scholarly journals Evaluating the Landslide Stability and Vegetation Recovery: Case Studies in the Tsengwen Reservoir Watershed in Taiwan

Water ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 3479
Author(s):  
Chun-Hung Wu
Keyword(s):  
Recovery Time ◽  
Vegetation Recovery ◽  
Typhoon Morakot ◽  
Mountainous Regions ◽  
Landslide Stability ◽  
River Geomorphology ◽  
Recovery Times ◽  
Southern Taiwan ◽  
Reservoir Watershed

The sediment yield from numerous landslides triggered in Taiwan’s mountainous regions by 2009 Typhoon Morakot have had substantial long-term impacts on the evolution of rivers. This study evaluated the long-term evolution of landslides induced by 2001 Typhoon Nari and 2009 Typhoon Morakot in the Tsengwen Reservoir Watershed by using multiannual landslide inventories and rainfall records for the 2001–2017 period. The landslide activity, vegetation recovery time, and the landslide spatiotemporal hotspot analyses were used in the study. Severe landslides most commonly occurred on 35–45° slopes at elevations of 1400–2000 m located within 500 m of the rivers. The average vegetation recovery time was 2.29 years, and landslides with vegetation recovery times exceeding 10 years were most frequently retrogressive landslide, riverbank landslides in sinuous reaches, and the core area of large landslides. The annual landslide area decline ratios after 2009 Typhoon Morakot in Southern Taiwan was 4.75% to 7.45%, and the time of landslide recovery in the Tsengwen reservoir watershed was predicted to be 28.48 years. Oscillating hotspots and coldspots occupied 95.8% of spatiotemporal patterns in the watershed area. The results indicate that landslides moved from hillslopes to rivers in the 2001–2017 period because the enormous amount of sediment deposited in rivers resulted in the change of river geomorphology and the riverbank landslides.

scholarly journals Impacts of climate and vegetation on actual evapotranspiration in typical arid mountainous regions using a Budyko-Based framework

2020 ◽  
Author(s):  
Yuanhui Yu ◽  
Yuyan Zhou ◽  
Weihua Xiao ◽  
Benqing Ruan ◽  
Fan Lu ◽  
...  
Keyword(s):  
Climatic Factor ◽  
Actual Evapotranspiration ◽  
Vegetation Coverage ◽  
Dominant Factor ◽  
Contributing Factors ◽  
Mountainous Regions ◽  
Production Improvement ◽  
Negative Effect ◽  
Reservoir Watershed ◽  
Seasonal Index

Abstract It is important to understand how actual evapotranspiration (ETa) changes and what the dominant contributing factors are. This study investigated the impacts of climatic factor and vegetation coverage on the variations of ETa using a Budyko-based framework. Climatic seasonal index and vegetation coverage index were selected as indicating factors. Two reservoir watersheds, i.e. the Wangkuai Reservoir Watershed and the Xidayang Reservoir Watershed, of the Daqing River Basin were selected as case studies. Also, relationships between the ETa and climatic and vegetation factors were analyzed. Results showed that the improved vegetation conditions positively contributed to the ETa changes, leading to an increase of 42.15 and 58.56 mm of ETa in the two watersheds, while the increasing climate seasonality had a negative effect, resulting in a drop of 11.48 and 13.47 mm of ETa. Vegetation coverage was recognized as the dominant factor to the changes of ETa, compared to the climatic factor. Our research could offer supporting information for water resources management, agricultural production improvement and eco-environment construction in arid regions.

Impacts of human activities on coral reef ecosystems of southern Taiwan: A long-term study

2012 ◽  
Vol 64 (6) ◽  
pp. 1129-1135 ◽  
Author(s):  
Pi-Jen Liu ◽  
Pei-Jie Meng ◽  
Li-Lian Liu ◽  
Jih-Terng Wang ◽  
Ming-Yih Leu
Keyword(s):  
Coral Reef ◽  
Human Activities ◽  
Term Study ◽  
Long Term Study ◽  
Coral Reef Ecosystems ◽  
Southern Taiwan

Recovery of ectomycorrhizal fungi after exposure to subfreezing temperatures

1979 ◽  
Vol 57 (17) ◽  
pp. 1845-1848 ◽  
Author(s):  
R. C. France ◽  
M. L. Cline ◽  
C. P. P. Reid
Keyword(s):  
Growth Rate ◽  
Ectomycorrhizal Fungi ◽  
Recovery Time ◽  
Growth Form ◽  
Rapid Recovery ◽  
Active Growth ◽  
Growth Recovery ◽  
Recovery Times

Seventy-three isolates of eighteen ectomycorrhizal fungi were examined for their growth recovery after a 48-h exposure to −10 °C. Survival of all isolates was 97%. Recovery time to active growth varied between species and within species. Of surviving isolates, 72% initiated growth in less than 2 weeks after thawing. Growth rate was not affected for isolates exhibiting rapid recovery but was significantly lowered for isolates with recovery times of more than 5 weeks. Variation in growth form occurred with some species of Suillus and Xerocomus.

scholarly journals Development of a management tool for reservoirs in Mediterranean environments based on uncertainty analysis

2012 ◽  
Vol 12 (5) ◽  
pp. 1789-1797 ◽  
Author(s):  
R. Gómez-Beas ◽  
A. Moñino ◽  
M. J. Polo
Keyword(s):  
Uncertainty Analysis ◽  
Water Cycle ◽  
Integrated Management ◽  
Management Tool ◽  
Short Term ◽  
Climate Fluctuations ◽  
The Social ◽  
Reservoir Watershed ◽  
Supply Capacity

Abstract. In compliance with the development of the Water Framework Directive, there is a need for an integrated management of water resources, which involves the elaboration of reservoir management models. These models should include the operational and technical aspects which allow us to forecast an optimal management in the short term, besides the factors that may affect the volume of water stored in the medium and long term. The climate fluctuations of the water cycle that affect the reservoir watershed should be considered, as well as the social and economic aspects of the area. This paper shows the development of a management model for Rules reservoir (southern Spain), through which the water supply is regulated based on set criteria, in a sustainable way with existing commitments downstream, with the supply capacity being well established depending on demand, and the probability of failure when the operating requirements are not fulfilled. The results obtained allowed us: to find out the reservoir response at different time scales, to introduce an uncertainty analysis and to demonstrate the potential of the methodology proposed here as a tool for decision making.

scholarly journals Post-disaster assessment of landslides in southern Taiwan after 2009 Typhoon Morakot using remote sensing and spatial analysis

2010 ◽  
Vol 10 (10) ◽  
pp. 2179-2190 ◽  
Author(s):  
F. Tsai ◽  
J.-H. Hwang ◽  
L.-C. Chen ◽  
T.-H. Lin
Keyword(s):  
Spatial Analysis ◽  
Change Detection ◽  
Satellite Images ◽  
Regional Scale ◽  
Typhoon Morakot ◽  
Change Detection Analysis ◽  
Detection Analysis ◽  
Disaster Assessment ◽  
Southern Taiwan ◽  
Post Disaster

Abstract. On 8 August 2009, the extreme rainfall of Typhoon Morakot triggered enormous landslides in mountainous regions of southern Taiwan, causing catastrophic infrastructure and property damages and human casualties. A comprehensive evaluation of the landslides is essential for the post-disaster reconstruction and should be helpful for future hazard mitigation. This paper presents a systematic approach to utilize multi-temporal satellite images and other geo-spatial data for the post-disaster assessment of landslides on a regional scale. Rigorous orthorectification and radiometric correction procedures were applied to the satellite images. Landslides were identified with NDVI filtering, change detection analysis and interactive post-analysis editing to produce an accurate landslide map. Spatial analysis was performed to obtain statistical characteristics of the identified landslides and their relationship with topographical factors. A total of 9333 landslides (22 590 ha) was detected from change detection analysis of satellite images. Most of the detected landslides are smaller than 10 ha. Less than 5% of them are larger than 10 ha but together they constitute more than 45% of the total landslide area. Spatial analysis of the detected landslides indicates that most of them have average elevations between 500 m to 2000 m and with average slope gradients between 20° and 40°. In addition, a particularly devastating landslide whose debris flow destroyed a riverside village was examined in depth for detailed investigation. The volume of this slide is estimated to be more than 2.6 million m3 with an average depth of 40 m.

scholarly journals Discharge of landslide-induced debris flows: case studies of Typhoon Morakot in southern Taiwan

2014 ◽  
Vol 2 (1) ◽  
pp. 315-346
Author(s):  
J.-C. Chen ◽  
M.-R. Chuang
Keyword(s):  
Debris Flow ◽  
Case Studies ◽  
Debris Flows ◽  
Maximum Flow ◽  
Field Investigation ◽  
Typhoon Morakot ◽  
Flow Discharge ◽  
Modeling Software ◽  
Southern Taiwan ◽  
Deposition Depth

Abstract. Three debris-flow gullies, the Hong-Shui-Xian, Sha-Xin-Kai, and the Xin-Kai-Dafo gullies, located in the Shinfa area of southern Taiwan were selected as case studies of the discharge of landslide-induced debris flows caused by Typhoon Morakot in 2009. The inundation characteristics of the three debris flows, such as the debris-flow volume, the deposition area, maximum flow depth, and deposition depth, were collected by field investigations and simulated using the numerical modeling software FLO-2D. The discharge coefficient cb, defined as the ratio of the debris-flow discharge Qdp to the water-flow discharge Qwp, was proposed to determine Qdp, and Qwp was estimated by a rational equation. Then, cb was calibrated by a comparison between the field investigation and the numerical simulation of the inundation characteristics of debris flows. Our results showed that the values of cb range from 6 to 18, and their values are affected by the landslide ratio The empirical relationships between Qdp and Qwp were also presented.

3D ordered porous SnO2 with a controllable pore diameter for enhanced formaldehyde sensing performance

2020 ◽  
Vol 13 (07) ◽  
pp. 2051044
Author(s):  
Dan Sun ◽  
Huixiao Guo ◽  
Yu Li ◽  
Haiying Li ◽  
Xiaosong Li ◽  
...  
Keyword(s):  
Oxygen Vacancies ◽  
Porous Structures ◽  
Gas Sensitivity ◽  
Long Term Stability ◽  
Response Recovery ◽  
Recovery Times ◽  
Formaldehyde Sensing ◽  
Different Diameters ◽  
Ordered Porous

This paper reports the preparation of 3D ordered porous SnO2 with different diameters (103, 546, and 1030[Formula: see text]nm) by a simple template method. We find that 103[Formula: see text]nm porous SnO2 nanomaterials have the highest response (30) and fastest response/recovery time (3/10 s) for 100 ppm HCHO (formaldehyde) compared with the response and response/recovery times for 546 nm (20 and 3/17[Formula: see text]s, respectively) and 1030 nm (10 and 6/20[Formula: see text]s, respectively) porous SnO2 nanomaterials at a low working temperature (220∘C). All three sensors show good long-term stability, repeatability, and linearity. The results show that decreasing the diameter of the porous SnO2 materials effectively increased the gas sensitivity to HCHO. The increase in the gas sensitivity was attributed to the ordered porous structures, large specific surface area, and additional oxygen vacancies on the surface.

Using Acute Performance on a Comprehensive Neurocognitive, Vestibular, and Ocular Motor Assessment Battery to Predict Recovery Duration After Sport-Related Concussions

2017 ◽  
Vol 45 (5) ◽  
pp. 1187-1194 ◽  
Author(s):  
Alicia M. Sufrinko ◽  
Gregory F. Marchetti ◽  
Paul E. Cohen ◽  
R.J. Elbin ◽  
Valentina Re ◽  
...  
Keyword(s):  
Recovery Time ◽  
Symptom Assessment ◽  
Cognitive Testing ◽  
Ocular Motor ◽  
Motor Speed ◽  
Multinomial Regression ◽  
Symptom Scale ◽  
Level Of Evidence ◽  
Recovery Times ◽  
Visual Motor

Background: A sport-related concussion (SRC) is a heterogeneous injury that requires a multifaceted and comprehensive approach for diagnosis and management, including symptom reports, vestibular/ocular motor assessments, and neurocognitive testing. Purpose: To determine which acute (eg, within 7 days) vestibular, ocular motor, neurocognitive, and symptom impairments predict the duration of recovery after an SRC. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: Sixty-nine patients with a mean age of 15.3 ± 1.9 years completed a neurocognitive, vestibular/ocular motor, and symptom assessment within 7 days of a diagnosed concussion. Patients were grouped by recovery time: ≤14 days (n = 27, 39.1%), 15-29 days (n = 25, 36.2%), and 30-90 days (n = 17, 24.6%). Multinomial regression was used to identify the best subset of predictors associated with prolonged recovery relative to ≤14 days. Results: Acute visual motor speed and cognitive-migraine-fatigue symptoms were associated with an increased likelihood of recovery times of 30-90 days and 15-29 days relative to a recovery time of ≤14 days. A model with visual motor speed and cognitive-migraine-fatigue symptoms within the first 7 days of an SRC was 87% accurate at identifying patients with a recovery time of 30-90 days. Conclusion: The current study identified cognitive-migraine-fatigue symptoms and visual motor speed as the most robust predictors of protracted recovery after an SRC according to the Post-concussion Symptom Scale, Immediate Post-concussion Assessment and Cognitive Testing, and Vestibular/Ocular Motor Screening (VOMS). While VOMS components were sensitive in identifying a concussion, they were not robust predictors for recovery. Clinicians may consider particular patterns of performance on clinical measures when providing treatment recommendations and discussing anticipated recovery with patients.

scholarly journals Analysis of changes in post-seismic landslide distribution and its effect on building reconstruction

2015 ◽  
Vol 15 (4) ◽  
pp. 817-825 ◽  
Author(s):  
W. T. Yang ◽  
M. Wang ◽  
N. Kerle ◽  
C. J. Van Westen ◽  
L. Y. Liu ◽  
...  
Keyword(s):  
Wenchuan Earthquake ◽  
Dynamic Process ◽  
Flash Floods ◽  
Mountainous Regions ◽  
Environment Exposure ◽  
High Resolution Images ◽  
Local Residents ◽  
Seismic Landslide ◽  
Landslide Debris

Abstract. Six years after the devastating Ms 8.0 Wenchuan earthquake, new landslides, debris flows, and flash floods still occur frequently in the earthquake-stricken regions. This shows that the geological hazards that occur after a major earthquake in a mountainous environment can be a long-term threat. However, post-earthquake reconstruction and relocation of local residents often neglect this evolving threat, and its interaction with existing and rebuilt houses has not been well studied. Here we show that the evolving mountain environment, including the changed geographic distribution of new landslides and the continuously uplifting riverbed, creates emerging risks for existing and rebuilt houses. We use spatial analysis of landslide debris and the location of houses from high-resolution images and field survey in the study area and find that new landslides and the houses rebuilt after the Wenchuan earthquake have a similar trend of moving to lower elevations, gentler slopes, and closer to rivers. This study confirms that the persistent downward movement of landslide debris has rapidly filled up riverbeds over the past 6 years. The elevated riverbeds make the study area extremely susceptible to flash floods, creating further risks to newly rebuilt houses that are closer to the river. We highlight the often neglected dynamic process that involves changes in the natural environment and man-made constructions and their interaction. This dynamic process requires long-term monitoring and adaptive management of mountainous regions after major earthquakes that can fully consider the sophisticated evolving risks caused by the changing environment, exposure, and vulnerability in the region.

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