Response of debris flow occurrence to daily rainfall pattern and critical rainfall condition in the Anning River–Zemu River Fault Zone, SW China

2019 ◽  
Vol 79 (4) ◽  
pp. 1735-1747 ◽  
Author(s):  
Huayong Ni ◽  
Zhi Song
Keyword(s):  
Debris Flow ◽  
Fault Zone ◽  
Daily Rainfall ◽  
Rainfall Pattern ◽  
Sw China ◽  
Rainfall Condition ◽  
Critical Rainfall

Outlining a stepwise, multi-parameter debris flow monitoring and warning system: an example of application in Aizi Valley, China

2020 ◽  
Author(s):  
Ningsheng Chen
Keyword(s):  
Debris Flow ◽  
Early Warning ◽  
Pressure Sensors ◽  
Warning System ◽  
Point Of View ◽  
Economic Point ◽  
Flow Monitoring ◽  
Vibration Sensors ◽  
Wide Range ◽  
Critical Rainfall

<p>Abstract: In recent years, the increasing frequency of debris flow demands enhanced effectiveness and efficiency are essential not only from an economic point of view but are also considered as a frontline approach to alleviate hazards. Currently, the key issues are the imbalance between the limited lifespan of equipment, the relatively long period between the recurrences of such hazards, and the wide range of critical rainfall that trigger these disasters. This paper attempt to provide a stepwise multi-parameter debris flow warning system after taking into account the shortcomings observed in other warning systems. The whole system is divided into five stages. Different warning levels can be issued based on the critical rainfall thresholds. Monitoring starts when early warning is issued and it continues with debris flow near warning, movement warning and hazard warning stages. For early warning, historical archives of earthquake and drought are used to choose a debris flow susceptible site for further monitoring, Secondly, weather forecasts provide an alert of possible near warning. Hazardous precipitation, model calculation and debris flow initiation tests, pore pressure sensors and water content sensors are combined to check the critical rainfall and to publically announce a triggering warning. In the final two stages, equipment such as rainfall gauges, flow stage sensors, vibration sensors, low sound sensors and infrasound meters are used to assess movement processes and issue hazard warnings. In addition to these warnings, community-based knowledge and information is also obtained and discussed in detail. The proposed stepwise, multi-parameter debris flow monitoring and warning system has been applied in Aizi valley China which continuously monitors the debris flow activities.</p>

Study on multiple rainfall data applied to debris flow warning in Taiwan

2020 ◽  
Author(s):  
Yi-Chao Zeng ◽  
Chyan-Deng Jan ◽  
Mu-Jung Lin ◽  
Ji-Shang Wang ◽  
Hsiao-Yuan Yin ◽  
...  
Keyword(s):  
Debris Flow ◽  
Observational Data ◽  
Water Conservation ◽  
Spatial Interpolation ◽  
Rain Gauge ◽  
Rainfall Data ◽  
Mountain Area ◽  
Rainfall Condition ◽  
Capture Ratio ◽  
Spatial Coverage

<p>Due to climate change, precipitation characteristics have been significantly variation and rainfall patterns are presented more concentrated, high-intensity and long-duration trend in the past two decades. Catastrophic debris-flow disaster threaten lives and property of residents. For mitigation impact of debris-flow, SWCB (Soil and Water Conservation Bureau, Taiwan) has had a leading role in sponsoring debris-flow research and developing a rainfall-based debris-flow warning model. Early warning criteria for debris-flow triggered are also determined depending on the historical rainfall data, and the observational data of rain-gauge are adopted to issue debris-flow warning. However, application of rain-gauge rainfall data has some disadvantages such as low density in mountain area, observation failure to properly represent actual rainfall condition, and data transmission likely interrupted during heavy rainfall or Typhoon. In order to improve the efficiency of debris-flow warning system, two types of gridded precipitation are analyzed and discussed in this study, which are the spatial interpolation rainfall of rain-gauge and the radar-estimated rainfall (QPESUMS). For comparison the differents of multiple rainfall data mentioned above with rain-guage, the third quartile is firstly applied to calculate the regional representative rainfall from grid cells within warning issued area. The results show that the spatial interpolation rainfall underestimates the rainfall intensity and cumulative rainfall owing to the influence of complex topography. By contrast, the radar-estimated rainfall has the advantage in comprehension of the rainfall spatial variability and provide a more complete spatial coverage. Besides, for assessing the appropriate and feasibility of multiple rainfall data applied to debris flow warning, the disaster–capture ratio has been proposed which is defined as the number of debris-flow hazards after issuing warning divided by total number of debris- flow hazards. According to analyis results of historical disaster records from 2012 to 2016, the disaster–capture ratio are 47.6%, 38.1% and 61.9% as warning issued refer to rain gauge, the spatial interpolation rainfall and the radar-estimated rainfall respectively. By the aforementioned process, we realize that the application of radar-estimated rainfall to debris flow warning is obviously increasing efficiency of debris-flow warning ,and gives assistance for reducing uncertainty of rainfall observational data, especially in mountain area.</p>

scholarly journals Impact of Climate Change on Rainfall Pattern in Upper Kumaon Himalaya Region

2021 ◽  
Author(s):  
A. Singh ◽  
R. B. Singh ◽  
S. Anand ◽  
A. Mohanty ◽  
S. S. Dash
Keyword(s):  
Climate Change ◽  
High Altitude ◽  
Human Life ◽  
Rainfall Variability ◽  
Parametric Method ◽  
Daily Rainfall ◽  
Research Area ◽  
Rainfall Data ◽  
Rainfall Pattern ◽  
Kumaon Himalaya

Abstract Every single aspect of environment is affected by climate change. Change in rainfall pattern is an immense important research area in climate-change based study. Rainfall pattern has direct impacts on food production and frequencies natural disasters (landslide, cloudburst, flood, drought etc.). Consequently, that appropriate and systemic consideration since it distresses the most of the human life. Situation in Himalayan region is worst. High altitude, less agricultural area, harsh climate with high fragility makes mountain region more vulnerable in term of climate change. The objective of this study is to identify yearly, seasonal, and monthly rainfall trends in the Upper Kumaon region (UKR). Long-term gridded daily rainfall data (1950–2018) were used. Rainfall data was processed and analyzed for a period of 68 years (1950–2018) at four places (four in each Kumaon division) in the surrounding area of Almora, Bageshwar, Pithoragarh, and Champawat. The regression analysis (parametric) method and variability analysis were used to examine historical trends in daily rainfall. The rising and falling trends in rainfall, as well as anomalies, have been studied using regression.The result shows that rainfall demonstrate statistically significant changes occurred in last 34 years. Rainfall variability is higher in low altitude region than high altitude region of Upper Kumaon region.

scholarly journals Study on the Early Warning and Forecasting of Flash Floods in Small Watersheds Based on the Rainfall Pattern of Risk Probability Combination

2021 ◽  
Author(s):  
Lu Lu ◽  
Wenlin Yuan ◽  
Chengguo Su ◽  
Qianyu Gao ◽  
Denghua Yan ◽  
...  
Keyword(s):  
Early Warning ◽  
Rainfall Intensity ◽  
Flash Floods ◽  
Rainfall Pattern ◽  
Moisture Condition ◽  
Soil Moisture Condition ◽  
Small Watersheds ◽  
Rainfall Process ◽  
Risk Probability ◽  
Critical Rainfall

Abstract Flash floods cause great harm to people's life and property safety. Rainfall is one of the main causes of flash floods in small watersheds. The uncertainty of rainfall events results in inconsistency between the traditional single rainfall pattern and the actual rainfall process, which poses a great challenge for the early warning and forecasting of flash floods. This paper proposes a novel rainfall pattern based on total rainfall and peak rainfall intensity, i.e., the rainfall pattern of risk probability combination (RPRPC). To determine the joint distribution function with the best fitting effect, copula functions are introduced and optimized. On this basis, the HEC-HMS hydrological model is used to simulate the rainfall-runoff process, a trial algorithm is used to calculate the critical rainfall (CR), and an optimistic-general-pessimistic (O-G-P) early warning mode considering the decision maker's risk preference is proposed. The small watershed of Xinxian in Henan province, China, is taken as a case study for calculation. The results show that the RPRPC is feasible and closer to the actual rainfall process than the traditional rainfall pattern (TRP) and that the HEC-HMS model can be applied to small watersheds in hilly areas. Additionally, the influence of antecedent soil moisture condition (ASMC) and rainfall pattern on critical rainfall varies with the change of peak rainfall intensity and rainfall duration. Finally, the O-G-P early warning mode is effective and provides a valuable reference for the early warning and forecasting of flash floods in small watersheds in hilly areas.

scholarly journals Paleogene extension in the Northern Aegean: Colluvial/debris flow deposits of the Early-Middle Eocene in NW Thrace Basin, Turkey

2021 ◽  
Vol 72 (3) ◽  
Author(s):  
Serdar Akgündüz ◽  
Hayrettin Koral
Keyword(s):  
Debris Flow ◽  
Fault Zone ◽  
Middle Eocene ◽  
Late Eocene ◽  
Coarse Grained ◽  
Fine Grained ◽  
Metasedimentary Rocks ◽  
Early Oligocene ◽  
Thrace Basin ◽  
Nw Turkey

The Thrace Basin consists of Paleogene–Neogene deposits that lie in the lowland south of the Strandja highlands in NW Turkey, where metagranitic and metasedimentary rocks occur. The Akalan Formation consisting of colluvial fan/debris flow deposits represents the base of the sequence in the northern Thrace basin where it is bounded by a right lateral strike-slip oblique fault called “The Western Strandja Fault Zone”. This formation exhibits a coarse-grained, angular and grain-supported character close to the fault zone which has releasing-bends. Fine-grained, rounded, and matrix-supported sediments occur away from the contact. During this study, the Akalan Formation is described for the first time as having larger benthic foraminifera (LBF) of Coskinolina sp of Ypresian–Lutetian, Nummulites obesus of early Lutetian, Dictyoconus egyptiensis of Lutetian, Orbitolites sp. of Ypresian–Bartonian, Miliola sp of early–middle Eocene, Idalina grelaudae of early Lutetian–Priabonian, Ammobaculites agglutinans, Amphimorphina crassa, Dentalina sp., Nodosaria sp., Operculina sp., Lenticulina sp., Quinqueloculina sp. and Amphistegina sp. of Eocene. This unit passes upward with a conformity into reefal limestones of the middle/late Eocene–early Oligocene Soğucak Formation. At times, the limestone overlies the conformity, there is an indication of a prograding sedimentary sequence. The new stratigraphic, paleontological, sedimentological and structural findings related to the NW Thrace Basin suggest a strong transtensional/extensional tectonic control for the initial Paleogene sedimentary deposition during the Ypresian–Lutetian period as shown by fossil content of the Akalan Formation. Right lateral-slip extensional tectonics appears to have had activity during the middle–late Eocene transgressive deposition of the Soğucak Formation when the basin became deepened and enlarged.

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