Dai hoc Thai Nguyen : PHAN TICH HIEN TR^NG VA NGUYEN NR^N TRAN LU QUET BUN DA TAI XA NAM LUC, HUYEN B A C HA, TINH LAO CAI Trin Tuin Dgt\ Nguyen Hi?u\ La Thanh Ha^ Hoang Duy lOianh Abstract Theanalysis of the current situation show that- debrisfloodhappenedin Nam Luc commune (Bac Ho district Lao Cai) in August 2012 is due to the blockage of theflowin the upstream The mam reason for this phenomenon as following: having thehigh risk of landslide and rockfallon the slopes along Ihe valley;The valley has steep slopes andsome narrow sections;the valley slopes with strong erosion and cavitation erosio slot to the top, where weathering crust is thick; There are the debris fans -production of ancient large-scale floods in the past along iheNam Luc stream; there are landslide md rock fall phenomenonabove the ancient pediments where havethick weathering crust and rich clay These characteristicsare also important signs to warningdebrisfloods in the region have similar nahtral conditions I Gl