Evaluación del impacto del cambio y variabilidad climáticos en la oferta hídrica de la principal cuenca abastecedora del sistema Chingaza por medio de un modelo Swat

Abstract

The Chingaza System, the main source of water for Bogota and its surroundings, is facing increasing pressure due to increased demand and the impacts of climate change and variability. This study focuses on assessing the influence of climate change and variability on the surface water supply of the main watershed supplying the Chingaza System, by analyzing changes in precipitation patterns that directly or indirectly affect the availability of surface water in the watershed. Given the importance of this ecosystem in regulating the hydrological cycle, understanding these impacts is essential to ensure the sustainability of water supply to the region. To carry out this study, an exhaustive compilation of hydrometeorological data was conducted, which was subjected to consistency and imputation analysis to ensure its quality. Subsequently, the SWAT hydrological model was used to delimit the basin and simulate its hydrological behavior, calibrating and validating the results with observed data. Additionally, a detailed analysis of historical climate variability was carried out at a daily level, using the hypothesis tests: Pettitt, Mann Kendall, Fligner-Killen and Kruskal-Wallis, to identify differences in the behavior of precipitation and flow under different ENSO conditions. Finally, climate change scenarios were used to project future climate scenarios and evaluate their potential impacts on the surface water supply of the basin. The results showed differences in the behavior of precipitation and flow under different ENSO conditions. El Niño decreases precipitation in the dry months (December-March), especially in the northeast, but increases rainfall in July, and La Niña decreases precipitation in the rainy months (June-July), shifting the peak rainfall to May and increasing precipitation in October-December and January-March. The amount of precipitation compared to the Neutral phase in La Niña indicates decreases of 2.13% and in El Niño decreases of 4.11%, although the amount of precipitation that varies during the condition is not very significant. The behavior of the flows shows that it is mostly conditioned by the behavior of precipitation. Subsequently, it was determined that the MRI-ESM2 0 model was the best fit to evaluate the behavior of precipitation and flow in the climate change scenarios SSP2-4.5 and SSP5-8.5 for the year 2100, finding decreases in precipitation, through the displacement of its spatial distribution in the direction of east to west in a range between 10% to 25%, decreases in the flow of the Chuza River in a range between 10% to 43% and decreases in the flow of the Guatiquia River in a range between 11% to 40%. The results of this research will serve as a basis for making informed decisions on water resource management and developing adaptation strategies to climate change.