في هذه الدراسة تم تجميع 53 عينة مياه آبار جوفية , من مناطق مختلفة من شمال غرب الجماهيرية , تم فيها قياس درجة التفاعل والتوصيل الكهربي والكاتيونات والأنيونات الذائبة .ومن تم حساب بعض المؤشرات المستعملة في تحديد مدى تسبب هذه المياه لحدوث الترسبات القشرية أو التآكل في المنظومات المائية وتحديداً pH ,IL , IR ، كما تم وضع نموذج حسابي يعتمد على تفاعلات التوازن الكيميائي , وذلك لحساب مدى تشبع المياه بالجير ومقارنة النتائج بالمؤشرات السابقة تشير النتائج المتحصل عليها أنه حوالي 98 % , 100% , 84.9 % , 84.9% من العينات المائية وقعت في المدى الذي يشير إلى أن هذه المياه قد ينتج عنها حدوث ترسبات قشرية التي قد تحمي المعدن من التآكل وذلك باستعمال كل من pH , IL , IR والنموذج الحسابي المقترح للجير على التوالي . كما تشير النتائج أن حوالي 2% , 15% , من العينات المائية وقعت في المدى غير المؤكد لحدوث ترسبات قشرية أو تآكل عند استعمال مؤشرpH , IR , وحوالي 15% منها وقعت في المدى الذي يؤكد على عدم حدوث ترسيب باستعمال النموذج الحسابي المقترح للجير وبالتالي ممكن أن تتسبب هذه العينات في حدوث تآكل، وأن 100 % من العينات وقعت في المدى الذي يدل على عدم ترسب الجبس وعند حساب مكونات التركيزات الكلية الذائبة في التركيب الكيميائي لهذه المياه وجد أن متوسط مساهمة كل من Ca+2 , +2 Mg ، Na+ ،+ K الحرة كانت %83.9 ، 85 %، 98 %، 98.7% على التوالي والباقي يتمثل في مساهمة الأيونات المعقدة والمزدوجة من هذا التركيب في حين تمثل نسبة مساهمة كل من HCO3- ، SO4-2 الحرة 95.7 % ، 80 % على التوالي وباقي النسبة تمثل الأيونات المعقدة والمزدوجة في حين كانت مساهمة CO3-2 الحرة وMgCO30 في التركيز الكلي للكربونات الذائبة هي 38 % ، 37 % على التوالي والباقي تمثل الأيونات المعقدة والمزدوجة الأخرى. Abstract In this study 53 well water samples were collected from the north western areas of Libya. Measurements of pH, EC, soluble cations and anion were conducted .Corrosion and encrustations indices namely Langelier (IL) and Ryzner (IR) were calculated. A mathematical model was also developed to calculate undersaturation and oversaturation of water samples with respect to calcite and gypsum and also to calculate the percentage contribution of different ionic species and ion pairs to the total soluble constituents of Ca, Mg Ca, Mg, Na, K, CO3, HCO3, and SO4. The results obtained from this study indicate that 98%, 100%, 84.9% and 84.9% of the samples were in the range where encrustation could occur and no,respecti- corrosion using pH, IL, IR, and the developed mathematical model vely. The rest of the samples have fallen in the range of uncertain corrosion and encrustation occurrence. The data obtained from the mathematical model revealed that, on the average, 84% , 85% , 98% and 99% was the contribution of free Ca+2, Mg+2, Na+2 and K+ to the total soluble of these constituents in the water samples, respectively. The contribution of the free HCO3-, and SO4-2 were about 95% and 80%, respectively. The rest was ion pairs and complexes of these ions.
مها محمود عمران بالحاج (2010)

Sodicity and salinity can adversely affect soil structure and are common constraints to plant growth in arid regions. Current remote sensing techniques cannot distinguish between the various classes of salt-affected soils. Field and laboratory measurements of salt-affected soils are time-consuming and expensive. Mapping of the salt-affected soils can be used in soil conservation planning to identify regions with different degrees of limitations. There is a need to use existing field and laboratory measurements to create maps of classes of salt-affected soils. The objectives of this study are to classify salt-affected soils, use existing field data to interpolate and validate geospatial predictions of the classes of salt-affected soils using Geographic Information Systems (GIS), and create maps showing the different classes and distribution of salt-affected soils. The classification framework for salt-affected soils is based on electrical conductivity (ECe), soil pH and the sodium adsorption ratio (SAR), and provides four degrees of limitations to salt-affected soils: slight (normal soils), moderate (saline soils), severe (sodic soils), and extreme (saline-sodic soils). Spatial interpolation of the field data from northwestern Libya was verified by cross-validation, and maps of the salt-affected soils in the region were created. The majority of soils in this region of Libya are normal (slight degree of limitation). Twenty percent of the topsoil is saline-sodic (extreme degree of limitation). Land use recommendations and rehabilitation strategies can be developed from such maps of salt-affected soil classes. The methodology followed in this study can be applied to other arid regions around the world, particularly in developing countries where budgetary constraints limit detailed field and laboratory measurements of sodicity and salinity. arabic 11 English 70
Hamdi Zurqani, Elena Mikhailova, Christopher Post, Mark Schlautman, Julia Sharp(2-2018)

Summary: One of the main characteristics of trickle irrigation system is that water leaving an emitter enters the soil and moves both laterally and vertically. There has been much speculation on the shape and moisture distribution within the wetted soil volume. This knowledge is important in the design, operation and management of a trickle irrigation system. A simulation study of soil water distribution under a prairie field in Tripoli Libya, by the use of the two dimensional model Hydrus 2D model was carried out. Sandy soil was irrigated using surface point source with application rates of 1.5, 2, 2.7, 3, 3.5, 4.5, 4.8 and 6 l/h. The surface wetted radius, vertical advance of wetting front and the distribution of moisture content in the soil profile were determined. Three statistical criteria were used to compare the quality of simulation results, such as mean bias error (MBE), root mean square error (RMSE) and Theil’s Inequality coefficient (U). Simulation positions of the wetting front were in agreement relative to the observed measurements of the wetting front. Specifically, in the lateral, the experimentally determined wetting front was closely estimated by the model. In the downward direction the simulated wetting front advanced much slower than the observed especially at later stage of infiltration. Considering the difficulties in estimating the dynamic water conditions in the field there was generally good agreement (especially in the lateral direction) between the measured and simulated values. In the deeper downward direction the simulated moisture content distributions were less than the measured. On the other hand, the Hydrus_2D model described the water content distribution quite well at relatively high levels of moisture contents; however, it did not do as well at lower moisture content. The discrepancies between the simulated and measured values may be due to variation in the size of the surface source of water during infiltration and to the natural variation of soil properties. However, due to the complex mechanisms of water movement under the complicated boundary and initial conditions from a surface point source the results support the use of Hydrus 2D as a tool for investigating and designing point source trickle irrigation system. Keywords: Trickle irrigation, wetting front, soil moisture distribution, Hydrus _2D model
Ahmed Ibrahim Ekhmaj, M.S.M. Amin, Abdul Hakim Almdny, W. Aimrun, .M. Abdulaziz, (1-2006)