Análise de mudanças em corpos d'água, uso da terra e cobertura vegetal com eventos climáticos extremos no páramo do Equador (1998-2015)

Abstract

The paramo is a high mountain ecosystem of great importance, located in the inter-Andean at a height that oscillates between 3,200 and 4,700 meters above sea level. Its principal function, but not unique, is related to the capacity of its soil in absorbing rainwater like a sponge, and filters and releases it into other ecosystems. This water that comes from high lands is distributed to the lowlands, where it is used by millions of people near and far from the paramo for irrigation, drinking water supply, and hydroelectric generation. Unfortunately, the area is undergoing strong changes by the influence of anthropogenic processes that may disturb its balance. This study analyses land cover and land-use changes over the period 1998 to 2015 in the paramo area by satellite image interpretation (Landsat TM, Landsat OLI) and the use of the maximum likelihood algorithm, which also allowed the construction of thematic maps of land use and vegetation. The cross-tabulation matrix made it possible to identify the area of land cover and land use for each year and the rates of change were determined based on this. The results show that the vegetation has decreased considerably, while the populated areas, and the agricultural activities have increased. The indicators of climatic extremes of temperature and precipitation on the paramo were analyzed using data from daily series of meteorological observations provided by INAMHI for the period 1998-2015. The trend analysis of the used indexes is performed by linear regression using the least squares method and then specialized with interpolation based on the semivariogram method. Temperature-related indices evidence clearly increasing trends in the extremes of this variable, with some of them remaining statistically meaningful and exhibiting an increase on hot days (TX90p) and warm nights (TN90p). In the case of precipitation-related indices, there are varied trends with few significant values and a decrease in dry days (CDD), very rainy days (R95p) and total precipitation (PRCPTOT). Finally, a combined analysis was developed to find a relationship between changes in vegetation and land use and the behavior of climate extremes indices. It was not possible to find a direct pattern between these variables; however, there are indices with trends that are coherent with the vegetation cover index. The areas that did not change reflect only small variations in mean temperature trends (mean TMAX), and something similar was found in the conserved and restored areas.