Avaliação da produção de sedimentos em áreas de diferentes escalas na bacia experimental do riacho Gravatá, semi-árido alagoano

Abstract

The current water resource management in the Brazilian Semi-arid area is scarce in information on methods that seek the optimization of the use of its water, which is fundamentally important having in view the serious panorama experienced in relation to the water availability. Searching to explore and understand the behavior of hydrosedimentology variables in the semi-arid region is increasingly common the study in experimental basins. In this context, this paper presents the instrumentation of an experimental basin in the semi-arid regions of the State of Alagoas, with emphasis on hydrosedimentology monitoring processes. This study was entirety developed from subsidies from hydrosedimentology monitoring processes in the field, having as the general objective to quantify the production of sediments in two different scales of experimental units: plots and microbasin. The selected microbasin has contributing area of 0.183 ha, and an average declivity of 6.5% and being constructed in the outlet a sediment pit for collecting the superficial discharge. In another area, three plots were installed, with 3 m² each, in a land with average declivity of 13%. The monitoring in the plots happened as of simulated rainfall, the simulator being calibrated to produce heavy rain for each of the plots. In relation to soil cover, the microbasin was studied in uncovered soil conditions, while as in the plots was done the plantation of cultivated corn hill under which is quite usual in the region. The production of sediment in the microbasin and in the plots was calculated from samples of the superficially drained material. The data observed made it possible to correlate the production of sediments with variables related to the total and effective rainfall. A growth tendency in the production of sediments due to the increase in superficial draining for both the monitored events in the microbasin as well as the monitoring done in the plots was observed. In the plots, the protection of the soil exerted by the corn cultivation provided a reduction in the production of sediments for all the simulated pluviometric intensities.