PDC Sustainable Land Use & Water Management 2 — Questions and Answers
Question 1: In permaculture water management, what does the principle 'slow it, spread it, sink it' primarily aim to achieve?
- Maximize surface runoff speed for irrigation efficiency
- Retain water on the land to recharge groundwater and reduce erosion (Correct answer)
- Channel water directly to storage tanks as quickly as possible
- Eliminate all standing water to prevent mosquito breeding
Correct answer: Retain water on the land to recharge groundwater and reduce erosion
Slowing, spreading, and sinking water keeps it on the land longer, reducing erosion and recharging aquifers.
Question 2: Which swale design feature ensures overflow water is safely discharged without causing erosion?
- A clay-lined base to prevent seepage
- A reinforced spillway or overflow structure at the swale end (Correct answer)
- Planting only deep-rooted trees along the berm
- Increasing swale depth beyond 6 feet
Correct answer: A reinforced spillway or overflow structure at the swale end
A properly designed spillway channels excess water safely away, protecting the swale structure during heavy rainfall.
Question 3: What is the primary hydrological function of riparian buffer zones in permaculture land design?
- To create wildlife corridors only
- To filter runoff, stabilize banks, and moderate water temperature in waterways (Correct answer)
- To provide timber harvesting areas near streams
- To channel stormwater into municipal systems
Correct answer: To filter runoff, stabilize banks, and moderate water temperature in waterways
Riparian buffers filter sediments and nutrients, prevent bank erosion, and shade streams to maintain aquatic ecosystems.
Question 4: In keyline design, what determines the placement of primary irrigation channels?
- The location of existing roads and fences
- The keyline contour that runs perpendicular to valley slope change points (Correct answer)
- The highest elevation ridge lines on the property
- The location of existing water sources like springs
Correct answer: The keyline contour that runs perpendicular to valley slope change points
Keyline channels follow the keyline—a contour through the keypoint where valley floor slope transitions—to move water from valleys toward ridges.
Question 5: Which soil texture is MOST prone to compaction and reduced water infiltration in agricultural land use?
- Sandy loam
- Gravelly coarse sand
- Heavy clay soil (Correct answer)
- Silty loam
Correct answer: Heavy clay soil
Heavy clay soils compact easily under foot or vehicle traffic, drastically reducing pore space and water infiltration rates.
Question 6: A permaculture designer wants to harvest maximum rainwater from a roof. Which factor has the greatest impact on catchment volume?
- Roof pitch angle
- Roof surface material reflectivity
- Total roof catchment area (Correct answer)
- Gutter pipe diameter
Correct answer: Total roof catchment area
Catchment volume equals rainfall depth multiplied by catchment area, making total area the primary determinant of harvest potential.
Question 7: What is the ecological role of 'pioneer species' in permaculture land succession planning?
- They are invasive plants that must be controlled immediately
- They stabilize soil, fix nutrients, and create conditions for later successional species (Correct answer)
- They are planted only for immediate food production
- They replace climax vegetation permanently
Correct answer: They stabilize soil, fix nutrients, and create conditions for later successional species
Pioneer species improve soil structure, fix nitrogen, and provide shelter, enabling more complex plant communities to establish over time.
PDC Sustainable Land Use & Water Management 2
In permaculture water management, what does the principle 'slow it, spread it, sink it' primarily aim to achieve?