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Estimating the rainfall erosivity factor from monthly precipitation data in the Madrid Region (Spain)

Abstract

The need for continuous recording rain gauges makes it difficult to determine the rainfall erosivity factor (Rfactor) of the Universal Soil Loss Equation in regions without good spatial and temporal data coverage. In particular, the R-factor is only known at 16 rain gauge stations in the Madrid Region (Spain). The objectives of this study were to identify a readily available estimate of the R-factor for the Madrid Region and to evaluate the effect of rainfall record length on estimate precision and accuracy. Five estimators based on monthly precipitation were considered: total annual rainfall (P), Fournier index (F), modified Fournier index (MFI), precipitation concentration index (PCI) and a regression equation provided by the Spanish Nature Conservation Institute (RICONA). Regression results from 8 calibration stations showed that MFI was the best estimator in terms of coefficient of determination and root mean squared error, closely followed by P. Analysis of the effect of record length indicated that little improvement was obtained for MFI and P over 5- year intervals. Finally, validation in 8 additional stations supported that the equation R = 1.05·MFI computed for a record length of 5 years provided a simple, precise and accurate estimate of the R-factor in the Madrid Region.

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Spatial variability of concentration and aggressiveness of precipitation in North-East of Algeria

Abstract

In this study, the spatial variation of daily and monthly concentration precipitation index and its aggressiveness were used in 23 rainfall stations in the extreme north-east of Algeria over the period 1970–2010. The trend was analysed by the Mann–Kendall (MK) test. The results show that daily precipitation concentration index (CI) values are noticeably higher in places where the amount of total precipitation is low, the results of MK test show that areas of high precipitation concentration tend to increase. The seasonality and aggressiveness of precipitation are high in the eastern and western parts of the study region (eastern and central coastal of Constantine catchments), whereas a moderately seasonal distribution with low aggressiveness is found in the middle of the study area (plains and central Seybouse catchment). As a result, the modified Fournier index (MFI) has a significant correlation with annual precipitation, whereas the CI and monthly precipitation concentration index (PCI) show an opposite correlation in relation to annual precipitation.

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A novel fuzzy clustering approach to regionalise watersheds with an automatic determination of optimal number of clusters

for regional precipitation frequency analysis. J. Hydrol. Hydromech., 57, 4, 226-249. Gabriels, D., 2006. Assessing the modified Fournier Index and the Precipitation Concentration Index for some European countries. In: Boardman, J., Poesen, J. (Eds.): Soil Erosion in Europe. John Wiley & Sons, Chichester, pp. 675-684. Goyal, M.K., Gupta, V., 2014. Identification of homogeneous rainfall regimes in northeast region of India using Fuzzy Cluster Analysis. Water Resour. Manag., 28, 4491-4511. Goyal, M.K., Sharma, A. 2016. A

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