Flashcards on Gronddreineringstelsels en Beplanning
Gronddreineringstelsels en Beplanning: 'n Omvattende Gids
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Soil Drainage Systems
20 cards
Card 1
Question: Why must soil be drained?
Answer: High water table = wet soil and poor plant growth; poor aeration in the root zone; build-up of salts (brackishness); low-lying areas or near rivers ha
Card 2
Question: What factors influence the type of drainage system chosen?
Answer: Soil texture and class (sand, clay, mixed); depth of the groundwater table (affects pipe depth); and layers that prevent water movement (clay, limesto
Card 3
Question: What decisions are made after examining soil and drainage conditions?
Answer: Which crops to grow, the irrigation method, and which drainage system to implement.
Card 4
Question: What are open drains (ditches) and when are they used?
Answer: Open drainage ditches laid along land contours; advantages: quick, easy, low cost; problems: weeds, insect/disease breeding, hinder tractor movement,
Card 5
Question: What are pipe drainage systems?
Answer: Systems where pipes remove water from soil; common types include unglazed clay pipes and PVC pipes.
Card 6
Question: Describe unglazed clay drainage pipes.
Answer: Diameter 75–200 mm, segments 3 m long, water enters through openings between segments.
Card 7
Question: Describe PVC drainage pipes and their characteristics.
Answer: PVC (polyvinyl chloride) pipes 50–150 mm, typically 6 m long, have very narrow slits in the walls to prevent fine sand and plant roots entering.
Card 8
Question: What spacing factors should be considered for pipe drainage?
Answer: Soil texture and depth of impermeable layers; coarser (coarse) textures require wider spacing.
Card 9
Question: Why must pipe diameters be chosen correctly?
Answer: If cross-section is too large, costs are unnecessarily high; main lines must be large enough for free flow and to carry water from lateral lines.
Card 10
Question: What minimum slope (gradient) is recommended for drain lines?
Answer: Minimum slope of 0.2% (20 mm drop per 10 m length).