Graphical analysis applications to study variability and trends of rainfall and streamflow in Colombian catchments

Monitoring trends and continuous changes to complement local studies on discharge and precipitation are becoming increasingly important, assessing systematically its temporal and spatial variation characteristics. It is also necessary to provide detailed study on the driving mechanisms of those variations, which can be a result of anthropogenic activities as it specifically affects particular regions and terrains. These data play very significant roles in measuring and forecasting potential impacts and lead to future improved regional flow regulations for better water resources management. One of the most effective methods for observing the effects of climate change on hydrometeorological variables is the trend analysis, with recently new graphical methods that represents an innovative alternative to the classical ones. In this work, mean monthly, annual mean, minimum and maximum precipitation was examined to analyze spatiotemporal variations, seasonality shifts and trends with records that can extend from 1910 to 2019 in the hydrometeorological network. The flow discharge were also analysed considering catchments with unimpaired streamflow in unregulated rivers. Different homogeneity and shift detection methods were used to check their homogeneity before conducting trend analysis. Innovative Polygon Trend Analysis (IPTA), Innovative trend analysis (ITA) with the Significance Test and Mann-Kendall (MK) non-parametric methods were compared, showing their sensitivity and their ability to explain a monthly trend sequence and periodicity in the studied region in order to explain adequately the temporal internal variability.