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Lake Poopó is a large endorheic lake located in the Andean Mountain Range Plateau or Altiplano, Bolivia. A general decline in the lake water level has been observed in the last two decades, with devastating impacts for the fishing and cattle breeding livelihoods of local communities. Several factors have been associated to the lake decline: climate warming, intensification of quinoa farming, mining activities and population growth. Being an endorheic catchment, evapotranspiration (ET) losses are expected to be the main water output mechanism.
This study analysed ET, vegetation and precipitation spatio-temporal trends in the Lake Poopo catchment using MODIS ET and normalized difference vegetation index (NDVI) products, and CHIRPS-v2 precipitation products validated to in-situ meteorological data for the period 2002 to 2015. ET, NDVI and precipitation trends were investigated for individual sub-catchments, for the wet and rainy seasons, and for land use type.
Our analysis revealed that ET losses and NDVI in the wet season have increased throughout the study period, while they remained approximately stationary in the dry season. An analysis across land cover types showed that only croplands experienced an increase in NDVI and ET losses, while natural covers showed either constant or decreasing NDVI trends, together with increases in ET. The comparatively larger increase in vegetation and ET over agricultural regions, strongly suggests that cropping practices exacerbated water losses in these areas.
Additionally, an intensity-duration analysis of the wet season in the Altiplano has shown a sustained shortening of the season, exacerbating the uneven distribution of water inputs throughout the year and highlighting the need for adequate water resources planning.
Our study results provide essential quantitative information for the sustainable and socially-fair joint planning of water resources and land use in the Lake Poopó catchment.
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