Reflorestamento em microbacias hidrográficas com vistas à retenção de água no solo – estudo de caso.

Abstract

The management of the country roads contributed for the erosive process, mainly in the areas that the soil was moved by implements from conventional tillage. This work had as objective to quantify the reforestation for water retention in the Palmital Stream watershed, County of Jaboticabal, SP. The methodology esteems the retention of water in watersheds considering the world medium value of destiny of the water in the hydrologic cycle; the use/occupation of the soil (forest, pasture and agriculture); and its permeability. The watershed in this study presents an area of 10,625.21 ha, being 237.75 ha at forest, 467.01 ha in pasture and 9,237.57 ha in agriculture. The medium values of the permeability identified in the soils were of 94.81 mm h-1 in forest; 8.99 mm h-1 in pasture and 36.01 mm h-1 in agriculture (sugar cane). Considering that should infiltrate in the soil 20.55% of the water that precipitates on the watershed, and, that the losses of water in forest areas is considered standard, the total estimated volume to compensate the excessive loss that occur in the areas of pasture and agriculture is 11.80 million of m3/ano. The compensatory forestation to retain that volume of loss should contemplate an area of 911.30 ha (8.87% of the area of the watershed).