Soil and Water Conservation Engineering

9.

Agricultural Drainage Systems

9.1.

Drainage Fundamentals

9.1.1.

Need for Drainage

9.1.2.

Waterlogging Problems

9.1.3.

Salt Accumulation

9.1.4.

Crop Response to Drainage

9.1.5.

Environmental Benefits

9.1.6.

Economic Justification

9.2.

Drainage Problems

9.2.1.

Surface Waterlogging

9.2.2.

Causes and Effects

9.2.3.

Identification Methods

9.2.4.

Subsurface Waterlogging

9.2.5.

High Water Table

9.2.6.

Perched Water Tables

9.2.7.

9.3.

Surface Drainage

9.3.1.

9.3.2.

Grading Principles

9.3.3.

Equipment and Methods

9.3.4.

Grade Requirements

9.3.5.

Surface Smoothing

9.3.6.

Open Ditch Systems

9.3.7.

9.3.8.

Collection Ditches

9.3.9.

9.3.10.

Design Procedures

9.3.11.

Hydraulic Design

9.3.12.

Cross-Section Design

9.3.13.

Grade Selection

9.3.14.

Erosion Protection

9.4.

Subsurface Drainage

9.4.1.

Pipe Drainage Systems

9.4.2.

Drain Pipe Materials

9.4.3.

Corrugated Plastic Pipe

9.4.4.

9.4.5.

9.4.6.

Pipe Installation

9.4.7.

Trenching Methods

9.4.8.

Bedding Requirements

9.4.9.

Backfilling Procedures

9.4.10.

9.4.11.

Soil Suitability

9.4.12.

Construction Methods

9.4.13.

Effectiveness and Longevity

9.5.

Drainage Design

9.5.1.

Design Criteria

9.5.2.

Drainage Coefficient

9.5.3.

Design Discharge

9.5.4.

9.5.5.

9.5.6.

Drainage Equations

9.5.7.

Hooghoudt Equation

9.5.8.

9.5.9.

Steady-State Solutions

9.5.10.

Unsteady-State Solutions

9.6.

Drainage System Layout

9.6.1.

Pattern Selection

9.6.2.

Parallel Systems

9.6.3.

Herringbone Systems

9.6.4.

9.6.5.

Outlet Requirements

9.6.6.

9.6.7.

Gravity Outlets

9.7.

Drainage Water Management

9.7.1.

Controlled Drainage

9.7.2.

9.7.3.

Water Table Management

9.7.4.

Environmental Considerations

9.7.5.

Water Quality Issues

9.7.6.

Disposal Methods

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