SECTION A

Hydrology and fluvial geomorphology

1 Fig. 1.1 shows components of the drainage basin system.

(a) Using Fig. 1.1, identify: (i) output A; Evaporation [1] (ii) store B. Groundwater [1] (b) With reference to Fig. 1.1, describe the effect of the trees on the drainage basin system. [3]

Vegetation increases infiltration This it because it intercepts some rainfall and slows down at the speed at which it arrives to the surface.

The effect of trees is mainly: • to increase evapotranspiration • to slow down water reaching the ground surface by interception, thus reducing surface flow • stem flow will direct water to a particular part of the slope and reduce raindrop impact • to increase the rate of infiltration • the extraction of water by root systems

(c) Explain why, during a rain event, there could be more overland flow than infiltration. [5]

• the amount and intensity of rain overcoming the infiltration capacity of the soil
• the infiltration capacity of the soil which is governed by factors such as the porosity and permeability of the soil
• antecedent moisture conditions
• different land uses (e.g. forestry, arable, pastoral) and surfaces (e.g. impermeable surfaces in urban areas)
• steep gradient

[Total: 10]

Atmosphere and weather 2 Fig. 2.1 shows average annual solar radiation received on land.

(a) Using Fig. 2.1, give: (i) the average annual solar radiation at 50°S; 400- 699 1000-1299 [1] (ii) the maximum average annual solar radiation at 40°N. 1300-1599 1900–2199[1] (b) Briefly describe the general pattern of solar radiation shown in Fig. 2.1. [3] The average solar radiation is highest along the tropic of cancer at 2200-2500 whereas it is lowest along 60 degress north at 700-999

• the contrast/similarity between the northern and southern hemispheres • concentration of high average radiation between the tropics • contrast between the tropics and the equatorial areas • gradual transition north of the Tropic of Cancer and south of the Tropic of Capricorn