# Exam 2009-10

```UNIVERSTY OF NAIROBI
FIRST SEMESTER EXAMINATIONS
2009/2010
FIRST YEAR EXAMINATIONS FOR THE DEGREE OF MASTER OF SCIENCE IN
AGRICULTURE
ALM 603: WATER RESOURCE DEVELOPMENT
DATE -------------- TIME---------------------------------3(HRS)
i.
ii.
iii.
Show all your workings and reasoning.
iv.
v.
Marks for each question are given in brackets.
vi.
Good luck!
QUESTION ONE
i.
What are the main limitations of a catchment approach in water resource planning?
(6mks)
ii.
Explain the Thiessan polygon method for estimating catchment rainfall. (6mks)
iii.
Discuss the main causes of error in rainfall data (6mks)
iv.
Explain the double mass curve technique for checking rainfall data consistency.
QUESTION TWO
The soil infiltration function is important in the planning of water runoff and storage
systems
i.
Explain the meaning of the following terms as used in infiltration studies
o
Infiltration capacity
o
Transient infiltration
a)
Ponding time
o
Pre-ponding precipitation
(4mks)
ii.
By use of sketch explain the double ring infiltrometer method of determining soil
capacity(6mks)
iii.
How would you determine the soil ponding time? (5mks)
iv.
The soil infiltration function has been determined using Philp’s model as
I = 10 t-1/2 +20, cm/hr where I = instantaneous infiltration (cm/hr)
T = time (hr)
a)
Calculate the soil ponding time for a precipitation of 15cm/hr
(5mks)
b) What is the cumulative infiltration for this precipitation after a period of 8
hours (5mks)
QUESTION THREE
The project management body of knowledge (PMBOK) is one of the project cycles used in
the planning of water resource systems.
a) Name the 9 bodies of knowledge in PMBOK.(3mks)
b)
Discuss the main deliverables in the following water project cycle stages
o Feasibility studies
o Planning phase
o Closure phase
(11mks)
c)
Discuss the main project risks in small irrigation planning
o Technical risks
o Marketing risks
under the
o Financial risks
o Managerial risks
(11mks)
QUESTION FOUR
a) Explain the meanings of the following terms as used in the hydrological design of
water systems;
o The return period
o Risk of failure
o Deterministic model
o Stochastic model
b) The small scale water conservation structures are designed to have an average
lifetime of 10 years. What is the risk of failure if the systems are designed using a
return period of 30 years? (5mks)
c) Using examples, explains the Weibull model for determining the runoff return
period (4mks)
d) Explain how you would derive the design rainfall using:
o Annual maximum time series
o Peaks over threshold time series
QUESTION FIVE
i.
What is meant by the term hydrological flood routing(5mks)
ii.
Describe the steps involved in the hydrological design of flood spillways (5mks)
iii.
Compare and contrast earthen dams with masonny dams(5mks)
iv.
Briefly explain how the unit hygraph method can be used to estimate reservoir
filling (5mks)
v.
A stream had a flow of 250m3/s 1000 days into the drought, and a flow of 100
m3/s 150 days into the drought. Estimate the stream flow 200 days into the
drought (5mks)
```