COMPARISON OF THE METHODS: ALTERNATE BLOCKS AND HISTORICAL HIETOGRAM FOR THE SELECTION OF DESIGN STORMS, CHIQUITO RIVER WATERSHED, TEGUCIGALPA, HONDURAS

Abstract

When comparing the use of methods: alternating blocks and historical hyetograph, for the selectionl of design storms and flows in the basin of the Chiquito River, the difference between them is significant in the distribution and amount of precipitation. But there are some historical hyetographs, whose distribution and peak flows are similar to the distribution method of alternate blocks. The hyetographs presenting this similarity are the storms: August 8, 2001, October 23, 2006, May 24, 2011. The year 2011 is the most similar storm in all aspects with the generated by alternating blocks, precipitation generated by both methods is 103.1 mm and 123.7 mm, and peak flow at about 500 and 540 m3/s, respectively, for a return period 100 years. Method of alternating blocks is applicable within the Chiquito River basin for design storms, because, some storms have been found with similar distribution, such as 2001, 2006 and 2011, presented in this article. In the comparison of 7 scenarios of distribution, the historical hyetograph generated less precipitation than the method of alternating blocks with percentages in the range of 41 to 83%. However, in 2 stages of distribution, the method of historical hyetograph presented a higher rainfall that generated by the method of alternating blocks with percentages about 135 to 145%, respectively.