TABLE OF CONTENTS

LIST OF TABLES................................................................................................................iii

LIST OF FIGURES..............................................................................................................iii

DECLARATION......................................................................................................................iv

ACKNOWLEDGEMENT.........................................................................................................v

ABSTRACT..............................................................................................................................vi

1.0 INTRODUCTION................................................................................................................1

1.1 Background:.....................................................................................................................1

1.2 Problem Statement...........................................................................................................2

1.3 Project Justification:.........................................................................................................2

1.4 Objectives.........................................................................................................................2

1.4.1 Main objective:..........................................................................................................2

1.4.2 Specific Objectives:..................................................................................................2

1.5 Scope:...............................................................................................................................2

1.6 Summary of Methodology...............................................................................................3

2.0 LITERATURE REVIEW.....................................................................................................4

2.1Introduction.......................................................................................................................4

2.2 Types of drainage.............................................................................................................4

2.3 Hydrological study...........................................................................................................5

2.4 Determination of runoff...................................................................................................5

2.5 Estimating the design flow:..............................................................................................6

2.6 Hydraulic design..............................................................................................................6

2.7 Culvert design..................................................................................................................7

2.8 Open drainage channels...................................................................................................8

2.8.1 Types of open drainage channels..............................................................................8

2.8.2 Factors to be considered for selection of channel type.............................................8

2.9 Culverts............................................................................................................................8

3.0 DATA COLLECTION AND ANALYSIS........................................................................10

3.1 Introduction....................................................................................................................10

3.2 Frequency Analysis........................................................................................................10

3.3 Estimation of design rainfall intensity:..........................................................................14

3.4 Channel design...............................................................................................................14

3.4.1 Determination of channel dimensions.....................................................................14

3.4.2 Culvert design.........................................................................................................19

4.0 CONCLUSION..................................................................................................................20

i

5.0 RECOMMENDATIONS...................................................................................................20

REFERENCES.........................................................................................................................22

APPENDICES..........................................................................................................................23

APPENDIX 1.......................................................................................................................23

APPENDIX 2: BOOKING SHEETS FOR LEVELLING...................................................24

APPENDIX 3: DETAILS OF THE CULVERT..................................................................26

APPENDIX 4: NORMOGRAPH........................................................................................27

APPENDIX 5: TABLE FOR MANNING’S n VALUES....................................................28

ii

LIST OF TABLESTable 3.1:Maximum daily rainfall 10

Table 3.2: Ranked rainfall data with corresponding return period 11

Table 3.3: Maximum 24 hour rainfall intensity and coefficient aT 12

Table 3.4: Return period and duration 13

Table3.5: Iterations for drain 2 17

Table 3.6: Iterations for drain 3 18

Table 3.7: Iterations for drain 4 18

LIST OF FIGURESFigure 3.1: Plot of daily maximum rainfall against return period 11

Figure 3.2: IDF for the rainfall data 13

Figure A1: Road area for which design was made 22

Figure A2 – Section through road showing culvert 25

Figure A3 – cross section through culvert 25

Figure A4 – Normograph 26

iii

DECLARATION We, the undersigned, hereby declare that this report is our original work. All errors and

omissions are solely our responsibility.

BWAMBALE BARNABAS ………………………….

BALUKU JOSEPH ………………………….

ARINANYE JAMES ………………………….

KWESIGA IVAN ………………………….

NALWOGA BENAH ………………………….

ASIIMWE BRIAN ………………………….

MULONDO SAMSON SIDNEY ………………………….

KASOBA ARNOLD ………………………….

MUGUMYA PETER ………………………….

SSEBBOWA WILLIAM …………………………

DATE: Monday, 30th November, 2009

iv

ACKNOWLEDGEMENTFirst of all we would like to sincerely thank Mr. F. Mukasa and Dr. Umaru Bagampadde

for the guidance and encouragement during the entire project period

We are also grateful to Mr. John Clifton of the Civil Engineering Surveying department

for having allowed us to use their equipment whenever we needed it.

Our thanks also go to the Geography and the Meteorological departments, Makerere

University for providing us with the topographical map and precipitation data

respectively.

Above all we thank the Almighty GOD for the gift of life and wisdom. With him, anything

is possible.

v

ABSTRACTThis project attempts to design an efficient, economic easy-to-maintain drainage system

for the Western gate of the university under construction. Various natural and man-

made facilities were considered.

The method used to analyze the catchment drainage was the Rational method:

Where

Q – discharge

C – runoff coefficient of the catchment

i – rainfall intensity

A – catchment area

Development of IDFs, determination of intensities and return periods for 20 years were

achieved by analysis of rainfall data.

Catchment areas were calculated from a detailed contour map of the area.

A land survey was also done to establish the existing levels and slopes which were used

in the design of the channels.

The discharge Q, for each drainage feature was computed and used to calculate the

dimensions of the channels using Manning’s equation. Four channel sizes were

developed to cater for different discharges. Culvert diameter was also calculated and the

culverts were to be put at points where channels cross the road.

Sketch drawings to be used as guide in construction have also been produced.

vi

1.0 INTRODUCTION

1.1 Background:Drainage is the process of interception and removal of water from over, and under the

vicinity of the road surface. Drainage can be surface (where water is conveyed on the

road surface and drainage channels), or subsurface (water flows underneath the

pavement structure).

Surface and subsurface drainage of roads critically affects their structural integrity, life

and safety to users, and is thus important during highway design and construction.

Road designs therefore have to provide efficient means for removal of this water; hence

the need for road drainage designs.

Drainage facilities are required to protect the road against damage from surface and sub

surface water. Traffic safety is also important as poor drainage can result in dangerous

conditions like hydroplaning. Poor drainage can also compromise the structural

integrity and life of a pavement. Drainage systems combine various natural and man

made facilities e.g. ditches, pipes, culverts, curbs to convey this water safely.

Various roads in Uganda have poor drainage facilities, with surface run off not being

catered for properly. Rainfall and surface run off onto and in the vicinity of the road

have to be removed quickly to ensure integrity of the road structure. The drainage

design must allow for storm water to be transported along or away from the road in the

cheapest, simplest and most efficient way without damaging the road or surrounding

structures.

The road under discussion is the new Western gate entrance to the University at the

Faculty of Technology. The road is under construction, and it was noticed that the

existing drainage does not cater for the design of the road; as such, water flows over the

road whenever there is a downpour. Hence there is a need for a comprehensive

drainage facility.

1

1.2 Problem StatementAs stated, the road is being redesigned to cater for an entrance to the University direct

from the Kikoni area of Makerere. Therefore a new drainage system has to be designed.

However, the existing road and drainage from the faculty down to Gatsby to Kikoni is

showing signs of failure, caused mainly by poor drainage.

Therefore, there is a need to improve on the current drainage design in some of the

areas leading to the existing road, and design of a new system leading to the new gate.

1.3 Project Justification:Poor drainage system has an immediate negative impact on the road performance, thus

the design of this drainage system was found necessary so as to ensure sustainability.

Designing this system will reduce on the cost of maintenance, ease access of students

from Kikoni to the university and reduce traffic at the main gate since the road will be in

good condition.

1.4 Objectives

1.4.1 Main objective:

Design of an efficient, easy-to-maintain drainage system from the new Western gate to

the Gatsby garage.

1.4.2 Specific Objectives: Reconnaissance study of the area.

Collection of data necessary for analysis of surface run off e.g. catchment areas,

levels for existing and new road surfaces, meteorological data.

Analysis. Determination of runoff onto the road and discharge into existing

conveyance channels.

Design of the drainage channels using results obtained.

1.5 Scope:This project was confined only to designing a drainage system for the road from the

junction to the faculty of Technology via Gatsby to the western gate.

2

1.6 Summary of Methodology Reconnaissance study of the area to determine existing conditions. This involved

taking photos of the existing drainage features, the road and the current state of

the project.

Literature review using the internet, various textbooks and existing reports on

similar projects, drainage design manuals.

Obtaining rainfall data from the meteorological department, and analysis to

determine rainfall intensities. The data used was 10 year maximum daily rainfall,

1999-2008.

Surveying along the road to determine slope of road, position of drainage

channels.

Use of topographic maps from the geography department to obtain catchment

areas and slopes.

Design of the channels. Involved analysis of the rainfall data to obtain catchment

and sub catchment discharges. These were used to select suitable drainage

channel cross-sections and culvert sizes to be used in the drainage design.

3

2.0 LITERATURE REVIEW

2.1IntroductionHighway drainage is the process of interception and removal of water from over, under

and in the vicinity of the pavement.

Highway drainage is one of the most important factors in road design and construction.

If every other aspect of the highway design and construction is done well but drainage

is not, the road will quickly fail in use due to ingress of water into the pavement and its

base.

The damaging effects of water in the pavement can be controlled by keeping water out

of places where it can cause damage or by rapidly and safely removing it by drainage

methods.

Improper drainage of roads can lead to;

Loss of strength of pavement materials

Hydroplaning

Mud pumping in rigid pavement

Stripping of the bituminous surface in flexible pavements

2.2 Types of drainageThere are basically two types of drainage applied to highways that is; subsurface

drainage and surface drainage.

Subsurface drainage is concerned with the interception and removal of water from

within the pavement. Some of the sources of subsurface water include; infiltration

through surface cracks, capillary rise from lower layers, seepage from the sides of the

pavement to mention but a few.

Application of side slopes on the road surface, installing of drainage beds in the

pavement and use of transverse drains are some of the measures of effecting subsurface

drainage.

Surface drainage deals with arrangements for quickly and effectively leading away the

water that collects on the surface of the pavement, shoulders, slopes of embankments,

cuts and the land adjoining the highway.

The water collected is led into natural channels or artificial channels so that it does not

interfere with the proper functioning of any part of the highway.

4

The main source of surface water in most places is precipitation in form of rain. When

precipitation falls on an area, some of the water infiltrates in to the ground while a

considerable amount remains on top of the surface as surface run off.

Surface drainage must be provided to drain the precipitation away from the pavement

structure. This can be done through use of shoulders, ditches and culverts.

Surface drainage design includes the prediction of runoff and infiltration as well as open

channel analysis and culvert design for movement of surface water to the convenient

locations or naturally occurring paths. So, the surface drainage study can be

conveniently divided into two parts namely.

Hydrological study - which is concerned with the determination of water reaching the

inlet of the drainage ditch or culvert.

Hydraulic study – it is concerned with design of facilities needed to handle the water

arriving at the inlet.

2.3 Hydrological studyThis deals mainly with precipitation and runoff in the area of interest. When rainfall,

which is the main source of water, falls onto an area some of the water infiltrates into

the soil while the remaining portion either evaporates or runs off.

The portion that remains as runoff is the one of major importance in the design of

surface drainage facilities.

2.4 Determination of runoffRunoff at a particular point is determined with respect to a given catchment area and

depends on a number of factors such; type and condition of the soil in the catchment,

kind and extent of vegetation or cultivation, length and steepness of the slopes and the

developments on the area among others.

The following formula known as the rational formula is used for calculation of runoff

Q = 0.028CIA

Where Q is maximum runoff in m3 per sec

C is a constant depending upon the nature of the surface

I is the critical intensity of storm in mm per hour occurring during the time of

concentration.

A is the catchment area in hectares

5

2.5 Estimating the design flow:1. Estimation of watershed area from a topographic map.

2. Obtain cover factor c from tables. It may be necessary to obtain the weighted

average in the drainage area, by weighting each c value with the proportion of

the drainage area it covers.

3. Hydraulic length, and slope G obtained from the site map. It may also be

necessary to determine the different and G values for different cover factors,

c.

4. Obtain the factor for each homogenous portion along the hydraulic length.

5. Determination of the concentration time, for each value, and

aggregate the values.

6. Use of the IDF graphs to obtain intensity i in mm/hr for different return periods

and concentration times.

7. Peak rate of runoff.

2.6 Hydraulic designThis involves the design of facilities used to direct water away from the road surface

where natural channels are not available to convey the runoff from a given catchment

safely across or along the road pavement. Such facilities include; side drains in the cut

sections, catch water drains, longitudinal drains along the edge of a pavement, kerb

inlets and many others.

The design involves the selection of suitable dimensions and the shapes for the drainage

facility to be used for a given project.

Most hydraulic designs are done by the use of Manning’s equation given by:

Where Q – Discharge (ft3/s)

V – Velocity (ft/s)

S – Slope, A – area (ft2)

P – Wetted perimeter (ft)

6

n – Manning’s constant

Area, wetted perimeter, hydraulic radius, and channel top width for standard channel

cross-sections can be calculated from geometric dimensions.

2.7 Culvert designThe following procedure is to be followed for the design of each of the culverts. 75% of

the quantity of flow is to be used for design i.e. when velocity is maximum in culvert.

Using Manning’s equation and a suitable slope for each section

NB: The slope chosen ensures sufficient flow velocity while avoiding silting, scouring

and sedimentation on the base of the culvert.

The minimum diameter of a pipe culvert under a road should be 600 mm or its

equivalent in corrugated metal pipe arches. Wherever culverts are laid on grade

producing self-scouring velocities and where maintenance is not likely to be a problem,

the minimum size may be decreased to 450mm diameter.

Similarly, the minimum size of precast concrete portal type culvert under a road should

be 750mm x 450mm. This may be reduced to 450mm x 300m wherever self-scouring

velocities through the culvert can be achieved, resulting in a maintenance free structure.

The 750 mm minimum recommendation applies for cross culverts where cross slopes

are not less than 3%. It also applies for side-drains or drives.

Assuming full flow,

=

=

Note:

In the design of open channels, it is also important to calculate the critical depth in

order to determine if the flow in the channel will be subcritical or supercritical. If the

flow is subcritical, it is relatively easy to handle the flow through channel transitions

because the flows are tranquil and wave action is minimal. In subcritical flow, the depth

7

at any point is influenced by a downstream control, which may be either the critical

depth or the water surface elevation in a pond or larger downstream channel. In

supercritical flow, the depth of flow at any point is influenced by a control upstream,

usually critical depth.

d = V/g

2.8 Open drainage channelsUsed to transport water under the influence of gravity; they have an open top and can

be either man made or natural. Open channel flow is assumed to occur in closed

conduits like culverts if they are partially full.

2.8.1 Types of open drainage channels Gutters

Chutes

Roadway channels

Toe-of slope channels

Intercepting channels

Median swales

Roadway open channel flows

2.8.2 Factors to be considered for selection of channel type Maintenance requirements: ease of maintenance, safety of maintenance staff,

costs associated with maintenance.

Landscaping of highway environment.

Site constraints within pavement environment e.g. width restrictions, existing

services.

Planned future expansions for the roads.

Existing and likely future channel conditions immediately upstream and

downstream as pertains to volumes of discharges.

2.9 CulvertsA transverse and totally enclosed drain under a road. They can either be prefabricated

or constructed in place.

8

They are constructed in many shapes: circular, box, elliptical, and from a variety of

materials depending on structural strength, cost, and durability. Most common are

concrete, corrugated steel and aluminium.

Their selection is based on

Channel characteristics

Construction process

Maintenance

Hydraulic performance

9

3.0 DATA COLLECTION AND ANALYSIS

3.1 IntroductionSome important terms and definitions used in obtaining the design flow

Return period, T

This is the average interval between occurrence of storms or floods of the same

magnitude. It is related to the exceedence probability, p, by .

Time of concentration,

The time required for a particle to flow from the hydraulically most distant point in the

water shed to the outlet or design point. Various factors affect the time of concentration;

slope of the path, length of flow, roughness of the flow path.

Peak design flow

This is the maximum flow rate of a flood wave passing a point along a stream. As the

wave passes the point, its flow increases to the maximum and recedes. It is a major

factor in culvert designs, and its magnitude is dependent on the selection of the return

period.

3.2 Frequency AnalysisThe Watkins and Fiddes method was used to develop the IDF curves.

Rainfall data was collected from the Makerere Meteorological Department showing

maximum rainfall depths from 1999 to 2008. The maximum rainfall depth in every

month was considered from which the maximum in every year was selected. An

assumed duration of 1 hour was used.

10

Table 3.1:Maximum daily rainfall.

The values of daily maximum rainfall against the duration (1 hour) were ranked from 1

to N, in descending order. Corresponding return periods were estimated using Weibull’s

plotting position formula:

Where r is the event rank number (1, 2, 3…N)

Year Duration(hrs)Max. daily rainfall(mm) Rank® Return period

2000 1 90.3 1 112006 1 86 2 5.52008 1 77 3 3.72003 1 72 4 2.82007 1 65.9 5 2.22002 1 59.9 6 1.82001 1 57 7 1.62004 1 54.4 8 1.41999 1 51.8 9 1.22005 1 47.2 10 1.1

Table 3.2: Ranked rainfall data with corresponding return period.

The maximum rainfall depths were plotted against return periods on a semi-log paper

and a line of best fit plotted through the points.

11

Figure 3.1: Plot of daily maximum rainfall against return period.

The correlation coefficient between the maximum daily rainfall and log of return period

was determined.

From the graph maximum rainfall depth at desired return periods were read off from

the graph. The maximum 24 hr intensity and coefficient were then computed for

each selected return period using the formulae below:

, and

Return periodMax 24hr rainfall(mm)

Max 24hr intensity(mm/hr) aT

1 56.858 2.369 44.3712 61.036 2.543 47.635 73.57 3.065 57.40710 94.46 3.936 73.7220 136.24 5.677 106.32950 261.58 10.899 204.136100 470.48 19.603 367.16

Table 3.3: Maximum 24 hour rainfall intensity and coefficient aT .

The desired sequence of duration (e.g. 10, 15, 30 minutes) was chosen for each set of

data, and used to calculate the rainfall intensity using the formula:

Where: i – intensity in mm/hr

12

t – Duration in hours

a, b, n – constants developed for each IDF curve

In determining the above coefficients, the following procedure was followed:

- A value of b = 1/3 was used for East Africa, as developed from studies.

- The effective duration of storms in the area, was estimated at 1. This was

done by study of local storm data.

- The value of n from the original Watkins and Fiddes equation was calculated

from:

Return period T (years) 1 2 5 10 20 50 100Duration t(min)              0 121.646 130.58 157.385 202.108 291.507 559.651 1006.5910 83.839 89.997 108.47 139.294 200.908 385.714 693.74720 64.38 69.109 83.295 106.964 154.278 296.191 572.7330 52.455 56.308 67.866 87.151 125.701 241.328 434.05440 44.371 47.63 57.407 73.72 106.329 204.136 367.1650 38.516 41.345 49.832 63.992 92.298 177.199 318.71260 34.073 36.575 44.083 56.61 81.65 156.757 281.94370 30.581 32.827 39.565 50.808 73.282 140.691 253.04880 27.761 29.8 35.918 46.124 66.526 127.721 229.7290 25.436 27.304 32.909 42.26 60.953 117.021 210.475100 23.483 25.208 30.382 39.016 56.274 108.037 194.317110 21.819 23.422 28.23 36.252 52.287 100.384 180.55120 20.384 21.822 26.373 33.867 48.848 93.781 168.678

Table 3.4: Return period and duration.

The Intensity Duration Frequency curves were then developed by plotting values of

intensity against duration for each return period.

13

Figure 3.2: IDF for the rainfall data.

3.3 Estimation of design rainfall intensity:The time of concentration was estimated from the normograph as 3.36 minutes for the

catchment. See appendix 1 for details.

Using the above time of concentration and considering a return period of 20 years, the

design intensity for the catchment was determined from the IDF as 150mm/hr.

3.4 Channel designThe design discharges for the different drains were determined by first sub dividing the

catchment into sub-catchments with similar characteristics. The area of each sub-

catchment were calculated and run off coefficients for each read from the table

3.4.1 Determination of channel dimensions1) Calculation of the weighted run off coefficient,

Where

14

– coefficient of runoff for a particular surface, read from table 1

- correspondng area

2) Calculation of actual discharge,

3) Consider a trapezoidal section of the drain, sketch shown below

Area

Wetted perimeter

Hydraulic radius

There were two unknowns in the above equations; a and b. one of the unknowns has to

be fixed in order to solve the equations; in this case, let a be fixed.

4) Velocity, V. calculated from Manning’s equation

Where

V – mean velocity

15

1

2

a

b

d

n – Manning coefficient of channel roughness

R – hydraulic radius

S – slope

5) Discharge Q is calculated from

The Q calculated above is compared to . In case of a big difference between the

values, iterations were carried out by varying the values of d until they were close as

possible. The corresponding depth d was taken as the corresponding design depth.

The true b value was then calculated from;

For drain 1

The discharge for this channel is 0.018 . This gives a small velocity that may be

safely carried by a kerb and gutter; hence design for a kerb and gutter.

Taking a uniform section

Where: = 0.377

= Manning's coefficient

= flow rate, m3/sec

16

= width of flow (spread), m

= cross slope, m/m

= longitudinal slope, m/m

The above equation neglects the resistance of the kerb face since this resistance is

negligible.

Data

Q=0.018 m3/s

n=0.012 (for Concrete gutter, troweled finish)

= 0.377

= 0.02 for intermediate surfaces

= 0.121

From the expression of Q in the equation above,

For drain 2,

Paved area A1 = 23482.78 m2

Vegetated area A2 = 3368.78 m2

Qac=0.853 m3/s,

Manning’s n=0.013 (concrete base with sides of dressed stone in mortar)

17

DRAIN 2

a(m) d(m) Q(m3/s) A(m2) V(m/s) b(m) Comment

0.400 0.700 0.540 0.525 1.029 1.100 LOW

0.400 0.750 0.785 0.581 1.351 1.150 LOW

0.400 0.800 1.118 0.640 1.747 1.200 HIGH

0.400 0.287 0.856 0.156 5.481 0.687 OK

Table3.5: Iterations for drain 2.

Calculating critical depth

Since dc > d flow in the channel is subcritical flow.

In the actual construction the depth of the channel will be considered as 0.3m

For drain 3

Q=0.099m3/s and manning’s for ordinary lined concrete n=0.013

DRAIN 3

a(m) d(m) Q(m3/s) A(m2) V(m/s) b(m) Comment

0.100 0.150 0.151 0.034 4.487 0.300 HIGH

0.100 0.100 0.075 0.015 5.000 0.200 LOW

0.100 0.125 0.077 0.020 3.791 0.225 LOW

0.100 0.145 0.100 0.025 4.020 0.245 OK

Table 3.6: Iterations for drain 3.

Since dc >d flow in the channel is subcritical flow which is desirable. A depth of 0.15

will be used.

For drain 4

Q=0.174m3/s and using manning’s for ordinary lined concrete n=0.013

18

DRAIN 4

a(m) d(m) Q(m3/s) A(m2) V(m/s) b(m) Comment

0.300 0.125 0.094 0.045 2.084 0.425 LOW

0.300 0.160 0.142 0.061 2.331 0.460 LOW

0.300 0.190 0.189 0.075 2.514 0.490 HIGH

0.300 0.182 0.176 0.071 2.467 0.482 OK

Table 3.7: Iterations for drain 4.

Since dc > d flow in this channel is subcritical

A depth of 0.2m will be used.

3.4.2 Culvert design75% of the quantity of flow is used for design i.e. when velocity in the culvert is

maximum.

Qd = 0.75 Q

= 0.75*0.174m3/s

= 0.128m3/s

Using Manning’s equation and a slope of 3.5% to ensure sufficient velocity and avoid

silting, scouring and sedimentation on the base of the culvert.

Manning’s coefficient n= 0.025

V= R2/3S1/2/n

=0.0351/2 R2/3 /0.025

= 7.483 R2/3

Assumption

Taking full flow

R = A/P

= (d2/4)/2 dπ

=d/8π

Therefore V =7.483(d/8 )π 2/3

But V =Q/A

19

= 0.128/ ( dπ 2/4)

Equating

7.483(d/8 )π 2/3 =0.128/ ( dπ 2/4)

d8/3 = 0.118

d = 0.448 m

This is equivalent to using culverts of diameter =450mm which is available on the

market.

For the cross section drawings, see the appendix

20

4.0 CONCLUSIONThe project required design of a suitable drainage system from the given data. Analysis

provided the following data.

Return period – 20 years

Time of concentration – 3.36 minutes

Design intensity – 150mm/hr

Discharges in :

o Drain 1 – 0.018

o Drain 2 – 0.853

o Drain 3 – 0.099

o Drain 4 – 0.174

The discharges above were used in the design of the drainage channels. The dimensions

produced are feasible and can be used for construction.

5.0 RECOMMENDATIONSThe following recommendations were made regarding the existing and proposed

drainage designs:

The data provided was insufficient; the maps were outdated and did not have some of

the new developments like the faculty extension, while the rainfall data lacked the

storm durations. The faculty should provide updated maps with all current features,

while the Meteorological department should be pressed to provide more

comprehensive rainfall data.

The slope cut on the upper section of the road junction is very steep and should not be

left bare as this will lead to erosion by run off. The slope should either be cut to reduce

the slope angle and grass planted on it or it can be stone lined so that the soil wall is

protected from erosion.

21

In order for the drainage channels to function efficiently and to enable them reach their

design life, routine maintenance works such as desilting should be done since the

designs were done without considering the expected sediment load.

Students should be given chance to participate in more feasible projects like this

particular one. This project has enabled us to apply concepts learnt in class for example

collecting and analyzing data, designing from first principles and making sound

engineering decisions in the field.

Sections of the drainage channel along Sir Apollo Kaggwa road are earth channel. This is

unsuitable for the volumes of water to be carried by the channel due to the ease with

which earth is eroded by high velocity water. We recommend that the earth channel

sections be lined with stone.

22

REFERENCESMinistry of Works Design Manual

Highways Engineering Volume Two by C.A. O’flaherty

The Hand Book of Highway Engineering by T.F.FWA, CRC press 2006

Open Channel Hydraulics by V.T. Chow

23

APPENDICES

APPENDIX 1

Figure A1: Road area for which design was made

A – drain 3, along route 1 B – drain 4, along route 2 C – drain 4, along route 3 D – proposed culvert

24

A

BC

D

APPENDIX 2: BOOKING SHEETS FOR LEVELLING

ROUTE 1

BS IS FS RISE FALL RL REMARKS1.605         100.000 BM 1

  2.65     1.045 98.955 CH 0+1000.204   3.76   1.11 97.845 CH 0+90

  1.12     0.916 96.929 CH 0+80  2.03     0.91 96.019 CH 0+70  2.81     0.78 95.239 CH 0+60

2.253   3.527   0.717 94.522 CH 0+50    3.585   1.332 93.190 CH 0+40

BS IS FS RISE FALL RL REMARKS2.023         93.190 CH 0+0400.951   3.132   1.109 92.081 CH 0+030

  2.225     1.274 90.807 CH 0+0202.348   3.425   1.2 89.607 CH 0+010

    3.512   1.164 88.443 CH 0+000

ROUTE 2 CH 0+000 TO CH 0+045

BS IS FS RISE FALL RL REMARKS3.512         88.443 CH 0+000

  2.320   1.192   89.635 CH 0+010  1.549   0.771   90.406 CH 0+020  0.811   0.738   91.144 CH 0+030

  0.605   0.206   91.350CH 0+035 (CULVERT)

    0.445 0.160   91.510 CH 0+042

ROUTE 3 (TOP SECTION)

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BS IS FS RISE FALL RL REMARKS1.280         91.510 CH 0+000

  1.442     0.162 91.348CH 0+008 (CULVERT)

  1.386   0.056   91.404 CH 0+010  1.376   0.010   91.414 CH 0+020

1.501   1.159 0.217   91.631 CH 0+030  1.045   0.456   92.087 CH 0+040    0.545 0.500   92.587 CH 0+050

Route Vertical distance(m) Distance along route(m) Horizontal distance(m) SlopeRoute 1 lower 4.747 40 39.94 0.119Route 2 -3.067 42 41.89 0.073Route 3 -1.077 50 49.99 0.022Route 1 upper 5.81 60 59.72 0.097

APPENDIX 3: DETAILS OF THE CULVERT

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Figure A2 – Section through road showing culvert

z

Figure A3 – cross section through culvert

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APPENDIX 4: NORMOGRAPH

Figure A4 – Normograph

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APPENDIX 5: TABLE FOR MANNING’S n VALUES

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