Geomorphology and morphometry of the de La Flecha river basin, San Juan, Argentina.

A geomorphologic and morphometric analysis was performed to determine the characteristics of the de La Flecha river basin, located in the southwest of San Juan province (31°50′S, 68°57′W), Precordillera of San Juan. The drainage networks were derived from shuttle radar topographic mission (SRTM), satellite imageries (Landsat TM and Spot image) and field works. The paper also addresses a preliminary evaluation of the flood hazard responsible for severe damage to people and infrastructure in the downstream region. The study area covers about 300 km, comprising of six sub-watersheds, ranging from 31.7 to 81.8 km. The irregular morphology of the basin and the diversity of alluvial deposits found along the de La Flecha river allow the authors to infer that it is in an active tectonic environment with strong lithological and structural controls. One feature common to all analyzed sub-basins is their elongated shape, which allows for a rapid concentration of water that intensifies the power of the flash floods. The drainage network in the different sub-basins has, in general, two predominant patterns; one is parallel to sub-parallel to the headers and foothill areas; and the other, in the alluvial zone, is divergent. Los Berros, Cañada Honda and Media Agua towns, located downstream of the basin, are the most affected by flash floods coming from the mountainous area. [ABSTRACT FROM AUTHOR]