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The Dunham River in 2002: Australia’s “Year of the Out-Back”

Kachana Pastoral Company filed this report in order to raise community awareness about loss of biodiversity in the region. This summary may seem long-winded to some, but after all we are facing a predicament that did not develop over night. Nor will it be solved over night.

Part one:

Most rainfall-catchment areas that I am acquainted with in this part of the country are in a similar predicament. There is a net export of soil and biomass each year. This process increasingly threatens what biodiversity is still here.

It needs to be stressed that when I refer to "rainfall-catchment areas" I mean the rugged “back country” that includes watersheds and upper catchment areas. Not the “downs type” country which very often is/was floodplain country. I refer primarily to country that belongs to the significant portion of Northern Australia which is not perceived to be actively contributing to our nation’s economy.

The backdrop as I understand it:

It is no longer a secret within the world scientific community that Australia experienced a major loss of biodiversity in conjunction with the advent of the first humans and the subsequent loss of mega-fauna numbers (we will never know the magnitude) and species (in excess of 90%) over time. With this "change" came a ripple effect that we can only speculate about: Most evidence of the disappearance of vegetation, invertebrates and micro-organisms has long since been extinguished.

Depending on which scientists we choose to believe, it seems that by the time the most recent wave of human occupation reached the Kimberley (in this case Europeans), the local ecology had stabilised under the evolved/adapted human behaviour patterns of the descendants of earlier human migrants. This behaviour included the use of fire. Once again we can only speculate about the exact nature of these behaviour patterns. Most of the knowledge has either been lost or become largely irrelevant as local environments have undergone further massive change as a direct result of further modification of human behaviour in recent decades. (Escalating environmental deterioration of large tracts of Out-Back Australia is a saddening testimony of this, as is the plight of many rural communities.)

In any case the "stability" of the "pre Captain Cook" environments "sustained" an annual export of soil contributing to what I heard one member of the Fisheries Dept call “a marine desert” off our North Australian shores. In addition to this much carbon was annually exhausted into the atmosphere. The pollutant nature of vegetation-fires was already being well researched within the scientific community by the mid nineties.

It is also worth noting that early missionary reports indicate that Kimberley aboriginal populations were under stress, by the time white man appeared on the local scene. This theory seems to be backed by Archaeological evidence. (Work on this continues.)

With respect to the rugged upper rainfall-catchment country which proved to be unsuitable for financially viable beef enterprises, the biggest single factor to induce "environmental change" was in all probability the cessation of “traditional burning”. This led to perennial grasses either being excessively "rested" (= not pruned and therefore becoming senescent) and/or being subjected to hot burns. There is ample scientific evidence on several continents that neither of these two practices is conducive to plant-health or an effective water cycle (emphasis on the biological component).

Through plain ignorance and a general lack of environmental literacy a disproportionate amount of blame is being thrown at introduced species or those who try and manage them. From an ecological aspect it could easily be argued that introduced herbivores turned feral contribute more to a visual impact through aggravating localised soil erosion, than they do to the loss of biodiversity. (I am not advocating the protection of feral animals by any means. I am merely implying that we may well be able to use them to advantage by recognising their functional roles within nature and then attempting to influence their behaviour accordingly. Cull animals produced by industry could be put to better use in a similar fashion.)

Current situational info.

The deterioration of the Ord River catchment and the salting of Lake Argyle are still hidden behind two dam walls, but the Dunham River is a different story. March 2000 I made a 37-page submission outlining and substantiating my concerns. This submission was tabled with “Ord Land and Water” and local authorities were made aware of it. To draw some attention to the issue of regional rainfall catchment health, I outlined one scenario that would affect local communities: the partial draining of Lake Kununurra. I believe we were only a five-inch storm away from that scenario last week. I flew the length of the Dunham four times after the event and what I saw indicated that the Dunham was behaving just as I anticipated. Like a slightly tilted bath-tub with both taps running (at times) and a face-towel partially obstructing the drain.

In this case the “taps” shut off just as the tub was beginning to overflow on one side (photos available). The rate with which the water flowed being a direct result of a close to non-effective water-cycle in upper-catchment areas. (I refer in particular to the biological facet of the water-cycle: the role of plant litter and healthy root-systems to retain and percolate the water and later transpiration.) The "face-towel partially obstructing the drain" is the result over time of nutrient-rich tail-water perennially feeding into the lower Dunham from the Packsaddle Plains irrigation area. This has led to prolonged growth periods and higher plant vigour in that area. This build-up of vegetation in the drainage channels of the lower Dunham slows the flow sufficiently to make it drop a higher portion of its sediment load in that area. Increasingly we notice the choking up of drainage lines. This process is of course greatly aided by the geographical features of that area. Apart from what can easily be observed and monitored on site there is further evidence for this development. Tributaries just upstream of the described areas have dropped much of their silt-load on site and gully development has stopped taking its natural course. This is due to everything being under water. Subsequent drainage was "slow" enough to significantly reduce the further gouging out of gullies. It is also evident that the Dunham did have another course running due east at some point in time. I will not speculate as to when that was, but the fact that water actually ran that direction last week tells me enough.

Flooding to date and future flooding in the area south west of Packsaddle plains is merely a symptom indicating the compounding effects of management practices (over time) both at the lower end as well as the upper end of the Dunham. ( http://www.abc.net.au/kimberley/stories/s492225.htm ) I believe Allan Savory would attribute the root cause to conventional decision-making and I second that. Either way it seems most unlikely that the Kununurra community will escape the law of the harvest. (Statisticians may very well calculate that the probability of a repeat performance of last week’s rainfall events plus the additional 5-inch storm is a very low risk. However with a continued rate of decline in upper catchment health it is more a question of “when” than “whether”. Possible obvious band-aid solutions to free up the drainage may buy us some time, but they will not detract from what is happening up this end.)

The Kununurra community should thank Roy Wilson (who manages cattle on Doon Doon) for the precautionary burning he conducted in the upper Dunham catchment last year. Much as I believe that current burning practices are not sustainable, there is little doubt in my mind that had he not done so, the same amount of water would have been released through the Dunham Gorge in a much shorter time frame. I have no details of the costs to repair damage to physical infrastructure downstream, but if it had not been for Roy these costs would have been considerably greater.

In the absence of effective regional “river-catchment strategies”, there will be a continued need for managers like Roy and myself to reduce excessive fuel loads with fire. So long as this is the case the “problem” of the Dunham will not go away.

By Chris Henggeler, land manager, Kachana (2002-02-27)

Part two:

The more environmentally literate reader may challenge the logic behind my presumption that Roy’s May-burning in 2001 mitigated flooding effect in February 2002. Rightly so. After over fifteen years' acquaintance with the particular area, I can honestly claim that since Roy took on the management of that part of the catchment: whatever is happening there now, is better than what was happening before.

A late dry-season “scorcher” used to be close to a certainty in that area. Had this been the case late 2001, run-off early 2002 would have been significantly higher.

I believe Roy’s results to date go a long way in demonstrating that any management has to be more beneficial than “no management”. These visible results on the ground also support Allan Savory’s concept of “brittleness”.

If people like Roy were given access to greater numbers of livestock and released of the pressure to compete with commercial beef enterprises, they could afford to get away with less burning.

As somebody who burns much biomass every year, I will argue that this is the ecological premium that we need to pay for insurance on our commercial and other activities. I cannot see this method to be sustainable.

If we wish to effectively address the down-stream symptoms of poor water-cycles, I strongly encourage that “the powers that be” offer people like Roy (who have spent their whole life in the bush) the opportunity to explore animal maintained landscapes.

By Chris Henggeler, land manager, Kachana (2002-02-27)

Part three:

If we wish to apply the cautionary principle, perhaps now is a good time to begin?

It is close to the end of the dry season and there has been a change in management in the upper Dunham area. On Doon Doon the first page of the next chapter of further flooding of the Dunham River has recently been written. With a fire lit mid September, that swept through several thousand square kilometres at least two things have been achieved:

Who will be faced the financial and social costs of crisis management? Are we in a position to gauge the ecological costs associated with atmospheric pollution, loss of nutrients and biomass and a further compromise of the water cycle and the energy flow?

The sad part is that what the mustering contractor did is both politically correct and still standard practice in many areas of Northern Australia. There is little a neighbour can do except for accepting an apology if one is given. This situation reminds me of last year when during an areal burning program incendiary capsules were dropped on the wrong spot: "Sorry. It was a mistake; we did not know we were over Kachana."

Fire may well be the physical force that attracts so much research, however in the reality beyond our taxpayer funded trials, both the cause and the effect of fire remain a social issue.

It is increasingly apparent that the health of the Dunham River is symptomatic of social dysfunction. There is no apparent communication between the few departments and few land managers who now shape its destiny. There is little in place to transfer any potential plan to practical results on the ground.

In times of fiscal restraint and in the absence of a landscape goal it seems there is little that will be done about the health of the Dunham. Fortunately the path of a flooding river is easier to predict than the path of a cyclone. As for the timing of such an event….during a wet season would be a safe bet.

By Chris Henggeler, land manager, Kachana (2002-10-22)