Modeling of groundwater flow for Mujib aquifer, Jordan

Jordan is an arid country with very limited water resources. Groundwater is the main source for its water supply. Mujib aquifer is located in the central part of Jordan and is a major source of drinking water for Amman, Madaba and Karak cities. High abstraction rates from Mujib aquifer during the previous years lead to a major decline in water levels and deterioration in groundwater quality. Therefore, proper groundwater management of Mujib aquifer is necessary; and groundwater flow modeling is essential for proper management. For this purpose, Modflow was used to build a groundwater flow model to simulate the behavior of the flow system under different stresses. The model was calibrated for steady state condition by matching observed and simulated initial head counter lines. Drawdown data for the period 1985–1995 were used to calibrate the transient model by matching simulated drawdown with the observed one. Then, the transient model was validated by using drawdown data for the period 1996–2002. The results of the calibrated model showed that the horizontal hydraulic conductivity of the B2/A7 aquifer ranges between 0.001 and 40m/d. Calibrated specific yield ranges from 0.0001 to 0.15. The water balance for the steady state condition of Mujib aquifer indicated that the total annual direct recharge is 20.4 × 10⁶m³, the total annual inflow is 13.0 × 10⁶ m³, springs discharge is 15.3 × 10⁶ m³, and total annual outflow is 18.7 × 10⁶ m³. Different scenarios were considered to predict aquifer system response under different conditions. The results of the sensitivity analysis show that the model is highly sensitive to horizontal hydraulic conductivity and anisotropy and with lower level to the recharge rates. Also the model is sensitive to specific yield     

Simultaneous determination of aquifer parameters and zone structures with fuzzy c-means clustering and meta-heuristic harmony search algorithm

This study proposes an inverse solution algorithm through which both the aquifer parameters and the zone structure of these parameters can be determined based on a given set of observations on piezometric heads. In the zone structure identification problem fuzzy c-means (FCM) clustering method is used. The association of the zone structure with the transmissivity distribution is accomplished through an optimization model. The meta-heuristic harmony search (HS) algorithm, which is conceptualized using the musical process of searching for a perfect state of harmony, is used as an optimization technique. The optimum parameter zone structure is identified based on three criteria which are the residual error, parameter uncertainty, and structure discrimination. A numerical example given in the literature is solved to demonstrate the performance of the proposed algorithm. Also, a sensitivity analysis is performed to test the performance of the HS algorithm for different sets of solution parameters. Results indicate that the proposed solution algorithm is an effective way in the simultaneous identification of aquifer parameters and their corresponding zone structures.     

The Geomorphologic Responses to Active Fault Propagation Fold in the Western Algerian Tell Chain: A Case Study from the Southern Part of Beni-Chougrane Mountains

Geotectonics - Located in the western part of the Tell Chain of Algeria, the Beni-Chougrane Mountains are characterized by recent tectonic activity in a compressive regime affecting the entire...     

Application of Harmony Search algorithm to the solution of groundwater management models

This study proposes a groundwater resources management model in which the solution is performed through a combined simulation-optimization model. A modular three-dimensional finite difference groundwater flow model, MODFLOW is used as the simulation model. This model is then combined with a Harmony Search (HS) optimization algorithm which is based on the musical process of searching for a perfect state of harmony. The performance of the proposed HS based management model is tested on three separate groundwater management problems: (i) maximization of total pumping from an aquifer (steady-state); (ii) minimization of the total pumping cost to satisfy the given demand (steady-state); and (iii) minimization of the pumping cost to satisfy the given demand for multiple management periods (transient). The sensitivity of HS algorithm is evaluated by performing a sensitivity analysis which aims to determine the impact of related solution parameters on convergence behavior. The results show that HS yields nearly same or better solutions than the previous solution methods and may be used to solve management problems in groundwater modeling.     

The variability of foF2 in different phases of solar cycle 23

In this paper we examined the variations of the foF2 with solar activity for different local time and different seasons. Beside this we evaluated International Reference Ionosphere (IRI) models at different phases of solar cycle 23, different latitudes and different local time. We studied F2 layer critical frequency (foF2) of the ionosphere by using the flare index calculated by the Kandilli Observatory. For this purpose, we identified the months similar with high flare activity during the solar cycle 23. We chose 6 months which represented the different phases (ascending branch, maximum and descending branch) of the solar cycle. We also took into account the fact that these months were in different seasons. The hourly monthly means of observed foF2 data from four ionosonde stations for 6 months were calculated. On the other hand, the identical foF2 values of the same months were calculated for the year 1996, which is the minimum year of the previous solar activity cycle. We subtracted the foF2 values of 1996 from the values of the selected months of the last solar cycle to obtain the residuals, Δ(foF2). Then the magnitude of the residuals is compared through the cycle. We used IRI-2007 as well as IRI-2001 models to see the degree of deviation of the observed results from the predicted ones. We found that the predicted values of the ΔfoF2, which are calculated by the IRI-2007, fitted well with the observed Δ(foF2) and showed that the Δ(foF2) are dependent on the solar cycle variations in general.     

Deterioration mechanisms of tuffs in Midas monument

Slightly weathered white and pink tuffs of the Midas monument have deterioration problems. In this study, depths and characteristics of the weathering zones developed within the tuffs are investigated through optical microscopy, X-ray diffractometry (XRD), chemical analyses, scanning electron microscopy (SEM) and some index parameters. Accelerated weathering tests including wetting–drying, freezing–thawing and salt crystallization are performed, and durability assessment methods are used to predict the durabilities of the tuffs. The findings are compared with field observations. By examining quantitative weathering indices and comparing them with thin section studies, it is found that thin section analyses of the crystals, LoI, and WPI are good indicators to quantify the depth of weathering for the tuffs. However, thin section studies have limited value for fine-grained tuffaceous matrix. The chemical weathering of the tuffs produces weathered zones that are 4.5-cm thick within the white tuff and 2.5-cm thick within the pink tuff. Physical weathering causes scaling of outer layers of the tuffs and fracturing of feldspars along their cleavage planes. However, variations of the index properties of the tuffs due to weathering are not so significant to quantify the weathering depths in the tuffs. Among the accelerated weathering tests, salt crystallization is found to be the most destructive environmental condition. Pigeon droppings rich in NO₃¹⁻ are found to be the main source of soluble salt at the Midas monument. The salt transported up by capillary rise due to surface water causes spalling of the tuffs in the capillary zone. Surface water and salt of any kind in the close vicinity of the monument should be totally eliminated for the purpose of conservation. Field observations and the durability equations reveal that the white tuff is less durable than the pink tuff. Wet-to-dry strength ratio yields a better stone durability assessment among various durability methods used in this study.     

Performances of Reverse Osmosis Membranes for Treatment of Olive Mill Wastewater

In the following study, two methods were employed in which olive mill wastewaters were treated by using reverse osmosis membranes (BW30 and XLE). In the first, wastewater was centrifuged and then passed through the reverse osmosis whereas in the second, an ultrafiltration was placed between the centrifuge and the reverse osmosis. The reverse osmosis experiments were conducted under 10, 15, 20, and 25 bar. The chemical oxygen demand (COD) removal efficiencies under 25 bar were found to be 97.5% for both BW30 and XLE membranes. The highest conductivity removal rates obtained under 25 bar for BW30 and XLE membranes were found to be 95.6 and 96.2%, respectively. As for the highest permeation flux values obtained under 25 bar, they were separately determined for BW30 and XLE as 15.3 and 21.2 L m^?2 h^?1, respectively. The performances of the membranes were also evaluated in terms of their mass transfer coefficients. According to this, all mass transfer coefficients were found to be <1 and also in proximate to one another; this clearly reflects the results as COD and conductivity removals were approximate and there was a lack of any significant difference, whether ultrafiltration was applied or not.     

Unsaturated characteristics of undisturbed expansive shale from Saudi Arabia

The aim of this paper is to evaluate the soil water characteristic curves (SWCC) of undisturbed expansive shale identified at different locations of Kingdom of Saudi Arabia. The SWCCs were evaluated for suction ranging from 0.5 to 400 MPa. Based on test results, all SWCCs reveal a bimodal curve indicating the presence of two distinct pore size distributions referred to as small and large micropores. Volume change measurements were performed to evaluate void ratio–suction relationships which confirmed the expansive nature of shale. Similarities between measured SWCCs and void ratio–suction relations developed for expansive shale originating from same geological formation suggests the impact of geological and environmental conditions on the unsaturated behavior of shale samples. Finally, a modified approach based on Mckeen’s classification methodology was proposed to assess the swelling potential using bimodal SWCCs. The modified approach was used to assess the relative contribution of different micropores on the swelling potential of shale.     

A new approximation in determination of zonation boundaries of ignimbrite by ground penetrating radar: Kayseri,Central Anatolia,Turkey

Ground penetrating radar (GPR) method is used as a tool to identify the zonation boundaries in ignimbrite series through their columnar section. Ignimbrites can be classified in terms of welding degree, colour, texture and mineralogical compositions. The research area comprises a part of İncesu (Kayseri) ignimbrite at Central Anatolia, Turkey. This ignimbrite is divided into three levels and each level has clear differences in terms of macroscopic and microscopic views. This paper presents the results of an application of GPR for the determination of zonation boundary within the ignimbrite flow unit in the view of their textural and petrological features. RAMAC CU II equipment was used with 250 MHz shielded antenna on parallel ten profiles to observe the physical difference among the ignimbrite levels of the study area. Two levels out of three have been defined at the İncesu ignimbrite and supported by field geology and petrographical studies. The first level, which is extremely fractured structure, is about 1.5 m thick and matches with middle level of the İncesu ignimbrite. The second level has an average 50–75 cm thickness and matches with lower level of the ignimbrite. In this manner, vertical lithological variations should be taken into consideration during petrological investigation of the ignimbrites.