Rainfall input generation for the European Soil Erosion Model

摘要

A procedure to generate rainfall input for the EUROpean Soil Model ispresented. To develop such a procedure, first of all the influence of rainfallevent amount, rainfall event duration, and time to peak intensity of eventrainfall on soil losses, calculated with EUROSEM, has been tested for severalrainfall stations. Results revealed that every tested rainfall parameter hadhighly significant influence on computed soil loss. Therefore, distributions foreach station of the dataset and for each of these rainfall parameters werecalculated. To simulate rainfall event amounts, a mixed exponential distributionwas applied. After transformation of rainfall event durations, theirdistribution could be simulated using a normal distribution. The location of thepeak intensity was estimated using a kernel estimator, because no specificdistribution characteristics could be identified. According to the respectivedistribution functions, parameter values for each of the tested rainfall eventcharacteristic were then generated. These values were used to select rainfallevents with identical parameter values out of the rainfall station-specificdataset. Computed soil losses for events selected this way were compared withsoil losses calculated with available station specific rainfall event data.Comparisons for the respective means and medians generally revealed goodagreement. A comparison of 75 % quartiles resulted in less good agreement,especially for test conditions with high soil losses. In general, the appliedprocedure was capable of simulation station-specific soil losses and ofreflecting different environment conditions for the respective stations.Therefore, it seems possible to produce site specific appropriate rainfall inputfor EUROSEM, only with the knowledge of distributions for the investigated basicrainfall parameters. These are normally easier to obtain than long term rainfallinformation with high temporal resolution which would otherwise be necessary. Inorder to improve the procedure and make it practically useful, it will benecessary to account for seasonal changes of distributions of basic rainfallevent parameters.