The diagram below shows a hydrological cycle.

KCSE Geography Paper 1 2009 Section B Question 7.

The diagram below shows a hydrological cycle.

(a) (i) What do the arrows labeled K, L, and M on the cycle represent? 

• K-Radiation/ half from the sun/ sun’s rays/ in solution
• L-Percolation/ Underground water
• M-Evapotranspiration / Evaporation/ water vapour

​(ii) Explain three factors that influence the occurrence of surface run- off 

• Amount of water/ nature of rainfall- there should be sufficient rainfall to make the soil saturated in order to allow the excess water to flow on the surface/ intense rainfall accelerates the rate of surface  run off be steep 15
• Gradient of the land- The gradient of the slope should be steep to allow flow of water by gravity
• Nature of rocks/ soils- The rocks/ soil should be responsible to allow for limited infiltration and percolation for the excess water to form  surface run- off
• Water table/ level of saturation – the water table should be high  to reduce infiltration and allows surface run- off

(b) (i) What is mass wasting?

• It is the movement of weathered/ rock material down the slope under the influence of gravity

​(ii) Give two processes of slow mass movement 

• Soil creep
• Talus creep/ screen creep
• Solifluction
• Rock creep

​(iii) State two physical conditions that may influence landslides 

• Steep slopes which allow soil to move down slowly
• Presence of loose soil/ absence of firm rock which means that soils are easily destabilized
• Occurrence of earthquakes which interferes with stability of soils
• Heavy rain facilities movement of material/ down slope.

​(c) Describe the following processes of mass wasting

(i) Rock Fall

• It occurs where rocks are well jointed and with steep slopes. Rocks parts are detached from the steep slopes and fall rapidly at the base of slope/ frequent freeze- thaw action on steep slope/ produces particles which get detached and fall at the base of rock face.

(ii) Subsidence

• Subterranean weathering leads to formation of caves/ cavers. Where the roof is too heavy to remain suspended, it collapses vertically.

(iii) Mud flows

• Wet and loose soil materials saturated with water will move down the hill. (As the semi- liquid mud collects more materials it comes rest at the roof of the slope.

​(d) Explain the effect of mass wasting on the following

(i)Tourism - Features created through mass wasting are tourist Attractions
(ii)Soil  Fertility -Mass wasting facilities soil leading to soil 

• Degeneration/ may lead to formation of fertile soil where such soils are deposited.

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