Metrics analysis of non fluvial lacustrine systems of the Lavrado, northeast region of Roraima State

Abstract

This study describe the morphometrics and seasonal dynamics of the lavrado's lacustrine systems, northeast portion of Roraima State in Brazil. The methods to identify the lake systems was performed by supervised classification based on Landsat 8 (OLI) of 2014 (rainy season) and 2015 ( dry season). The morphology of the permanent and temporary lakes was characterized by a shape index, which is a correlation of the lake perimeter with the geometry of a circle of equal area. Digital elevation models of SRTM were used to characterize the regional environment. The lavrado's lakes are develop in elevations between 50 and 200 meters of altitude, in regions dominated by agradationals geomorphological features. The lakes were classified as headwaters, isolated or connected ones. In relation to morphology the lakes are predominantly circular and semicircular in both seasons of the year. In the rainy season the lakes are interconnected to each other and also to the fluvial systems (fluvial-lacustrine connectivity), covering an area of 832,62 km²; during dry season the lakes cover 129,25 km² of the region, with about 17,000 lakes between perennial and seasonal.