Estrutura e dinâmica limnológica da bacia do ribeirão CAMBÉ (Londrina / PR)

Abstract

The limitation in access to drinking water and the continuous degradation of water bodies in urban areas require the adoption of sustainable and effective measures to restore their quality. The Ribeirão Cambé watershed, located in Londrina, Paraná State, shows signs of environmental degradation, with emphasis on low levels of dissolved oxygen (DO) in specific reaches, a parameter essential for aquatic life. This study aimed to analyze the structure and limnological dynamics of the Ribeirão Cambé watershed by evaluating the main limnological parameters that influence water quality, in order to support environmental restoration actions focused on mitigating anthropogenic impacts and restoring the ecological functions of aquatic ecosystems. The methodology involved the selection of seven strategic sampling points distributed along the watershed for limnological sampling and analyses during two seasonal campaigns: August 2024, corresponding to the dry period, and April 2025, corresponding to the rainy period. Parameters analyzed included channel width and depth, water and air temperature, solar radiation, relative humidity, electrical conductivity (EC), hydrogen potential (pH), turbidity, transparency, DO, and total dissolved solids (TDS). Additionally, land use and land cover mapping was performed through supervised classification of satellite images, allowing the relationship between limnological conditions and the characteristics of the drainage basin to be assessed. The results indicated low DO levels at several sites, especially at the headwaters and in the reservoirs of the Igapó complex, where concentrations below 2.5 mg·L⁻¹ were recorded, characterizing conditions of severe hypoxia. Parameters such as EC and TDS showed high values, reinforcing the diagnosis of contamination from urban sources. Turbidity was significantly higher during the rainy period, reflecting the intensification of erosive processes during the season. Land use and land cover analysis revealed that more than 30% of the drainage area corresponds to urbanized areas, with a high proportion of exposed soil and insufficient vegetation cover, factors that intensify the input of sediments and nutrients into the aquatic system. Principal Component Analysis (PCA) showed that limnological variability is structured by thermal, mineralization, and atmospheric gradients, with clear seasonal separation between the sampling campaigns. It is concluded that the Ribeirão Cambé watershed is in an advanced state of degradation, requiring urgent interventions that include control of pollution sources, effective management of basic sanitation, restoration of riparian vegetation, and the establishment of permanent monitoring programs.