scholarly journals Evaluation of hillslope failure and community adjustment after extreme weather event, Waimarama 26-27 April, 2011

2021 ◽  
Author(s):  
◽  
Albert Edward Frampton
Keyword(s):  
Water Content ◽  
Small Businesses ◽  
Extreme Event ◽  
Extreme Rainfall ◽  
Field Measurements ◽  
Economic Loss ◽  
Laboratory Analysis ◽  
Annual Rainfall ◽  
Financial Loss ◽  
North West

<p>In 2011, Waimarama received 80% of its annual rainfall in 48 hours. This extreme event with a return period of >100 years caused saturated hillslopes to collapse forming 100s of shallow landslides in the Puhokio Valley. This study collected soil samples from 54 exposed slip scarp horizons for laboratory analysis of soil mechanical properties. Field measurements of slip and slope angles, length, width and depth to determine that 23,212m³ of sediment was volume lost, from the 54 landslides. The field and lab measurements were used to generate a coherent understanding of landsliding at Waimarama. Laboratory analysis for liquid limits water content showed a high of 88.5% to a low of 18.8% and plastic limit water content had a high of 51% in the A horizon (organics) and low of 16.1%. Specific gravity also indicated a high reading 1.74 g/cm³ with a low of 1.16 g/cm³. The A horizon was able to tolerate high levels of water content in most tests, while the B horizon was capable of coping with some increase in water content. The C horizon was only able to handle low volumes of water, and was the main initiator of regolith collapse. The laboratory results indicated high saturation levels within the horizons of weak lithology of marine regolith that over caps impervious marine bedrock. The main cause for hillslope collapse and exposure of multiple translational and debris flow landslides was extreme saturation. However, towards the height of the rainfall event a 4.5 magnitude earthquake was recorded with unknown collateral consequences. Most slip locations were found in the aspects of east, south-east, west, and north-west, and on slope angles 15 -25°. The study confirmed previous surveys that regolith depth 80-100cm on impervious sandstone, siltstone/mudstone, when saturated over lengthy wet spells or from extreme precipitation, will collapse. In addition to the physical geographic study a survey was included to record individual and family accounts of the weather phenomenon. A questionnaire was prepared with specific questions that required yes or no answers. These questions dealt with loss of buildings, loss of land, animals, financial loss and recovery, economic loss, insurance and mitigation plans. The most affected were farmers and the next affected were householders while the holiday park was the worst affected of small businesses. Insurance was a significant help in most recoveries. Land rehabilitation was mitigated with new plantings and some aerial sowing, otherwise many slips were left to revegetate naturally. Economic and financial loss was severe for most farmers, due to pasture loss and animal relocation. Extreme rainfall causes slips that affect humans, but they can be mitigated. The Waimarama event is one of many events that can happen countrywide, the results can be a disastrous loss of personal, economic and financial assets, loss of infrastructure, including roading, bridges and communication. These are factors that many people and communities only realise when it happens to them. Mitigation against such events might include adequate insurance and knowledge of what to do, and where to go should an event happen unexpectedly and without warning.</p>

scholarly journals Evaluation of hillslope failure and community adjustment after extreme weather event, Waimarama 26-27 April, 2011

2021 ◽  
Author(s):  
◽  
Albert Edward Frampton
Keyword(s):  
Water Content ◽  
Small Businesses ◽  
Extreme Event ◽  
Extreme Rainfall ◽  
Field Measurements ◽  
Economic Loss ◽  
Laboratory Analysis ◽  
Annual Rainfall ◽  
Financial Loss ◽  
North West

<p>In 2011, Waimarama received 80% of its annual rainfall in 48 hours. This extreme event with a return period of >100 years caused saturated hillslopes to collapse forming 100s of shallow landslides in the Puhokio Valley. This study collected soil samples from 54 exposed slip scarp horizons for laboratory analysis of soil mechanical properties. Field measurements of slip and slope angles, length, width and depth to determine that 23,212m³ of sediment was volume lost, from the 54 landslides. The field and lab measurements were used to generate a coherent understanding of landsliding at Waimarama. Laboratory analysis for liquid limits water content showed a high of 88.5% to a low of 18.8% and plastic limit water content had a high of 51% in the A horizon (organics) and low of 16.1%. Specific gravity also indicated a high reading 1.74 g/cm³ with a low of 1.16 g/cm³. The A horizon was able to tolerate high levels of water content in most tests, while the B horizon was capable of coping with some increase in water content. The C horizon was only able to handle low volumes of water, and was the main initiator of regolith collapse. The laboratory results indicated high saturation levels within the horizons of weak lithology of marine regolith that over caps impervious marine bedrock. The main cause for hillslope collapse and exposure of multiple translational and debris flow landslides was extreme saturation. However, towards the height of the rainfall event a 4.5 magnitude earthquake was recorded with unknown collateral consequences. Most slip locations were found in the aspects of east, south-east, west, and north-west, and on slope angles 15 -25°. The study confirmed previous surveys that regolith depth 80-100cm on impervious sandstone, siltstone/mudstone, when saturated over lengthy wet spells or from extreme precipitation, will collapse. In addition to the physical geographic study a survey was included to record individual and family accounts of the weather phenomenon. A questionnaire was prepared with specific questions that required yes or no answers. These questions dealt with loss of buildings, loss of land, animals, financial loss and recovery, economic loss, insurance and mitigation plans. The most affected were farmers and the next affected were householders while the holiday park was the worst affected of small businesses. Insurance was a significant help in most recoveries. Land rehabilitation was mitigated with new plantings and some aerial sowing, otherwise many slips were left to revegetate naturally. Economic and financial loss was severe for most farmers, due to pasture loss and animal relocation. Extreme rainfall causes slips that affect humans, but they can be mitigated. The Waimarama event is one of many events that can happen countrywide, the results can be a disastrous loss of personal, economic and financial assets, loss of infrastructure, including roading, bridges and communication. These are factors that many people and communities only realise when it happens to them. Mitigation against such events might include adequate insurance and knowledge of what to do, and where to go should an event happen unexpectedly and without warning.</p>

Analysis of Pitted Courtyard Cave Dwellings Stability in Baishe Village when Rainfall Infiltration

2011 ◽  
Vol 250-253 ◽  
pp. 2468-2472 ◽  
Author(s):  
Jia Ming Han ◽  
San Qing Su
Keyword(s):  
Water Content ◽  
Field Measurements ◽  
Strength Criterion ◽  
Annual Rainfall ◽  
Rock Stress ◽  
Average Annual Rainfall ◽  
The Stability ◽  
The Relationship ◽  
Water Contents

Pitted courtyard cave dwellings were used as a long-term living form in Baishe village. After field measurements, the size of local pitted courtyards and cave dwellings had been mastered, and the variation of average annual rainfall and monthly rainfall had been analyzed. By the experiment, the changes of physical and mechanical indexes could be showed with different water contents. At the same time, based on the literature, the relationship could be established between rainfall and water content. Basis in the expression of room rock stress and the Mohr-Coulomb strength criterion, the stability of the cave dwellings could be analyzed under different water contents, and the definition could be found of safety factor of loess cave. Then, the stability variation of loess cave dwelling could be obtained in different rainfall, and the evaluation results are given.

scholarly journals Assessment of the rainfall exceedance in Nigeria

2021 ◽  
Vol 40 (4) ◽  
pp. 751-761
Author(s):  
A.O. Eruola ◽  
A.A. Makinde ◽  
G.A. Eruola ◽  
K.O. Ayoola
Keyword(s):  
Time Scales ◽  
Extreme Rainfall ◽  
Northern Region ◽  
Critical Values ◽  
Annual Rainfall ◽  
Crop Failure ◽  
North West ◽  
North East ◽  
Long Time ◽  
Average Monthly Rainfall

This study assessed rainfall extremes for agricultural overview in Nigeria using trend analysis and probability of exceedance expressed as normal for an average at 50% exceedance, wet for greater than average 20% exceedance and dry for lower than average 80% exceedance. The annual rainfall trend indicated variability in the six geopolitical regions with North-East having the lowest range and South-South area with highest. The average monthly rainfall exceedance showed that all part of the Nigeria experienced rainfall more than 100 mm at all levels of probability. The rainfall exceedance time series indicated extremes as well as critical values of 20% and 80% exceedance conditions at many stations during the study period. The critical values of exceedances in dry occurrences are in short-time scales in Northern region while, wet exceedances occurrences for long time scales in South-East, South-West, North-Central and North-West. The study revealed periods of extreme rainfall of significant magnitude susceptible to crop failure in the different regions if reliable cropping management plans is not put in place.

scholarly journals Validation of Satellite Rainfall Estimates over Equatorial East Africa

2021 ◽  
Keyword(s):  
East Africa ◽  
Prediction Models ◽  
Extreme Event ◽  
Weather Prediction ◽  
Extreme Rainfall ◽  
Rain Gauge ◽  
Annual Rainfall ◽  
Extreme Rainfall Events ◽  
Satellite Rainfall ◽  
Rainfall Estimates

Abstract Rain gauge data sparsity over Africa is known to impede the assessments of hydrometeorological risks and of the skill of numerical weather prediction models. Satellite rainfall estimates (SREs) have been used as surrogate fields for a long time and are continuously replaced by more advanced algorithms and new sensors. Using a unique daily rainfall dataset from 36 stations across equatorial East Africa for the period 2001–2018, this study performs a multi-scale evaluation of gauge-calibrated SREs, namely, IMERG, TMPA, CHIRPS and MSWEP (v2.2 and v2.8). Skills were assessed from daily to annual timescales, for extreme daily precipitation, and for TMPA and IMERG near real-time (NRT) products. Results show that: 1) the SREs reproduce the annual rainfall pattern and seasonal rainfall cycle well, despite exhibiting biases of up to 9%; 2) IMERG is the best for shorter temporal scales while MSWEPv2.2 and CHIRPS perform best at the monthly and annual timesteps, respectively; 3) the performance of all the SREs varies spatially, likely due to an inhomogeneous degree of gauge calibration, with the largest variation seen in MSWEPv2.2; 4) all the SREs miss between 79% (IMERG-NRT) and 98% (CHIRPS) of daily extreme rainfall events recorded by the rain gauges; 5) IMERG-NRT is the best regarding extreme event detection and accuracy; and 6) for return values of extreme rainfall, IMERG and MSWEPv2.2 have the least errors while CHIRPS and MSWEPv2.8 cannot be recommended. The study also highlights; improvements of IMERG over TMPA, the decline in performance of MSWEPv2.8 compared to MSWEPv2.2, and the potential of SREs for flood risk assessment over East Africa.

scholarly journals Quantification of PV Power and Economic Losses Due to Soiling in Qatar

2021 ◽  
Vol 13 (6) ◽  
pp. 3364
Author(s):  
Amr Zeedan ◽  
Abdulaziz Barakeh ◽  
Khaled Al-Fakhroo ◽  
Farid Touati ◽  
Antonio S. P. Gonzales
Keyword(s):  
Output Power ◽  
Power Plants ◽  
Economic Loss ◽  
Economic Losses ◽  
Energy Yield ◽  
Solar Pv ◽  
Financial Loss ◽  
Grid Systems ◽  
Dust Density

Soiling losses of photovoltaic (PV) panels due to dust lead to a significant decrease in solar energy yield and result in economic losses; this hence poses critical challenges to the viability of PV in smart grid systems. In this paper, these losses are quantified under Qatar’s harsh environment. This quantification is based on experimental data from long-term measurements of various climatic parameters and the output power of PV panels located in Qatar University’s Solar facility in Doha, Qatar, using a customized measurement and monitoring setup. A data processing algorithm was deliberately developed and applied, which aimed to correlate output power to ambient dust density in the vicinity of PV panels. It was found that, without cleaning, soiling reduced the output power by 43% after six months of exposure to an average ambient dust density of 0.7 mg/m3. The power and economic loss that would result from this power reduction for Qatar’s ongoing solar PV projects has also been estimated. For example, for the Al-Kharasaah project power plant, similar soiling loss would result in about a 10% power decrease after six months for typical ranges of dust density in Qatar’s environment; this, in turn, would result in an 11,000 QAR/h financial loss. This would pose a pressing need to mitigate soiling effects in PV power plants.

scholarly journals Geochemical and isotopic evidence of groundwater salinization processes in the Essaouira region, north-west coast, Morocco

2021 ◽  
Vol 3 (7) ◽  
Author(s):  
Otman EL Mountassir ◽  
Mohammed Bahir ◽  
Driss Ouazar ◽  
Abdelghani Chehbouni ◽  
Paula M. Carreira
Keyword(s):  
Groundwater Recharge ◽  
West Coast ◽  
Exchange Process ◽  
Environmental Isotopes ◽  
Annual Rainfall ◽  
Groundwater Salinization ◽  
Rock Interaction ◽  
North West ◽  
The North ◽  
Water Rock Interaction

AbstractThe city of Essaouira is located along the north-west coast of Morocco, where groundwater is the main source of drinking, domestic and agricultural water. In recent decades, the salinity of groundwater has increased, which is why geochemical techniques and environmental isotopes have been used to determine the main sources of groundwater recharge and salinization. The hydrochemical study shows that for the years 1995, 2007, 2016 and 2019, the chemical composition of groundwater in the study area consists of HCO3–Ca–Mg, Cl–Ca–Mg, SO4–Ca and Cl–Na chemical facies. The results show that from 1995 to 2019, electrical conductivity increased and that could be explained by a decrease in annual rainfall in relation to climate change and water–rock interaction processes. Geochemical and environmental isotope data show that the main geochemical mechanisms controlling the hydrochemical evolution of groundwater in the Cenomanian–Turonian aquifer are the water–rock interaction and the cation exchange process. The diagram of δ2H = 8 * δ18O + 10 shows that the isotopic contents are close or above to the Global Meteoric Water Line, which suggests that the aquifer is recharged by precipitation of Atlantic origin. In conclusion, groundwater withdrawal should be well controlled to prevent groundwater salinization and further intrusion of seawater due to the lack of annual groundwater recharge in the Essaouira region.

Numerical Study of Corrugated Metal Panels Subjected to Windborne Debris Impacts

2014 ◽  
Vol 626 ◽  
pp. 109-114
Author(s):  
Wen Su Chen ◽  
Hong Hao ◽  
Hao Du
Keyword(s):  
Extreme Event ◽  
Numerical Study ◽  
Numerical Models ◽  
Economic Loss ◽  
Wind Loading ◽  
Windborne Debris ◽  
Study Laboratory ◽  
The Impact ◽  
Metal Panels ◽  
Corrugated Metal

Hurricane, typhoon and cyclone take place more and more often around the world with changing climate. Such nature disasters cause tremendous economic loss and casualty. Various kinds of windborne debris such as compact-like, plate-like and rod-like objects driven by hurricane usually imposes localized impact loading on the structure envelopes such as cladding, wall or roof, etc. The dominant opening in the envelope might cause serious damage to the structures, even collapse. To withstand the impact of such extreme event, the requirements on panel capacity to resist windborne debris impact has been presented in the Australian Wind Loading Code (2011) [1]. Corrugated metal panels are widely used as building envelop. In a previous study, laboratory tests have been carried out to investigate the performance of corrugated metal panels subjected to a 4kg wooden projectile by considering various impact locations, impact velocities and boundary conditions. In this study, numerical models were developed to simulate the responses of the corrugated metal panels subjected to wooden debris impacts by using commercial software LS-DYNA. The predicted data from the numerical simulations were compared with the experimental results. The validated numerical model can be used to conduct intensive numerical simulation to study the failure probabilities of corrugated structural panels subjected to windborne debris impacts.

Non-invasive field measurements of soil water content using a pulsed 14MeV neutron generator

2012 ◽  
Vol 120 ◽  
pp. 130-136 ◽  
Author(s):  
S. Mitra ◽  
L. Wielopolski ◽  
R. Omonode ◽  
J. Novak ◽  
J. Frederick ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Neutron Generator ◽  
Field Measurements ◽  
Non Invasive ◽  
14Mev Neutron

scholarly journals Analysis of Daily Rainfall and Spatiotemporal Trends of Extreme Rainfall at Paraná Slope of the Itararé Watershed, Brazil

2020 ◽  
Vol 35 (2) ◽  
pp. 357-374
Author(s):  
Paulo Miguel de Bodas Terassi ◽  
José Francisco de Oliveira Júnior ◽  
Givanildo de Gois ◽  
Bruno Serafini Sobral ◽  
Emerson Galvani ◽  
...  
Keyword(s):  
Daily Rainfall ◽  
Extreme Rainfall ◽  
High Volume ◽  
Annual Rainfall ◽  
Annual Number ◽  
Subtropical Climate ◽  
Homogeneous Groups ◽  
The North ◽  
Spatiotemporal Trends ◽  
Mk Test

Abstract The knowledge of intensity and frequency of rainfall allows establishing predictive measures to minimize impacts caused by high volume of rainfall totals in a region. Therefore, the objective is to evaluate daily rainfall for Paraná slope of the Itararé watershed (PSIW) and to verify the spatiotemporal trend of intense and extreme daily rainfall. Rainfall data from 14 stations collected from 1976 to 2012 were used with less than 4% of data faults. Multivariate analysis based on cluster analysis technique (CA) was used applying the Euclidean distance for the identification of homogeneous groups, and the quantiles technique to classify daily rainfall. The Mann-Kendall (MK) test was used to identify trends for annual rainfall totals, annual number of rainy days (ANRD) and for the occurrence of intense (R95p) and extreme (R99p) rainfall. The CA technique identified three rainfall groups (HG I, II and III). Given the latitudinal position of the area, rainfall at the southern sector is characterized by its greater similarities with the subtropical climate, whereas in the North sector there is a consistent reduction of rainfall totals in autumn and, especially, during winter months, which are characteristic of the tropical climate. The MK test identified the downward trend of ANRD, with greater significance for the south-centered sectors of the basin. The observed trends for the intense (R95p) and extreme (R99p) daily rainfall show the predominance of reduction for the Southwest and central sector, followed by a significant increase in the Southeast and North sectors of the PSIW.

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