Trend analysis and identification of possible periods of change in the occurrence of extreme streamflow events in a tropical basin

Abstract

Knowledge of the hydrological patterns of a river basin is important for environmental management in times of scarcity and floods. Among the variables that can influence river streamflow are precipitation and land use, which can intensify the occurrence of extreme events. The objective of this work is to identify trends in the time series of minimum and maximum streamflows, on a monthly and annual scale, in a tropical basin, based on non-parametric techniques. We also aim to analyze the main climatic and anthropic factors that can explain the changes in the rates of streamflow. The Mann-Kendall, modified Mann-Kendall and Pettitt tests were used at different levels of significance, as well as the Theil-Sen slope, to identify the magnitude of the trends found. The results showed that the minimum and maximum streamflows had a decreasing tendency in the dry period of the basin, specifically in October. Changes in the monthly time series occurred mainly in 2012. Precipitation behaved similarly to that observed in streamflows, with significant changes in the dry and rainy seasons, mainly in the north of the basin. Land use and land cover showed little variation in the analyzed period and was not considered a determining factor in streamflow changes. The application of different statistical methods allowed for finding satisfactory results for the behavior of water in the basin, while the analysis of climatic and anthropic factors made it possible to know their possible influences on changes in streamflow trends.