Modeling soil erosion using RUSLE and GIS in a watershed occupied by rural settlement in the Brazilian Cerrado

The installation of a rural settlement complex in the watershed stream Indaiá has promoted changes in land-use and vegetation cover dynamics; however, the effects of intensive agriculture and cattle farming in rural settlements on soil loss rates are not well known. Predictive models implemented in geographic information systems have proven to be effective tools for estimating erosive processes. The erosion predictive model Revised Universal Soil Loss Equation (RUSLE) is a useful tool for analyzing, establishing and managing soil erosion. RUSLE has been widely used to estimate annual averages of soil loss, by both interrill and rill erosion, worldwide. Therefore, the aim of this work was to estimate the soil loss in the watershed stream Indaiá, using the RUSLE model and geoprocessing techniques. To estimate soil loss, the following factors were spatialized: erosivity (R), erodibility (K), topography (LS), land-use and management (C) and conservation practices (P); the annual soil loss values were calculated using the RUSLE model equation. The estimated value of soil loss in the hydrographic basin ranged from 0 to 4082.16 Mg ha^?1 year^?1 and had an average value of 47.81 Mg ha^?1 year^?1. These results have demonstrated that 68.16 % of the study area showed little or no soil loss based on the Food and Agriculture Organization’s (FAO 1980) classification. When comparing the average value of soil loss obtained using the RUSLE model with the Natural Potential for Erosion, a 16-fold reduction in soil was found, which highlighted the fact that vegetation cover (C factor) has a greater influence than other factors (R, K and LS) on soil loss prediction attenuation. These results lead to the conclusion that soil loss occurs by different methods in each settlement in the basin and that erosive processes modeled by geoprocessing have the potential to contribute to an orderly land management process.     

Estimation of Durability Aspects of Al Masjid Al-Haram Marble,Makkah City,Saudi Arabia

The durability is a measure of the rock’s ability to resist degradation during its working life. Rock durability is greatly related to the mineralogical composition of rocks, rock texture (crystal interlocking, crystal shape and size), and the nature of fluids that are in contact with rock. Marbles have been among the most important building materials since ancient times. The main aim of this study is to evaluate the durability of Al Masjid Al-Haram marble and Ordinary white marble “Carrara” (M₁ and M₂) and develop some correlations among the physical and mechanical properties such as P-wave velocity, slake durability index, dry uniaxial compressive strength (UCS_Dry), abrasion resistance, point load index, impact strength index, Brazilian tensile strength, and Shore hardness. After testing and the evaluation of the test results, strong statistical correlations were found between P-wave velocity and other rock properties. Statistical correlations between the UCS_Dry other tests were also carried out. The coefficients of regressions (R²) range from 0.6177 to 0.997. The study shows that the UCS_Dry values of M1 and M2 have positive relationship with P wave velocities. Concluding remark is that the rocks tested in the study have good durability characteristics and can be reliably used for construction projects. On the other hand, the derived empirical equations can be used for the estimation purposes for similar rock types.     

Evaluating the Performance of Using PPK-GPS Technique in Producing Topographic Contour Map

The Global Positioning System (GPS) is considered as one of the most powerful tools that are used in geodetic works. It is increasingly considered as an alternative tool for conventional surveying techniques. The goal of this research paper is to produce a methodology for generating topographic contour maps using the post-processed kinematic differential GPS technique (PPK-GPS). The performance of this technique is assessed by comparing it with the traditional spirit-leveling technique taking into consideration the accuracy, time, and cost. The study area is located along the Mediterranean coast in the Rosetta area of the middle Delta in Egypt with a total area of about 39 km². The field work includes 14 control points and about 50,000 PPK observations. In addition, 20 check cross sections that extend along the coastal line from Rosetta to El Burullus cities were observed using both spirit-leveling and GPS-PPK techniques. The results of the comparison indicate that the PPK-GPS technique can be used instead of spirit leveling in producing a topographic contour map with an accuracy of about 20 cm in orthometric height. We find that the PPK-GPS technique reduces the estimated time of leveling works in our study area by about 70%.     

Distribution,abundance and population structure of Hexaplex trunculus and Bolinus brandaris (Gastropoda: Muricidae) in offshore areas of the Gulf of Gabès,southern Tunisia

The banded murex Hexaplex trunculus and purple dye murex Bolinus brandaris are frequently caught as bycatch by bottom trawlers operating in the Gulf of Gabès, southern Tunisia. Although these muricid gastropods might importantly constitute an additional source of income for fishermen as well as help to diversify local shellfish production, information on their catches is relatively scarce. Hence, the present study aimed to assess the status of local populations of H. trunculus and B. brandaris, including data on their spatial and depth distributions, abundance, biomass, population structure and mortality. Fishing surveys using bottom trawls were performed between May 2006 and June 2007 in offshore areas of the Gulf of Gabès. In total, 198 fishing hauls were analysed, corresponding to a total fishing duration of 333.3 hours and a total prospecting area of 1 534 ha at depths of 20–86 m. Altogether, 3 026 H. trunculus and 3 599 B. brandaris of a broad size range (22.9?91.1 and 22.4?97.0 mm shell length, respectively) were sampled during the study period. GIS-produced maps were employed to determine the species’ spatial and bathymetric distributions by extrapolating their estimated fishing yield (bycatch per unit effort), abundance, biomass and mortality in relation to the total area surveyed in the gulf. The results provide valuable baseline information that may be applied to management proposals for regulating this untargeted resource, ultimately assisting sustainable exploitation and long-term preservation of this alternative fishing resource in the offshore areas of the Gulf of Gabès.     

Analogue modeling of the role of multi-level decollement layers on the geometry of orogenic wedge: an application to the Zagros Fold–Thrust Belt,SW Iran

International Journal of Earth Sciences - The presence of evaporate and incompetent formations (i.e., decollement horizons) within the sedimentary sequence of fold-thrust belts can control their...     

Landslide-hazard mapping through multi-technique activity assessment: an example from the Betic Cordillera (southern Spain)

Landslide hazard in a region limited to data from a regional scale about triggering factors is assessed via cross tabulation between determining factors and landslides with recent activity. Firstly, landslide susceptibility was evaluated and validated through a bivariate statistical method between the previously identified stability conditioning factors and the mapped landslides. In this way, the most susceptible areas for assessing landslide hazards were selected. The main problem to solve in this type of research is the landslide activity. For this purpose, several techniques were applied: news reports, differential interferometric synthetic aperture radar, digital photogrammetry, light detection and ranging, photointerpretation, and dendrochronology. Both the strong and weak points of these techniques are also mentioned. The landslide return period was computed via the association between landslide activity and triggering factors, in this case annual rainfall. Finally, landslide hazard was mapped solely based on landslides with recent activity and their computed return period. The relationship between landslide occurrence and triggering factors shows that, according to both the considered assumptions and the observations made, deep-seated landslides are triggered or reactivated together with superficial landslides once every 18 years, while superficial landslides as flows or falls occur once every 5 years. The results show that there is generally a low landslide hazard in the study zone, especially when compared to landslide susceptibility. This means that landslides are mainly dormant from a natural evolution point of view, but could be reactivated as a result of geomorphological, climate, or human changes. In any case, the landslide hazard is successfully assessed, with a prediction of a 6% annual probability of a high hazard in 5% of the area, intersecting with the main infrastructures of the region; thus, control strategies are justified in order to avoid damage in extraordinary rainfall periods.     

Application of quantitative mineralogy on the neutralization–acid potential calculations within µm-scale stratified mine tailings

Estimation of the long-term environmental impact of mining wastes is of socio-economic interest. Bulk analytical approaches of the neutralizing (NP) and acid potentials (AP) provide in general worst-case scenarios for acid rock drainage (ARD) predictions and long-term evaluation. Taking individual graded layers with variable reactive mineral ratios into consideration, alternating zones, highly contrasting in their neutralizing and acid potential, can be identified and quantified using scanning electron microscope–mineral liberation analyzer (SEM–MLA) and μ-energy-dispersive X-ray fluorescence (EDXRF)–petrographic analyst (PA) for the first time. The bulk NP and AP values increased by a factor of 2.13 and 1.37, respectively, compared to the average values of the mineralogical NP/AP. At the contrasting boundaries, precipitation of pore-clogging secondary phases might be enhanced. These new information can be used as input parameters to model the future behavior of a non-homogeneous multiplied laminated body with reactive transport modeling.     

Investigation of seawater intrusion using stable and radioisotopes at coastal area south of Beirut,the Capital of Lebanon

In this study, field measurements were made and environmental isotopes and radiological properties were determined in six selected wells located in the coastal area south of Beirut, the capital of Lebanon. It is one of the many district areas in Lebanon, threatened by the penetration of seawater into aquifers. Two sampling campaigns were carried out to determine possible seasonal variations. High electrical conductivity was observed, ranging from 1080 to 7900 μS/cm. The total dissolved solids values ranged from 530 to 5600 mg/L. This is attributed to a seawater intrusion confirmed by high chlorine concentrations that ranged from 400 to 3500 mg/L. Isotope data for δ¹⁸O/δ²H showed enrichment that is relatively small at the end of wet season due to recharge by local precipitation and infiltration. Carbon-14 ages and ²³⁴U/²³⁸U ratios confirmed the presence of young water. No radiological hazard was observed as all values lay below the guidance levels of the WHO.     

Groundwater beneath the urban area of Khan Younis City,southern Gaza Strip (Palestine): assessment for multi-domestic purposes

The present study research investigation is aimed to assess the groundwater quality for the urban area in Khan Younis City, southern Gaza Strip, for multi-domestic purposes. The physicochemical analysis of the groundwater wells shows the major ions in the order of Na⁺ > Mg²⁺ > Ca²⁺ > B³⁺ > K⁺ and Cl^? > HCO₃ ^? > SO₄ ^2? > NO₃ ^2? > F^? > PO₄ ^3?. Groundwater quality is classified as very hard-brackish water type. Ninety-five percent of the wells are classified as saline water type with high NO₃ ^2? concentrations. Based on water quality index (WQI), the groundwater falls into one of three categories: fair water (10%), poor water (15%), very poor (45%), and worst (30%). The high WQI values are because of high Na⁺, Cl^?, SO₄ ^2?, and NO₃ ^2? concentrations, while synthetic pollution index (SPI) values indicate that most about 80% of the wells are seriously polluted. Langelier Saturation Index (LSI) indicates that most of data are either slightly scale forming or corrosive water or slightly corrosive but non-scale forming, and 75% of the wells are suitable for construction purposes (have SO₄ ^2? concentrations <300 mg/L). The groundwater reaches alarming situation, where almost chemically unsuitable for drinking purposes and the water to be used after proper treatment such as desalination.     

Geochemical evaluation and environmental application of Yemeni natural zeolite as sorbent for Cd<Superscript>2+</Superscript> from solution: kinetic modeling,equilibrium studies,and statistical optimization

Yemeni natural zeolite was characterized by XRD, SEM, FTIR and XRF as well as its applicability as a sorbent material for Cd²⁺ ions in aqueous solutions. The zeolitic sample is clinoptilolite-K of heulandite group with intermediate Si/Al ratio. The removal% of Cd²⁺ by natural clinoptilolite was investigated as a function of contact time, zeolite dose, pH and initial concentration of Cd²⁺ ions. Kinetic experiments indicated that sorption of Cd²⁺ follows two steps: rapid ion exchange process on the outer surface is followed by slow adsorption process on the inner surface of clinoptilolite. The equilibrium was attained after 120 min, and the results were fitted well with pseudo-second order and Elovich kinetic models. The Cd²⁺ removal% is strongly dependent on pH value and increases with the increasing pH value. Equilibrium sorption isotherm of Cd²⁺ by clinoptilolite was described well using the Langmuir, Freundlich, and Temkin isotherms models. However, the data relatively well fitted with Freundlich model (R ² = 0.97) rather than by the other models. Response surface methodology in conjunction with central composite rotatable statistical design was used to optimize the sorption process. The model F-value indicated the high significance of second-order polynomial model to represent the interaction between the operating parameters. From the Design Expert’s optimization function, the predicted optimum conditions for maximum removal% of Cd²⁺ (80.77%) are 116 min contact time, 0.27 gm dose, and pH 7 at an initial Cd²⁺ concentration of 25 mg/L.