ground-water hydrologist Alfred Lohnburg describes his work for UNESCO in collaboration with the Mexican government. Lohnburg explains that extracting water from beneath Mexico City has resulted in the ground sinking, but no suitable alternative water source for the city has been identified. Lohnburg explains that his work focused mostly on identifying new water sources, and also involved education and training at the university in Mexico City. Lohnburg also describes water defecit issues in the arid regions of northern Mexico.