Processos hidrossedimentológicos em uma bacia experimental do semiárido brasileiro

Abstract

The caatinga biome is located in the most populous semi-arid region of the planet, and yet it is still very lacking in studies related to the hydrossedimentology area, especially in the monitoring of hydrological and sedimentological variables to better understand the processes involved. In this context, this research has the objective of monitoring and modeling the hydrosedimentological processes in the Curu Valley Experimental Basin - BEVC, with an area of 284.50 ha, located in the rural area of the municipality of Pentecoste, semi-arid region of the state of Ceará, in the Experimental Farm of the Federal University of Ceará. Two control sections equipped with regular sprinklers, rain gauges, rain gauge, class A tank and automatic level sensors were installed to monitor flow events in the basin, one at the Curu Valley Experimental Microbate - MEVC with 13.80 ha and another , Immediately upstream of the Açude Escola, located in the BEVC exudate, occupying an area of 256.60, which is 18 times larger than the MEVC. Two parcels of Wischmeier were planted at the MEVC with Caatinga cover, one with 40 years of fallow (preserved) and one with 8 years of fallow (Factor C), These uses together comprising 93.30% of the BEVC area. Factor C values estimated based on the measurements of the other RUSLE variables were 0.0061 for preserved caatinga and 0.0126 for thinned caatinga, respectively. The erosion in the basin was estimated for each event. Applying the RUSLE model with GIS tool support for the nested basins in a total of six runoff events, it was possible to estimate the average erosion rates of 0.95 ton ha-1 in the BEVC and of 0.11 ton ha-1 in the MEVC, these means being around 8 times larger from one basin to another. The sediment yield measured in the control sections of the two basins reveals that the MEVC has a higher ratio of sediment input corresponding to 26%, while the BEVC only 3.15%.