Water Flow and Precipitation Extremes Trends in Santa Catarina/Brazil: Implications for Resource Management

Código

I-EBHE0048

Autores

Paula Lidia Santana, Jéssica Aurora Bernardo, Patrícia Kazue Uda, ALEXANDRA RODRIGUES FINOTTI

Tema

WG 1.04: From local to large scale human-water dynamics

Resumo

Effective water resource management is crucial for the socio-economic and environmental development of regions. In places like Santa Catarina, Brazil, water is essential for agriculture, industry, domestic supply, and the preservation of aquatic ecosystems. This study analyzed rainfall and river flow data from Santa Catarina from 1991 to 2021, focusing on stations with complete data and less than 5% missing data. We used data from 17 pluviometric and 17 fluviometric stations for this analysis. For each station, we extracted the annual maximum values of precipitation and flow, using the hydrological year (September to August) as a reference. We then analyzed trends in these maximum values using the Mann-Kendall and Sen's Slope statistical techniques implemented in Python. The results showed no significant trends in all analyzed rainfall stations, indicated by high p-values and z statistics close to zero, suggesting that precipitation patterns have remained stable over the studied period. Most flow stations also did not show significant trends. However, two stations (84150100 and 84520010) exhibited a significant decreasing trend. At station 84150100 (city of Palhoça), we observed a significant decreasing trend in flow with a slope value of -6.98 m³/s, while the corresponding rainfall data showed no significant trend. This suggests that the reduction in flow may not be directly related to changes in precipitation. Factors such as changes in land use, dam management, or agricultural practices may be influencing flow. Similarly, at station 84520010 (city of Santa Rosa de Lima), the flow showed a significant decreasing trend with a slope value of -2.71 m³/s, with no significant trend in the corresponding rainfall data, indicating that other factors might be at play. These observations have important implications for water resource management. The decreasing trends in flow observed at some stations, without a corresponding reduction in precipitation, suggest that other factors like excessive extraction, changes in land use, and agricultural practices are affecting water availability. Effective water resource management should consider these factors and implement strategies to mitigate their impacts. Continuous monitoring of precipitation and flow data is crucial to quickly identify any changes that may require management actions. Continuous analysis helps differentiate between natural variability and anthropogenic impacts. Further studies are needed to better understand the causes of the observed trends in flow, including changes in land use, infrastructure construction, and irrigation practices. Hydrological models could simulate different scenarios to identify the key factors influencing flow. In conclusion, while precipitation data remain stable, some flow stations showed significant decreasing trends. These decreasing trends in flow are not accompanied by changes in precipitation patterns, suggesting that other factors are influencing flow. These observations highlight the importance of an integrated approach to watershed management, considering not only precipitation data but also the anthropogenic and environmental factors that may impact water resource availability.