Interação entre os regimes pluvial, hidrológico e hidrossedimentológico na Bacia do Córrego do Gigante – Poços de Caldas – MG

Abstract

Knowledge of the interaction between pluviometric regime, surface runoff, sediment production and transport is essential to predict and avoid possible economic, social and environmental problems. This context was searched in the Giant Stream Hydrographic Basin, an important headwater basin, with an area of 3.56 km², a direct contributor to the Cipó reservoir in Poços de Caldas - MG. Direct monitoring of precipitation, soil losses, and runoff and indirect monitoring of the suspended solids concentration by means of an optical turbidity sensor were promoted. The results showed a precipitation of 1579.6 mm for the hydrological year, of which 85% occurred in the rainy season and 333 mm in January. We classified 30 events as erosive, whose precipitated slides represented 57% of the total precipitate. In March, the highest precipitation intensities occurred, associated with the periods of 5, 10 and 30 minutes, and daily, as well as the highest monthly erosivity. The estimated hydrological indicators point to a regularized runoff regime, with a high minimum flow rate, due to the good water infiltration capacity in the soil. In terms of soil losses, the highest rates occurred in the Cambissolo exposed with 9.74 t.ha.ano-1, and in the exposed Latosol with 5.88 t.ha.ano-1, the average of the basin being 0.825 t. The mass of suspended solids transported was 0.070 and 0.14 t.ha-1, when estimated by direct sampling and turbidity, respectively, resulting in a low transport rate of suspended sediment, with the credit being attributed to the results. presence of native forest, reforestation, grazing without grazing and the positive effect of ciliary vegetation. The turbidity sensor presented qualitative, good performance, but in quantitative terms, the values were overestimated, thus, a careful analysis of the data series is recommended, and if necessary, to make the correct corrections in the high values and without consistency, which are present in the series.