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)

Abstract Laboratory experiment are conducted in the summer years (2010) to study the impact of adding a source of organic carbon (sawdust) on inorganic nitrogen in the soil Mixing (500 grams) soil texture sandy silt with rates by addition of compost poultry rates (0 - 15-30-60 ton/ ha), as well as the rates of carbon source sawdust (0.5-1%), where then mixed well with each other in order to become homogeneous, and placed in the pot and repeated three times each addition , just as the number of experimental units each experiment (180 experimental units), and incubated at room temperature while maintaining the moisture at field capacity gravimetric way through the different incubation periods, which is set in weeks (0-2-4-8-16 week) by using statistical decomposition split plot twice ( split-split-plot design) and determing the differences moral between averages using Duncan to isolate averages at the level of moral (5%) and analyze the results using a table (ANOVA), and then estimate the degree of interaction of soil (pH) and organic matter and nitrogen mineral and total ratio of carbon to nitrogen (C/N Ratio) during different incubation periods, The results showed fluctuations in the degree of interaction through different incubation periods were (pH) the highest value for (8.4pH) at the time of incubation (4-8 weeks) and the lowest value (7.8pH) at the time of incubation (16 weeks), the organic matter Tests showed an increase in organic matter with increased rates of adding compost and sawdust at the beginning of the period of incubation and decreases organic matter gradually with increasing duration of incubation (16 weeks) As a result of decomposition of organic matter by micro-organisms, while nitrogen mineral available results show an increased nitrogen available at the beginning of the period of incubation with increased rates of added fertilizer and organic sawdust With increasing time incubation fluctuation in the amount of nitrogen available Result of the succession of microbial occur collections and increasing the proportion of (C/N),The Results show in the amount of total nitrogen per transaction At the beginning of the period of incubation and after two weeks of incubation Results show increasing the amount of total nitrogen at a rate (60 ton / ha) and over a period of incubation at (16 weeks) results showed a decrease in the value of total nitrogen when treatment (60 ton / ha) and average (0.5%) sawdust, either carbon to nitrogen (C/N Ratio) Tests showed that the high proportion of carbon to nitrogen, with the rate Add compost and the proportion of sawdust at the beginning of the period of incubation with the passage of time and increase the period of incubation results show low (C/N Ratio) for each transaction with time as a result of mineral nitrogen liberate when the incubation period (4 weeks) and an increase of the period of incubation results show an increase ratio (C/N Ratio) for each transaction.
محمد الطاهر الفيتوري سالم (2013)

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)