Namanve Drainage Report

DRAINAGE DESIGN FOR ROADS IN NAMANVE INDUSTRIAL PARK

Table of Contents

1.0 INTRODUCTION..........................................................................................................3

1.1 BACKGROUND........................................................................................................................................31.2 CLIMATE...............................................................................................................................................41.3 LAND COVER, AND VEGETATION................................................................................................................61.4 DRAINAGE STATUS..................................................................................................................................6

2.0 METHODOLOGY.......................................................................................8

2.1 DESIGN APPROACH.................................................................................................................................82.2 STORMWATER COLLECTION......................................................................................................................82.3 STORMWATER CONVEYANCE.....................................................................................................................92.4 STORMWATER DISPOSAL..........................................................................................................................9

3.0 HYDROLOGICAL ANALYSIS.....................................................................10

3.1 ANALYSIS METHOD...............................................................................................................................103.2 ESTIMATION OF DESIGN FLOWS...............................................................................................................11

4.0 HYDRAULIC DESIGN...............................................................................14

4.1 CULVERT DESIGN.................................................................................................................................144.2 CHANNEL DESIGN.................................................................................................................................14

5.0 DRAINAGE SCHEDULES..........................................................................15

5.1 ROAD SOUTH B R1..............................................................................................................................155.2 ROAD SOUTH B R2..............................................................................................................................15

6.0 DIVERSION OF LARGE STREAM ALONG ROAD B R2...................................16

6.1 INTRODUCTION....................................................................................................................................166.2 DESIGN OF THE CHANNEL DIVERSION........................................................................................................17

APPENDICES................................................................................................19

APPENDIX A1: CROSS DRAINS - ESTIMATION OF DESIGN FLOWS............................................................................20APPENDIX A2: CROSS DRAINS - SIZING AND CONFIGURATION................................................................................21APPENDIX B1: SIDE DRAINS - ESTIMATION OF DESIGN FLOWS...............................................................................22APPENDIX B2: SIDE DRAINS - SIZING AND CONFIGURATION...................................................................................23APPENDIX C1 - WATER SURFACE PROFILE PLOTS FOR CULVERTS ALONG ROAD SOUTH B R1.......................................24Appendix C1 - Water Surface Profile Plots for Culverts along Road South B R1........................................25

Page | 1

List of Tables

TABLE 1: CLIMATE CHARACTERISTICS IN ZONE L (SOURCE: HYDROCLIMATIC STUDY (2001)).................5

Table 2: Sizes and numbers of culvert crossings..............................................................16

List of Figures

FIGURE 1: SITE LOCATION MAP SHOWING THE DRAINAGE PATHWAYS.................................................4

FIGURE 2: HYDROLCLIMATIC ZONES IN UGANDA (SOURCE: HYDROCLIMATIC STUDY (2001)).................5

FIGURE 3: AVERAGE RAINFALL FOR THE NAMANVE AREA (SOURCE: HYDROCLIMATIC STUDY (2001))......6

Figure 4: Project area natural drainage pattern.................................................................7

Page | 2

1.0 Introduction1.1 Background

The project is located within the Kampala Industrial Business Park at Namanve. It is located in central Uganda and is bounded by latitudes 0o20'3.2"N and 0o21'6.8" N and longitudes 32o40'29.3"E and 32o40'58.7"E (Figure 1). The business park was established in 1997 on over 850 acres of land. The business park is currently a hive of construction activity with many companies setting up factories, warehouses and business offices. The proposed project will involve constructing two linked roads. The first link, called South B R1, is 1427 m long. It starts at Old Jinja Road (also referred to as Bweyogerere Industrial Area Road) between the site for Luuka Plastics and Provident and ends at the site for Multiple ICD. The second link, called South B R2, is 3045 m long. It starts at Chainage 0+490 of road South B R1 and goes round in a loop before terminating at Chainage 1+210 of the same road.

The hydrology/drainage design was aimed at assessing the hydrology of the site and proposing appropriate cross and longitudinal drainage structures for the project roads. Construction of the roads will facilitate the development of the surrounding plots. Development of the plots will involve significant filling of the swamp thus exacerbating the drainage challenges.

1.2 Climate

Namanve is located in climatic Zone B of Uganda according to the Uganda Hydroclimatic Study (2001) (Figure 2).

The proposed site falls within climatic Zone B The zone receives an average of 1,270 mm of rainfall which is

principally spread over 2 rainy seasons: The long rains of March to May and the short rains of August to November

( and Figure 3).

1.3 Land cover, and vegetation

The plots surrounding Road B R1 have either been developed or are in the process of being developed. Road B R2 still goes through undeveloped land in which the current vegetation is mostly made of thick bushes with scattered trees mainly composed of short palms trees. There are numerous open ponds as a result of sand mining. The lower part of Road B R2 traverses through a wetland that is permanently water logged. Planned construction of industries should result in mainly impermeable conditions. The areas to the west of the project are mainly made up of residences with some industries.

3

Figure 1: Site location map showing the drainage pathways

Table 1: Climate characteristics in project area (source: Hydroclimatic study (2001))

Zone Districts, 2000 boundaries

Annual Rainfall and its zonal variability

Main rainy seasons Main dry seasons

Evaporation verses rainfall

B Luwero, Mukono, Kampala, and Mpigi.

Average of 1250 mm. Two rainy seasons, main season March to May with peak in April and secondary season August to November with a modest peak in October/November.

Main dry season December to February, secondary dry season is June to July.

Evaporation > rainfall by a factor of ~ 2 during the dry months, December to February. During the peak of the rainy seasons rainfall is greater and or equal to evaporation.

4

Figure 2: Hydrolclimatic zones in Uganda (source: Hydroclimatic study (2001))

5

Figure 3: Average Rainfall for the Namanve area (source: Hydroclimatic study (2001))

1.4 Drainage statusThe site is located within a low-lying part of the Namanve drainage basin which receives significant amounts of runoff from the surrounding hills with a high risk of flooding. Drainage of the proposed road links is mainly in a south easterly direction (Figure 4). Drainage challenges for the roads stem from two major factors. One factor is that most parts of the project roads are within a swampy setting that also forms part of the flood plain for multiple streams that flow into Namanve River. The lower parts of road South B R2 are located within a permanent swamp. The second factor is that the creation of the business park involved changing the land-use from forest cover previously to industrial area. As more of the companies that have been allocated land within the business park start construction activities, there is bound to be significant changes in runoff characteristics. The increasing percentage of impermeable surfaces will result in increased volumes of runoff. Channelization of the drains will result in higher peak runoff. The flat nature of the terrain will mean that chances of water stagnation are high.

6

Figure 4: Project area natural drainage pattern

7

2.0 Methodology2.1 Design approach

Drainage design included appropriate sizing of components, recommendations on road alignment for proper hydraulic characteristics and recommendation of protection systems against scour. The design was based on the latest Road Design Manual January 2010 Volume 2 (Ministry of Works and Transport), supplemented by other local and international guidelines. The approach was to undertake document review, as well as investigations to enable the Consultant to carry out a hydrological and hydraulic assessment for the proposed road links.

The design approach entailed the following five phases:

Desk study – appraisal of existing project documentation, design standards, and past studies.

Data collection – especially climatological and hydrological data necessary for hydrologic analysis. Data

included climatological and hydrological data. Other data included drainage area characteristics namely

size, topography, land-use, soils, and other developments that may impact on the site drainage patterns.

Field surveys - to identify locations of drainage structures (existing and proposed) along the roads and their

drainage characteristics. Important characteristics for major drainage systems include cross-section, slope,

roughness characteristics, flow controls, ponding, historical flood stages, vegetation, topography, land-use,

and scour evidence. Other issues of concern during the field surveys included: existing developments along

drainage channels, scour evidence, and land-use changes. The proposed locations of cross-drainage

structures are shown in Figure 4.

Hydrologic analysis – this involved use of recommended methods to estimate flood magnitudes for all

crossings. National standards were used to decide on the appropriate return periods to be used for the

designs.

Hydraulic design – Hydraulics principles of open channel flow, and closed conduit flow were used in sizing

of the drainage structures i.e. culverts and longitudinal drains. For the sizes and materials of all related

facilities, recommendations were made for culvert entrance and exit conditions, side drain cross-section and

alignment.

2.2 Stormwater collection

Stormwater collection is a function of the natural drainage systems of the catchments and the drainage of roadway. The quantity of the water to be drained depends on a number of variables that include; rainfall intensity, duration and frequency of rainfall, type and size of the area that contributes to runoff among others.

2.3 Stormwater conveyance

Stormwater conveyance will be through longitudinal and cross drainage structures. The main factors considered in selecting appropriate structures included; construction cost, ease of maintenance and performance record in similar conditions. Appropriate measures for protection against scour have been proposed.

8

2.4 Stormwater disposal

Stormwater disposal will be achieved in several ways

Stormwater through cross-drainage structures will be conveyed to the existing natural streams downstream

without any modifications whenever possible. Modifications may be required in some cases to improve

hydraulic flow conditions and also protect the drainage structures and the natural streams.

Stormwater through longitudinal drains will be directed away from the road off-shot drains or into inlets to

cross drains, whichever is applicable.

9

3.0 Hydrological Analysis3.1 Analysis method

Hydrological analysis dealt with estimating design flood magnitudes at each drainage structure as the result of precipitation. There are many methods available in literature for carrying out hydrological analysis and the selection of which method to use depends on the purpose of the analysis and the availability of hydrological data among others. The project area is characterised by scarcity of hydrological data as all the major rivers and streams are ungauged. For such sites, a class of analysis methods based on regionalisation has been found to give consistently good performance. For the current drainage design, the Generalised Tropical Flood Model was used. The steps involved in this approach are detailed in Watkins and Fiddes (1984) and updated as follows:

1. Generation of the catchment upstream of each drainage structure using digital elevation model (DEM) of the area. The 30 m ASTER GDEM Model (http://gdem.ersdac.jspacesystems.or.jp/) was used in this study

2. Estimation of catchment area (A), land slope (SL) and channel slope (So) from the DEM

3. Establishment of the catchment type from site inspection which was used to estimate the surface cover flow time, Ts. The values for Ts were set to 1 hour.

4. Determination of soil type by both geotechnical investigations and available soil maps, the soil permeability class (I) and slope class (S). The soils in the area are mainly of low permeability with impeded drainage when soils are wetted and the soil permeability was taken as 3. Slope classes were set to 3 owing to catchment slopes that ranged between 2 and 5%. Using the soil class and the slope class, the basic runoff coefficient was estimated using equation (1);

(1)

5. Determination of land use factor (CL) and catchment wetness factor (CW). Land-use factors were set to The catchment has largely bare soils and built-up area with cultivation is some parts. Therefore, CL was set to 1.5. Central Uganda is within a wet zone and CW was set to 1.0.

6. Estimation of the runoff coefficient from equation (2);

(2)

7. Estimation of the base time from equation (3)

(3)

Where; Tb = base time (hr)

A = catchment area (km2)

S = Slope class

C = 30 for humid catchments

8. Computation of the design storm rainfall for each recurrence interval, to be allowed for during base time

10

http://gdem.ersdac.jspacesystems.or.jp/

(a) the 2 year, 24 hr rainfall (P2)= 70 for the region (Appendix 4.3, Drainage Design Manual, 2010)

(b) 10 year : 2 year ratio = 1.49 (Appendix 4.4, Drainage Design Manual, 2010)

(c) selection of design return period, T, as shown in the section below

(d) determination of T:2 year ratio (rT:2) (Appendix 4.5, Drainage Design Manual, 2010)

(e) determination of area reduction factor using the 'Kampala Equation' (equation 4)

(f) (4)

(g) where T is selected as 8 hours since daily rainfall is used

(h) Determination of rainfall ratio from equation (5)

(i) (5)

(j) Where; Tb is the base time

a. b = 0.3

b. n = 0.95

(k) determination of the design rainfall intensity using equation (6)

(l) (6)

9. Calculation of the average flow during base time from equation (7)

(7)

10. Estimation of the design peak using a peak factor of 2.5 (applicable to humid catchments)

3.2 Estimation of design flows

Highway drainage facilities are designed to convey predetermined discharges in order to avoid significant flood hazards. Provisions are also made to convey floods in excess of the predetermined discharges in a manner that minimizes the hazards. Peak discharge magnitudes are a function of their expected frequency of occurrence, which in turn relates to the magnitude of the potential damage and hazard. The chief interest in hydrological analysis rests in estimating runoff and peak discharges for the design of highway drainage facilities. The aim is to develop a flood versus frequency relation as a tabulation of peak discharges versus the probability of occurrence or exceedance. The Ministry of Works’ Road Design Manual Volume 2 (2010), pg 10 notes that Design flood standards are influenced by many factors including:

(a) safety;

11

(b) the level of hydraulic performance required;

(c) environmental impact;

(d) construction and operation costs;

(e) maintenance requirements;

(f) serviceability;

(g) Legal and statutory requirements.

Longer return periods are considered essential for some cases including the following;

(a) Where there is high potential damage to the road and high associated cost of repairs

(b) Long time needed for repairs to make the route usable for traffic again

(c) Detours not available

(d) Long period of flooding

(e) High traffic density

(f) Deep flow depth and high flow velocity of floodwaters

(g) High strategic importance (military, police, fire brigade, medical services, etc.)

(h) High economic importance.

The Ministry of Works Road Design Manual (2010), recommends the following recurrence intervals for highways on the basis of the geometric design of the road

Structure Type Geometric Design Standards

BIa, BIb, BII, GA BIII, GB GC

Gutters and Inlets* 5/10 - -Side Ditches 10 10 5Culvert, pipe (see Note)

Span < 2m25 10 5

Culvert, 2m < span < 6m 50 25 10Short Span Bridges 6m <

span < 15m50 50 25

Medium Span Bridges 15m < span < 50m

100 50 50

Long Span Bridgesspans > 50m

100 100 100

Check/Review Flood 200 200 100

BIa = Bitumen Ia, BIb = Bitumen Ib, BII = Bitumen II, BIII = Bitumen III GA = Gravel A, GB = Gravel B, GC = Gravel C

Source: MoWT Drainage Design Manual, 2010, Section 3, Table 3.2, Pg 10

Based on the above Table, the following recurrence intervals were adopted

For culverts with a total span less than 2 m the design recurrence interval was set to 25 years while for

larger culverts with total spans up to 6 m the design recurrence interval was set to 50 years

For all longitudinal drains the design storm with a recurrence interval of 10 years was selected

12

All culverts were checked for performance under a storm event less frequent than the design storm event shown above as the Check/Review Flood. All other drainage structures were checked for the storm having the next lower frequency than the design storm event. For example, culverts designed for a 25-year storm were checked for adequate performance with a 50-year interval storm event.

The detailed analysis of the design floods at all culvert crossings are shown in Appendix A1 while the analysis for longitudinal drains are shown in Appendix B1

13

4.0 Hydraulic DesignHydraulic design was aimed at sizing and alignment of the drainage structures in such a way that they can safely convey the design flood without significant damage to the drainage structure or roadway. Hydraulic designs were carried out in two stages namely;

Sizing and alignment of cross drainage structures (mainly as culverts).

sizing and alignment of longitudinal drainage structures (mainly as trapezoidal drains)

4.1 Culvert Design

A culvert conveys surface water through a roadway embankment or away from the highway right-of- way. In addition to this hydraulic function, it must also carry construction and highway traffic and earth loads; therefore, culvert design involves both hydraulic and structural design. The hydraulic and structural designs must be such that minimal risks to traffic, property damage, and failure from floods prove the results of good engineering practice and economics. Culverts are considered minor structures, but they are of great importance to adequate drainage and the integrity of the facility.

Culvert design was carried out using the HY8 Culvert Hydraulic Analysis Program from the US Federal Highway Authority (https://www.fhwa.dot.gov/engineering/hydraulics/software/hy8/). HY8 is windows based and enables users to analyze:

The performance of culverts

Multiple culvert barrels at a single crossing as well as multiple crossings

Roadway overtopping at the crossing and

Develop report documentation in the form of performance tables, graphs, and key information regarding the

input variables

The resultant water surface profiles for the major culvert crossings are presented in Appendices C1 and C2 while Appendices A1 and A2 present the hydraulic designs of all culverts.

4.2 Channel Design

Channel design involved selection of trial channel characteristics, application of Manning’s equation for channel analysis, and then iteration until the trial characteristics meet the desired criteria. The following considerations where taken into account:

potential flooding caused by changes in water surface profiles

disturbance of the stream/river system upstream or downstream of the highway right-of way

changes in lateral flow distributions

changes in velocity or direction of flow

need for conveyance and disposal of excess runoff

14

https://www.fhwa.dot.gov/engineering/hydraulics/software/hy8/

need for channel linings to prevent erosion

The selection of the channel lining depends on channel material, the permissible velocities and the maximum allowable shear stresses. All longitudinal drains have been designed as concrete lined channels will have side slopes of 0.5:1. This is because other types of lining are not suitable for the area. Grass lining is not suitable for a highly built-up area with limited spaces for operating while stone pitching may not withstand the movement of heavy trucks in the industrial area.

The designs of the side drains are presented in Appendices B1 and B2.

5.0 Drainage schedules5.1 Road South B R1

Roadway drainage will be in form of both longitudinal and cross drains. The sizing and alignment for cross drains are presented in Appendices A1, A2 while the sizing and alignment for longitudinal drains are shown in Appendices B1 and B2. The water surface profiles for all cross drains are shown in Appendix C1.

There will be 4 new culvert cross drains in addition to the existing one at Ch. 0+170. All cross drains will be concrete pipe with a diameter of 1200 mm. Culvert entrances and exits will be made of vertical headwall with 45 deg wing-walls. The culverts culvert inlets have been provided with vertical headwalls and wing walls to protect the embankments and also allow for hydraulically smooth flow. The minimum culvert slope has been set to 0.5% to allow for self cleaning. Most of the crossings will have drop inlets at the entrances.

All side drains will be lined with concrete. The total length of side drains will be 2,515 m of which 1,100 m will be located on the left of the road while 1,415 m will be located on the right.

5.2 Road South B R2

Roadway drainage will be in form of both longitudinal and cross drains. The sizing and alignment for cross drains are presented in Appendices A1, A2 while the sizing and alignment for longitudinal drains are shown in Appendices B1 and B2. The water surface profiles for all cross drains are shown in Appendix C2.

There will be 7 new culvert cross drains. The sizes and numbers of culvert crossings are shown in Table 2. Culvert entrances and exits will be made of vertical headwall with 45 deg wing-walls. The culverts culvert inlets have been provided with vertical headwalls and wing walls to protect the embankments and also allow for hydraulically smooth flow. The minimum culvert slope has been set to 0.5% to allow for self cleaning. Most of the crossings will have drop inlets at the entrances.

All side drains will be lined with concrete. The total length of side drains will be 1,270 m of which 705 m will be located on the left of the road while 565 m will be located on the right.

Table 2: Sizes and numbers of culvert crossings

Type Size Number of crossings Number of barrels

Concrete pipe 900 mm 2 2

Concrete pipe 1200 mm 3 5

15

Concrete box 1500 mm rise x 2000 mm span 2 4

6.0 Diversion of large stream along Road B R26.1 Introduction

Between chananges 0+620 and 0+820, Road B R2 runs over an existing major stream that is a tributary of River Namanve (. Mecause maintaining the road along the current route will require some interventions in order to maintain the functionality of the stream and that of the road. The viability of 3 possible interventions was considered in order to select the best. The options are

1. Maintain the road and stream at current locations: This option would require construction of box culverts over the stream before constructing the road. The section to be covered would be about 180 m in length. This option is not considered viable because of the costs involved in constructing the box culverts. Additionally, maintenance of the culverts would be a challenges over such a length.

2. Maintain the stream at current location and divert the road: This option would require carrying out adjustments to the geometric profile of the road. Uganda Investment Authority has already demarcated and assigned the plots and, presumably, titles have been issued. This option does not seem viable because the process of adjusting plot boundaries would be tedious. Also changing the geometric profile of the road will have an impact on project cost.

3. Maintain road at current location and divert the stream: This option is the most viable. Part of the land into which the stream will be diverted in designated a green area (in from of PN Mashru plot). It will be necessary to negotiate with Rwenzori beverages for some extra land. The cost of constructing a new open channel will be much less than the cost of constructing the box culverts in Option 1 above.

16

Figure 5: Proposed channel diversion

6.2 Design of the channel diversion

The channel has been designed as a compound trapezoidal channel with a low flow section (Figure 6). The purpose of the low flow section is to maintain velocities that are sufficient for channel self-cleaning during the dry season. The channel will be concrete lined. Sizing of the proposed channel is shown in

17

b1

n2:1

n1:1 d

D

Free board

b2

Figure 6: Configuration of proposed diversion channel

Table 3: Sizing of the proposed diversion channel

Variable Units EstimateFlow variablesDrainage Area (km2) km2 1.81Catchment Slope (%) % 2.6%Channel slope % 0.5%Return Period (Years) Years 50.00Design Flow (m3/s) m3/s 17.15

Channel type Compound with low flow section

Low flow section Channel lining option 3 Channel lining Concrete Manning's n 0.013 base width, b1 m 1.00 depth, d m 0.50 side slope, n1 H:1 1.00 Flow area m2 0.50 wetted perimeter m 2.41 Flow velocity m/s 1.90 Discharge m3/s 0.95Flood flow section Channel lining option 3 Channel lining Concrete Manning's n 0.013 base width, b2 m 4.00 depth, D m 1.40 side slope, n2 H:1 1.00 Flow area m2 4.76 wetted perimeter m 7.96 Flow velocity m/s 3.86 Discharge m3/s 18.38Combined sectionTotal flow m3/s 19.33Comparison with maximum discharge OKOverall channel size Free board m 0.2 Top width m 6.8 Total depth m 2.1

18

Appendices

19

Appendix A1: Cross Drains - Estimation of Design Flows

BR1-C01existing

culvert at 0+170

RHS

BR1-C02 305 RHS 0.065 2.6% 3 1 3 1.5 1.00 41% 62% 1.8 70.0 1.49 25 1.20 1.78 0.30 0.95 0.99 0.77 95.77 0.57 2.50 1.44

BR1-C03 560 RHS 0.072 2.6% 3 1 3 1.5 1.00 41% 62% 1.9 70.0 1.49 25 1.20 1.78 0.30 0.95 0.99 0.78 96.16 0.62 2.50 1.56

BR1-C03 1095 RHS 0.081 2.6% 3 1 3 1.5 1.00 41% 62% 1.9 70.0 1.49 25 1.20 1.78 0.30 0.95 0.99 0.78 96.62 0.69 2.50 1.72

BR1-C04 1410 RHS 0.075 3.0% 3 1 3 1.5 1.00 41% 62% 1.9 70.0 1.49 25 1.20 1.78 0.30 0.95 0.99 0.78 96.32 0.65 2.50 1.61

BR2-C01 310 RHS 0.128 3.7% 3 1 3 1.5 1.00 41% 62% 2.2 70.0 1.49 25 1.20 1.78 0.30 0.95 0.99 0.79 98.43 0.98 2.50 2.45

BR2-C02 490 RHS 0.022 3.7% 3 1 3 1.5 1.00 41% 62% 1.5 70.0 1.49 25 1.20 1.78 0.30 0.95 1.00 0.74 92.06 0.23 2.50 0.58

BR2-C03 750 RHS 1.81 2.6% 3 1 3 1.5 1.00 41% 62% 5.5 70.0 1.49 50 1.34 2.00 0.30 0.95 0.97 0.89 121.66 6.86 2.50 17.15

BR2-C04 1090 RHS 0.065 2.9% 3 1 3 1.5 1.00 41% 62% 1.8 70.0 1.49 25 1.20 1.78 0.30 0.95 0.99 0.77 95.77 0.57 2.50 1.44

BR2-C05 1680 RHS 0.295 3.7% 3 1 3 1.5 1.00 41% 62% 2.8 70.0 1.49 50 1.34 2.00 0.30 0.95 0.99 0.83 114.25 2.05 2.50 5.12

BR2-C06 2300 LHS 0.0539 3.3% 3 1 3 1.5 1.00 41% 62% 1.8 70.0 1.49 25 1.20 1.78 0.30 0.95 1.00 0.77 95.08 0.49 2.50 1.23

BR2-C07 2940 LHS 1.75 3.6% 3 1 3 1.5 1.00 41% 62% 5.4 70.0 1.49 50 1.34 2.00 0.30 0.95 0.97 0.89 121.55 6.72 2.50 16.79

Basic runoff coeff. (Cs)

Runoff coeff (Ca)

Base Time (TB) - hrs

Average flow during base time

Peak flow factor

T-yr peak flow (m3/s)

Namanve South B R2b n ARF rainfall

ratioSerial No Inlet

LocationArea drained (km2)

Catchment slope (%)

Slope class (S)

Surface cover flow time (Ts) - hrs

Soil class (I)

Land-use factor (CL)

Catchment wetness factor (Cw)

T-yr- 24hr storm depth

Namanve South B R1Serial No Inlet

LocationArea drained (km2)

Catchment slope (%)

Slope class (S)



2yr, 24 hr rainfall (mm)

10:2 year ratio

Return period (T) - years

Soil class (I)

Land-use factor (CL)

Catchment wetness factor (Cw)


Runoff coeff (Ca)

rainfall ratio

T-yr- 24hr storm depth

Average flow during base time

Peak flow factor


T:10 yr ratio

T:2 yr ratio

Proposed Chainage(s)

(m)

Culvert to be retained

DEM Location(s)

(m)

b n ARF


10:2 year ratio

Return period (T) - years

T:10 yr ratio

T:2 yr ratio

20

Appendix A2: Cross Drains - Sizing and Configuration

BR1-C01

BR1-C02Pipe culvert(s)

1200 1200 1 3.29 OK 1.1 OK 3.4 500 10 2.0 6.98 7.79 1142.23 1142.12 1140.84 8.7% 1140.43 14.77 8.7% 1139.15 YesVertical headwall with 45 deg wingwalls

Vertical headwall with 45 deg wingwalls


1200 1200 1 3.29 OK 1.0 OK 2.7 500 10 2.0 6.98 9.98 1145.66 1145.38 1145.48 -0.6% 1143.86 16.96 0.5% 1143.77 YesVertical headwall with 45 deg wingwalls


BR1-C03Box culvert(s)







1200 1200 1 4.05 OK 1.8 OK 5.0 500 10 2 7.61 9.06 1138.29 1136.91 1136.18 4.3% 1136.49 16.67 4.3% 1135.77 YesVertical headwall with 45 deg wingwalls



900 900 1 2.27 OK 0.7 OK 2.8 500 10 2 9.51 10.02 1138.19 1135.94 1135.68 1.3% 1135.94 19.53 1.3% 1135.68 NoVertical headwall with 45 deg wingwalls



1500 2000 2 17.92 OK 2.2 OK 2.2 500 10 2 8.44 8.42 1138.18 1136.46 1136.47 -0.1% 1136.08 16.86 0.5% 1135.99 YesVertical headwall with 30 deg wingwalls






1200 1200 2 7.85 OK 1.8 OK 2.7 500 10 2 9.99 10.00 1138.14 1135.64 1135.63 0.0% 1135.64 19.99 0.5% 1135.54 NoVertical headwall with 45 deg wingwalls








Namanve South B R1

Namanve South B R2Road top width (m)

Rise/ diameter, D (mm)

Span - box culvert (mm)

Culvert Slope

Culvert Slope

Outlet typeNeed for encasement

Culvert length (m) - horizontal

Outlet invert (m)

Road embankment slope (1:H))

Inlet station (m)

Outlet station (m)

Road Level (m)

Inlet Ground Level (m)

Inlet typeSerial No Hw/D < 1.5, Ok

Outlet velocity (m/s)

Min Cover (mm)

Headwater depth, Hw (m)

No. of barrels

Total flow capacity (m3/s)

Ground slope (%)

Inlet invert (m)

Flow capacity ok?

Outlet Ground Level (m)

Structure proposed

Road Level (m)

No. of barrels

Min Cover (mm)

Road top width (m)

Inlet invert (m)

Culvert length (m): horizontal

Outlet invert (m)

Total flow capacity (m3/s)

Flow capacity ok?

Road embankment slope (1:H))

Inlet type Outlet typeRise/ diameter, D (mm)

Span - box culvert (mm)

Headwater depth, Hw (m)

Hw/D < 1.5, Ok

Outlet velocity (m/s)

Structure proposed

Serial No Need for encasement

Outlet Ground Level (m)

Inlet station (m)

Ground slope (%)

Inlet Ground Level (m)

Outlet station (m)

21

Appendix B1: Side Drains - Estimation of Design Flows

Serial No. Start Ch.

End Ch. Length (m)

Side on Road

Start Ground level (m)

Start Road Level (m)

End Ground Level (m)

End Road Level (m)

Area drained (km2)

Catchmt slope (%)

Slope class (S)


Soil class (I)

Land-use factor

(CL)

Catchmt wetness factor (Cw)


Runoff coeff (Ca)



10:2 year ratio

T - years T:10 yr ratio

T:2 yr ratio

b n ARF rainfall ratio

T-yr -24hr storm depth (mm)

Average flow during base time (m3/s)

Peak flow factor


NSBR1-D01 0 680 680 Right 1141.732 1141.504 1146.949 1146.180 0.007 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.06 2.5 0.145

NSBR1-D02 0 120 120 Left 1141.201 1141.504 1140.928 1141.795 0.001 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.01 2.5 0.026

NSBR1-D03 400 680 280 Left 1143.147 1143.498 1146.400 1146.180 0.003 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.02 2.5 0.060

NSBR1-D04 680 1095 415 Right 1146.949 1146.180 1138.810 1139.069 0.004 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.04 2.5 0.089

NSBR1-D05 680 1080 400 Left 1146.400 1146.180 1138.266 1138.988 0.004 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.03 2.5 0.085

NSBR1-D07 1100 1420 320 Right 1138.810 1139.069 1140.100 1140.362 0.003 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.03 2.5 0.068

NSBR1-D07 1120 1420 300 Left 1138.225 1139.149 1140.068 1140.362 0.003 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.03 2.5 0.064

Serial No. Start Ch.

End Ch. Length (m)

Side on Road

Start Ground level (m)

Start Road Level (m)

End Ground Level (m)

End Road Level (m)

Area drained (km2)

Catchmt slope (%)

Slope class (S)


Soil class (I)

Land-use factor

(CL)

Catchmt wetness factor (Cw)


Runoff coeff (Ca)



10:2 year ratio

T - years T:10 yr ratio

T:2 yr ratio

b n ARF rainfall ratio

T-yr -24hr storm depth (mm)

Average flow during base time (m3/s)

Peak flow factor


NSBR2-D01 0 140 140 Right 1145.515 1145.189 1140.003 1140.520 0.001 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.01 2.5 0.030

NSBR2-D02 0 120 120 Left 1145.376 1145.189 1140.544 1140.052 0.001 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.01 2.5 0.026

NSBR2-D03 200 240 40 Right 1138.800 1139.253 1138.372 1138.683 0.000 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.00 2.5 0.009

NSBR2-D04 1940 2140 200 Left 1139.891 1140.341 1139.302 1140.412 0.002 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.02 2.5 0.043

NSBR2-D05 2340 2700 360 Left 1141.160 1141.148 1141.961 1142.915 0.004 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.03 2.5 0.077

NSBR2-D06 2340 2700 360 Right 1140.220 1141.066 1141.894 1142.835 0.004 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.03 2.5 0.077

NSBR2-D07 3020 3045 25 Left 1138.862 1139.560 1139.297 1139.527 0.000 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.00 2.5 0.005

NSBR2-D08 3020 3045 25 Right 1138.782 1139.560 1138.973 1139.527 0.000 3% 3 1 3 1.5 1.0 41% 62% 1.6 70 1.5 10 1.00 1.50 0.3 0.95 1.00 0.75 77.88 0.00 2.5 0.005

Namanve South B R1

Namanve South B R2

22

Appendix B2: Side Drains - Sizing and Configuration

Serial No. Lining choice (1-Grass, 2-stone pitching, 3-Concrete)

Lining material

side slope (1:n)

Base width (m)

Depth (m)

Roughness (n)

Area (m2)

Perimeter (m)

Min channel slope (%)

Road slope (%)

Ground slope (%)

Adpoted slope (%) - Abs

Flow capacity (m3/s)

Flow capacity ok?

Flow vel (m/s)

Max permissible velocity (Vmax) - m/s)

Shear Stress (Tmax) - N/m2)

Max permissible shear stress (Tmax) - N/m2)

Selected channel lining ok?

Free-board (mm)

Top width (m)

Channel Slope (%)

Start invert (m)

End invert (m)

NSBR1-D01 3 Concrete 0.5 0.30 0.60 0.013 0.36 1.64 0.5% 0.69% 0.77% 0.77% 0.88 OK 2.07 10.00 45.16 1000 OK 0.20 1.10 0.77% 1140.704 1145.380NSBR1-D02 3 Concrete 0.5 0.30 0.60 0.013 0.36 1.64 0.5% 0.24% 0.23% 0.50% 0.71 OK 0.36 10.00 29.43 1000 OK 0.20 1.10 -0.50% 1140.704 1140.104

NSBR1-D03 3 Concrete 0.5 0.30 0.60 0.013 0.36 1.64 0.5% 0.96% 1.16% 1.16% 1.09 OK 0.85 10.00 68.38 1000 OK 0.20 1.10 1.16% 1142.698 1145.380NSBR1-D04 3 Concrete 0.5 0.30 0.60 0.013 0.36 1.64 0.5% 1.71% 1.96% 1.96% 1.41 OK 1.26 10.00 115.44 1000 OK 0.20 1.10 -1.96% 1145.380 1137.241NSBR1-D05 3 Concrete 0.5 0.30 0.60 0.013 0.36 1.64 0.5% 1.80% 2.03% 2.03% 1.44 OK 1.22 10.00 119.69 1000 OK 0.20 1.10 -2.03% 1145.380 1137.246NSBR1-D07 3 Concrete 0.5 0.30 0.60 0.013 0.36 1.64 0.5% 0.40% 0.40% 0.50% 0.71 OK 0.97 10.00 29.43 1000 OK 0.20 1.10 0.50% 1138.269 1139.562NSBR1-D07 3 Concrete 0.5 0.30 0.60 0.013 0.36 1.64 0.5% 0.40% 0.61% 0.61% 0.79 OK 0.91 10.00 36.16 1000 OK 0.20 1.10 0.61% 1138.225 1139.562

Serial No. Lining choice (1-Grass, 2-stone pitching, 3-Concrete)

Lining material

side slope (1:n)

Base width (m)

Depth (m)

Roughness (n)

Area (m2)

Perimeter (m)

Minnimum channel slope (%)

Road slope (%)

Ground slope (%)

Adpoted slope (%) - Abs

Flow capacity (m3/s)

Flow capacity ok?

Flow velocity (m/s)

Max permissible velocity (Vmax) - m/s)

Shear Stress (Tmax) - N/m2)

Max permissible shear stress (Tmax) - N/m2)

Selected channel lining ok?

Free-board (mm)

Top width (m)

Channel Slope (%)

Start invert (m)

Outlet invert (m)

NSBR2-D01 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 3.34% 3.94% 3.94% 1.54 OK 0.57 10.00 231.74 1000 OK 0.20 0.98 -3.94% 1144.389 1138.877NSBR2-D02 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 4.28% 4.03% 4.28% 1.60 OK 0.49 10.00 251.97 1000 OK 0.20 0.98 -4.28% 1144.389 1139.252NSBR2-D03 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 1.42% 1.07% 1.42% 0.93 OK 0.16 10.00 83.88 1000 OK 0.20 0.98 -1.42% 1138.453 1137.883NSBR2-D04 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 0.04% 0.29% 0.50% 0.55 OK 0.82 10.00 29.43 1000 OK 0.20 0.98 -0.50% 1139.541 1138.541NSBR2-D05 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 0.49% 0.22% 0.50% 0.55 OK 1.47 10.00 29.43 1000 OK 0.20 0.98 0.50% 1140.348 1141.961NSBR2-D06 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 0.49% 0.46% 0.50% 0.55 OK 1.47 10.00 29.43 1000 OK 0.20 0.98 0.50% 1140.220 1141.894NSBR2-D07 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 0.13% 1.74% 1.74% 1.02 OK 0.10 10.00 102.42 1000 OK 0.20 0.98 1.74% 1138.760 1138.727NSBR2-D08 3 Concrete 0.5 0.20 0.60 0.013 0.30 1.54 0.5% 0.13% 0.76% 0.76% 0.68 OK 0.10 10.00 44.97 1000 OK 0.20 0.98 0.76% 1138.760 1138.727

Namanve South B R1

Namanve South B R2

23

6.3 Appendix C1 - Water Surface Profile Plots for Culverts along Road South B R1

24

Appendix C1 - Water Surface Profile Plots for Culverts along Road South B R1

25

26

Documents

Namanve Drainage Report