Identify possible human factors A and B and possible physical factors C and D.

Explain how two physical factors other than precipitation can affect the magnitude of floods.

“River management strategies always result in unwanted impacts.” Using examples, discuss this statement.

A and B could be urbanization, deforestation, overgrazing, relevant farming methods, bridges and blockages (no credit for flood defences). C and D could be soil type, steepness of slopes, drainage density, frozen ground, vegetation, saturated ground,
tidal influences.

Award [1 mark] for each correct factor.

Possible factors include: basin shape, drainage density, rock type, soils, relief, vegetation.

In each case award [2 marks] for explanation of how the factor operates/links made with hydrological processes and [1 mark] for link clearly established with flood [1 mark] magnitude. For example:
Basin shape: rounded basin shape has potential for high magnitude flash flooding [1 mark] due to arrival of high volume of water at the same time [1 mark]. Whereas elongated basin shapes encourages lower peak discharge over an extended period of time [1 mark].

A range of river management strategies is required, some of which can have unwanted impacts – channel straightening, artificial levées (also accept dams and reservoirs). These could be balanced with measures that do not have such large impacts, such as flood relief basins and channels, afforestation, wetland restoration, river restoration schemes, water quality measures. Example of a named basin should be included.

In addition to physical impacts, there are human (social, cultural, economic) impacts to consider, including land zoning issues, transport changes, gains and losses for different user groups (eg diversions, or forced migration from dam-building).

To access band D, examples must be used. However, the use of one named river basin and strategy which includes a range of impacts (eg Aswan High Dam) is unlikely to progress beyond the D/E border. At bands E and F, a range of impacts should be discussed and a conclusion arrived at.

Marks should be allocated according to the markbands.

Posed few problems.

A small number of candidates found it difficult to link a factor with flood. Many misunderstood basin shape and drainage density, or confused a river channel for a basin. There were some good responses on the influences of rock type and vegetation on flooding.

A variety of river management case studies were used and most candidates were able to discuss a range of impacts, their merits and disadvantages. The weaker responses were limited by a single case study and sketchy detail.