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
17.2 Types and Applications of Agricultural Drainage Systems
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
17.5 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
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.