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Evaluation of Methods of Calculation of Concentration Times and Peak Flow in Hydrographic Basins: Case of Rio Pacora

Author(s): José R. Fábrega

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Keywords: Pacora River Basin; Panama; Concentration times; Peak flows;

Abstract: Panama`s water resources greatly determine its economic activities. Panama has an average annual precipitation and runoff of 3000 mm and 1764 mm respectively. Concentration and peak times (tp and tc) are fundamental parameters for watershed management. However, the equations widely used to calculate these parameters were obtained for areas with different characteristics than those in the tropics. This paper reviews the variability among these equations. As a case study, we use the Pacora River Basin located between the coordinates 8 ° 00 `and 8 ° 20` N and 79 ° 15 `and 79 ° 30` W. It has 6 sub-basins and a total area of 369 km2. Its topography is varied, ranging from smooth slopes in the lower part (<8%) to steeper ones in the upper part (up to 75%) tp and tc were calculated by Kirpich`s methods, "Curve Number "Of the SCS and Johnston & Cross. Tc (hr) values of 6.6, 50.2 and 2.01 and tp (hr) of 4.6, 30 and 1.41 were obtained for Kirprich, SCS and Johnston & Cross respectively. In this sense, Kirprich and Johnston & Cross, may be the most appropriate, since the SCS method fits better with basins under 800 Ha. Total tp and tc values resulted from the summatory of tp and tc sub-basins values. As a conclusion, there is a necessity in tropical basins to have more monitoring and controlled experiments in order to validate existing methodologies.

DOI: https://doi.org/10.3850/38WC092019-1457

Year: 2019

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