Spatial variability of the rainfall erosivity in southern region of Minas Gerais state, Brazil

Abstract

Rainfall erosivity and its spatial variability were studied for 54 pluviometric stations in Southern Minas Gerais State (48º00' -44º00'W; 23º50' -20º00'S), aiming to plan the land-use strategies. Therefore, erosivity factor was determined for the pluviometric stations, using long-term rainfall data sets obtained along with the Brazilian National Water Agency-ANA, which varied from 15 to 40 years. The monthly and annual erosivity indexes were generated using Fournier equation for Lavras, MG and the spatial distribution of rainfall erosivity was studied on the basis of geostatistical approaches considering only the distance which separates them, developing the isotropic experimental semivariogram. The semivariogram adjustment was done based on the Weighted Least Squares method and the spatial dependence degree. Once the structure and the semivariogram adjustment were defined, the ordinary kriging maps were created, providing erosivity spatial behavior in Southern Minas Gerais. It was observed that the Southern Minas Gerais presents high erosivity patterns, ranging from 5,145 to 7,776 MJ mm ha -1 h -1 year -1, in Ijaci (north of region) and Itajubá (southern region), respectively. Besides, it was verified that the erosivity indexes are intensely influenced by the topography, associated with climatic conditions. Higher erosivity is connected to areas with a higher altitude, such as along the Mantiqueira Range Mountain, and on high plateaus and mountain ranges in the North-Central part of the region. The geostatistical approach using longterm rainfall data in Southern region of Minas Gerais state, which is a relatively heterogeneous region in terms of altitude, soil depth and slope, showed to be adequate to the proposal of this study.

Spatial Distribution of Annual and Monthly Rainfall Erosivity in the Jaguarí River Basin

“…Aquino et al (2012) concluded that the erosivity of the south region of the state of Minas Gerais was considered high and strongly influenced by altitude in association with climatic characteristics. Higher erosivity is associated with higher altitude areas, such as along the Mantiqueira Range and high plateaus and mountains in the north-central part of the region.…”

“…Studies of erosivity mapping on a national scale (Silva, 2004;Oliveira et al, 2012;Mello et al, 2013) and for the states of Minas Gerais (Mello et al, 2007;Moreira et al, 2008), with specific details for the south of the state of Minas Gerais (Aquino et al, 2012), and São Paulo (Vieira and Lombardi Neto, 1995;Moreira et al, 2006) showed analysis on a regional scale with low spatial resolution. However, river basins are the basic unit of planning and management of water resources, and the planning and implementation of soil and water conservation practices require a level of spatial detail consistent with their scale .…”

Soil loss by water erosion in areas under maize and jack beans intercropped and monocultures

“…All plots were limited by a galvanized zinc metal plate, inserted 20 cm into the soil and 20 cm left over the soil surface. At each plot lower side, an outlet was set to deliver soil and water into two 250 liter reservoirs connected to each other by a GEIB divisor, with 9 entrance windows, such that after the first reservoir was completely filled, one ninth of runoff was carried to the second reservoir, such as described by Aquino et al (2012).…”

Erosividade das chuvas e tempo de recorrência para Lavras, Minas Gerais

“…Pode-se observar que os maiores valores de erosividade ocorrem de outubro a março e, no período de abril a setembro, são consideravelmente menores. Essa distribuição temporal é característica da região, com verão chuvoso e inverno seco, sendo que vários pesquisadores, em diversas regiões do país, têm encontrado situação semelhante (Dias & Silva, 2003;Silva et al, 2009;Bertoni & Lombardi Neto, 2010;Silva et al, 2010;Aquino et al, 2012;Aquino et al, 2013).…”

“…Para todas as durações de chuvas intensas estudadas, as regiões norte e nordeste apresentaram as menores intensidades. Aquino et al (2012) observaram que a região sul de Minas Gerais apresenta elevada erosividade das chuvas, sendo os maiores índices observados nas áreas de maiores altitudes e nos planaltos e serras elevadas.…”