Determination of Storm Profiles in the Central Andes of Peru

ABSTRACT

The central Andes of Peru, is a region with complex topography that presents a high variability in the distribution of rainfall and remains little known. The design of hydraulic works has as an important income the risk associated with extreme storms.

This investigation has analyzed 70 storms with durations between 0.7 and 13 hours, of pluviometric stations located between 8° and 13° south latitude. The hietograms of each storm were obtained, the dimensionless mass curves registered were probabilistically synthesized and finally, storm profiles were obtained for each group with probabilities of 10%, 50% and 90% of occurrence. Undoubtedly the dimensionless mass curves condense valuable information of temporary rainfall at each measurement point. Its importance is recognized in the definition of design storms, the distribution of precipitation and time were expressed as accumulated percentages to make valid comparisons between storms following the methodology proposed by Huff in 1967.

53% of storm events prevail in the first third (Type I), the set of curves defined in the second third (Type

1. are represented by 24% of the events and 23% of the remaining events represent the third third (Type

• out of a total of 70 storms. The storm profiles obtained indicate that on average: for the first group the heaviest rains (51%) will fall in the first 30% of the storm's weather; for the second group it indicates that there is an almost direct relationship between rainfall and duration, with the heaviest rainfall (68%) in the range of 30% to 70% of the storm's weather; finally for the third group the heaviest rains (57%) will fall in the last 30% of the storm's time. These results can be used as a reference for the central Andes of