hans-joachim picht is coordinating the construction of 370 rainwater retention basins in the andes. during heavy rainfalls, up to 15 liters of water per second can flow into the reservoirs. >> what we see here is exactly what we want to achieve -- the water that flows down from the small catchment area you see behind us is collected in this atajado. if it weren't, it'd just run off and collect in the valley far below. there the rivers would swell and that could cause major damage. >> he sees some of this damage on his travels around the country. a sociologist, picht has been working in the highlands of norte potosi for years. it's one of bolivia's poorest regions. the potato harvest is looking good this year, but climate change has led to several crop failures in the past. at times, the potato farmers have actually had to buy potatoes -- a disaster for the many families who barely scrape by as it is. hans-joachim picht is going to see a farming family who've been having problems with their new atajado. the basin is losing water -- even though it's been sealed a number of times with