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.

     

Utilization of low quality water of mountain reservoirs: a case study from Al Jabal Al Akhdar,Oman

Al Jabal al Akhdar (Green Mountain) in arid northern Oman has freshwater resources that had supported small communities for hundreds of years. Jabal Akhdar receives more rainfall (300-400 mm) when compared to the desert plains. In the last few years, this region had undergone enormous changes due to rapid development. The resident and transient populations have increased and their activities exert severe stress on the water resources. There are 24 retention reservoirs in the area, but most are eutrophic and the nutrient loading is due to input of animal fecal matter via surface run-off. As expected, these waters contaminated with coliform bacteria and some have pathogenic Escherichia coli. Drinking water needs of all the villages met by groundwater extraction. Because of poor quality, the surface water in the reservoirs is under-utilized. A low-cost low-maintenance treatment system designed, constructed and operated in one village to clean the reservoir water for non-drinking human use. The treatment unit improved the water quality parameters. A survey among the adult male population of the village showed their eagerness to adopt this system and use the treated reservoir water for uses other than agriculture. Establishment of these treatment units in other villages should reduce the pressures on groundwater extraction.     

Investigation of recharge dynamics and flow paths in a fractured crystalline aquifer in semi-arid India using borehole logs: implications for managed aquifer recharge

The recharge flow paths in a typical weathered hard-rock aquifer in a semi-arid area of southern India were investigated in relation to structures associated with a managed aquifer recharge (MAR) scheme. Despite the large number of MAR structures, the mechanisms of recharge in their vicinity are still unclear. The study uses a percolation tank as a tool to identify the input signal of the recharge and uses multiple measurements (piezometric time series, electrical conductivity profiles in boreholes) compared against heat-pulse flowmeter measurements and geochemical data (major ions and stable isotopes) to examine recharge flow paths. The recharge process is a combination of diffuse piston flow and preferential flow paths. Direct vertical percolation appears to be very limited, in contradiction to the conceptual model generally admitted where vertical flow through saprolite is considered as the main recharge process. The horizontal component of the flow leads to a strong geochemical stratification of the water column. The complex recharge pattern, presented in a conceptual model, leads to varied impacts on groundwater quality and availability in both time and space, inducing strong implications for water management, water quality evolution, MAR monitoring and longer-term socio-economic costs.     

Natural and human-induced sinkhole hazards in Saudi Arabia: distribution,investigation, causes and impacts

Approximately 60 % of the 2,150,000 km² area of Saudi Arabia is underlain by soluble sediments (carbonate and evaporite rock formations, salt diapirs, sabkha deposits). Despite its hyper-arid climate, a wide variety of recent sinkholes have been reported in numerous areas, involving significant property losses. Human activities, most notably groundwater extraction, have induced unstable conditions on pre-existing cavities. This work provides an overview of the sinkhole hazard in Saudi Arabia, a scarcely explored topic. It identifies the main karst formations and the distribution of the most problematic sinkhole areas, illustrated through several case studies covering the wide spectrum of subsidence mechanisms. Some of the main investigation methods are presented through selected examples, including remote sensing, trenching and geophysics. Based on the available data, the main causal factors are identified and further actions that should be undertaken to better assess and manage the risk are discussed.     

Investigation on the effective remediation of quinoline at solid/solution interface using modified agricultural waste: an inclusive study

This research work explores the potential of modified agricultural waste for the sorption of quinoline from aqueous media. A quinoline removal efficiency of around 97 % and sorption capacities of ~20 (batch) and ~35 mg g^?1 (fixed-bed) were achieved. Pseudo-second-order kinetics and Temkin isotherm best represented the equilibrium sorption data. The sorption of quinoline is exothermic and spontaneous in nature with a slight increase in the system entropy. The quinoline sorption mechanism is controlled by H-bonding, π–π dispersive interactions, boundary layer, and intraparticle diffusion. Microwave–chemical integrated regeneration technique retrieves the sorption capacity of the exhausted sorbent with 99.15, 97.64, and 95.55 % of the original, in three sorption–regeneration cycles. Energy recovery (19.365 MJ kg^?1) from the quinoline-loaded sorbent and the potential utilization of left-over ash materials enhanced the prospective of the sorbent for the remediation of pollutants for a clean and green environment.     

The vein-type barite mineralization of the Draïssa ore field,Ougarta; SW- Algeria: mineralogy,trace elements and halogens

The Draïssa barite vein system in the Ougarta district is located in southwestern Algeria. It is the principal mineral deposit of economic interest of the area. The mineralization is hosted by Cambrian sedimentary rocks that unconformably overlie Precambrian formations. The mineralized structures consist mostly of barite and quartz with minor sulfide minerals and trend dominantly NE-SW, NW-SE, and E-W. Siliceous alteration zones are associated with the vein system. Samples of barite ore are characterized by low total REE contents ranging from 9 to 50 ppm and positive Eu (2–2.15 ppm) and Y (1.2–11.1 ppm) anomalies, indicating hydrothermal activity during mineralization. Halogen data of the barite show that the Cl/Br molar ratio is 189:571 and the Na/Br ratio is 34:376, indicating that the sulfur was derived from seawater. The Ba-enrichment trend in the volcanic rocks of Draïssa is interpreted as possible probable source of the Ba (424–3039 ppm Ba). It appears that the barite-quartz deposits were formed in two stages. Endogenous fluids deposited the primary vein materials, consisting of quartz associated with copper sulfides. Exogenous fluids (cold seawater) became heated during ascendant fluid movement. Mineralization was governed by convective motions and the barite and galena fillings were deposited in openings created by normal faulting.     

Probabilistic tsunami hazard assessment along Oman coast from submarine earthquakes in the Makran subduction zone

The Sultanate of Oman is among the Indian Ocean countries that were subjected to at least two confirmed tsunamis during the twentieth and twenty-first centuries: the 1945 tsunami due to an earthquake in the Makran subduction zone in the Sea of Oman (near-regional field tsunami) and the Indian Ocean tsunami in 2004, caused by an earthquake from the Andaman Sumatra subduction zone (far - field tsunami). In this paper, we present a probabilistic tsunami hazard assessment for the entire coast of Oman from tectonic sources generated along the Makran subduction zone. The tsunami hazard is assessed taking into account the contribution of small- and large-event magnitudes. Results of the earthquake recurrence rate studies and the tsunami numerical modeling for different magnitudes were used through a logic-tree to estimate the tsunami hazard probabilities. We derive probability hazard exceedance maps for the Omani coast considering the exposure times of 100, 250, 500, and 1000 years. The hazard maps consist of computing the likelihood that tsunami waves exceed a specific amplitude. We find that the probability that a maximum wave amplitude exceeds 1 m somewhere along the coast of Oman reaches, respectively, 0.7 and 0.85 for 100 and 250 exposure times, and it is up to 1 for 500 and 1000 years of exposure times. These probability values decrease significantly toward the southern coast of Oman where the tsunami impact, from the earthquakes generated at Makran subduction zone, is low.     

Performance evaluation of artificial neural networks for planimetric coordinate transformation—a case study,Ghana

Two national horizontal geodetic datums, namely, the Accra and Leigon datum, have been the only available datum used in Ghana. These two datums are non-geocentric and were established based on astro-geodetic observations. Relating these different geodetic datums mostly involves the use of conformal transformation techniques which could produce results that are not very often satisfactory for certain geodetic, surveying and mapping purposes. This has been ascribed to the incapability of the conformal models to absorb more of the heterogeneous and local character of deformations existing within the local geodetic networks. Presently, application of new approaches such as artificial neural network (ANN) is highly recommended. Whereas the ANN has been gaining much popularity to solving coordinate transformation-related problems in recent times, the existing researches carried out in Ghana have shown that only three-dimensional conformal transformation methods have been utilized. To the best of our knowledge, plane coordinate transformation between the two local geodetic datums in Ghana has not been investigated. In this paper, an attempt has been made to explore the plane coordinate transformation performance of two different ANN approaches (backpropagation neural network (BPNN) and radial basis function neural network (RBFNN)) compared with two different traditional techniques (six- and four-parameter models) in the Ghana national geodetic reference network. The results revealed that transforming plane coordinates from Leigon to Accra datum, the RBFNN was better than the BPNN and traditional techniques. Transforming from Accra to Leigon datum, both the BPNN and RBFNN produced closely related results and were better than the traditional methods. Therefore, this study will create the opportunity for Ghana to recognize the significance and strength of the ANN technology in solving coordinate transformation problems.