Management strategies for controlling the shallow watertable aquifer

• Main Author: Manghi, Fakhri
• Format: Dissertation
• Language: Arabic
• Published: ProQuest Dissertations & Theses 01.01.1994
• Subjects: Civil engineering; Hydrologic sciences; Hydrology; Mechanical engineering
• ISBN: 9798207877907

Agricultural land in the world suffers from waterlogging and salinity problems. Managing the shallow watertable is being necessary to reduce the serious damage to the land production. Managing a shallow watertable is handled either by using the horizontal drainage, or by using the watertable aquifer as a source to supply plant requirements and reducing the watertable level, and/or integrated water management by involving both irrigation scheduling and horizontal drainage. A comprehensive study of different combination of management strategies that reduce the shallow watertable level for different multiaquifer systems is investigated in this dissertation by developed a subsurface quasi-three-dimensional finite-element numerical flow model. The numerical model is capable of simulating two different multiaquifer systems. For the Multilayer System Type One, the numerical model consists of: (1) one-dimensional vertical unsaturated through the vadose zone, (2) two-dimensional (X,Y space) for each aquifer, and (3) one-dimensional vertical flow through the aquitard between these aquifers. For the Multilayer System Two, the numerical models consists of: (1) one-dimensional vertical unsaturated-saturated flow, and (2) a two-dimensional (X,Y space) for confined aquifer. The management strategies used in this study for both multilayer systems are vertical and horizontal drainage, as well as irrigation scheduling. Irrigation scheduling involves reducing irrigation application and using watertable aquifer as a contribution source for consumptive crop use. The overall investigation of all watertable control management strategies indicates the following: (a) reducing irrigation application may help in the prevention of watertable build up, but it may cause water shortage to the crop; (b) depending upon watertable as a source to supply some plant water requirements, by drying the unsaturated zone may cause severe damage to plant growth; and (c) a very low hydraulic conductivity of the aquitard and/or a watertable aquifer may prevent flux moving from the watertable to the confined aquifer if the vertical drainage is practiced. It is concluded that the integrated management strategy which involves irrigation and drainage may be very powerful and useful to control the watertable level for both multiaquifer systems as well as reduce the impact of waterlogging on the plant growth.