Farmers and engineers have rebuilt stone terraces on a steep valley in the Philippines. Fig. 1 is a cross-section through one terrace during the wet season....
Question 1 Report
Farmers and engineers have rebuilt stone terraces on a steep valley in the Philippines. Fig. 1 is a cross-section through one terrace during the wet season. Rice is grown on the level surface, while a small channel takes surplus water from one terrace to the next. The cap figure is part of a fieldwork resource about farming in a mountainous rural ecosystem where flat land is scarce.
(a) Identify the crop grown on the terrace. [1]
(b) State why the terrace surface is made level. [2]
(c) Describe two ways in which the stone wall changes movement of water and soil downslope. [4]
(d) Explain why terrace farming can allow cultivation on steep slopes. [6]
(e) Describe three difficulties that may limit farming on these terraces. [6]
(f) What evidence could fieldwork students collect to judge whether restored terraces have reduced soil erosion? [6]
Answer Details
(a) The crop is rice. [1]
(b) A level terrace holds water for the rice crop and reduces the speed at which water flows downslope. [2]
(c) The stone wall slows runoff and traps soil or sediment. It prevents soil moving to lower slopes and directs surplus water into a channel. Any two developed effects. [4]
(d) Terraces create level planting areas on steep slopes. They retain water for rice, while walls break one long steep slope into shorter sections. Runoff loses speed, less soil is removed, and fertile soil remains available for cultivation. [6]
(e) Terraces can be expensive and labour-intensive to build or repair. Intense rain may collapse walls; machinery access is difficult because plots are small; water supply may be unreliable; and younger workers may leave for urban jobs. Any three developed difficulties. [6]
(f) Collect comparable evidence over time, for example measure sediment depth or volume behind walls, compare soil depth on restored and unrestored slopes, and use erosion pins to record soil loss. Fixed-point photographs, runoff turbidity measurements and mapping gullies or rills are also valid. Three valid methods. [6]
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