Multilayer Artificial Neural Networks (ANNs) with the backpropagation algorithm were used to estimate the decrease in relative saturated conductivity due to an increase in sodicity and salinity. Data from the literature on the relative saturated hydraulic conductivity measured using water having levels of sodicity and salinity in different types of semiarid soils were used. The clay content of these soils is predominantly montmorillonite. The input data consisted of clay percentage, cation exchange capacity, electrolyte concentration, and estimated soil exchangeable sodium percentage at equilibrium stage with the solution applied. The data was divided into three groups randomly to meet the three phases required for developing the ANNs model (i. e. training, evaluation, and testing).The activation function selected was the TANSIG layer in the middle, while the exit function was the PURELIN layer. The comparisons between the experimental and predicted data on relative saturated hydraulic conductivity during training and testing phases showed good agreement. This was evident from the statistical indicators used for the evaluation process. For the training phase, the values of mean absolute error (MAE), root mean square error (RMSE), the correlation coefficient (r) and the determination coefficient (R2) were 0.08, 0.13, 0.91, and 0.83, respectively. The performance of the ANNs model was evaluated against a part of the data selected randomly form the whole set of data collected (i. e. data not used during the model testing phase). The resultant values for MAE and RMSE, r and R2 were 0.12, 0.16, 0.82 and 0.68, respectively. It should be noted that many factors were not considered, such as soil pH, type of clay, and organic matter, due to the limitations of the data available. Using these factors as input in ANNs might improve model predictions. However, the results suggested that the ANNs model performs well in soils with very low levels of organic matter.
Younes Daw Ezlit, Ahmed Ibrahim Ekhmaj, Mukhtar Mahmud Elaalem(5-2014)

أجريت هذه الدراسة على حوض وادي كعام من واقع ما توافر من بيانات ومعلومات للفترة 1980 -2004، وذلك لتقييم عملية حصاد مياه الأمطار من خلال دراسة بعض المعاملات الهيدرولوجية والتي من أهمها الهطول والجريان السطحي وكذلك البخر. ومن خلال تحليل البيانات وجد أن عمق الهطول المحسوب بطريقة ثيسن 200.6 ملم أما عن طريق خطوط تساوي المطر 202.4 ملم، معدل حجم الجريان السطحي الذي إنساب للبحيرة 17.3 مليون م3، وأن معامل الجريان السطحي للمنطقة الذي تم حسابه من النسبة بين حجم ما يصل لبحيرة السد من مياه الأمطار إلى الحجم الكلي للهطول 3.2 % ، ولدراسة البخر في المنطقة تم استخدام برنامج كروبوات الذي أساسه معادلة بنمان – مونثيت ومدخلاته بعض المعلومات المناخية المتمثلة في الرطوبة النسبية ، متوسط درجات الحرارة الشهرية العظمى ، متوسط درجات الحرارة الشهرية الصغرى ، سرعة الرياح ووجد أن المعدل العام لعمق البخر طوال فترة الدراسة 1532.9ملم ، أما معدل حجم البخر الكلي من سطح البحيرة كان 4668014.2 م3 ، تم حساب المعدل العام للرشح من خلال الموازنة المائية لبحيرة التخزين طوال فترة الدراسة كان 4.2 مليون م3 وهي تعبر عن معدلات التغذية للخزان الجوفي ، تم حساب معدل الإطماء بأخذ النسبة بين حجم الرواسب وحجم المياه المتدفقة لبحيرة التخزين ، معدل الإطماء في بحيرة تخزين المياه يبلغ حوالي 8.2 x 410 م3 / سنة ، تعتبر هذه القيمة مؤثرة جداً على عمر السد لو إستمرت بمعدلاتها الحالية . أوصت الدراسة بضرورة إستخدام ما يتم حصاده من مياه الأمطار في أغراض التنمية الزراعية بالمنطقة ودراسة إجراء عمليات تغذية الخزان الجوفي عن طريق حفر آبار لحقن المياه للخزان الجوفي مباشرة أو للإستمرار في عمليات ضخ المياه للمزارع ولو بدون أي مقابل تلافياً لإرتفاع فقد تلك المياه بالبخر، كما أوصت الدراسة بضرورة إتباع أساليب مقاومة التعرية والإنجراف خصوصاً على مجاري الأودية. Abstract This study is conducted in Wadi Caam dam area, that located around 130 Km east of Tripoli city. The dam is an earth fill dam with catchment area around 2312 km2. The purpose of the dam is to supply water for agriculture downstream of the dam and recharging the groundwater aquifer in the area. The main goal of this study is to investigate the impacts of dam construction on some hydrological parameters due to changes in human activities because of the dam construction. The second goal is to estimate the groundwater recharge from the lake of the dam based on the hydrologic cycle concept. The climatic data used in this study covers 20 years of time period (1979 – 2005) and include temperature, humidity, wind speed, and rainfall. These data are collected for different climatic stations inside and near the catchment area.Based on the climatic data and other related information, the hydrologic parameters are determined. The average annual rainfall depth in the area is determined based on Theissen polygon and isohyets methods. The average annual depth is 200.6 mm for Theissen and 202.4 mm for isohyets. These values considered high Compared with hydroproject value which is 181 mm. According to stream flow measurements, the average annual runoff volume during the period of study is 17.3 x106 m3. This value is closed to hydroproject value that is 19.6 X106 m3 .According to the relation between rainfall and runoff, the average runoff coefficient during the period of study is found to be 3.2 %. This value is considered low compared with hydroproject value that is about 5.5%. The modified penman-monteith formula is used to determine the average annual evaporation applying the software (cowpat). The estimated annual evaporation is 1532.9 mm which is very closed with Hadroprogect, which is 1500 mm. According tow this evaporation rate, the average annual evaporation from the dam lake is 4.7 x106 m3.Water budget method is applied to determine the annual Infiltration through the lake which is found to be about 5.1 x106 m3. This value is highly different from hydroproject value witch is 10X106 m3.The annual sedimentation in Dame Lake is calculated from the annual changes in dead storage level. The annual sedimentation rate per cubic meter of incoming flow during the period of study is about 4.66x10-3 m3
عبد المعطي عياد محمد زريبة (2010)

Emitter spacing and emitter flow rates should be matched with the soil’s wetting characteristics to achieve precision and high irrigation efficiency. A method for determining surface wetted radius and depth of the wetted soil volume under drip irrigation was developed. The wetted soil volume was assumed to depend on the depth of saturated hydraulic conductivity, volume of water applied, average change of moisture content and the emitter application rate. Empirical equations relating the wetted depth and width to the other parameters were obtained. Many experiments were used to verify these equations. Very good agreement between the theoretical and experimental results improves the validity of these equations. The results show that the suggested equations can be used for a wider range of discharge rates and other soil types. DIPAC will ensure that water and fertilizer reach the crop root zone precisely and efficiently. Keywords: trickle irrigation, wetting front, surface wetted radius, emitter spacing
Ahmed Ibrahim Ekhmaj, MOHAMAD S. M.AMIN(9-2006)