Analysis of the impacts of extreme hydrological events on streamflow trends in the western region of Santa Catarina State, Brazil, using the Mann-Kendall test.

Código

I-EBHE0113

Autores

NEUDI JOSÉ BORDIGNON, RENÉE BEJAMINI

Tema

WG 2.1: Drought in the Anthropocene

Resumo

Extreme weather events, especially those related to water, have become increasingly frequent and intense due to global climate change. Among these events, severe droughts stand out, directly affecting the availability of water resources, agriculture, industry, biodiversity, and the populations' quality of life. The state of Santa Catarina, in southern Brazil, has faced a series of severe droughts in recent years, such as those that occurred from 2020 to 2022. The western region of the state was extremely affected, experiencing one of the most critical drought periods in the last six decades. In this region, several factors have contributed to the intensification of droughts, among them, the climatic variability stands out, exacerbated by the La Niña phenomenon, which causes a decrease in rainfall in the region. The impacts of droughts have been significant and multifaceted. Agriculture, one of the pillars of the region's economy, has suffered major losses, with decreases in grain production, milk, and meat. Water scarcity has also affected industry and city water supplies, leading to the adoption of rationing measures and the search for alternative water sources. Research has the potential to assist in water resources management by providing crucial information to ensure long-term water security. Planning and managing these resources should consider climate variability and the hydrological characteristics of local basins, thus ensuring water supply in the future. The Mann-Kendall (MK) statistical test is an important tool in the analysis of streamflow time series in hydrological studies. Through its application, it is possible to detect significant trends over time, even in the presence of non-normally distributed data. Additionally, the MK test is robust against extreme values and does not require specific assumptions about the data distribution shape. This makes it a reliable and versatile choice for identifying changes in streamflow patterns, aiding in efficient water resources management, and decisionmaking in climate change scenarios. This paper analyzes trends in the behavior of annual minimum specific flows with 95% permanence time, average flows, and maximum flows with 5% permanence time at a streamflow station operated by the National Water Agency (ANA) in the western region of Santa Catarina state. The Mann-Kendall (MK) test is applied to two distinct time periods: 1960 to 2019 and 1960 to 2022. The results indicate that extreme events in recent years in the region may change trends in flow series spanning more than 6 decades. Attention is drawn to the fact that in the region, maximum flows appear to be exhibiting different behavior trends compared to minimum and average flows in recent years.