Water-energy nexus modelling approach to assess potential climate change impacts in hydropower generation in La Paz, Bolivia

Climate change impacts the biosphere, for instance it affects global resources. Given the variable landscape, streamflow generation in mountainous catchments is likely to be stricken with changes at faster rates compared to other geographical locations. La Paz and El Alto are two important cities in the Bolivian Andes, where a large amount of energy supply is generated through hydropower plants distributed in a cascade scheme. Such cascade is located in the headwaters of the Amazon basin, in the downstream direction. The mountains are partially glacierized; such characteristic increases its sensitivity to climate change. Thus, all the elements together constitute a heterogeneous landscape worth studying. To address the study, the approach considers the models WEAP and LEAP; for the baseline, inputs are historical field data whereas to define future scenarios are considered model outputs from the Global Circulation Model HAD GEM2 – ES, RCP (Representative Concentration Pathway) 8.5 scenario from the Fifth Assessment Report of the United Nations Intergovernmental Panel on Climate Change. WEAP works on the water balance whereas LEAP is applied to the energy sector. For this study, the interaction between the water and energy is evaluated considering the impacts of climate on the partially glacierized watersheds which feed upstream flow into the hydropower plants. The interpretation of the results by comparing the simulation of electricity generation with the projected energy demand, and climate change impacts on watershed surface runoff generation, indicates a possibility that in average, electricity demand surpassed energy generation by 2013, implying the necessity to import energy from other systems belonging to the SIN, or to improve the capacity of the plants or implement new power plants.