NURSING NIAGARA

Dominion, Volume 21, Issue 189, 12 May 1928, Page 21

NURSING NIAGARA

SAFEGUARD AGAINST EROSION

Realising that Niagara Falls have other value than that of providing power, the Governments of Canada and the United States have appointed an international Niagara Board, consisting of two representatives of each country, to recommend measures for safeguarding the falls. While there is no reason for immediate alarm, certain developments of the last half-century show that a change is taking place which, if not checked, will eventually produce disastrous results. The report of the board states that supervision and control by the two Governments can preserve the scenic beauty of the falls for the enjoyment of future generations, and that by remedial work designed to distribute water, an enhancement ct the present scenic beauty ol the spectacle can be ensured. The board’s business has been to determine how the scenic beauty of the falls and

rapids can best be preserved, by what means and to what extent impairment by erosion or otherwise can be overcome, and what quantity of water may be diverted, either temporarily or permanently (writes Frank White in the “Argus”). Serious recession is taking place on the Canadian or Horseshoe Falls. A study of the geological structure of the fails and gorge, in conjunction with an analysis of the rate and character of the recession of the crestline as disclosed bv surveys made from time to time between .1764 and 1927, leads the board to conclude that there is no danger of the Horseshoe degenerating into a cascade or destroying itself by cutting a deep “notch.” On the contrary there is every reason to believe that the active part of the Horseshoe will broaden and the Crestline lengthen in graceful curves, and that, if adequately supplied with water, the main part of the Horseshoe 100 or 200 years hence will present an appearance equal o r superior to that of the present. The board’s investigations, made with the aid of competent geologists, show a mean rate of recession of the crest of the active part of the fall of 3.7 ft yearly since 1842, and of 2.3 ft yearly since 1906, indicating that the Horseshoe is now cutting back at a decreasing rate and that the rate will continue to decrease. The United States and Canadian flanks of the Horseshoe are not now perceptibly receding, and they are already practically bare. Within recent years a 415 ft. section of the crest on the Canadian flank has been filled up and converted from crest into a part of the wall of the gorge. Within the reasonably near future the Goat Island shelf will be completely dry, even in high-water seasons, and this part of the fall, if left to Nature, will take its natural place as a part of the wall of the gorge. The recession of the American Falls is negligible. Since these falls became separated from the Canadian, the Crestline has not receded much, if any more, than the dry crest of the adjacent walls of the gorge. There has never been sufficient flow over the falls to cause any material wearing away of the talus, composed of huge masses of rock which has fallen from the cliffs, and which, as long as it exists, prevents undercutting and consequent erosion. No increase in flow within reason will change the situation. Low flow over the falls results in a marked thinning out of the sheet of water, leaving the cliff behind the fall visible through the curtain at certain points and in certain lights, and gives an angular appearance to the crest.

The withdrawal of water for power purposes is subject at all times to the control of the two Governments. Increases may 'be conditioned by the construction of remedial works designed to distribute the waters of the river so as to_ ensure at all seasons unbroken Crestline on both the Canadian and American Falls and an enhancement of their scenic beauty. As the falls are in no danger of “committing suicide,” the board has rejected all plans involving elaborate works in the main part of the rapids as unnecessary to accomplish the’desired results and as destructive to some of the principal natural scenic effects. The type of construction considered by the board as best suited properly to rewater the flanks of the Horseshoe is a combination of excavations and submerged weirs carried from the shores near the flanks in to the adjacent main currents only far enough to accomplish the desired deflection of water to the flanks. This plan is susceptible of progressive extension upstream and into the rapids to the extent required to mask the effect of any reasonable additional diversions which may be agreed upon. The initial remedial works proposed consist of the removal of exposed shoals, in conjunction with the construction of submerged weirs lying diagonally and irregularly across the current, with incidental and co-ordinated excavation designed to deflect water from the heavy currents to the north and south of the central shoal, to distribute the water over the floor of the shelf adjacent to both shore lines and to the crest of the fall, and to merge into the general effect of the existing cascades. The sum of 1,750,000 dollars (£350,000) has bene set down as a conservative estimate of the amount required to carry out the board’s proposals. This work offers opportunity to test the effect of temporary additional withdrawals of water and the efficiency of remedial works to offset such withdrawals.