The lithology, geologic structure, and climate in Jujuy Province, Argentina combine to place at serious risk the people who live along the Rio Grande, the major river that drains the east side of the Cordillera Oriental and the west side of the Sierras Subandinas. Relief is great, as much as 4,000 m in 15 to 20 km, and the streams that drain the mountains have high gradients. Rapid runoff during the wet season changes the Rio Grande, nearly dry most of the year, into a torrent that erodes bridge abutments and floods the valley floor. Poorly consolidated deposits of late Tertiary rocks and Quaternary deposits along the sides of the valley erode readily and yield large volumes of sediment in addition to that coming from higher parts of the basin. These processes are common to all rivers that drain mountainous regions, but lack of understanding of the geomorphic regime of the rivers has led to unexpected hazardous conditions that are expensive to correct.
Most communities are along transportation routes that follow the river.
Many bridges and levees are inadequately designed for the high runoff rates and sediment load, thus are frequently damaged or destroyed. Dam construction causes aggradation upstream and scouring downstream. Application of adequate geomorphic and geologic information provided prior to new construction may reduce the costs of future repair.