Evaluation of border dyke systems

Abstract

Irrigation is the application of water to soil for the purpose of supplying moisture necessary for the growth of a crop. Irrigation has been practiced since the beginning of civilization and its importance in the present world is well recognized as a means of developing a profitable agriculture. The rapid growth in the world population and the consequent need for additional food supplies are making irrigation absolutely necessary in the world today. In surface irrigation by flooding, two general methods are used; uncontrolled flooding or controlled flooding. In irrigating by uncontrolled flooding, or wild flooding, water is applied to an area which has undergone no prior land preparation. In most cases, this unsystematic method produces inefficient irrigation. Low spots in the field are over-irrigated whereas high areas are under-irrigated. In the controlled flooding method, predetermined rates and quantities of water are applied to areas which have been prepared for irrigation. This method of irrigation includes border dyke, border ditch, and border check systems. For proper design of these systems, the size of stream is balanced against the intake rate of the soil, the total depth of water to be stored in the root zone, and the area to be covered by the stream. With the completion of the South Saskatchewan Dam, it is expected that the irrigated acreage of the province will increase substantially. Further, it is expected that most of the new area coming under irrigation will be irrigated by some surface irrigation method. One of the most common and diversified of the surface irrigation methods, which is adaptable to both close growing and row crops, is the border dyke or border strip method. In this method, water is introduced to land which is bounded by low, flat levees or dykes which extend in the direction of the steepest slope. The present procedures used in design of border dyke systems 2. are empirical. The experimental data reported in the literature were obtained from systems whose soils, topography and other conditions differ widely from those which will be encountered in the South Saskatchewan River Development Project. Thus, it is questionable whether these data can be applied directly to the design of systems in Saskatchewan. There is a great need for experimental data from systems installed on areas which are similar to those that will be encountered under the proposed project. The study reported in this thesis was undertaken in an attempt to satisfy some of these needs. Experimental data collected from existing border dyke systems located in Saskatchewan are presented. In addition, a rational approach for evaluating several factors affecting the design of these systems for example, soil intake rate, is given.