Hydrological Response Assessment of Land Cover Change in a Peruvian Amazonian Basin Impacted by Deforestation Using the SWAT Model

Abstract

The watershed hydrologic conditions in the Madre de Dios (MDD) Basin in the Peruvian Amazon have been irreversibly impacted by deforestation and changes in land cover. These changes have also had detrimental effects on the geomorphology, water quality, and aquatic habitat within the basin. However, there is a scarcity of hydrological modeling studies in this area, primarily due to the limited availability of hydrometeorological data. The primary objective of this study was to examine how deforestation impacts the hydrological conditions in the MDD Basin. By implementing the Soil and Water Assessment Tool (SWAT) model, this study determined that replacing 12% of the evergreen broadleaf forest area with bare land resulted in a significant increase in surface runoff, by 38% monthly, a 1% annual reduction of evapotranspiration, and an average monthly streamflow increase of 12%. Changes in spatial patterns reveal that the primary impacted watershed is the Inambari River subbasin, a significant tributary of the Madre de Dios River. This area experiences an annual average surge of 187% in surface runoff generation while witnessing an annual average reduction of 8% in evapotranspiration. These findings have important implications, as they can contribute to instances of flooding and extreme inundation events, which have already occurred in the MDD region.

Effects of changes in use and soil cover on real evapotranspiration from the creation of a remote sensing product in the Xingu basin

“…Numerous studies have shown that deforestation significantly reduces precipitation and ET (Costa and Foley, 2000;Nóbrega, 2014;Santos et al, 2017;Saddique et al, 2020). Other works carried out in the Amazon Forest highlight the impact of vegetation cover changes on the water balance (Pongratz et al, 2006;Hayhoe et al, 2011;Griffiths et al, 2018;Cabral Júnior et al, 2022) and actual ET (Souza et al, 2019;Kohler et al, 2021;Paiva et al, 2023).…”

“…According to the Brasil Revealed Report produced by MapBiomas (2022), out of the 44.5 million hectares deforested on a large scale, primarily along the margins of the remaining Amazon Forest, about 13.6% were converted to agricultural land and 86.3% into pastures. In this context, it is clear that deforestation causes a decrease in ET rates, especially during the dry season (Caioni, 2021;Zhang et al, 2022;Paiva et al, 2023).…”