Groundwater resources and vulnerability for mountain communities in the Andes

Sammanfattning: The purpose of the thesis is to review the effect of ongoing climate change and population growth ongroundwater resources of Katari Basin (Bolivian Andes) and the consequence of reduced groundwaterresources on the quality of water. El Alto city, situated in the Katari basin is most vulnerable to thewater shortage because of climate change and high population growth rate. The expected increase intemperature in Bolivian Andes will decrease the availability of water which will ultimately decreasegroundwater recharge. Decrease in annual precipitation and main rainy season precipitation is alsopredicted by the most stations along the Bolivia/Peru border. The region is undergoing an acceleratedglacier recession and the projected climate change will lead to the disappearance of small glacierswhich will eventually decrease the expected water supplies in the future. The increased water demandby the growing population of El Alto will lead to increased groundwater discharge and the balancebetween recharge and discharge of groundwater resources will be affected severely. Consequently,small reduction in groundwater recharge can severely affect the streamflow. Moreover, thegroundwater in Katari Basin contains high levels of Arsenic, Boron, Antimony, Manganese andsalinity while the surface water is also contaminated by mining activities, agricultural runoff anduntreated sewage water.Change in temperature and precipitation will eventually impact the water demand and if the surfacewater will not be enough to fulfil the increasing demand of water then the dependence on groundwaterwill increase. The decline of glaciers can impact the efficiency of groundwater recharge as thedecrease in snowfall will ultimately lead to the shift from more effective recharge agent (snowfall) toless effective recharge agent (rainfall). Although, groundwater is more resilient to climate change thansnow and glaciers but the water resources are especially vulnerable in cities because of not onlyclimate change but also due to the increase in population. The communities living in mountains areless resilient to local change in water availability because the catchment area of the basin is smaller ascompared to the water resources at the lower elevations which receive water from a larger catchmentarea. The inter-Basin water transfer may resolve the water scarcity issues. The complex topographyand steep climatological gradients of mountain regions are difficult to represent in GCMs therefore theGlobal Climate Models (GCMs) show uncertainties in predicting climate change.