State two causes of water pollution.

KCSE Geography Paper 2 2007 Section B Question 10.

a) i) State two causes of water pollution.

• Oil leaks from ships/ trucks
• Industrial effluent when discharged into rivers/ lakes
• Washing away ( into rivers and lakes) chemical/ fertilizers/ pesticides/ insecticides
• Washing/ bathing/ watering animals in rivers/ lakes
• Disposing of raw sewages into rivers/ lakes
• Surface turnoff/ soil erosion into water depositing silt
• Dumping of solid waste into water courses

ii) Give two effects of water pollution on the environment 

• It may cause death of aquatic life
• It destroys aesthetic/ beauty of beach/ water bodies
• It leads to spread of waterborne diseases
• Causes foul smell
• Results to eutrophictaion/ water hyacinth/ water weeds/ alga

b) Explain four methods used to control floods on rivers in Kenya.  

• Dykes are constructed along river  banks levee of rivers to increase their height in order to prevent water from over flowing
• Dredging of river channels to deepen/ widen them to make it possible for them to accommodate excess water
• Dams are build across the rivers to control the amount of water discharges downstream/ construction of earth dams to hold back water
• Training/ re- directing a river/ straightening of a river to control its wild flow ( training means cut meander loops
• Planting of trees in the catchment areas to reduce surface run off and increase infiltration 
• Divering tributaries to other rivers to reduce the volume

​c) Explain how the following soil conservation methods improve the quality of soil:

i)Contour farming

• It helps to rap water hence improving soil moisture content
• It helps to reduce the speed of water down slope thus preventing the removal of top soil.

ii)Mulching

• The mulch adds humus in the soil as it decomposes thus enriching the soil
• The enhances the rentention of water in the soil by protecting from  direct sunlight / wind.
• It controls / stop run –off / speed of surface run – off by acting as acover to the soil
• It provides a suitable habitat for organism that aerate the soil by burrowing.

iii) Crop rotation

• Since different crops utilize different mineral, rotation helps in balancing the mineral content in the soil.

​d) You intend to carry out a field study on pollution in the local open air market.
(i) State three reasons why it would be necessary for you to visit the market before the actual study.

• To get permission from the relevant authority
• To be able to formulate the objectives / hypothesis
• To familiarize with the area of study.
• To be able to prepare a working schedule / to decide on the appropriate method of data collection.
• To determine the respondents / resource persons
• To asses the likely problems to be encountered.
• To determine the equipment /materials required.

​(ii) Give two methods that would to collect information on pollution 

• Interviewing
• Taking photographs / sketching / filming
• Observation
• Measuring the extent of polluted area
• Administering questionnaires
• Tape recording / video taking / shooting

​(iii)Give two follow-up activities you would carry out after the field.

• Discussing the findings
• Analyzing the data
• Writing a report
• Giving relevant advice to the stake holder
• Drawing sketches
• Displaying photographs / sketches.

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