Precipitation Trends Over The Southern Andean Altiplano From 1981 To 2018

This study undertakes a spatio-temporal assessment of the annual and seasonal precipitation trends over the Desaguadero-Poopo (DP) system in Bolivia for the period 1981-2018. Given the insufficient spatial density of meteorological stations in the study, the high-spatial resolution Climate Hazards group Infrared Precipitation with Stations (CHIRPS) satellite product was used. CHIRPS precipitation data was validated against 7,636 gauge measurements and used to map the spatial distribution of precipitation trends. In addition, the temporal changes in the onset, duration and average intensity of the wet season were explored. Results showed a good, statistically significant agreement between CHIRPS data and onsite records of monthly precipitation at the pixel and regional scales. The spatio-temporal precipitation assessment revealed that statistically significant increases in annual precipitation (2-6 mm yr(-1)) occurred in two zones at the north and north-western part of the DP system. Only the southern part showed decreasing precipitation trends at a rate of -1 mm yr(-1) while the central part did not show significant changes. Overall, a general increasing trend of about 2.5 mm yr(-1) was observed for the entire DP system during the 38-year study period, with the months of December and February showing the highest significant increases. The analysis of the onset and cessation times of the rainy season indicated a statistically significant decrease in its duration at a rate of -0.4 day yr(-1) and an increment of the average precipitation intensity. Our results reveal trend in the temporal concentration of precipitation in a water scarce region, which highlights the need for the management of the resource, so it can meet societal and environmental demands throughout the year.