| Date | November 2021 | Marks available | 1 | Reference code | 21N.1.bp.7 |
| Level | SL and HL | Paper | 1 | Time zone | |
| Command term | Estimate | Question number | 7 | Adapted from | N/A |
Question
The map shows the land use of areas affected by a landslide in a mountainous region of an Asian country with heavy seasonal rainfall.
[Source: Perera, E. N. C., Jayawardana, D. T., Jayasinghe, P., Bandara, R. M. S. and Alahakoon, N., 2018. Direct impacts
of landslides on socio-economic systems: a case study from Aranayake, Sri Lanka. Geoenvironmental Disasters,
5(11), p.3. Source adapted. https://geoenvironmental-disasters.springeropen.com/articles/10.1186/s40677-018-0104-
6#rightslink Attribution 4.0 International (CC BY 4.0) http://creativecommons.org/licenses/by/4.0/.]
Identify the land use with the largest area.
Estimate the distance, in metres, between A and B of the landslide on the map.
Outline one physical factor that increases the speed of onset in a mass movement event.
Suggest how two pre-event management strategies could reduce the negative impact of mass movement in an area such as this.
Markscheme
Tea
850 (accept 820 to 900)
Award [1] for cause and [1] for development.
For example: Prolonged rainfall [1] will saturate the soil and accelerate soil movement on a slope [1].
Other possibilities include:
- relief/gradient
- soil structure
- geology.
In each case, award [1] for a valid strategy and up to [2] for development, explanation or exemplification. (If strategy and/or development is not specific to mass movement hazard then maximum [2].)
For example: Increasing slope stability by terracing [1] therefore reducing the slope angle [1] and preventing damage to settlement / farmland [1].
Other strategies include, but are not limited to:
- land use zoning – infrastructure and buildings
- banning logging on steep slopes / Plant trees
- improving drainage/diverting surface water
- restraining structures e.g. gabions/walls
- netting/rock traps.
Examiners report
These were done with no problems.
These were done with no problems.
This was generally well answered with slope/gradient and rainfall being the most popular answers.
Many were able to give two pre-event management strategies with some explanation. However, they were unable to link this to an impact in a meaningful way. Strategies were often too general or did not relate to mass movement.
