Show weather lier men tell army ha how W big dams must be bc the biggest rain that 4 might tall fall on a river or creek water watershed Is one of the i things that engineers need to know in building a dam tor flood control this hypothetical r rain aln must be at t maximum intensity and duration the runoff run off from such a rain determines th the e size she of the dam and more especially the size of the spillway huge losses may be avoided if the dam and spillway are big enough to withstand any flood that may develop ruke huge savings result when construction does not exceed needs for which the dam D built I 1 1 rainfall records and specialists of the united states weather bureau provide the corps of engineers united states army with essential information on possible maxi mUrn precipitations in a num number berof of watersheds watershed sor or basins where flood control projects are under way the figures turned over to the the engineers by the river and of the the weather veather bureau represent the maximum in rain intensity and duration that may be expected the biggest rain that maya may be expected would equal any big rains that hava fallen or might fall on the river basin in question the arkansas Arkan river basin above caddoa colo where a dam is to be built is 13 a good example in hecking checking its records the weather bureau r eau considered oil all big rains in that part of the united states state s and determined ter mined whether or not they might have fallen 0 on the upper arkansas watershed the probability of a bigger rain iain than the hypothetical rain is a virtual impossibility says the weather bureau the weather bureau has figures on the maximum rainfall fo together rother such watersheds among them the arkansas river basin sin above caddoa the st francis river above Wa mo the white river above the mud mountain damsite in washington wolf creek above port supply in oklahoma and mill creek in cincinnati it is planned to 1 make a similar study of all principal river basins in the country |