Document Details Document Type : Article In Journal  Document Title : Estimation of Direct Evaporation Rate from Surface Soil of Namman Basin تقدير معدلات التبخر المباشر من التربة السطحية بوادي النعمان   Subject : Civil Engineering  Document Language : Arabic  Abstract : A drainage lysimeter was utilized to estimate direct evaporation from surface soil of Namman basin located south east of the Holly city of Makkah. A sandy soil from the site of the experiment was used in the lysimeter and the experiment consisted of three consecutive stages. In each stage of the experiment, different water depths were supplied to the soil in the lysimeter. Water content of soil layers and drainage discharge from the lysimeter were measured in daily bases for continuous 26 days. The equation of water balance was applied to compute the evaporation rate from soil surface. The study results indicated that evaporation rate was high during the first few days immediately after supplying the soil with water. The evaporation rate then rapidly decreased until it became negligible at the eighth day of each stage. Mean daily evaporation depth from the soil was estimated to be about 0.5 cm/day. Although the values of daily evaporation were different among the three stages of the experiment, they all have similar temporal trend and it was possible to find one regression equation to represent them. The equation has only two variables which are time and depth of water supplied to the soil. Most of water evaporated when soil was supplied by 5 cm of water while less than one third of water evaporated when the depth of supplied water increased to 15 cm. The current experiment simulates the direct evaporation from one meter depth of sandy soil during winter season. It is recommended to conduct at least three similar experiments during the other three seasons of the year and using different soil type from the study region.  ISSN : 1319-1047  Journal Name : Engineering Sciences Journal  Volume : 20  Issue Number : 1  Publishing Year : 1430 AH 2009 AD  Article Type : Article  Added Date : Wednesday, November 4, 2009  Researchers Researcher Name (Arabic) Researcher Name (English) Researcher Type Dr Grade Email عبدالله سعد الوقداني Al-Wagdany, Abdullah Saad Investigator Doctorate awagdani@kau.edu.sa Files File Name Type Description  24348.pdf pdf Estimation of Direct Evaporation Rate from Surface Soil of Namman Basin Back To Researches Page