scholarly journals The 20 February 2010 Madeira Island flash-floods: VHR satellite imagery processing in support of landslide inventory and sediment budget assessment

2013 ◽  
Vol 13 (3) ◽  
pp. 709-719 ◽  
Author(s):  
C. Lira ◽  
M. Lousada ◽  
A. P. Falcão ◽  
A. B. Gonçalves ◽  
S. Heleno ◽  
...  

Abstract. On 20 February 2010, an extreme rainfall episode occurred on Madeira Island, which caused an exceptionally strong flash flood and several soil slip-debris flows, producing 45 confirmed deaths and 6 persons declared missing, as well as extensive material damages. In order to understand and quantify the importance of landsliding in routing sediment through mountainous drainage, such as Madeira Island's landscape, it was essential to perform extensive landslide analysis. This study describes the methodology used to semi-automatically detect the landslides, produce the landslide inventory maps and estimate the sediment volume produced during this particular event which ranged from 217 000 m3 to 344 000 m3 and 605 000 m3 to 984 000 m3 for the Funchal and Ribeira Brava basins, respectively. These results contributed to the design and implementation of measures to prevent damages caused by landslides in Madeira Island.

Author(s):  
Benjamin Crosby

Funding has enabled the design and implementation of a preliminary landslide inventory including roughly 500 deposits throughout GTNP. The three most common mass movement deposits were related to debris flows, translational earth slides and translational rock slides. More than 10% of the features were field-verified during campaigns mapping along the Teton Fault and in areas across varying lithology and relief including Steamboat Mountain, Paintbrush Canyon, Cascade Canyon, Two Ocean Lake, Open Canyon and lower Granite Canyon. Features were mapped according to protocols established by the Oregon Department of Geology and Mineral Industries (DOGAMI) and supported by the USGS. The Story Map remains under development, awaiting revised mapping and feedback from GTNP staff.   Featured photo taken from the AMK Ranch photo collection. https://flic.kr/p/RdWTqz


2021 ◽  
Vol 27 (1) ◽  
pp. 3-27
Author(s):  
Jeremy T. Lancaster ◽  
Brian J. Swanson ◽  
Stefani G. Lukashov ◽  
Nina S. Oakley ◽  
Jacob B. Lee ◽  
...  

ABSTRACT The post–Thomas Fire debris flows of 9 January 2018 killed 23 people, damaged 558 structures, and caused severe damage to infrastructure in Montecito and Carpinteria, CA. U.S. Highway 101 was closed for 13 days, significantly impacting transportation and commerce in the region. A narrow cold frontal rain band generated extreme rainfall rates within the western burn area, triggering runoff-driven debris flows that inundated 5.6 km2 of coastal land in eastern Santa Barbara County. Collectively, this series of debris flows is comparable in magnitude to the largest documented post-fire debris flows in the state and cost over a billion dollars in debris removal and damages to homes and infrastructure. This study summarizes observations and analyses on the extent and magnitude of inundation areas, debris-flow velocity and volume, and sources of debris-flow material on the south flank of the Santa Ynez Mountains. Additionally, we describe the atmospheric conditions that generated intense rainfall and use precipitation data to compare debris-flow source areas with spatially associated peak 15 minute rainfall amounts. We then couple the physical characterization of the event with a compilation of debris-flow damages to summarize economic impacts.


2014 ◽  
Vol 711 ◽  
pp. 388-391
Author(s):  
Ji Wei Xu ◽  
Ming Dong Zhang ◽  
Mao Sheng Zhang

On July 9 2013, debris flows occurred around Longchi town with large scale and wide harm, which was a great threat to people's life and property as well as reconstruction work. Debris flow ditch in the surrounding town was studied. This paper focused on loose materials, topography and rainfall characteristics, and explored the formation mechanism of debris flow in Longchi town. The result shows that: a small catchment area in valleys also have the risk of large range of accumulation of debris flow, the debris flow is caused by a lot of loose materials in mountains after earthquake and extreme rainfall. Research results contribute to a better understanding of trigger condition of debris flow after earthquake.


Landslides ◽  
2020 ◽  
Vol 17 (12) ◽  
pp. 2795-2809 ◽  
Author(s):  
Erin K. Bessette-Kirton ◽  
Jeffrey A. Coe ◽  
William H. Schulz ◽  
Corina Cerovski-Darriau ◽  
Mason M. Einbund

Abstract Mobility is an important element of landslide hazard and risk assessments yet has been seldom studied for shallow landslides and debris flows in tropical environments. In September 2017, Hurricane Maria triggered > 70,000 landslides across Puerto Rico. Using aerial imagery and a lidar digital elevation model (DEM), we mapped and characterized the mobility of debris slides and flows in four different geologic materials: (1) mudstone, siltstone, and sandstone; (2) submarine basalt and chert; (3) marine volcaniclastics; and (4) granodiorite. We used the ratio of landslide-fall height (H) to travel length (L), H/L, to assess the mobility of landslides in each material. Additionally, we differentiated between landslides with single and multiple source areas and landslides that either did or did not enter drainages. Overall, extreme rainfall contributed to the mobility of landslides during Hurricane Maria, and our results showed that the mobility of debris slides and flows in Puerto Rico increased linearly as a function of the number of source areas that coalesced. Additionally, landslides that entered drainages were more mobile than those that did not. We found that landslides in soils developed on marine volcaniclastics were the most mobile and landslides in soils on submarine basalt and chert were the least mobile. While landslides were generally small (< 100 m2) and displayed a wide range of H/L values (0.1–2), coalescence increased the mobility of landslides that transitioned to debris flows. The high but variable mobility of landslides that occurred during Hurricane Maria and the associated hazards highlight the importance of characterizing and understanding the factors influencing landslide mobility in Puerto Rico and other tropical environments.


2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Yonggang Ge ◽  
Jianqiang Zhang ◽  
Xiaojun Guo

After analysing the catastrophic debris flows on August 18, 2012, and on July 9, 2013, in Jushui River basin, An County, the Wenchuan Earthquake seriously striken areas, it was found that they were characterized by the clay soil content of 0.1~1.2%, the density of 1.68~2.03 t/m3, the discharges of 62.2 m3/s to 552.5 m3/s, and the sediment delivery modulus of 1.0~9.4 × 104 m3/km2. Due to intense rainstorm, many large debris flows produced hazard chain, involved in flash flood, debris flow, dammed lake, and outburst flood, and rose Jushui River channel about 1~4 m as well as amplified flood. The hazards and losses mainly originated from the burying and scouring of debris flows, flood inundating, and river channel rise. The prevention of debris flows is facing the intractable problems including potential hazard identification, overstandard debris flow control, control constructions destructing, and river channel rapid rise. Therefore, the prevention measures for the basin, including hazard identification and risk assessment, inhabitants relocating, monitoring and alarming network establishing, emergency plans founding, and river channel renovating, and the integrated control mode for watershed based on regulating the process of debris flow discharge, were recommended for mitigation.


2014 ◽  
Vol 142 (1) ◽  
pp. 222-239 ◽  
Author(s):  
Samantha L. Lynch ◽  
Russ S. Schumacher

Abstract From 1 to 3 May 2010, persistent heavy rainfall occurred in the Ohio and Mississippi River valleys due to two successive quasi-stationary mesoscale convective systems (MCSs), with locations in central Tennessee accumulating more than 483 mm of rain, and the city of Nashville experiencing a historic flash flood. This study uses operational global ensemble forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) to diagnose atmospheric processes and assess forecast uncertainty in this event. Several ensemble analysis methods are used to examine the processes that led to the development and maintenance of this precipitation system. Differences between ensemble members that correctly predicted heavy precipitation and those that did not were determined, in order to pinpoint the processes that were favorable or detrimental to the system's development. Statistical analysis was used to determine how synoptic-scale flows were correlated to 5-day area-averaged precipitation. The precipitation throughout Nashville and the surrounding areas occurred ahead of an upper-level trough located over the central United States. The distribution of precipitation was found to be closely related to the strength of this trough and an associated surface cyclone. In particular, when the upper-level trough was elongated, the surface cyclone remained weaker with a narrower low-level jet from the south. This caused the plume of moisture from the Caribbean Sea to be concentrated over Tennessee and Kentucky, where, in conjunction with focused ascent, heavy rain fell. Relatively small differences in the wind and pressure fields led to important differences in the precipitation forecasts and highlighted some of the uncertainties associated with predicting this extreme rainfall event.


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