Geomorphology and natural hazards of the selected glacial valleys, Cordillera Blanca, Peru

Abstract

Field reconnaissance geomorphologic mapping and interpretation of satellite data was used to prepare geomorphological maps of the selected glacial valleys in the Cordillera Blanca Mts., Peru. The valleys are located about 5 km apart, but show important differences in geology and landforms presence and distribution. Above all, the presence of small glacial lakes near the ridge tops is typical for the Rajucolta Valley, whereas no such lakes occur in the Pumahuaganga Valley. Detailed field assessment of possible hazardous geomorphological processes on the slopes around the Rajucolta and Uruashraju Lakes was performed. Shallow landslides and debris flows often channeled by gullies are the main dangerous processes possibly affecting the glacial lakes. In the case of the Rajucolta Lake, evidences of shallow landslides were also found. Mapping showed that newly formed small glacial lakes and moraine accumulations located on the upper part of the valley slopes may be source of dangerous debris flows and outbursts floods in the future. In some cases, those processes may affect glacial lakes on the main valley floor, which often store considerable amount of water. Thus the possibility of triggering large glacial lake outburst flood should be carefully evaluated.