Projected effects of climate change in precipitation and streamflows of the Upper Orinoco River Basin from global and regional climate models

We studied the projections of streamflows under climate change scenarios in the Upper Orinoco River Basin by using precipitation from 15 global and regional climate models for the period 2020-2099. For this purpose, we calibrated and validated a hydrological model with a very good performance. Our results show that both precipitation and streamflow have a significant reduction for the RCP8.5 scenario that ranges from 5 and 7% in relation to the long-term means at the end of the century. The changes in both variables are not significant for the RCP2.6 scenario. Moreover, we compute several indicators of change in the streamflow to quantify alterations in high-, mid-, and low-range flows. Our results suggest that the main alterations for the future runoff would be evidenced in the mid-range and low flows, which could increase around similar to 5 and similar to 25%, respectively. These alterations could lead to changes in the hydrological, environmental, and ecological balance of the basin. This work provides information regarding the possible effects of climate change on the streamflow of one of the most important river basins of northern South America, which is pivotal for supporting future decision-making on water supply for social, environmental, and productive sectors.