Thesis (M.Sc.) - Cairo University - Faculty of Engineering - Department of Civil Engineering

The agricultural subsurface drainage system is used all over the Nile Delta of Egypt to drain excess water from the soil to enhance crop production and to ensure irrigated agriculture sustainability. The design spacing between lateral drains is playing an important role in determining the efficiency of the subsurface drainage. The main input for the design is the value of the saturated hydraulic conductivity of the soil. Currently, the design practice involves using a grid of 500mX500m in field investigations to measure the hydraulic conductivity at each point of the grid using the auger-hole method. The main objective of this study is to determine the optimal sampling density to be used in the design. Using geostatistical analysis (Kriging) and a data base of over 6000 hydraulic conductivity tests from different projects in the Nile Delta of Egypt, the optimal sampling density was obtained and correlated with the soil clay content using empirical equations. Also, a new design procedure based on Kriging was developed to enhance the future design of the subsurface drainage system. Using the available data base, a contour map of the hydraulic conductivity in the Nile Delta was developed to help the decision makers in taking critical decisions such as preliminary cost estimate for the subsurface drainage project even before conducting a detailed field investigation

Issued also as CD