Efectos sobre la precipitación y temperatura de la cuenca del río Guavio asociados a un embalse

Abstract

In recent years the importance of reservoirs for the use of surface water resources, hydroelectric power production, flood control and drinking water supply; has generated an increase in their development and construction along the Colombian river basins. However, the benefits generated by the reservoirs have been causing a series of environmental impacts that have contributed to the affectation of water resources and climatic variability, due to the fact that the large amount of artificially concentrated water for the construction of reservoirs within riverbeds has an impact on hydrometeorological variables.

Taking into account what has been previously exposed, the determination of the influence of reservoirs on the variables of the hydrological cycle of the Colombian basins is a topic of great importance and interest at present. Therefore, this degree work had the purpose of determining the effects of a reservoir on the precipitation and temperature of the Guavio River basin and its sub-basins on a monthly and annual scale, through the application of tests for trend analysis such as the Mann Kendall and Pettit test, in addition to the Wilcoxon and Pearson correlation tests applied for the period from January 1977 to December 2017. The degree project was carried out in five phases which included (i) the collection of the information; (ii) the delimitation of the basin and sub-basins object of analysis and determination of the stations to use by means of a consistency analysis; (iii) the interpolation of the precipitation and obtaining data of the Normalized Difference Vegetation Index (NDVI); (iv) the application of the analysis of tendencies and the (v) test of correlation between the NDVI, the precipitation and the temperature at monthly and annual scales.

The results of the Mann Kendall and Wilcoxon tests indicated that on an annual and monthly scale in only certain months of the year there were statistically significant trends in which there was a reduction in precipitation and an increase in temperature, in addition to significant differences in the variables analyzed in the period before and after the reservoir began operating; these results were replicated in three subbasins in general (Sueva, Batatas and Chivor River sub-basins). However, for the Sueva River basin and sub-basin it was concluded that the fluctuations in the hydrological variables studied were associated to a greater extent to the transformation of coverages, because they presented a statistically significant correlation between precipitation, temperature and the NDVI.

On the other hand, it was evidenced that the reservoir is causing alterations on the precipitation and temperatures on an annual and monthly scale, causing the most significant effects on the sub-basins of the Batatas and Chivor rivers, which are closer to the reservoir. However, it is not possible to assert in what proportion the reservoir has contributed to generate changes on the analyzed climatological variables, because these are also influenced by factors such as the dynamics of soil use and climatological phenomena like the one of the boy and the girl.

Finally, these results allowed us to reach the conclusion that the conditions on rainfalls and temperatures generated by the reservoir can affect the operation of the hydroelectric plant and other ecosystem services in the basin.