Flood Control And Soil Erosion Are National Problems

Otago Daily Times, Issue 27404, 1 June 1950, Page 4

Flood Control And Soil Erosion Are National Problems

Staff Reporter

Much of the high country in the vast hinterland of Central Otago is little better than a desert waste. Much of it has been in this state for years, and thousands of acres annually are being added to the sorry tragedy. Two factors alone are responsible for this—the gross mismanagement of the land in past years and the depredations of rabbits. It has been said that it took China 3000 years to lay waste much of its arable land; that the United States of America achieved the same result in 300 years, but that New Zealand has beaten them both. In 100 years her people have destroyed land which nature took aeons of time to build up.’

In Central Otago great mountain ranges, barren of any type of vegetation, and in many instances of soil also, present a shocking indictment of man —of his folly and stupidity. In many instances, huge slopes, thousands of feet high, and comprised of a friable conglomerate, are slowly but inexorably moving down into the valleys.

use is it to spend vast sums yearly in combating floods on the coast and at the same lime completely to ignore the source of the trouble—the rapid erosion of the soil from the mountains at the headwaters of our rivers? THE TOLL OF EROSION Go where you will throughout Central Otago high country, and the ravages of erosion and flooding be-

Successive seasons of flood, rains and snow, accentuated by frost, accelerate the movement. Natural watercourses, small and large, have filled or are rapidly filling with debris and shingle, and the mountain torrents, silt laden, flood the coastal lowlands. On . their headlong rush to the sea they gouge away the precious but immensely rich small alluvial flats..

Such is the sorry picture for all to see. Posterity will condemn this generation as it condemns those in bygone ages who misused the land—civilisations now lying buried beneath drifting sand. Here in New Zealand history is repeating itself. To those who see. the problem is to arrest the soil’s decay and reverse the process. They are not visionaries, nor are they alone the land users. How to find a solution to this tragic problem is a matter which is exercising the minds of thinking men in all walks of life. It is a problem to which all should address themselves—townsman and country dweller alike, for the immediate future must inevitably “ reap the whirlwind ” unless it is solved. While too blithe an indifference is shown to the problem of erosion and the steady destruction of the soil going on im'our back country, flood damage mounts on coastal lands, and tens of thousands of pounds are spent annually trying to grapple with the menace. .City dwellers must ultimately be the greater sufferers. It is their roblem just as surely as it is that of the highcountry runholder. These views, without exception, are those of the members of the Otago Catchment Board, who spent all last week, early and late, on moutnains, downs and valleys, discussing ways and means of combating the evils of soil despoliation. Much has been said and written during the past year con--erning the desirability or otherwise )f catchment boards. A COMMON TASK The writer accompanined the Otago 3oard during its week’s tour of infection and is convinced that in its oresent form, comprising as it does ■pecialised members, plus the people’s elected representatives, it can grapple with the problem. It must, however, have the 100 per cent, backing of all he people. There is a Herculean task ahead of it. The cost of arresting the soil's decay is not going to be slight. If

come apparent. Each year the process is being accelerated by wind, rain, and frost. In the valleys where the bigger rivers flow, and in their tributaries, is a choking accumulation of boulders and gravel, all waiting for the next big flood to drive it headlong down towards the sea. Set in the pavement of the main street in Alexandra is a brass plate containing the simple words: “ The flood of 1878 came to here.” That plate must be nearly 50 feet above the level of the river just now. Board members, looking at it, posed the question: What would happen to Balclutha today if we had a similar flood? It could be wiped out. A flood of such dimensions today would pour off land protected by natural growth to a far less degree than it was in 1878— some 72 years ago. Such a flood could cause incalculable damage to land, property, and life. It is estimated that only 12 per cent, to 20 per cent, of the rainfall soaks into the soil today as against 90 per cent. 100 years ago. This means that 80 per cent, of today’s rainfall rushes down into the valleys, carrying with it millions of tons of topsoil and gravel. On the Dunedin side of Miller’s Flat.

the task is npt tackled now, in later years it will be beyond computing. Much criticism and some resentment have been expressed concerning the imposition of a special boat'd rate. “My land never floods, or erodes. Why should I pay a special rate? ” is a comment frequently heard. To that there is only one answer. The problem of saving the soil of this country is not an individual, but a national one. In future im-

where the Main State highway runs parallel with the Clutha River, much future trouble is in store. At one point one may go through a gate at the side of the road, walk a few paces and see a whirling cauldron of water, 30ft deep, quietly but irresistibly eating into a steep sand and gravel face. When viewed by Otago Catchment Board members as they stood on the grassy bank directly above, the river was at a record low level. So low was it that up river a short distance there was a long shingle'beach before seen by old identities. One good flood could tear that bank out and the bitumen road with it. The building of a new section of highway would be costly. That would be a charge against everybody's purse. One of the major tasks and responsibilities facing catchment boards in general is the checking of such river erosion. How can the regeneration of the high country, be brought about? How is it possible to reclothe it with natural grasses, hold the topsoil and the rain on the slopes where it falls, rather than have them both hurled down into the valleys and rivers? It is proposed to deal with this phase of the problem in succeeding articles.

poverishment, all must suffer; in future progress and prosperity, all must share. .If the public as a whole must, in the cause of national preservation, be asked to contribute, so also must it see that its policy decisions, arrived at through its elected board representatives, are carried out. Personal. sectional and financial interests must be subordinated in the jnterest of land rehabilitation. Much land in the future will require to be spelled completely unless it is to join the hundreds of thousands of acres already completely abandoned. As Otago Board members ask. of what