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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Sediment management and morphodynamics : Modeling the erosivity of frontal storms in the semi-arid climate of central chile
Modeling the erosivity of frontal storms in the semi-arid climate of central chile
Author : GABRIEL P. LOBO1), CARLOS A. BONILLA(1)
ABSTRACT
CLIGEN (CLImate GENerator) is a stochastic weather generator that produces daily estimates of precipitation and
individual storm parameters, including time to peak, peak intensity and storm duration. These parameters are typically
used as inputs for other models, such as the Water Erosion Prediction Project (WEPP) model. Although CLIGEN has
proven to be effective for predicting daily estimates, some discrepancies have been observed when generating storm
parameters, such as the storm duration. Therefore, a study was conducted to evaluate and improve CLIGEN for storm
generation. Individual rainfall events were identified from 1-h pluviograph records that were collected from 30 sites in
Central Chile. In this study, 415 years of data were used; 18,012 storms were analyzed. In addition, rainfall erosivity was
computed for all storms using the prescribed method to compare the energy provided by the measured and generated
rainfall events. Using measured rainfall data, a procedure was developed to improve the CLIGEN estimates by calibrating
the input parameter that controls the storm durations. This procedure in turn improved the rainfall intensities and
erosivities. The model was tested before and after calibration with the measured rainfall data from the 30 sites in both the
wet and the dry seasons. Based on a monthly rainfall analysis, the results demonstrated that the number of storms and
rainfall amounts, which are not affected by the calibration process, were accurately estimated with CLIGEN. However,
before the calibration, especially in the wet season, the storm durations and maximum intensities were consistently
overestimated and underestimated at most of the sites and for most months. Therefore, the annual rainfall erosivities were
underestimated with CLIGEN at 19 of the 30 sites. After performing the calibration, the R2 value for the CLIGEN-generated
storm durations increased from 0.41 to 0.65. The maximum intensities also exhibited an improvement; the R2 value
increased from 0.31 to 0.60. Consequently, annual rainfall erosivities were generated with an R2 value of 0.89; these
erosivities were accurately estimated at 29 of the 30 sites. Therefore, this calibration procedure proved to be an effective
alternative for generating more reliable storm patterns. This paper explains the procedure in detail and analyzes the
parameters related to the individual storm generation process.
File Size : 821,810 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Sediment management and morphodynamics
Date Published : 19/08/2015
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