DEBRIS FLOW AND LANDSLIDE HAZARDS UNDER CERTAIN TYPES OF ATMOSPHERIC CIRCULATION

Abstract. The work examines the seasonality and large-scale atmospheric circulation patterns of debris flows in the Trentino-Alto Adige region (Eastern Italian Alps). Analysis is based on classification algorithms applied on a uniquely dense archive of debris flows and hourly rain gauge precipitation series covering the period 2000–2009. Results highlight the seasonal and synoptic forcing patterns linked to debris flows in the study area. Summer and fall season account for 92% of the debris flows in the record, while atmospheric circulation characterized by Zonal West, Mixed and Meridional South, Southeast patterns account for 80%. Both seasonal and circulation patterns exhibit geographical preference. In the case of seasonality, there is a strong north–south separation of summer–fall dominance while spatial distribution of dominant circulation patterns exhibits clustering, with both Zonal West and Mixed prevailing in the northwest and central east part of the region, while the southern part relates to Meridional South, Southeast pattern. Seasonal and synoptic pattern dependence is pronounced also on the debris flow triggering rainfall properties. Examination of rainfall intensity–duration thresholds derived for different data classes (according to season and synoptic pattern) revealed a distinct variability in estimated thresholds. These findings imply a certain control on debris-flow events and can therefore be used to improve existing alert systems.

Download Full-text

Debris flows in the eastern Italian Alps: seasonality and atmospheric circulation patterns

Natural Hazards and Earth System Science ◽

10.5194/nhess-15-647-2015 ◽

2015 ◽

Vol 15 (3) ◽

pp. 647-656 ◽

Cited By ~ 18

Author(s):

E. I. Nikolopoulos ◽

M. Borga ◽

F. Marra ◽

S. Crema ◽

L. Marchi

Keyword(s):

Debris Flow ◽

Atmospheric Circulation ◽

Debris Flows ◽

Large Scale ◽

Rain Gauge ◽

Italian Alps ◽

Synoptic Pattern ◽

Atmospheric Circulation Patterns ◽

Circulation Patterns ◽

Synoptic Forcing

Abstract. The work examines the seasonality and large-scale atmospheric circulation patterns associated with debris-flow occurrence in the Trentino–Alto Adige region (eastern Italian Alps). Analysis is based on classification algorithms applied to a uniquely dense archive of debris flows and hourly rain gauge precipitation series covering the period 2000–2009. Results highlight the seasonal and synoptic forcing patterns linked to debris flows in the study area. Summer and fall season account for 92% of the debris flows in the record, while atmospheric circulation characterized by zonal west, mixed and meridional south and southeast (SE–S) patterns account for 80%. Both seasonal and circulation patterns exhibit geographical preference. In the case of seasonality, there is a strong north–south separation of summer–fall dominance, while spatial distribution of dominant circulation patterns exhibits clustering, with both zonal west and mixed patterns prevailing in the northwest and central east part of the region, while the southern part relates to meridional south and southeast pattern. Seasonal and synoptic pattern dependence is pronounced also on the debris-flow-triggering rainfall properties. Examination of rainfall intensity–duration thresholds derived for different data classes (according to season and synoptic pattern) revealed a distinct variability in estimated thresholds. These findings imply a certain control on debris-flow events and can therefore be used to improve existing alert systems.

Download Full-text

Group-occurring landslides and debris flows caused by the continuous heavy rainfall in June 2019 in Mibei village, Longchuan County, Guangdong Province, China

10.21203/rs.3.rs-161293/v1 ◽

2021 ◽

Author(s):

Huilin Bai ◽

wenkai feng ◽

Xiaoyu Yi ◽

Hongyu Fang ◽

Yiying Wu ◽

...

Keyword(s):

Debris Flow ◽

Debris Flows ◽

Heavy Rainfall ◽

Guangdong Province ◽

Residual Soil ◽

Landslide Hazards ◽

Loose Deposits ◽

Slope Structure ◽

Granite Residual Soil ◽

June 10Th

Abstract From June 10th to 13th, 2019, a continuous heavy rainfall occurred in Longchuan County, Guangdong Province, causing many landslide hazards. Among Longchuan County districts, Mibei village is one of the hardest-hit areas and suffered severe losses. In this paper, field investigation, remote sensing image interpretation , and UAV aerial photography were used to investigate and analyze hazard characteristics. Combined with rainfall monitoring data, laboratory and field tests data, and existing research results, the characteristics and failure mechanism of group-occurring landslides in Mibei village were studied. Because of the continuous heavy rainfall, 327 landslides occurred in the study area, mainly distributed in the north of the Mibei river and along the X158 road. The terrain slope of landslide hazards ranged from 35° to 45°, and the slope structure can be divided into two types. Granite residual soil was the main part of landslide mass, and sliding surface developed along with the interface between bedrock and covering layer. The continuous heavy rainfall from June 10th to 13th was the main triggering factor of the disaster. The total precipitation was 281.3 mm, and the rainfall on June 10th was 153.5 mm. The rain led to the continuous increase of volume water content in granite residual soil and completely weathered granite. The shear strength and parameters of the two materials changed differently, and slope stability continued to decrease, and then landslides occurred under terrain conditions and engineering excavation space. Untimely support and unreasonable support measures for the excavation slope exacerbated the disaster. The development degree of debris flows in the study area was very low, and debris flows were shown as the secondary disaster of landslides. The branch gully terrain is the key to transforming the landslide into the debris flow, and a large amount of loose deposits in the main gully will become the potential source of debris flow in the future.

Download Full-text