ИСТИНА

One of the largest valleys of the western Lovozerskiye Mountains was investigated immediately before and repetitively after a 2017 complex debris flow event providing a dataset of valley bottom morphology, sediment composition and vegetation changes. Post-event survey has established the limits of morphodynamic zones of the flow. It have apparently started as a slushflow on a steep step of streambed profile bellow the vast flattened floor of glacial cirque. Downstream it transformed into a granular debris flow. Maximum splash levels were determined by debris traces and large plant remnants about 2 and 3 m for the deposition and transit zones respectively. Detailed sketches of valley floor and a lithological map were compiled. Repeated large-scale aerial photography using UAV was accomplished for further monitoring. All that allows approximating a volume of transported sediment load and depositional rates, evaluating magnitude and ecological affects of the recent event.