Assessing NDVI Spatial Pattern as Related to Irrigation and Soil Salinity Management in Al-Hassa Oasis,Saudi Arabia

Sustainability of irrigated agriculture in arid and semi arid lands depends, mainly on the level of soil salinity and the quality of irrigation water. Remotely sensed data can provide information about the extent of vegetated irrigated areas. Al-Hassa oasis, Saudi Arabia is probably the largest oasis in the world depends mostly on tapped ground water to irrigate mainly date palm groves for its economic survival. This study tried to investigate the extent of soil salinity and the quality of irrigation water and the relationship with vegetation growth, employing NDVI derived from Landsat satellite imagery.     

Numerical analysis of soilbags under compression and cyclic shear

This paper presents a finite element model for analysing the behaviour of granular material wrapped with polyethylene bags under vertical compression and cyclic shearing. The simple Mohr–Coulomb model is used to represent the soil behaviour. The polyethylene bag is represented by a linear-elastic–perfect-plastic model. The soil-bag interface is modelled with contact constraints. The main purpose of the numerical analysis is to validate the anticipated performance of soilbags under various loading conditions and hence the effectiveness of soilbags as a method of ground improvement.     

Investigation of rock quality of Shirinrud dam site by engineering seismology

At this paper, we studied about the rock quality of Shirinrud dam site by engineering seismology. Shirinrud dam site is located 80 km far from Kerman and 18 km far from Hojadk village. The dam and its constructions are established in the Bidu Formation which consists of seven rock units, and the refraction profiles were surveyed on Jb_3/2, Jb₄, and Jb₅ rock units. To evaluate the rock mass quality and basement topography at this site, nine refraction seismic profiles by primary waves and two refraction seismic profiles by secondary waves were surveyed. We used some methods such as Palmer method, the reciprocal method, plus–minus method, etc. to process and interpret data. Based on investigations, primary wave velocity in unit Jb_3/2 varies between 2,100 and 2,200 m/s, in unit Jb₄ is between 2,100 and 4,200 m/s, and in unit Jb₅ is between 2,500 and 3,000 m/s. The Q values on these three units are 0.05, 1.2, and 1.9, and the rock mass rating (RMR) values are 27.1, 40.5, and 33.5, respectively. With respect to wave velocity, Q, and RMR values, the units Jb_3/2, Jb₄, and Jb₅ are evaluated as very weak, intermediate, and weak, respectively.     

Groundwater geochemistry in the Meshkinshahr basin of Ardabil province in Iran

The chemical analysis of 59 water wells in Meshkinshar area, Ardabil province NW of IRAN has been evaluated to determine the hydrogeochemical processes and ion concentration background in the region. The dominated hydrochemical types are Na–SO₄, Ca–HCO₃, Na–HCO₃ and Na–Cl in the whole area. Based on the total hardness, the groundwater is soft. According to electrical conductivity and sodium adsorption ratio, the most dominant classes are C1–S1, C2–S1 and C3–S1. The major ion concentrations are below the acceptable level for drinking water. The groundwater salinity hazard is medium to high but the Na hazard is low to medium and in regard of irrigation water the quality is low to medium. So the drainage system is necessary to avoid the increase of toxic salt concentrations.     

An improvement in mass flux convective parameterizations and its impact on seasonal simulations using a coupled model

A new closure and a modified detrainment for the simplified Arakawa–Schubert (SAS) cumulus parameterization scheme are proposed. In the modified convective scheme which is named as King Abdulaziz University (KAU) scheme, the closure depends on both the buoyancy force and the environment mean relative humidity. A lateral entrainment rate varying with environment relative humidity is proposed and tends to suppress convection in a dry atmosphere. The detrainment rate also varies with environment relative humidity. The KAU scheme has been tested in a single column model (SCM) and implemented in a coupled global climate model (CGCM). Increased coupling between environment and clouds in the KAU scheme results in improved sensitivity of the depth and strength of convection to environmental humidity compared to the original SAS scheme. The new scheme improves precipitation simulation with better representations of moisture and temperature especially during suppressed convection periods. The KAU scheme implemented in the Seoul National University (SNU) CGCM shows improved precipitation over the tropics. The simulated precipitation pattern over the Arabian Peninsula and Northeast African region is also improved.

     

Performance evaluation of land change simulation models using landscape metrics

This study proposes a landscape metrics-based method for model performance evaluation of land change simulation models. To quantify model performance at both landscape and class levels, a set of composition- and configuration-based metrics including number of patches, class area, landscape shape index, mean patch area and mean Euclidean nearest neighbour distance were employed. These landscape metrics provided detailed information on simulation success of a cellular automata-Markov chain (CA-Markov) model standpoint of spatial arrangement of the simulated map versus the corresponding reference layer. As a measure of model simulation success, mean relative error (MRE) of the metrics was calculated. At both landscape and class levels, the MRE values were accounted for 22.73 and 10.2%, respectively, which are further categorised into qualitative measurements of model simulation performance for simple and quick comparison of the results. Findings of the present study depict a hierarchical and multi spatial level assessment of model performance.     

Landslide susceptibility mapping using AHP and fuzzy methods in the Gilan province,Iran

GeoJournal - Landslides are natural destructive phenomena that can cause great damage to property and life loss. One of the fundamental proceedings to reduce the possible damage is identifying...     

Levels and distributions of organic source tracers in air and roadside dust particles of Kuala Lumpur,Malaysia

The concentrations of n-alkanes, unresolved complex mixture (UCM), petroleum molecular markers, other tracers of cooking and burning emissions, and natural background in atmospheric particles and roadside dust particles were measured at eight locations in the city center and the suburbs of Kuala Lumpur, Malaysia. Atmospheric particles were collected using high-volume filtration (PM-10, GFF) over 24 h average periods. Road dusts were swept up, dried and sieved. Both types of samples were extracted with dichloromethane/methanol mixture (3:1 v/v) by ultrasonic agitation. The extracts were then fractionated by column chromatography and the alkanes subjected to gas chromatography–mass spectrometry (GC–MS). Total extracts were also analyzed directly by GC–MS after silylation. The molecular distributions of compounds as well as diagnostic geochemical ratios were determined in order to identify the sources of the organic compounds. Samples collected from a rural area and lubricating oils were also analyzed for comparisons. Anthropogenic and biogenic sources such as vehicular emissions, waxes of higher plants, food cooking operations, and biomass and domestic refuse burning processes contributed to the organic matter content of atmospheric and to lesser extent, roadside dust particles.     

Adsorption of barium ions by β-manganese dioxide and its activation in oleate flotation

The Ba²⁺ ion adsorption isotherms on β-MnO₂ were of the Langmuir type. The endothermic heat of adsorption (40 kJ mol^?1) is ascribed to entropy contributions associated with the $\text{Na}{}^{\mathrm{+}}\text{Ba}{}^{\mathrm{2+}}$ ion-exchange mechanism. The Ba²⁺ ion adsorption density was higher at pH 10 than that at pH 7, due to the more negative surface charge at the higher pH. Ba²⁺ ions were found to reverse the sign of the ζ potential of the MnO₂ particles.More oleate was adsorbed by β-MnO₂ in the presence of Ba²⁺ ions than in their absence. The oleate adsorption isotherms on Ba²⁺-activated MnO₂ were of the Freundlich type and indicated an exothermic process. Hallimond flotation recovery of Ba²⁺-activated MnO₂ was higher at pH 10 than at pH 7, although less oleate was adsorbed at the higher pH. At pH 7, Mn²⁺-activation led to higher recoveries than Ba²⁺-activation. It seems that the attraction between the surface and the activator plays an important rôle in determining the flotation recovery.