2023 NJC J1 MYE Seminar Test 1 Ans Key

Humanities Department H2 Geography (9173) Name: _________________________ Class: ______________ Duration: 1 h 30 mins Senior High 1 H2 Geography Seminar Test 1 – SUGGESTED MARKING GUIDE Section A Cluster 2: Tropical Environments 1 Resource 1 shows land use changes within the Enkare Narok drainage basin in Narok county in Southwest Kenya from 1985 to 2019. Resource 2 shows an aerial view of the Enkare Narok River within the E nkare Narok drainage basin. Resource 3 shows a news excerpt on Naroosura River’s flow. Resource 4 shows flood risk map of Kenya. (a) Describe the changes in land use within Enkare Narok drainage basin shown in Resource 1. [4] Award 1 mark for each description of the changes in land use, up to a maximum of 4 marks. Award a maximum of 1 additional mark for further development of each description, where applicable. Possible responses include: • [General] Forest and rangeland land uses were dominant in 1985 but in 2019, agriculture became the dominant land use in Enkare Narok drainage basin [1 mark]. o In 1985, forest and rangeland accounted for 98.1% of land use whereas in 2019, agriculture made up more than half (55.4%) of the land use [1 additional mark] • [Specifics] Agriculture experienced the largest increase in terms of land use, from 0% in 1985 to 55.4% in 2019 [1 mark] • [Specifics] On the other hand, forest saw the largest decrease in terms of land use, from 46.5% in 1985 to only 6.2% in 2019 [1 mark] • [Specifics] Built up area made up 1.9% of the land use in northwest region of the drainage basin. It then spread north and eastwards to make up 12.5% of the drainage basin in 2019 [1 mark] • [Anomaly] Agriculture and built up areas saw increase in land uses from 1985 to 2000 and then from 2000 to 2019 w hile forest saw a decrease over the 2 time periods. However, rangeland saw an increase [1 mark] o of 2.5% from 1985 to 2000 then a decrease of 27.2% from 2000 to 2019 [1 additional mark] AO2

Humanities Department H2 Geography (9173) (b) With reference to Resource 1, explain how land use changes may affect water storages and pathways in the Enkare Narok drainage basin. [6] Award 1 mark for each explanation of how land use changes may affect water storages and pathways in the Enkare Narok drainage basin, to a maximum of 6 marks. Award a maximum of 1 additional mark for further development of each explanation, where applicable. Award a maximum of 3 marks for explanation of either impact on pathways or water storages only. Possible responses include: Impact on pathways: • The decrease in forest and rangeland land uses and increase in built up areas and agriculture would lead t o the reduction in density of vegetation within the drainage basin and cause less infiltration and percolation, but more overland flow [1 mark]. o This is because vegetation helps to intercept precipitation and reduce the intensity of rainfall reaching the earth’s surface, thereby increasing the chance of infiltration OR The decomposition of vegetation also produce humus that helps to increase soil porosity and hence, infiltration capacity of the ground which promotes infiltration [1 additional mark] • The lowered amount of precipitation infiltrating into the ground means that there would be less sub-surface lateral flows (e.g. throughflow and baseflow) [1 mark] • As there is the generation of more overland flow, water would be transported to the channel much faster, which increases the peak channel flow with a shorter lag time [1 mark] Impact on water storages: • The change in dominant land use from forest and rangeland uses to built up areas and agriculture means that there is presence of less dense vegetation. This would mean less interception storage within the drainage basin [1 mark] • Due to less infiltration and percolation, sub-surface water storage which include both soil moisture and groundwater storage would be less, particularly for areas covered by built up areas [1 mark] • In general, channel storage as a whole could be reduced due to less evapotranspiration (due to reduction of vegetation) and hence less precipitation into the drainage basin [1 mark] AO2

Humanities Department H2 Geography (9173) (c) Describe the main features of a meander, such as the one shown in Resource 2, using a well- labelled cross-section diagram. [4] Award 1 mark for each description of the main features using a well -labelled cross section diagram, up to a maximum of 4 marks. Award a maximum of 1 additional mark for further development of each description, where applicable Possible cross-section diagram labels include: • Asymmetrical cross section • Concave bank o River cliff • Convex bank o Point bar and slip off slope • Sinuous channel (if aerial view is accompanied with the cross section diagram) AO1

Humanities Department H2 Geography (9173) (d) Explain how meanders, such as the one shown in Resource 2, are formed. [6] Award 1 mark for each explanation of the formation of a meander, to a maximum of 6 marks. Award a maximum of 1 additional mark for further development of ea ch explanation, where applicable. Award a maximum of 3 marks for explanation of meander from the aerial view or from the cross section view only. Possible responses include: Aerial view: • [flows] In an almost straight channel (sinuosity<1.5), there is a main downstream flow with thalweg that swings from side to side, and a secondary helicoidal flow [1 mark] • A sinuous path is created within a straight channel [1 additional mark] • [riffles] Alternating bars of sediment form by deposition in the lower velocity areas on either side of the thalweg and extend downstream [1 mark] • These bars deflect the flow against the opposite bank, initiating erosion, channel curvature and the formation of meanders. [1 additional mark] • [pools] At areas where velocity is higher, erosion takes place, resulting in the formation of pools [1 mark] • As this process continues, a series of pools and riffles is soon formed. [1 additional mark] Cross section: • [concave bank + river cliff] Helicoidal flow causes the water to pile up against the outer concave bank resulting in the formation of river cliff [1 mark] • [convex bank + slip off slope] When the water moves towards the convex bank due to the helicoidal flow, frictional drag with the river bed will lead to a loss of energy. Deposition of materials takes place at the convex bank. Formation of a slip-off slope at the convex bank. [1 mark] • [surface flow] The surface flow of water from the convex bank back to the concave bank then completes the cycle. [1 mark] AO1 (e) Using Resource 3, explain the possible changes to fluvial processes in the Enkare Narok River over a year. [4] Award 1 mark for each explanation of possible changes to fluvial processes in the Naroosura River, to a maximum of 4 marks. Award a maximum of 1 additional mark for further development of each explanation, where applicable. Possible responses include: • The rainfall pattern of Narok County in Kenya shows that it has 2 wetter seasons which peak in Apr and Dec and dry season in the middle of the year (May – Oct), as well as in Jan – Feb [1 mark]

Humanities Department H2 Geography (9173) • Wet season: higher discharge would mean that the river has higher energy to engage in erosion [1 mark] • Dry season: lower discharge at the start and middle of the year would r