save the Blue Tier
water catchment
- d. e. leaman, hydrologist
FORESTRY AND RISK TO WATER SUPPLY: BLUE TIER - SUMMARY OF DISCUSSION
I prepared a report on the possible water supply issues associated with extensive forest operations around Blue Tier for Friends of Blue Tier in July. I suggested that too much of the George River catchment might have already been regenerated or converted to plantations and that further operations might well drive the river dry for extended periods in Summer. The Forest Practices Board (FPB) has now responded to this report with a series of criticisms.
The Board review has concluded that my work was invalid (basically plain wrong) because I had made several significant "errors". They also implied that I was alarmist and unscientific. This is, frankly, insulting and unnecessary. The quality of my work and my reputation has always been important to me and any report that I have prepared has been done with due care; something appreciated during my years in government service and then more than twenty years as a consultant. One cannot survive on alarmist rubbish. I have, however, always told it like I believe it to be, warts and all. I therefore stand by what I wrote. I wrote, with concern, as a Tasmanian who could see real problems ahead.
The "errors" assigned to me are either creations of the Board or due to my allowance for the unknown. I bent over backwards to give the benefit of all doubt to the forest industry and was shocked to find that it did not matter. The indicators were too clear, no matter what one assumed. The supposed errors include incorrect rainfall, wrong forest plan, wrong proportion of catchments, no allowance for coupe balancing, wrong estimates for evapotranspiration and tree demand, and unrealistic scenarios. Some of my "errors" were created by the Board by assigning to me factors I had never defined and then showing that they were wrong This is classic propaganda, discrediting technique and unacceptable. In fact, all my values are reasonable and conservative. I worked out the best case for forestry not the worst case scenario. I found that changes in assumptions would not make much difference. Everyone should be aware that calculations by me, and the Board to date, have been based on research in Victoria. Why is that? The Board, however, misuses some of this information to suggest that short term run off from cleared coupes can balance the long term growth demand of replacements. I argue that this theory is invalid and certainly should be verified by actual observations before basing widespread forest practices on it. There are cumulative and long term consequences from these logging practices and they are being ignored. It is easy for FPB to say that these practices have not caused any loss of water when local studies are not undertaken to confirm or deny it. The real problem is that, if I and other researchers are right, it will be the next generation who will find out what we have lost. The onus of proof should be on those making the greatest changes in our landscape. The Forest Practices Code and supporting legislation ensures that it falls on the rest of us. It is for this reason that I encourage concerned communities to monitor their own supplies.
It seems strange that everyone, Board included, can admit that growing trees use more water than a mature forest and that there might have to be trading rights with other users, such as farmers. Why should we than accept that water supplies for towns or individuals would not be affected in the same way? Of course they will be. The question is always - how much and is it a problem? We must pull our head out of the trees and look at the bigger, and much longer term, issues - and water is first among these.
I began work on catchment behaviour in 1966 with the principal aim of defining how water moved and was stored in ground: the crucial, hidden part of the water cycle. I soon found that seasonal, frost effects and vegetation growth changes were recognizable in my data. Now in semi-retirement, I am close to completing this study. Its original aims have been hijacked by the forest problem because the groundwater responds to forest demands and so reduces stream flow. Again the question is, how much? I have found a way of examining the history of east Tasmanian rivers and early results are staggering. I know enough by now to be really concerned. We all should be. No one should barge ahead with huge scale land use changes without due care and knowledge, or base everything on a dubious theory. It is irresponsible to do so.
Anyone who actually reads my documents, rather than hears about them, will find that I am not anti-forestry but we do need careful, sensible operational policies which consider all factors in catchments, including water balances, shared usage and involve full accounting of practices.
If you would like to read my complete reply to the Forest Practices Board report, their criticisms, and my original report, please contact either B. Hansberry (03 6373 6146) or L. Nicklason (03 6363 6195) of Friends of the Blue Tier. Think about what might be at stake here and what might be done about it.
D. E. Leaman, Ph.D., Hydrologist
Leaman Geophysics, Hobart, Tasmania
[Republished with permission of the author and editors of Upper Catchment Issues, which first published this in Vol.2#1B, ISSN 1444-9560. The original paper as well as it'ssummary are available online.]