2005-2021年大河坝流域极端气候及其对滑坡的影响OA

[Objective]To investigate the characteristics of extreme climate over the past 2005-2021 years in the Daheba river basin on the northeastern margin of the Tibetan Plateau and the mechanisms through which it influences landslide development.[Methods]Based on meteorological data from the Xinghai Station from 1960 to 2021,22 extreme climate indices were calculated using the RClimDex model to analyze the variation trends of temperature and precipitation.Multi-source remote sensing images and unmanned aerial vehicle(UAV)-derived digital surface model(DSM)data were used to interpret the spatiotemporal distribution of newly formed(Type Ⅰ)and expanded(Type Ⅱ)landslides in 28 debris flow gullies from 2005 to 2021.Pearson correlation analysis revealed the driving mechanisms of climate factors on landslide development.[Results]1)From 1960 to 2021,the climate showed significant trends of warming and wetting,with increases in the frequency and intensity of extreme high-temperature events and decreases in extreme low-temperature events.Precipitation patterns shifted toward high-frequency,short-duration heavy rainfall.2)Landslide activity intensified.From 2005 to 2021,the number of landslides increased from 218 to 1 125(average annual growth rate of 10.5%),and the landslide area expanded from 6.25×10⁴ to 44.69×10⁴ m²(average annual growth rate of 12.3%).Among them,Type Ⅰlandslides accounted for 56%(average thickness of 0.65 m),and Type Ⅱ landslides accounted for 44%(average thickness of 1.35 m).Landslide development accelerated after 2016,with engineering disturbances in 2018 caused a sharp increase in landslide density along roads.3)Newly formed landslides(56%)were correlated with extreme precipitation(Rx5day,r=0.68),while expanded landslides(44%)were driven by cold night frequency(TN10p,r=0.64)and dry day count(CDD,r=-0.67).4)The loess-cobble-sand structure regulated landslide types.Shallow landslides(0.65 m thick)were caused by the low permeability of loess(1.81 m/d),while the deep landslides(1.35 m thick)were associated with the high permeability of cobble layers(3.02 m/d).[Conclusion]Extreme climate events drive landslides through direct(rainfall)and indirect(freeze-thaw)effects,and the loess-cobble-sand structure and human engineering activities further aggravate disaster risks.The results can provide a reference for predicting debris flow material sources on the northeastern margin of the Tibetan Plateau.