Surface soil assessment in the Ubhur area,north of Jeddah,western Saudi Arabia,using a multichannel analysis of surface waves method

Ten boreholes drilled in Ubhur area up to the depth of bedrock indicted the shallow depth of bedrock where the average depth ranges between 10 and 15 m. The standard penetration test N-values of these boreholes were measured and averaged. Based on N-values to the depth of bedrock, Ubhur area can be classified as site class C and D. Multichannel analysis of surface waves technique has been applied along seventy six profiles using 24-channel geophone array and 4.5Hz vertical geophones with 1m geophone spacing and sledgehammer and/or weight drop as seismic energy sources. Values of shear wave velocity to 30 m are calculated and then averaged (Vs30) where it ranges between 310.08 m/s and 1139.8 m/s. Therefore, Ubhur area can be classified into site class B, C and D based on site classification of the national earthquake hazards reduction program (NEHRP) recommendations. Accordingly, the greatest part of the study area falls in site class C while class B and D covered limited areas in the western and the eastern parts respectively. Depending on the shallow depth of bedrock in the study area, the Vs30 parameter is not applicable in the study area so the average values of Vs for the soil thickness, excluding the bedrock, have been calculated and mapped for site class C and D only. So Vs30 approach is not applicable for areas with shallow depth of bedrock which gives higher classification.     

Site response analysis for deep and soft sedimentary deposits of Dhaka City,Bangladesh

Natural Hazards - The ground motion intensity of an earthquake is significantly changed when seismic waves propagate from the bedrock to the near-surface soft geological materials. The ground where...     

Hydrochemical classification and multivariate statistical analysis of groundwater from Wadi Sahba area in central Saudi Arabia

The central region of Saudi Arabia is underlain by thick sedimentary formations belonging to the Mesozoic and Cenozoic era. These sedimentary formations form a prolific aquifer supplying groundwater for agricultural and domestic usage in and around Riyadh. The region south of Riyadh City is well known for agricultural activities. Wadi Sahba, which is an eastward extension of Wadi Nisah, has readily available groundwater resources in the Cretaceous Biyadh sandstone aquifer to sustain agricultural activities. The objective of the present study was the hydrochemical assessment of groundwater in the area to understand the main hydrological processes which influence groundwater chemistry. To achieve this objective, 20 groundwater samples were collected from agricultural farms in the Wadi Sahba in central Saudi Arabia, and the major physiochemical constituents were analyzed and interpreted. The average TDS value of the analyzed samples is 1578.05 mg/l, whereas the average EC concentration is 3220.05 μS/cm. Groundwater facies classification inferred from the Piper plot shows that groundwater in the study area belongs to the Ca-SO₄-Cl type and Ca-Na-SO₄-Cl type. The Ca-SO₄-Cl type of groundwater facies is influenced mainly by gypsum dissolution and base ion exchange, whereas the Ca-Na-SO₄-Cl type is influenced by gypsum and halite dissolution. All the groundwater samples are undersaturated with respect to these two principal mineral phases. The Q-mode cluster analysis results in two main groups of groundwater samples, mainly based on the TDS content. Cluster 1 has an average TDS value of 1980 mg/l, whereas cluster 2 has an average TDS of 1176 mg/l. The groundwater facies identified through the Piper plot reflects the major hydrological processes controlling groundwater chemistry in the area and was found to be more useful in this study as compared to cluster analysis.     

The probability distributions and fractal dimension of sunspot cycles associated with ENSO phenomena

Various methods have been used to secure the certainty of significant relations among the sunspot cycles and some of the terrestrial climate parameters such as temperature, rainfall, and ENSO. This study investigates the behavior of ENSO cycles and mean monthly sunspot cycles. Sunspot cycles range from 1755 to 2016 whereas, ENSO cycles range from 1866 to 2012. In this regard, the appropriateness of distributions is investigated with the help of Kolmogorov-Smirnov D, Anderson-Darling, and chi-square tests. It is found that most of the sunspot cycle follows generalized Pareto distribution whereas, generalized extreme value distribution was found appropriate for ENSO cycles. Probability distribution is used to analyze the behavior of each sunspot cycle and ENSO cycle separately. Probability distribution indicates the tail behavior of each cycle; tail explored correlation cycles. Furthermore, self-similar and self-affine fractal dimension methods are used to compute Hurst exponents to determine the persistency of the available data. Fractal dimension has an ability to study the complexity involved in sunspot and ENSO cycles. The fractal dimension and Hurst exponent describe persistency (smoothness) and complexity of data. Hurst exponent measures long-term behavior of time series, making it more helpful for forecasting. This is the measure of regularity or irregularity (chaos) of the time function in the form of their persistency or anti-persistency, respectively. Hurst exponents are computed using rescaled range analysis method and box counting methods. Both these methods are suitable for long-term forecasting. The results of this study confirm that during the period 1980–2000, ENSO cycles were very active. Simultaneously, ENSO was active for the periods 1982–1983, 1986–1987, 1991–1993, 1994–1995, and 1997–1998; these periods include two strongest periods of the century viz., 1982–1983 and 1997–1998. Sunspot cycles and ENSO cycles both were found to be persistent. Self-similar fractal dimensions exhibited a better persistency and a better correlation as compared to self-affine fractal dimension. This research is a part of a larger research project investigating the correlation of sunspot cycles and ENSO cycles, and the influence of ENSO cycles on variations of the local climatic parameters which in turn depends on solar activity changes.     

Delineating key determinants of domestic fuelwood consumption of rural households in western Himalaya-policy implications

A study was carried out in district Samba of Western Himalayan province of Jammu and Kashmir of India.The data were collected in an interview schedule in personal interview with 180 household heads.The association between the level of fuelwood consumption（low versus high consumption） and different factors,each individually,was investigated using chi-square test of association at 0.001 level of significance.It was found that out of 25 socio-economic,biophysical and alternate fuel factors,15 factors（each individually） significantly influenced the domestic fuelwood consumption.Logistic regression models of alternate fuel use,social,economic and biophysical factors were developed to identify key variables influencing fuelwood consumption levels within each respective category.A composite model was also developed to identify key factors when all variables in all the pre-said categories were considered simultaneously.Surprisingly,in contrast to expectation the model with alternate fuel use did not provide a good fit.The biophysical model also did not provide a good fit.The economic and composite models were the same with equal level of accuracy of predication.This implies that economic aspects,rather than the availability of alternate fuels,dominate fuelwood consumption levels of rural households.Strategies to increase the exposure of the head of household to outside world needs to formulated to reduce the domestic fuelwood consumption levels.Households nearer to state forests are to be educated about efficient use of fuelwood and be encouraged to intensify use of Liquified Petroleum Gas.The wider implications of study are：the availability of alternate fuels is not a necessary condition to decrease household level domestic fuelwood consumption.Economic factors needs to be considered in designing strategies to reduce fuelwood consumption.Increased employment opportunities would increase the opportunity cost of fuelwood collection and this would reduce its use.     

Chasing Chinese Caterpillar Fungus (Ophiocordyceps sinensis) Harvesters in the Himalayas: Harvesting Practice and Its Conservation Implications in Western Nepal

The Chinese caterpillar fungus is famous for its high market value, unusual life history, and significant medicinal uses. It is harvested by very poor communities and sold for an extraordinarily high price. Most of the studies on this species are focused on therapeutic uses, chemical analyses, ecology, and trade. However, harvesting techniques and intensity of the harvests remain undocumented. We document harvesting techniques, trends of harvest, and perceptions of the Chinese caterpillar fungus harvesters in Dolpa, Nepal, based on surveys, focus-group discussions, and direct observations. Along with increasing market value, intensity of the harvest has been increasing. The Chinese caterpillar fungus harvest has now become the second most important livelihood strategy for the local communities, after agriculture. Reported per-capita harvest based on the first day of collection has declined over the last 4 years, apparently because of the decline in the stock and the increasing number of harvesters.     

Rainfall-induced landslide susceptibility zonation of Puerto Rico

Landslides are a major geologic hazard with estimated tens of deaths and $1–2 billion in economic losses per year in the US alone. The island of Puerto Rico experiences one or two large events per year, often triggered in steeply sloped areas by prolonged and heavy rainfall. Identifying areas susceptible to landslides thus has great potential value for Puerto Rico and would allow better management of its territory. Landslide susceptibility zonation (LSZ) procedures identify areas prone to failure based on the characteristics of past events. LSZs are here developed based on two widely applied methodologies: bivariate frequency ratio (FR method) and logistic regression (LR method). With these methodologies, the correlations among eight possible landslide-inducing factors over the island have been investigated in detail. Both methodologies indicate aspect, slope, elevation, geological discontinuities, and geology as highly significant landslide-inducing factors, together with land-cover for the FR method and distance from road for the LR method. The LR method is grounded in rigorous statistical testing and model building but did not improve results over the simpler FR method. Accordingly, the FR method has been selected to generate a landslide susceptibility map for Puerto Rico. The landslide susceptibility predictions were tested against previous landslide analyses and other landslide inventories. This independent evaluation demonstrated that the two methods are consistent with landslide susceptibility zonation from those earlier studies and showed this analysis to have resulted in a robust and verifiable landslide susceptibility zonation map for the whole island of Puerto Rico.     

Catastrophic movement of rocks and proposed solutions to avoid its risks in the Abu El-Reesh area, northeast Aswan City, Egypt

Catastrophic mass movement of rocks and torrents affected the Abu El-Reesh area, northeast of Aswan City. The present article aims to evaluate the potential catastrophic movement of rocks, delineate the risk zones, and suggest suitable solutions to avoid the potential risks in this area. The sedimentary succession of Abu El-Reesh area is mainly represented by the Nubian sandstone sequence of Upper Cretaceous (up to 60?m thick) forming a huge scarp at the eastern border of the study area. This sequence comprises two vertically successive rock formations: Timsah Shale Formation and Umm Barmil Sandstone Formation. The Timsah Shale Formation forms the lower part of the sedimentary succession with a thickness of 6?C40?m. It is composed of shale beds with intercalations of sandstones, siltstones, and mudstones. This formation is overlain by the Umm Barmil Sandstone Formation, representing the cap rock of the succession, with a thickness of 4?C20?m. The western scarp face has an irregular concave slope, with slope angles ranging from 22° to 46° in the lower part of scarp and become steep (60°?C86°) at its upper part. The drainage patterns are mainly coarse dendritic and discharge into the Nile River, passing through densely populated zones. These zones are exposed to the torrents during rare rainfall events. Three sets of vertical joints (trending NNW, NNE, and WNW) dissect the cap rocks and intersect with the horizontal bedding planes to form separated cubes and polygonal blocks. Potential catastrophic movement of rocks in Abu El-Reesh area is related to several reasons, including: existence of competent sandstones underlain by incompetent shales, dissection of the coherent cap rock due to intersection of vertical joint sets and bedding planes, presence of exposures with steep slopes, rainfall, and human activities (mining works, sewage water, and irrigation). Based on the dominance of either one or more of these reasons, three subareas (El-Khalasab, El-Shadeeda and El-Aqaba) represent the main risk zones, subjected to rock movements and torrents in the study area. Several solutions have been suggested for avoiding the risks related to the potential catastrophic movement of the rocks and torrents in the study area. The fractured rock masses at the top of scarp should be released either mechanically or manually. All buildings that were built on the slope surface of the scarp should be removed. Also, buildings which were constructed in the inlets of wadis and through the rain spillways should be removed. An unsafe boundary separating safe building borders from unsafe zone (with average width 50?m from the base of scarp) is delineated. As a result, resettlement for people living in this unsafe zone should be transferred to another safe area.     

Distribution of total petroleum hydrocarbons in Dezful aquifer,Southwest of Iran

Determination of total petroleum hydrocarbon distribution (TPH) in groundwater of Dezful aquifer was the main purpose of this study. The study area, which is located between latitudes 32°00′ and 32°35′?N and longitudes 48°10′ and 49°35′?E, covers about 1,920 km² in the north of Khuzestan Province, Iran. Hydrocarbon pollutants in the area were being released into the aquifer, from a variety of sources. An oil pipe crash accident, which occurred on 19 Feb. 2009 in the vicinity of the northern part of the study area, released about 6,000 barrels of crude oil to the Karkhe River. Other possible sources of TPH in the region are asphalt factories, gas stations, and the Sabzab oil pump station. Since the main source of drinking water in the Dezful area is groundwater reservoirs, this study would be very crucial, especially when there is considerable agricultural activity in the area as well. In order to determine the presence of TPH and heavy metals in the groundwater, samples were taken from wells with different usage within two periods, i.e., in Nov. 2008 and May 2009. The second sampling operation was carried out to determine the effect of the accident in the water resources. In situ groundwater parameter measurements including pH, dissolved oxygen, temperature, and electrical conductivity were also carried out in the field. Based on the results, there are four zones in the study area which were contaminated with TPH from different origins: (1) southeast of Dezful City, which was contaminated by Shokati gas station; (2) southeast of Shush City, which was contaminated by an asphalt factory; (3) southwest of Dezful City, which was contaminated by Sabzab oil pump station; and (4) the shores of Karkhe River which were contaminated due to the pipeline crash accident. This could be a serious threat to the environment and human health because TPH concentration was higher than the EPA standard in the study area. Heavy metals were not distributed in a uniform pattern in the aquifer. The concentrations were lower than the contamination level based on the EPA drinking standard, and there was no meaningful relation between concentrations of TPH and the heavy metals. It was recommended that a monitoring network should be designed to monitor oil contaminants in the ground and surface water monthly because of importance of the water resources and presence of potential oil contaminant sources.