11. a) Surface irrigation is a method of applying water to agricultural fields by allowing it to flow over the surface of the soil. Outline four surface irrigation methods. (8 marks)

b) Controlling soil erosion is essential to prevent the loss of valuable topsoil, maintain soil fertility, and protect water quality. Explain six cultural measures taken to control soil erosion. (12 marks)

12. a) Wind erosion can have several detrimental effects on the environment, agricultural productivity, human health, and infrastructure. Highlight four factors that influence wind erosion. (8 marks)

b) Physical soil conservation structures are man-made structures designed to prevent soil erosion and promote soil conservation. Describe six physical soil conservation structures used on cropland in Kenya. (12 marks)

13. Gully erosion occurs when surface runoff concentrates into a flow that erodes the soil and creates significant incisions in the land. Describe five methods of controlling gully erosion. (20 marks)

14. a) Explain three soil conservation measures that can be used to reduce the risk of landslides. (6 marks)

b) Discuss seven catchment factors that have a direct influence on the accumulation of runoff on the land. (14 marks)

To control gully erosion, methods such as terracing, check dams, and planting vegetative cover are essential. These techniques help slow down water flow, prevent soil loss, and stabilize the landscape. Effective implementation of these practices can significantly enhance land productivity and environmental health.

Explanation:

Methods of Controlling Gully Erosion

Gully erosion can significantly damage land and reduce agricultural productivity. To manage gully erosion effectively, several methods can be employed, including:

Terracing: This involves creating stepped levels on steep slopes to slow down water runoff and allow for water absorption.
Check Dams: Small barriers made of earth, stone, or wood are built across gullies to trap sediment and reduce flow velocity.
Vegetative Cover: Planting grasses, shrubs, or trees in and around gully areas helps stabilize the soil with their roots and reduces runoff.
Drainage Control: Diverting excess water away from gullies can prevent further erosion by managing water flow effectively.
Reinforcement with Materials: Using geotextiles or gravel can help to stabilize the soil and reduce erosion in vulnerable areas.

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