact can be seen when the water use of pasture is compared with the water use of plantations. According to modeling done by the CSIRO land and water division, a hectare of pasture planted in an area with annual rainfall of 1,200 millimetres will use seven megalitres per hectare per year. The same area planted with forest will use nine megalitres per hectare per year.

The higher the rainfall, the larger the difference, and as the forest grows it pulls water from run-off and ground water for at least the first 50 years of its life. Because the trees are harvested within 30 to 40 years, there is no let-up on their water consumption. Old growth forest - forests older than 100 years - have much less demand for water because their growth has slowed.

While some states such as Tasmania have large private owners of plantations, the bulk of Australia�s plantation forests are owned by state governments. Perhaps not surprisingly, no state government has any plans to introduce fees or any other restriction on the water use of plantations. As a spokesman for the NSW Minister for Land and Water Conservation, John Aquilina said: �We have no plans to introduce charges because they (plantations) don�t use dams or irrigation�.

But as water restrictions begin to bite across rural and urban Australia, it is unlikely other stakeholders will maintain such a benign position.

Col Thomson, chair of the NSW Irrigators Council, believes these kinds of major changes to land use have to be factored into the water equation. �Land use planning decisions like forestry can change the volume of water available for both irrigation and the environment,� he says. �These considerations must be taken into account prior to any major changes to our land use. That�s why irrigators are seeking secure water access rights in terms of a share in the available water resource.�

Nor is it only irrigators who are starting to scrutinize the water consumption of forestry.

Hydro Tasmania is Australia�s largest generator of electricity from renewable energy sources, contributing more than 60 per cent of Australia�s renewable energy. With a workforce of about 680, it owns 27 hydro, one thermal and two diesel power stations and a wind farm. It has electricity generating assets of about $3 billion with a total generating capacity of 2,262 megawatts. With more than 50 large dams, Hydro Tasmania is the biggest dam owner in Australia.

It is also extremely concerned about its water supply. Tasmania has more than 220,000 hectares under plantation.

In the five years to 2001, 62,831 hectares of native forest were cleared for plantation use.

Two weeks ago a concerned member of the public - who had seen their own water supply reduced by 80 per cent in the summer time - approached Peter Rae, chairman of Hydro Tasmania to ask him how Hydro was dealing with the upsurge in plantations, given the amount of water consumed by fast-growing eucalypt nitens - the preferred tree for plantation use in Tasmania.

Rae could not give an immediate answer, because Hydro has been focusing on issues of silting and debris damage created by run-off not the effect of changes to land use. At an emergency meeting the next day, it was decided that a scooping study would be conducted over the next four weeks to try to estimate the impact of forestry on the water catchment areas of Hydro.

P28 Andrew Scanlon, Hydro�s principal consultant on renewable energy and environment, is overseeing the study. He believes the results will give Hydro some idea of the size of the emerging problem.

Launceston Council already has the results of the first study it has done on the impact of forestry on the town�s water supply.

Conducted by the CSIRO�s land and water division and the CRC for Catchment Hydrology, the results, according to Steve Radcliffe, manager of the project, sound a warning.

�We modelled a number of different scenarios for logging and rotation cycles,� says Radcliffe. �We found that if the current logging practices are maintained, there will be a 20 per cent reduction in Launceston�s water supply within 50 years. That�s why these plantations need to be very closely monitored.�

As Prime Minister John Howard discusses the idea of scrapping the complex array of state-based-water licensing systems in favour of a national code, none of his federal ministers has even considered the implications of forestry�s water use.

Everyone from Deputy Prime Minister John Anderson and Forestry and Conservation Minister Ian Macdonald to Agriculture Minister Warren Truss has said water remains a state responsibility, and no, they have not considered pricing mechanisms for the water consumed by forestry.

Shadow environment minister Kelvin Thomson is not convinced the science exists to accurately price water consumer by plantations. �I don�t think there is enough information available to quantify plantations� water use,� he says. �When that information becomes available, it is important that a national water policy reflect the real value of water and we clarify who is using what.�

However, Murray Peel of the CRC for Catchment Hydrology and University of Melbourne says the modeling for forestry hydrology is freely available and it is possible to model accurately for almost every catchment area of Australia. �We used the Macaque model to investigate the Launceston study and it gave us a high degree of accuracy,� he says.

But his prediction for the future of forestry in Australia are probably not what the state or federal ministers want to hear.

�The current pattern of converting pasture to tree farms or plantations is going to create huge problems down the track,� Peel says. �And if the Federal Government does achieve its vision of trebling the amount of land under plantation by 2020, Australia will have very real problems with water.�

Page 4 Weekly Times 3/1/01

Row looms over water threat to blue gums. By Nikki Borchard

A heated debate between irrigators and forestry developers has broken out in South Australia over state government plans to amend water legislation.

Significant forestry development in the south-east of South Australia, particularly blue gum plantations, has caused concern over its impact on the sustainability of water resources.

As a result, water resources minister Mark Brindal last month proposed the introduction of water licences for new forestry plantations to deal with significant land use change.

But forestry developers claim such amendments to the Water Resources Act would freeze plantation development and threaten the future of forestry.

One of Australia�s largest plantation companies, Timbercorp Limited, argued that plantation developers should not have to pay for what they did not use.

�The industry cannot proceed with further expansion until it gains a clearer view of the effects of his (Mr Brindal) proposals,� Timbercorp chairman David Muir said. �But if they are implemented as he has stated, the freeze will become permanent.�

He said industry saw no reason to pay for a resource it did not use, and the added cost could only detract from its economic viability.

But irrigators claim they face having their groundwater licences reduced as a result of the effect of land use changes and recharge.

Mt Gambier dairy farmer Gary Spain said it came down to the fact that

�you can�t allow one industry out of the water net to expand at the detriment or expense of others�. �We all acknowledge that we just can�t have open slather irrigation,� Mr Spain said.

�But for forestry to operate in this area, it needs to operate under the same regime and be accountable for their impact. �So long as there is a level playing field, market forces will prevail.�

However, Mr Muir argued it was �a scientifically dubious proposition that forestry plantations were reducing groundwater resources and hindering their recharge�.

Mr Brindal told the South Australian parliament in November that there were two main schools of thought on the issue - a traditionalist view and a contemporary view.

�Traditionalists do not believe that water rights should be seperated from land and that any loss of water resource caused by land use change - such as forestry - should be borne by irrigators,� Mr Brindal said. �But the contemporary view would require an amendment ensuring that plantations in sensitive areas of the south-east - to be known as Recharge Water Management Areas - will be accountable for their impact upon the recharge of the unconfined aquifer.�

Mr Brindal will meet irrigators and plantation developers in the south-east next week.

Border Watch

p3 3/1/01

Bluegum water use research

Early research by the CSIRO has suggested that bluegums can use underground water.

Embryonic results at a Beachport planting indicate that bluegums could be taking groundwater specifically on that site.

But CSIRO Forestry and Forestry Products research scientist Richard Benyon said the results were not yet conclusive enough to publish. He said the Beachport trial site did not have the same characteristics as other plantings around the Wattle Range Council area, where most bluegums were going.

�We cannot yet say that (the trees use underground water) for the majority of bluegums in the region,� Mr Benyon said. �The CSIRO is hoping for extra funding to gain knowledge about the water use of bluegums in the Wattle Range area and we hope to focus this research over the next few years.�

Two bluegum sites were being tested, the Beachport plantation and a small one at Padthaway. At this stage the Padthaway site had not used underground water but this water table was much lower than at Beachport and further south.

Meanwhile, the Beachport site had soils which were too different to provide a conclusive result for plantings in the Wattle Range and Mount Gambier districts. A wet winter did not make results any easier to determine and more information would be known after summer.

�I think a lot of sites around Wattle Range perhaps have more clay in the soil. But some early results give an indication that the (Beachport bluegums) may be taking some groundwater,� Mr Benyan said.

�At Beachport the bluegums use at least as much water as they receive from rainfall, a possibly use a bit more than that from the shallow water table, but that is not a generalisation.

�We really need to focus on where the trees are going into the ground rather than 40 hectares at Beachport and five hectares at Padthaway. �The main reason for doing the work there was to look at how management of the plantations affected water use and to see if we could grow bluegums to produce higher value products.�

Mr Benyon said main research on water use of bluegums had not yet started and would not begin until funding was received.

He hoped money would come from the industry and State Government. He said research would start early next year, and continue for several years to take into account climate and soil differences among other variations.

Rob Vertessy from the CRC for Catchment Hydrology (CSIRO).

�The afforestation of agricultural and pastoral areas, if conducted on a sufficiently broad scale, will profoundly influence the hydrology of catchments. Principal amongst the consequences will be reduced water yields and reduced groundwater recharge, though changes in the seasonal distribution of runoff, the timing and magnitude of peak flows, and the persistence of low flows can also be expected.

While hydrologic changes may appear within four years of plantation establishment, the full effects may not be felt for ten or more years. In the case of groundwater, the benefits of reduced recharge may take several decades to appear... models show that runoff reductions will be greatest in high-rainfall areas and that pine plantations will have a greater impact than eucalypts.

For areas with 800mm mean annual rainfall, mean annual runoff may decline by up to 165mm under eucalypts and up to 210mm under pines. For areas with mean annual rainfall of 1200mm, the mean annual runoff reductions may be 265 and 350mm...�

�There is a growing body of evidence to show that, in addition to reducing groundwater recharge, trees can use significant quantities of groundwater, depending on the depth and quality of this. For these reasons, tree planting is regarded as an effective strategy for salinity abatement. However, there are circumstances where reduced recharge and groundwater abstraction by trees may be undesirable�

�... One of the best local examples of altered flow durations has emerged from the Tumut catchment experiment� planted with pine �It reveals significant changes in the duration of daily flows of all magnitudes. Redhill catchment now ceases to flow for about 40% of the time, assuming that 0.001mm per day is a �no flow� threshold.� ...

�The Tumut data ... show that the maximal hydrologic impacts of pine plantations may not be felt until the stand has reached about 10-15yr of age. Hence, any catchment containing a significant proportion of young stands will not exhibit the maximum hydrologic effects of afforestation�

Effect of Reafforestation on Stream Flows, salinities and groundwater Levels in the Pine Creek Catchment. (Shepparton Dryland Region Land and Water Salinity Management Plan - June 1995).

Between 1988 and 1994, the Rural Water Commission monitored stream flow in the Pine Creek Catchment - near the town of Broadford, which is part of the Sunday Creek catchment in the Goulburn River system. Pine Creek drains a catchment of 3.2 km2 (320 ha) almost all of which was located within the "Glenburnie" property, a grassland property which was converted to pine plantations in 1986 by Smorgon Forests, a part of the Smorgon group of companies. The site is now under the ownership of Midway Wood Products Pty Ltd who own a export woodchip mill at Geelong.

The Pine Creek study is very important because if quantifies the impacts of stream flow on a 'larger scale' than similar studies conducted in Victoria. Most other reports looking at the impacts of plantation establishment on water yields in Victoria only deal with plantation impacts on a much smaller scale.

Key findings of the report include;

"* Stream flows from the Pine Creek catchment have reduced significantly over the period from late 1988 to 1994, while the total rainfall on the catchment has remained relatively constant.

* Salt loads from the Pine Creek catchment have decreased over the study period from approximately 0.45 to 0.3 tonnes/ha/yr. The magnitude of salt inflows to the stream are not solely related to surface flow, demonstrating that ground water intrusion to the creek is also contributing a proportion of the inflow. Over the last six years, groundwater levels have declined by approximately 2 m, which is consistent with the decreasing salt inflows to the creek over time.

* Discharge of flow and salt load from the catchment has significantly diminished due to the change in land use from open grassland/bare land to Pine plantation due to the increased uptake of water by the pine trees (interception and evapotranspiration)."

p12 "Stream Flow ... This trend is supported by the annual flow volumes shown in Table 3, which indicates that the flows have decreased considerably from approximately 690 ML in 1989 to 240 ML in 1993. The data also shows that this decrease in flow occurs with little change in annual rainfall which varies from 865 mm/yr in 1989 to 914 mm/yr in 1993."

Table 3: Annual Stream Flow, Rainfall and Salt load - Pine Creek (405290A)

	1989	1990	1991	1992	1993
Flow (ML/yr)	687	263	163	308	239
Rainfall (mm/yr)	865	643	647	857	914
Salt Load (t/yr)	153	119	92	93	41
Rainfall (ML/yr)	2768	2058	2070	2742	2925
Flow as % of Rainfall (ML/yr)	25%	13%	8%	11%	8%
Salt Load/Rainfall (t/ML)	6%	6%	4%	3%	1%

p14 "It has been hypothesised that the flow reductions in Pine Creek have resulted from the continued growth of the pine plantations across Glenburnie. This hypothesis gains added support from an inspection of cumulative flow plotted against cumulative flow."

p27 Conclusions. Stream flows from the Pine Creek catchment have reduced significantly over the period from late 1988 to 1994, while the annual rainfall on the catchment has remained relatively constant. The much larger Sunday Creek catchment (which includes the Pine Creek catchment) and adjacent Mollison Creek catchment, do not exhibit similar trends, demonstrating that the observed decline in the Pine Creek's flow is likely due to local catchment land use ... Both the flow and the salt load from the catchment have significantly diminished due to the change in land use from open grassland/bare land to Pine plantation. Due to increased uptake of water by the pine plantation (interception, evapotranspiration etc.), the amount of rainfall runoff and groundwater recharge has reduced and hence so has the salt load being discharged to the stream."

The Latrobe River Basin. Water Resources and Aquatic Environment.

A Review October 1986, The Latrobe Valley and Sewerage Board.

p40 "3.2 Groundwater

The aquifer systems in the Latrobe basin are of two major types, fractured rock systems and sedimentary rock systems (Harris 1967a). The whole of the basin is underlain by rocks that theoretically could contain groundwater in fractured rock aquifers. Because of the limited water in such aquifers, they are only of importance where they are not overlain by more recent sediments. Sedimentary rock aquifer systems occur in Tertiary or Quaternary age rocks which outcrop in parts of the basin such as the Central Latrobe Valley. These sedimentary rocks differ from the older Palaeozoic and Mesozoic sedimentary rock in that they have not experienced intense compaction and folding. The grains are generally uncemented and there are many pore spaces that can hold water. The fractured rock and sedimentary rock aquifer systems may be further subdivided as follows (Harris 1976a; Nahm 1977):

(1) fractured rock aquifer systems:

(a) Palaeozoic sedimentary and igneous rock aquifer systems;

(b) Mesozoic sedimentary aquifer system; and

(c) Tertiary volcanics aquifer system;

(2) sedimentary rock aquifer systems:

(a) Latrobe Valley Group aquifer system;

(b) Boisdale Formation aquifer system; and

(c) Quaternary sedimentary aquifer system.

The distribution of these systems within the basin is shown in Figure 3.8.

3.2.1 Palaezoic sedimentary and igneous rock aquifer system

Aquifers in this category lie mainly in the north of the basin. Generally the rocks in which they occur are highly consolidated, with grains or minerals so tightly packed that there is no space for groundwater to move through. Such rocks contain water mainly because of joints, fractures or faults resulting from earth movements after their consolidation (Nahm 1977). The groundwater in these rocks is generally under water-table conditions (i.e. unconfined), and is often in direct hydraulic connection with surface streams. Recharge is vertically from the surface through the soils and discharge is by evapotranspiration or to streams by springs and seeps (Harris 1976a).

These systems seldom contain aquifers that will produce good yields from bores and they are little used for water supply, being mostly in mountainous, forested areas. However, the groundwater in them is generally of excellent quality (<200 mg/L dissolved solids) and provides much of the summer and autumn base flow of upland rivers (Harris 1976a). Recharge of some of these aquifers may have been reduced by land clearing, resulting in increased surface runoff and hence reduced infiltration.

3.2.2 Mesozoic sedimentary aquifer system

This system occurs in the South Gippsland Highlands (Strzelecki Ranges) and is similar in may respects to the previous one. It supplies streams such as the Morwell River, and generally has a somewhat higher dissolved solids content than the Palaezoic system (Harris 1976a).

3.2.3 Tertiary Volcanics aquifer system

Basalt rocks known as the Thorpdale Volcanics outcrop in various parts of the basin and underlie the Latrobe Valley coal measures. In the Thorpdale area they overlie sand and gravel beds, known as the Childers Formation. The Thorpdale Volcanics and Childers Formation are hydrogeologically connected and behave as a single aquifer system (Nahm 1977). The groundwater in the volcanics occurs in abundant permeable structures such as cooling cracks, joints and fissures, and in weathered zones and spaces between baslat flows which are often filled with scoria. It often occurs under water-table conditions, is recharged vertically from the soil, and discharges either to underlying aquifers or to springs and seeps. Quality is generally good (<1000 mg/L dissolved solids) and yields from bores are low to moderate (Harris 1976a).

3.2.4 Latrobe Valley Group aquifer system

This is a large system extending through the central part of the basin from west of Moe to east of Sale. It lies within the Latrobe Valley Group of non-marine sediments, brown coals and volcanics. The aquifers consist of medium to coarse sands seperated by relatively impermeable brown coals and clays. (Harris 1976a). There appear to be two major confined aquifer systems: the Morwell Formation aquifer system and the Traralgon Formation aquifer system (Brumley et al. 1981; Brumley and Reid 1982). Total storage is estimated at 3300 GL for the former and 17 000 GL for the latter. Recharge occurs around the margins of the Gippsland Basin (Harris 1976a), for example in the hills west of Morwell (Brumley and Reid 1982) and discharge is probably to the Gippsland Lakes and Bass Strait.

The aquifers underlying the coal seams at Morwell contain water under pressure. As the weight of overburden and coal is removed during mining, upward movement of the floor of the open cut results (Haris 1976a). To relieve this pressure, large volumes of water are pumped from the aquifers: at the Morwell Open Cut, 354 GL were extracted between 1960 and 1980, an average of 48 ML/day. Current pumping rates are about 72 ML/day (26 GL/year) (Brumley and Reid 1982). Recently, extraction of groundwater has also begun at Loy Yang. Evans (1986) has modelled groundwater behaviour in relation to the Morwell and Loy Yang open cuts.

The quality of the groundwater in the Latrobe Valley Group aquifer system varies enourmously from place to place. Temperatures of up to 70 C have been recorded, probably because of high geothermal fluxes along major fault zones (Thompson 1980). Dissolved solids content ranges from around 100 mg/L to over 3000 mg/L, but is generally below 500mg/L (Brumley and Reid 1982). The soluble iron content is often high: up to 4 mg/L (Harris 1976a; Brumley and Reid 1982).

3.2.5 Boisdale Formation aquifer system

This formation includes one of the most important aquifer systems in the Gippsland area. Within the Latrobe basin it is confined to the north-east, from near Glengarry to Lake Wellington. The formation consists of sequences of sand and clay, in some places containing ligneous clay and thin brown coal seams (Nahm 1977). Recharge of the aquifers is thought to be occurring through the overlying Quaternary river sediments along the Avon, Macalister and Thomson Rivers, close to the highlands. Discharge may be upwards through Quaternary sediments under Gippsland Lakes and Bass Strait (Harris 1976a).

Groundwater in the Boisdale formation is generally under pressure (i.e. confined) and flows naturally from bores. Quality is generally good, with dissolved soilds below about 500 mg/L (Harris 1976a; Nahm 1977). The iron content may be high, but can be reduced by aeration.

3.2.6 Quaternary sedimentary aquifer system

These alluvium aquifers occur mainly along major lowland streams (e.g. the Latrobe and Morwell Rivers, the Moe Drain and Traralgon Creek) where there are large areas of Quaternary sediments (gravel, sand and clay beds) mostly deposited by fluviatile processes (Nahm 1977). The amount of water contained in these sediments depends on the thickness to surface waters. These water-table aquifers are generally unconfined and in direct hydraulic connection with surface water bodies. Recharge is probably from rainfall (through the soil) or from surface waters, and discharge is to deeper aquifers, surface waters or to the atmosphere by evapotranspiration (Harris 1976a). Between the Latrobe and Thomson Rivers, the groundwater in these aquifers has a disolved soilds content of about 700-1400 mg/L (Harris 1976a)."

p8 Water the lifeblood of Gelliondale Nursery The Yarram Standard News 3/3/04

Manager of Hancock Victorian Plantations' Gelliondale Nursery, Chris Barclay, has welcomed news of a study into the lowering water levels of the Latrobe Aquifer. The Federal Government has appointed Dr Tom Hatton from CSIRO Land and Water to lead a team of experts to review all issues relating to groundwater pressures in the Gippsland Basin. Their report is due to be submitted by June 30 this year.

"Its very timely", said Mr Barclay, in charge of an operation which draws 160 to 220 megalitres of water every year. The exact figure depends on the season, but water is the lifeblood of this extremely successful local business. "The resource is in danger. We need to understand what the effect of our management of the aquifer is. I'm including all stakeholders, from irrigators and other farmers to business people and the general community. Only then will we be able to make the resource sustainable," Mr Barclay said.

The nursery is shortly to make a presentation to the Groundwater Committee, chaired by Bill Bodman, which is developing a mangement plan for the Yarram catchment. "There's currently a moratorium on new water licenses being issued of alterations to old licenses under water protection legislation. We would like to alter our license in order to maintain our sustainability," said Mr Barclay. He said that there was an urgency about finding the effect the various stakeholders were having on the aquifer they drew their water from. "We have a temporary license transfer which will meet our requirements for the next couple of years while the committee develops its management plan," said Mr Barclay.

One of the most important investments the nursery has made in recent years is its $120,000 computerised irrigation system. With the tap of a few computer keys, Mr Barclay can look up the pressure the pumps are are running at and later them if necessary, check the flow rates, measure the soil moisture and much more. The system which is put out by Intelligent Irrigating Systems, measures total rainfall and wind speed and turns the pumps off if necessary. It also notifies nursery staff if a main is blown.

With the help of Mission Australia, Gelliondale Nursery is currently advertising for additional staff to work on cutting and setting young trees, commencing next month, and harvesting plants from May. "We expect we will have 55 to 60 of our regular workers returning and we will take on an additional 12 to 15 people," said Mr Barclay. Summer is a quieter time of year at the nursery, but there is still work to be done. Seeds were sown in January and six to eight weeks later multiplication has begun.

"Our multiplication facility is one of the first built in Australia," said Mr Barclay, pointing out the 'igloo' where Rhonda Smith was busy watering and setting tip cuttings. "We get about 45 plants from one seed by the time we take ten tips from each plant and multiply these, too," said Mr Barclay. There is currently activity in the seed orchard too. A team of workers is applying giberellic acid in a trial designed to look at its effect on the promotion of flowering and the retention of cones.

Mr Barclay explained that giberellic acid is used in the horticultural industry for the retention of blossom and fruit, such as apples. A hole is drilled in each tree, the formulation is injected and the hole covered with vaseline to stop it evaporating out of the tree. "The trials are done over a period of several weeks. They are screening trials in which we will try to identify which cones react well to the giberellic acid," said Mr Barclay. Gelliondale Nursery expects to send out the gate about six million trees this year, but clearly it is much more than a simple tree producer. "This is probably one of the most advanced tree breeding centres in Australia, or even in the southern hemisphere. We get visitors from as far away as Chile coming to see what we do here," said Mr Barclay proudly.

Victorian Government White Paper on Water June 2004

p35 Addressing Impacts of Catchment Land Use

Different land use changes can affect the water balance of a catchment by intercepting and using rainfall that would otherwise become surface runoff or recharge to groundwater.

The initiatives below seek to address the impacts of catchment land use in order to protect the future integrity of water entitlements and to achieve environmental objectives for water systems.

There is a significant difference in the effect of different land uses, and research shows that the magnitude of the effects of forests is potentially much greater than that of grazing, agriculture or horticulture.

This significant issue is also being addressed at a national level as part of the National Water Initiative.

Impacts of new plantation forestry

The Government encourages private forestry investment in Victoria with a view to delivering economic, environmental and regional developmental benefits for the State. However, the potential impacts of plantations on water resources must be understood and recognised in the planning frameworks within which these developments take place.

Policy

Sustainable forest and timber management remains a priority for the Government. As part of this commitment, the water resource impacts of new plantations need to be considered.

Any significant water resource impacts from new plantations will be managed within the context of the environmental benefits of plantation development.

Plantations are managed through various frameworks including the Planning and Environment Act 1987, the Catchment and Land Protection Act 1994, and the Code of Forest Practices for Timber Production (DNRE, 1996).

These provide for the protection of natural resources including water, and are particularly directed towards protection of water quality. However, apart from a few minor exceptions, they do not address the impacts of plantations on the quantity of surface water and groundwater resources.

Victoria's new water allocation framework is premised on water users and the environment having access to safe and secure entitlements that are not eroded by the actions of third parties.

As a first step, the Government will undertake a statewide assessment to identify high, medium or low hydrologic impact zones where new plantation development would potentially have a high, medium or low impact on current water availability and the Environmental Water Reserve. Appropriate tools and controls will then be developed, in consultation with stakeholders, to account for the impact of new plantations on water resources, water salinity, greenhouse and other environmental benefits and costs of plantations. Tools could include planning provisions, incentives and pricing systems.

Action 2.20 The Government will:

*undertake a statewide assessment to identify high, medium or low hydrologic impact zones for new plantation developments;

*develop appropriate tools, for example planning provisions, incentives and pricing systems, in consultation with stakeholders to account for the impact of new plantations on water resources, water salinity, greenhouse and other environmental benefits and costs of plantations; and

*apply existing planning arrangements until the new arrangements are in place.

The project will assess the impact of other significant land use changes on the water resource. The current mix of land uses will act as the baseline - so existing land uses will not be affected by the new planning arrangements.

Setting up plantation development zones and controls will provide essential information to catchment managers to assist in balancing the environmental and economic benefits from plantations (i.e. for salinity control or forestry activities) against the impact on water resources.

Letter published in Sunday Age Newspaper (Melbourne 11/7/04)

Water and logging

While I agree with most of Matthew Bell's comments ('How big must water-waste numbers get?' Letters, 4/7) regarding logging in Melbourne's water supply catchments, a number of points also need to be made.

The often mooted solution to logging Melbourne's water supplies is to grow more plantations outside these water catchments. It must be pointed out that recent research presented on the website Hancock Watch, reveals that more than 130 rural towns in Victoria already get their drinking water from catchments with plantations located in them.

Plantations are logged on rotations of about 30 years, meaning that these "false" forests are forever thirsty. It would appear that plantation water consumption will be significantly more than that of a native forest which is supposed to be logged every 80 years.

Plantations in many cases are aerially bombarded with herbicides in order to stop competing species, often indigenous species, from slowing down the growth of the planted trees. These herbicides can make their way into water supplies, especially after high rainfall. Water pollution from plantations is commonplace in Tasmania.

Many existing plantations in Victoria were established with scant regard to water protection, meaning that many drainage lines and creeks inside plantations remain unprotected after logging and subsequent spraying. Old logging scars are revealed by new logging. Associated soil loss can also play havoc with water quality.

The recent government report 'Our Water, Our Future' states that already established plantations will remain exempt from new policies that determine where to locate new plantations with regard to minimising impacts on water yield.

This is an outrageous outcome considering that about 180,000 hectares of plantations in Victoria are under the control of the US multinational John Hancock Financial Services and most of the profits from logging these plantations and the water they consume will move overseas.

ANTHONY AMIS, Friends of the Earth, Melbourne

by philip hopkins age may 17 2005

Regulating plantation forestry's water use will destroy the buoyant plantation sector, a senior Timbercorp executive has told a forestry conference.

Tim Browning, Timbercorp's general manager forestry, said the plantation sector had a rosy future, with Australian eucalypt woodchip in demand, particularly in China, but issues such as water use were a threat. Mr Browning said plantation water use should not be regulated.

"Plantation trees are a dryland crop - not irrigated at all, relying only on rainfall and groundwater," he told a Timber Communities Australia conference in Launceston. "The only regulation that should apply is that which applies to all dryland crops."

Mr Browning said there may be a case for assessing the impacts of dryland crops on catchments and apportioning groundwater use on scientific principles, but he said he was "...yet to see it. All we have seen are justifications for discriminating against plantations on the basis of their alleged excess consumption of groundwater."

Mr Browning said the case was weak. A new South Australian regulatory regime, touted as a model for regulation everywhere, would stop plantation development. Mr Browning said the SA model involved matching complex water allocations to plantation development potential.

"Where notional potential does not match actual experience, water allocations can be bought to offset the excess of land planted," he said. "The local council in the first instance, and then the Minister for Environment and Conservation, determines where plantations can be sited."

He said this meant two powerful negative forces were bought to bear:

*Regulators prejudiced against plantations on the basis of a preconceived notion that trees soak up water that might be used more productively.

*A system of de facto water licensing aimed specifically at plantations. Mr Browning said land access in SA was now restricted through discriminatory regulation.

"The cost of establishing and maintaining plantations has risen to a level that is not competitive," he said. "I confidently predict that new planting will now start to decline . . . the drive for the establishment of a long-term, sustainable timber resource will stall." Australia has 1.72 million hectares of plantations. About 75,000 hectares a year have been planted in the past 5 years.

Return to the menu