A case study of factors controlling water quality in two warm monomictic tropical reservoirs located in contrasting agricultural watersheds

摘要: Abstract The integration of internal (e.g., stratification) and external pollution) factors on a comprehensive assessment reservoir water quality determines the success ecosystem restoration initiatives aids watershed management. However, integrated analyses are scarcer than studies addressing separately. Integration is likely more efficient in small well-characterized (experimental) watersheds, because isolation factor contributions presumably clearer. But those uncommon. This work describes two 5.5 m-deep reservoirs (MD-Main VD-Vocoroca dams) located Pindorama Experimental Center, state Sao Paulo, Brazil, considering interplay between dimension, seasonal thermal stratification, chemical gradients, erosive rainfall events, presence natural biofilters, land uses landscape patterns around within contributing watersheds. monitoring agricultural activities parameters occurred October 2018–July 2019. A 4 °C stratification (difference surface bottom temperature), which decreased until disappearance January (VD) or April (MD). longer period MD was justified by its larger area relative to VD (≈10×). Thermal triggered hypoxia at both (DO ≈ 1 mg/L), prolonged severe MD. Hypoxia activated Ec TDS peaks explained bottom-sediment nutrient releases, phosphorus. peak reached 560 μS/cm 290 μS/cm VD. smaller probably action macrophytes. In March, 240 NTU turbidity MD, caused precedent lack vegetation protection alongside south border. As expected, study accomplished clear contributions, verified Factor Cluster analyses. Our results can subsidize watersheds requiring restoration, where challenging.