HIDROSSEDIMENTOLOGIA DE UMA BACIA HIDROGRÁFICA TROPICAL INTRAMONTANA

Abstract

Understanding the hydro-sedimentological dynamics of a watershed is fundamental in decision-making and in a management planning for the rational use of natural resources. As a result, this work aims to analyze the hydro-sedimentology of the Pau Amarelo stream watershed in an intramontane tropical environment. To this end, between February 2017 and May 2019, monitoring of flow, water level, precipitation and concentration of suspended sediments was carried out. From this data collection, statistical analysis was performed between different parameters and daily calculations of flow and sediment yield through rating curves. The accumulated rainfall recorded was close to the normal rainfall in 2017 and above in 2018. The average flow monitored was 0.216 m³.s-1. The concentration of suspended sediments observed ranged from 0.14 mg.L-1 to 11.80 mg.L-1. The results showed that the average velocity is the main factor of variation of the results in the flow, corresponding on average to 61% of the entire average, for width and depth values close to 20%. It was verified through the flow duration curve that the Q90, in the study period, was 0.034 m³.s-1. The analysis of the relationship between rainfall and flow indicates that the flow does not present a direct response to rainfall, especially in low-magnitude rainfall, with other factors that regulate the flow, such as the duration of the event and the interception carried out by the forest. The sediment rating curve that best represented the dataset was the one constructed by dividing it into three sections separated by the flow. The observed and estimated data on the concentration and suspended sediment yield show that the use and land cover of the Atlantic Forest worked as a positive factor in reducing the suspended sediments yield, even in the face of a strongly dissected relief, with accentuated slopes and soils susceptible to erosion.