Monitoring of erosivity in the area of contribution of the reservoir of the hidroeletric Cachoeira Dourada, GO/MG

Abstract

The erosivity index (EI30) was determined as well as their spacing in the contribution basins of the Cachoeira Dourada hydroelectric plant reservoir at the border with states Goiás and Minas Gerais, located between coordinates 48º 32’ to 49º 34’ W and 18º 20’ to 18º 53’ N. Data from 8 locations referring to 30-year average monthly and annual precipitations were used. An annual average precipitation of 1,441mm was found during that period, being the highest index in January and the lowest in July, with 7.5mm. The EI30 varied from 7,100 MJ to 8,500 MJ mm (ha h)-1, whose most significant period was concentrated between the months of october to march, with 7,880.3 MJ mm (ha h)-1, corresponding to 94% of the annual average EI30 index. The average variation coefficient of precipitations for all seasons was 82.73%. There is an irregular distribution of rain in the region and, thus, an uneven spacing of the erosivity indexes within the reservoir influence area. The highest precipitations coincide with the period of soil preparation and development of annual cycle plants, mainly soybean and corn.