NYJC Prelim_H2_GEO_9751_P2_Answer

NYJC Preliminary Examination 2018 Paper 2 Mark Scheme 1. (a) With reference to Resources 1 and 2, suggest a suitable hypothesis for the group’s investigation. [1] • landuse changes has led to a heightening of flood risk and a reduction to the liveability of the area. • an area with a higher proportion of vegetation cover is less prone to flooding than one with a lower proportion. Point marked (b) What safety precautions should the team take when condu cting the stream investigation? [5] • do a visual check if there are dangerous animals in the river or along the river banks e.g. crocodiles, monitor lizards etc. • determine the best section for maki ng wading measurement s by noting the potential risk such as slippery rocks, deep segments, pot holes, quick sand etc. • always probe the stream bed ahead with a rod when mo ving from bank to bank. Keep your feet spread apart and alignment of legs paralle l to the flow for better stability. • wear a safety jacket when wading and conducting discharge measurements. Tie the tagline securely so that you may pull yourself out, if necessary. • always follow safety precautions when ent ering the stream. If the water is too deep or swift, select another site. Never venture out into the stream alone without another person available to assist you in case of emergency. • determine whether the river stage is rising or falling. Beware of rapid rises in river stage when wading and anticipate and allow fo r changes in flow conditions at the end of the measurement. It is a good idea to select an obj ect (rock, stump, mark along bank, etc.) that is just above water surface and keep watching it to determine if the river stage is rising or falling. • find out if there are dam s at the upper reaches of the stream. Notify dam, reservoir or gate operators before entering stream. Point marked (c) Calculate the mean velocity of the c hannel in Resource 3 and sketch one line graph to represent the cross- sectional velocity of the upstream segment of Stung Chrey Bak Stream. [4] Award 1 mark for the mean velocity of the channel • Mean velocity of the channel – 1.6 m/s For the sketching of line graph, 1 mark awarded for each of the following: • Title

2 Higher 2 Geography / 9751 / 02 • Relative accuracy of the line graph • Appropriate labels for both axes Line graph showing the cross-sectional velocity of the upstream segment of Stung Chrey Bak Stream Point marked (d) The team concluded that some of the data collected may not have been completely reliable and/or accurate. What improvements can be made in the planning and data collection process for this stream investigation? [6] Limitations: • data was done over two days in December during the dry season • only one measurement (at 10am for bot h days) were taken for each stream segment • measuring tape was unweighted. In addition, there were some boulders on the c