Future water resource availability under changing climate in Bolivian Andes

In Bolivian Andes, retreats of tropical glaciers are rapid, thus water resources currently available from glacierized catchments for drinking, agriculture, industry and hydropower would be changed in its volume and variations due to changing climate. Water resources in La Paz and El Alto, the capital city areas of Bolivia, strongly depend on the runoff from partially glacierized catchments located in the Cordillera Real, which is a combined contribution of surface and subsurface flow from glacierized and non-glacierized areas due to rainfall, snow melt and glacier melt. To predict the long-term availability of water resources for the capital city areas, we applied a semi-distributed conceptual glacio-hydrological model that considers various runoff pathways from partially glacierized high-altitudinal catchments located in the outer tropics under future climate conditions based on the two GCM outputs (MRI-AGCM and INGV-ECHAM4) with bias corrected by reanalysis data (ERA-INTERIM) and downscaled to our target area using the data monitored at several weather stations. The model was applied to the watershed from which current water resources for La Paz and El Alto are supplied, and eight additional catchments that are considered to be potentially effective in compensating reduced runoff from the current water resource area. As a result, we found that the current water resource area cannot support the demand due to glowing population and the decrease of runoff towards the future. We indicated that the partially-glacierized catchments located in the vicinity of the current water resource catchment can be exploited as additional water resources to compensate the potential shortage in water supply predicted for the middle of this century.