Management of dry lands questions.

A large part of the drylands suffers from erosion due to water because rainfall usually comes in few, intensive storms. Give a detailed account of the rainfall erosivity factor, including the sub-factors that aggravate it, and how the factor may be controlled.

Clearly differentiate the following terms:

1. Winter -from continental-rainfall pattern
2. Climate change from global warming
3. Ephemeral annual from succulent perennial plants
4. Bench terracing from progressive bench terrace formation
5. Runoff-from flood flow-water harvesting
6. Agents from factors of erosion
7. Soil erosion from soil loss
8. Detachment limited – from transport limited-soil loss
9. Pipe-from tunnel-erosion
10. Unit plot from runoff plot

In order to curb soil and water loss, a farmer has decided to alternate strips of maize (Zea mays L.) and bambarranuts (Voandzea subterranea L.) that reduces soil loss by a third . The farmer will plant these two crops along the contour, thus minimising soil loss to a quarter. If the field is 50 m by 221 m on a gradient of 18%, the rainfall erosivity index in that area is 500 Jha^-1 and the soil`s resistance to erosion is 5, calculate the annual soil loss from this field.

Useful formulae/information:

1. A=R x K x LS x C x P
2. LS=(l/22.1 m)^m x (0.065 +0.045s +0.0065s^s)
3. V=A x R x Ro
4. One bucket has a volume of 20 litres.

A family of 5 people lives in a dryland that receives 600 mm rainfall per annum. To supplement their water needs, this family collects water from their rooftop which has a span of 30 m by 10m. The water needs for this family are: 20 L per person per day for bathing, 1.4 m³ per week for animal drinking, 420 L per week for washing clothes, two buckets per day for washing utensils and ten buckets daily for toiletry. If the runoff coefficient from the roof top rainwater harvesting is 90%, calculate how long (number of days) the harvested water will last this family.

Useful formulae/information:

1. A=R x K x LS x C x P
2. LS=(l/22.1 m)^m x (0.065 +0.045s +0.0065s^s)
3. V=A x R x Ro
4. One bucket has a volume of 20 litres.

1. Briefly describe the characteristics of dryland areas
2. Mention the two characteristics/ parameters used to classify dryland.
3. Describe one characteristic mentioned in (a) above.

Given the annual rainfall of a given dryland is 675 mm and annual evapo-transpiration is 2552 mm. Calculate the aridity index of this area and mention the type of dryland and two possible crops that can be grown in the region.

Describe the importance of rain water harvesting

A family of 5 people living in dryland area has a house with a roof area of 20m by 15 m. Given that runoff coefficient of the roofing material is 78% and the maximum annual rainfall is 600 mm.

1. How much water will be collected from this roof? Express your answer in and L
2. Suppose this mentioned above family uses 90000 L per year (365 days) for domestic purposes. Is the amount of water  harvested enough for domestic purpose of this family in a year? Give reason.
3. The family mentioned in above used to buy one bucket (20 L) of water per which cost 150Tshs/=. How much money will this family save per year if they decide to harvest rain water.

1. Differentiate between conventional agriculture and conservational agriculture.
2. Discuss the advantages and disadvantages of using heavy machinery on farm land.

1. What do you understand by the term “Vulnerability to climate change” ?
2. Developing countries claimed to be the most vulnerable to climate change. Discuss.