Evaluación de la amenaza por sequía en el sector agrícola de la cuenca del río Prado bajo los escenarios del cambio climático

Abstract

This project evaluated the threat of drought in the agricultural sector in the Prado river basin, specifically in the Cunday sub-basin, which is located in the north central part of the Prado river basin in the department of Tolima, from the variations in temperature and precipitation over time. In accordance with the above, three situations were defined, the base period (1981 - 2012), and future conditions (2012 - 2099), defined by the climate change scenarios RCP 4.5 and RCP 8.5, which represent stabilization and a high level of emission. , respectively, according to the IPCC [1].

Initially, the production of runoff and soil moisture in the sub-basin was determined by means of the SWAT hydrological model. To carry out this process, it was necessary to have the precipitation and the temperature of the baseline and of the climatic scenarios. These variables were acquired from observed historical data, while predictions were obtained from global circulation models, which were corrected for bias and scale reduction.

Finally, from the baseline and future data, the calculation of the selected drought indices, Standardized Precipitation Index (SPI), Runoff Index (SRI), and Standardized Soil Water Index (SSWI) was performed. To combine the three indices (precipitation, soil moisture and runoff), the multivariate standardized drought index (MSDI) was calculated, which probabilistically combines each index and will eventually make the general characterization of drought [2]. As a result, the MSDI evaluated in the baseline presented a lower frequency of dry events compared to future scenarios. In the RCP 4.5 and 8.5 scenarios evaluated, the MSDI demonstrated that the drought durations will have a similar persistence. In addition, agricultural droughts will be more frequent in future conditions, increasing the intensity in the moderate, severe and extremely dry classifications, with respect to the baseline where most of the events were concentrated in conditions close to normal.