Temporal and Spatial variations of Rainfall Erosivity in  Southwest of Iran

Torabian Moghadam, Elahe; Naderi, Mehdi; Mohammadi, Jahangard; Fatahi, Rouhallah

Temporal and Spatial variations of Rainfall Erosivity in Southwest of Iran

Document Type : Complete scientific research article

Authors

¹ shahrekord university

² Assis. Prof of soil sci of Agric, Shahrekord University.

³ Assoc. Prof of soil sci of Agric, Shahrekord University.

⁴ Assis. Prof of water Eng. College of Agric., ShahreKord Univ

Abstract

Rainfall erosivity index is the most important factor which impacts soil erosion. The objective of this research was mapping spatial and temporal variations of rainfall erosivity in the southwest of Iran. Properties of 10,000 rain storm belong to 27 climatological stations were analyzed and their synthetic energy (E) and maximum 30 minute rainfall intensity (I30) were calculated. The mean annual and monthly rainfall erosivities were calculated for all stations' data. Mapping spatial variations was carried out using Spline algorithm. The results showed that the monthly erosivityindex values decrease from the north to the south and from the west to the east of the region. Maximum and minimum values of annual erosivityequal to 26.39 and 6.11 MJ.mm.ha-1.h-1.yr-1 which were belong to Ivan (Ilamprovince) and Brojen station (ChaharmalVaBakhtiariprovince), respectively. Temporal studies of rainfall erosivity index indicated that maximum rainfall erosivity was equal to 183.7 MJ.mm.ha-1.h-1.yr-1andoccured in winter. Existence of significant correlation coefficients between the means of monthly and annual rainfall values and their corresponded rainfall erosivitieswere 0.94 and 0.93, respectively, and such significant correlation coefficients facilitate indirect estimations of monthly and annual rainfall erosivitiesthroughrainfall values and simple or multiple regression models. The results revealed higher reliability of multiple regression models consist of both means of annual rainfall and rain storm intensities than simple regression models for estimation annual rainfall erosivity.

Keywords