17. AGRICULTURAL DRAINAGE CRITERIA This article discusses the role of drainage criteria in the design of agricultural drainage systems. For this purpose the kinds of drainage systems are thoroughly analysed and the important design factors are identified. As the aim of drainage systems is to enhance crop production, the relations between the system's parameters and agricultural performance need to be assessed. TABLE OF CONTENTS 17.1 Introduction 17.2 Types and Applications of Agricultural Drainage Systems 17.2.1 Definitions 17.2.2 Classification 17.2.3 Applications 17.3 Analysis of Agricultural Drainage Systems 17.3.1 Objectives and Effects 17.3.2 Agricultural Criterion Factors and Object Functions 17.3.3 Water table Indices for Drainage Design 17.3.4 Steady-State Versus Unsteady-State Drainage Equations 17.3.5 Critical Duration, Storage Capacity, and Design Discharge 17.3.6 Irrigation, Soil Salinity, and Subsurface Drainage 17.3.7 Summary: Formulation of Agricultural Drainage Criteria 17.4 Effects of Field Drainage Systems on Agriculture 17.4.1 Field Drainage Systems and Crop Production 17.4.2 Water table and Crop Production 17.4.3 Water table and Soil Conditions 17.4.4 Summary 17.5 Examples of Agricultural Drainage Criteria 17.5.1 Rain-Fed Lands in a Temperate Humid Zone 17.5.2 Irrigated Lands in Arid and Semi-Arid Regions 17.5.3 Irrigated Lands in Sub-Humid Zones 17.5.4 Rain-Fed Lands in Tropical Humid Zones References |
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Drainage criteria are determined on the basis of
costs and benefits of the drainage system.
The agricultural benefits are largely due to the lowering of the water table permitting the soil to be oxygenized. The negative effects may stem from the discharge as the chemicals carried in the water may do damage downstream. The positive effects include an increase of the crop yield and the opportunity to introduce more valuable crops. |