(i) Define the term stream discharge.

(ii) State two river transport processes and outline how each process operates.

Explain how hydrographs can be used to forecast and manage flooding.

Examine the possible impacts of the mismanagement of groundwater resources.

(i) The rate of stream/river flow/the volume/amount of water passing a point per unit of time (may specify hours/days – any unit of time is acceptable). Must have time.

(ii) Suspension, solution, saltation, traction, flotation. 

In each case award [1] for naming the process and [1] for some specific detail of the process eg may quantify the particle size (accept “large” or “small”), rock type, chemical processes, or use specialist vocabulary.

For example, award [2] for “Some material is carried in solution, such as material dissolved by carbonation” or “suspension is when small particles are carried in the water”.

Do not award more than [1] for an outline that does no more than define the terms (“suspension is when particles are carried in the water” or “solution is when the load is dissolved in the water”).

Award [1] for the description of a hydrograph (drawn, stated or implied), for example “the hydrograph shows response of a river/stream to a precipitation event over time”.

Award [1] for each explanation of how a hydrograph is used to help with flood management/warning. Award additional marks for any development that uses specialist knowledge of hydrographs and/or floods. There may be other valid approaches and these should be credited. Answers may focus on ideas of “archive” hydrographs, “live” hydrographs (using GIS etc), or both.

For example:

• historical hydrographs can be used as models for future flooding [1], allowing estimate of time lag to peak discharge to be made [1] which provides vital information for evacuation times [1] or provides guide to extent of possible flooding/areas at risk [1]
• knowledge of rural and urban hydrographs helps us know what might happen in particular locations [1] because urban hydrographs are flashy [1]
• discharge prior to rainfall event shown on hydrograph [1] shows how much/little rain is needed before bankfull discharge is reached [1]
• return periods for high-magnitude floods [1] can be estimated eg one in a hundred year events [1] which may influence land-use zoning [1] and flood protection schemes eg size of levees [1]
• credit other valid points not covered by the markscheme.

Groundwater management may comprise over-abstraction or pollution, either of which may constitute unsustainable management depending on the scale or rate of the change. The focus may be on agriculture and groundwater pollution and may make use of a detailed local case study.

The impacts could be physical (subsidence, ecosystem damage), human (dwindling supplies, conflicts and possible attempts at resolution either locally or internationally eg transboundary aquifers). Mismanagement may also comprise distribution inequities or losses due to inefficient storage and transfer technology.

An entirely physical or human answer can be awarded full marks if it covers a range of (at least three) well-developed impacts.

Good answers may be carefully structured around different types of impact (either for processes, people or ecosystems), or may examine the temporal and/or spatial extent of any impacts. Another approach might be to examine different kinds of mismanagement, or contrasting views of user groups about what constitutes mismanagement (may use concept of sustainable development).

For band D, expect some description of some problems related to water quality and/or quantity.

At band E, expect either more detailed explanation of some impacts or an examination of the meaning of “mismanagement” (eg unsustainability).

At band F expect both of these elements.

There may be other approaches and these should be credited.

Marks should be allocated according to the markbands.

(i) Many candidates did not give a full definition of “stream discharge”, omitting reference to time/cumecs.

(ii) Most candidates correctly named the river transport processes, but often failed to give descriptive detail to gain full marks.

Most candidates understood the concept of a hydrograph, but were often let down by the explanation of how hydrographs might be used to forecast and manage flooding. There were some very good sketches of hydrographs, although annotations would have helped answer the question more succinctly.

Most candidates were able to describe groundwater resources and outline some impacts of mismanagement. Many, however, were unable to develop their explanation of why mismanagement had occurred. The Aral Sea is not really considered to be a groundwater store; those that used this example told the story of mismanagement rather than focusing on the question. The very strongest responses used case studies with factual detail and figures illustrating the costs of abuse of groundwater resources to society and the environment.