Dynamics of forest conversion and climate trends in the Madeira river basin

Abstract

The Madeira River basin is an example of an important portion of the Amazon region that is characterized by a high rate of conversion of forest into pastures and urban centers, evidencing an accelerated transformation in land cover and use with significant anthropic activity over the last three decades, which configures a potential impact in terms of modifying the climate behavior of the region. The present work seeks to analyze, in the Madeira River basin, the hydroclimatic impacts through the study of the variability of the two main components of the water balance and the energy balance at the scale of a watershed, namely precipitation and evapotranspiration, with additional emphasis on the temperature, which has served as a world reference to specify and demarcate changes in climate, given its space-time dynamics of anthropic occupation. More specifically, the occupancy history was initially analyzed using MODIS images for the period 2001-2013. In addition, precipitation data from the CHIRPS satellite product (1981-2017), evapotranspiration data determined by the SSEBop algorithm (2002-2017) via the sensor that produces the MODIS image and surface temperature of the MODIS satellite product (2001-2017) were examined, being such information treated as geospatial variables distributed in the study area. An extensive evaluation study regarding the identification of the presence or not of linear hydroclimatic trends in the Madeira River basin was carried out using the Mann-Kendall test. Although some trends were captured in the analyzed time series, the results obtained also showed that, given the limited database currently available, there is not necessarily a direct and clear relationship between the effect of human occupation and the climate regime of the basin, in contrast to the scientific framework recommended worldwide warning of climate change in the Anthropocene. In part, the high climate variability in the study region imposes limits with respect to clearly understand and separate the signals that can be attributed to the change in land cover and use from the signals associated with climate change that act on broader spatio-temporal scales. In this sense, new studies on monitoring hydrometeorological and hydroclimatic phenomena with corresponding measurements at different scales should be encouraged to better understand the processes of aggregation and disaggregation of the physical mechanisms acting at the scale of a watershed.