Muthurajawela BP-6 25 Conservation Zone
Outer Circular Highway
Muthurajawela BP-7 40 BP-1 50 Buffer Zone Kalu Oya
115 95 75 (4.83) (5.43) (6.01) BP-5 BP-4 BP-3
25 BP-2
Kandy Old Negombo Canal Road 160 BP-9 (4.40)
20
BP-10 Isolation Bund (Crossing Culvert) BP-145 180 BP-11
BP-13 185 (3.81)
BP-15180 10 BP-12 (3.29) Legend
75 Runoff at Max. Water Level (m3/sec) (6.01) Max. Water Level (m) Flow Direction at Max. Water Level
Channel (Runoff Confined) BP-17100 85 BP-16
Channel (Present Condition)
Kelani Ganga
Colombo Negombo Katunayake Road Expressway The Study on Storm Water Drainage Plan Figure 4.16 for the Colombo Metropolitan Region Diagram of Basic Flood Runoff Distribution in the Democratic Socialist Republic of Sri Lanka JAPAN INTERNATIONAL COOPERATION AGENCY in the Kalu Oya Basin (50-year Return
F - 56 Muthurajawela BP-6 10 Conservation Zone
Outer Circular Highway
Muthurajawela BP-7 10 BP-1 25 Buffer Zone Kalu Oya
30 30 30 (2.14) (2.66) (3.45) BP-5 BP-4 BP-3
5 BP-2
Kandy Old Negombo Canal Road 30 BP-9 (1.97)
10
BP-10 Isolation Bund (Crossing Culvert) BP-145 35 BP-11
BP-13 35 (1.83)
BP-1530 5 BP-12 (1.74) Legend
30 Runoff at Max. Water Level (m3/sec) (3.45) Max. Water Level (m) Flow Direction at Max. Water Level
Channel (Runoff Confined) BP-1730 5 BP-16
Channel (Present Condition)
Kelani Ganga
Colombo Negombo Katunayake Road Expressway The Study on Storm Water Drainage Plan Figure 4.17 for the Colombo Metropolitan Region Diagram of Probable Flood Runoff Distribution in in the Democratic Socialist Republic of Sri Lanka the Kalu Oya Basin (50-year Return Period) JAPAN INTERNATIONAL COOPERATION AGENCY
F - 57 Kalu Oya at Negombo Road
200 10-year Return Period
Basic Flood 150 Probable Flood 3
/sec) 110 m /sec 3 100
Runoff (m Volume 2.52 MCM 50 20 m3/sec
0 0 6 12 18 24 30 36 42 48 Time (Hours)
Kalu Oya at Negombo Road
200 25-year Return Period
150 m3/sec Basic Flood 150 Probable Flood /sec) 3 100 Volume 3.18 MCM Runoff (m 50 30 m3/sec
0 0 6 12 18 24 30 36 42 48 Time (Hours)
Kalu Oya at Negombo Road
200 185 m3/sec 50-year Return Period
Basic Flood 150 Probable Flood /sec) 3 100 Volume 3.65 MCM Runoff (m 50 35 m3/sec
0 0 6 12 18 24 30 36 42 48 Time (Hours)
The Study on Storm Water Drainage Plan Figure 4.18 for the Colombo Metropolitan Region Runoff Hydrograph in Kalu Oya at in the Democratic Socialist Republic of Sri Lanka Negombo Road JAPAN INTERNATIONAL COOPERATION AGENCY
F - 58 0
Katunayake
Mapalam Oya Negombo Lagoon Colombo-Katunayake Expressway
Conservation Zone of Muthurajawela Marsh (Retention Area) Attanagalu Oya Gampaha
Ja Ela Old Negombo Canal Improvement Uruwal Oya
Diversion Channel to Muthurajawlera Marsh
Storm Water Retention Area
Buffer Zone
Old Negombo Canal
Hamilton Canal P Kalu Oya Wattala Construction Storm Water Retention Facilities in Urban Area ( )
Outer Circular Wattala Pumping Station Highway and Gate Kelani Ganga
Scale Colombo Kalu Oya Channel Improvement
The Study on Storm Water Drainage Plan Figure 4.19 for the Colombo Metropolitan Region in the Democratic Socialist Republic of Sri Lanka Conceivable Structural Measures for Kalu Oya Basin JAPAN INTERNATIONAL COOPERATION AGENCY
F - 59 Kalu Oya at Inland Retention Area (Return Period 50-year) 2.60
2.50
2.40
2.30
2.20
2.10
K15 2.00 K0
K13 1.90 K14
1.80 Allowable Water Level + 1.67 m K11 1.70 Average Water Level in Retention Area (m)
K16 1.60
K18 1.50
1.40
K19 1.30
1.20 0 50 100 150 200 250 300 350 400 450 500 Retention Area (ha)
The Study on Storm Water Drainage Plan Figure 4.20 for the Colombo Metropolitan Region Relationship between Retention Area and in the Democratic Socialist Republic of Sri Lanka Water Level in the Kalu Oya Basin JAPAN INTERNATIONAL COOPERATION AGENCY
F - 60 Outer Circular Highway 0 Upper Retention Area (89 ha)
ga an G i n a el K
a y
a O
l
E alu
a K
J
Ragama Bridge KO-5 L=50m B=10m Lower Retention Area (360 ha)
L = C 1 h B ,2 an = 0 n 2 0 e 5m m l Im p t L r emen = o prov 3 v al Im ,8 em Can 0 mbo 0 en ego 40m n, B t Old N m, B= ,500 = L= 4 Bridge KO-4 5 L=50m B=20m 0m
Ja Ela Bridge KO-8 L=40m B=10m Wattala ke aya Bridge KO-3 tun Bridge KO-7 -Ka L=50m B=10m bo y L=40m B=10m Bridge KO-2 Legend olom wa Bridge KO-6 C ress l L=50m B=10m Exp ana L=40m B=10m bo C River/Canal gom d Ne Bufferzone Bridge KO-1 Channel Improvement Ol L=45m B=10m River Basin Boundary Conservation Zone of Wattala Gate Town Muthurajawela Marsh Storm Water (Retention Area) Retention Area Conservation Zone of Marsh Conservation Zone of Canal Proposed Bridge Marsh amilton Muthurajawela H Gate (Retention Area) Expressway/Highway
Scale The Study on Storm Water Drainage Plan Figure 4.21 0 1 2 3 km for the Colombo Metropolitan Region Proposed Storm Water Drainage Plan in the Democratic Socialist Republic of Sri Lanka for Kalu Oya Basin JAPAN INTERNATIONAL COOPERATION AGENCY
F - 61 Muthurajawela BP-6 10 Conservation Zone Outer Circular Highway
Kalu Oya Muthurajawela BP-7 15 BP-1 25 Buffer Zone
30 30 30 (1.79) (2.54) (3.44) BP-5 BP-4 BP-3
5 BP-2
Kandy Old Negombo Canal Road 40 BP-9 (1.60)
10
BP-10 Isolation Bund (Crossing Culvert) BP-1435 50 BP-11
BP-13 50 (1.52)
BP-1525 0 BP-12 (1.48) Legend
30 Runoff at Max. Water Level (m3/sec) (3.44) Max. Water Level (m) Flow Direction at Max. Water Level
Channel to be Improved BP-1725 0 BP-16
Retention Area
Kelani Ganga
Negombo Colombo Road Katunayake Expressway The Study on Storm Water Drainage Plan Figure 4.22 for the Colombo Metropolitan Region Diagram of Probable Flood Runoff in the in the Democratic Socialist Republic of Sri Lanka JAPAN INTERNATIONAL COOPERATION AGENCY Kalu Oya Basin (50-year Return Period)
F - 62 0
, 0 m m ,20 25 = 1 .T= L O.C W.
t en em ov pr Im l m ne 0 n 5 ha .= C .T ya .C O .O lu a , W K m ed 0 os 0 p ,8 ro 3 P = L
Scale 0 500 m 1 km Note) W.O.C.T. means width of channel top The Study on Storm Water Drainage Plan Figure 4.23 for the Colombo Metropolitan Region General Plan of Proposed Kalu Oya and in the Democratic Socialist Republic of Sri Lanka Old Negombo Canal Improvement JAPAN INTERNATIONAL COOPERATION AGENCY
F - 63