Research Article
Zaffani AG, Cruz NR,
Abstract
River pollutant loads encompass a combination of natural and anthropogenic factors related to land use and land cover (LULC). Progressive changes in LULC can significantly alter pollutant behaviors of changing flows and pollutant concentrations, reducing biodiversity, and emerging uncertainties regarded to poor gauged basins. To assess the factors involved in the generation of pollutant loads, this paper examined empirical uncertainties from observed pollutant loads in river basins through nested catchment experiments (NCE). Monitored river flows, concentration and drainage areas of each NCE were associated with LULC in order to determine specific pollution generation coefficients per unit of drainage area (Ys) of BOD, a- chlorophyll, NTK, TSS, and Total Coliforms. Three Brazilian watersheds were tested with drainage areas ranging from 0.93 km² to 242 km², and under different conditions of: (1) LULC (urban, forest and agricultural), (2) numbers of NCEs (2 to 11), (3) sampling seasons (1 to 4), (4) antecedent precipitation index (dry or wet conditions) and (5) biomes (Atlantic Forest and Cerrado-savanna). LULC appraisal showed complex upstream-downstream uncertainties of BOD, a-chlorophyll, and TSS from both urban and rural areas. Therefore, limitations of addressing representative values of specific pollution loads were preliminarily regarded due to the lack of continuous spatiotemporal schemes of experimental data at NCEs linked to existing point-sources and progressive LULC. Conclusions of this paper would benefit decision-makers on adapting resilient-driven land use plans to cope with regional pollution disaster risk management in Brazilian river basins.