Characterization of aquatic environments in the De Ondas River, Bahian Cerrado

This work sought to characterize the types of environments present in the De Ondas River, with the aim of obtaining information on their structural complexity and supporting public policies for water resource management that will allow the shared water use and will protect the biodiversity of the river basin. The De Ondas River watershed is located in the Cerrado Region, in the western part of Bahia State, and covers an area of 5.559 km². In order to perform the characterization, two stretches were demarcated, one in the upper part of the basin and another in the lower. Afterwards, a topobathymetric survey was conducted, and characterizations of the bottom and of hydraulic properties were done for both the rainy and dry seasons. The topobathymetric survey in the upper course showed altitudes ranging from 699.82 m to 714.06, whereas in the lower course these varied from 439.45 m to 446.91 m. Bathymetric profiles allowed the visualization of the structure and distribution of the bottom of the channel environments. The granulometric analysis of the higher part of the basin showed that sand was predominant (88.94%), while in the lower part boulders (76.9%) and cobble (23.1%) predominated. In the higher part of the basin, the water flow varied from 5.20 m³s-1 (dry period) to 9.07 m³s-1 (rainy period); and in the lower part, from 25.73 m³s-1 (dry period) to 66.44 m³s-1 (rainy period). The complexity of the environments of these stretches favors biological diversity in the river, resulting in different environments that aid aquatic species in adapting to the channel structure. The study of the physical characteristics of the De Ondas River produced a great amount of information regarding the micro-environments of the stretches examined, and will support studies related to aquatic biota and water resource management.