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URBAN STORMWATER QUALITY AND LOAD ESTIMATION FROM URBAN RESIDENTIAL AREA IN SKUDAI, JOHOR, MALAYSIA...
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Transcript of URBAN STORMWATER QUALITY AND LOAD ESTIMATION FROM URBAN RESIDENTIAL AREA IN SKUDAI, JOHOR, MALAYSIA...
URBAN STORMWATER QUALITY AND LOAD ESTIMATION FROM URBAN RESIDENTIAL AREA IN
SKUDAI, JOHOR, MALAYSIA
Siti Nazahiyah Bte Rahmat
Faculty of Civil and Environmental Engineering Universiti Tun Hussein Onn Malaysia (UTHM)
INTRODUCTION
Two main impacts of urbanization.
First the hydrology is modified causing more rapid flow
path;
Second, increase of human activities that adds
pollutants.
NPS - need to estimate NPS loads to the receiving watercourses
Crucial for sustainable water resource management
OBJECTIVES
Specifically the study will:-
i. Quantify loadings of pollution from the residential catchment
ii. Determine the first flush phenomenon
METHODS
I. Measurement of rainfall, streamflow and water quality
II. Analysis of samples for BOD5, COD, SS, Nutrients (NO3-N, NO2-N, NH3-N, P).
STUDY SITE
Taman Universiti
N
TAMAN UNIVERSITI – JALAN PERTANIAN
Study catchment
LegendResidential area Rain gaugePervious area Catchment boundaryPavement roads Drainage network
Monsoon drain Scale 1 : 4,200
Catchment outletN = 1º 32’ 24”E = 103º 37’ 6”
Figure 1: Residential catchment
Physiographical conditions of sub catchment
Land useLow cost residential area: high density single-storey
houses
Area (ha) 3.34
Elevation (mas1) 45.5 - 66
Slope (%) 2.53
Drain gradient (%) 1.08
Drainage density (km/km2) 78.3
Outlet for the residential catchment
Sampling point
ANALYSIS AND RESULTS
Rainfall characteristics of monitored storms
Event measuredRainfall (mm)
Intensity (mm/hr)
Days since last storm (hr)
* 8-Nov-03* 11-Nov-0311-Jan-042-Mar-044-Mar-046-Mar-04
12-July-048-Sept-044-Nov-0427-Dec-04
--
1.521.5218.82.8196.8658
--
3.52.5169.3168.8279.6
--
12023 45
46.4245021-
Note:* rain gauge was not installed yet
EVENT MEAN CONCENTRATION (EMC)
EMC – total constituent mass discharged, during an event, divided by the total runoff volume of the event.
EMC = M = QiCi / Qi (1) V
Qi is the time - variable flow and
Ci is the time - variable concentration
Event Means Concentration (EMC)
Site Events BOD5
(mg/l)
COD(mg/l)
SS(mg/l)
NO3-N
(mg/l)
NO2-N
(mg/l)
NH3-N
(mg/l)
P(mg/l)
Residential 8-Nov-03 73 238 274 0.69 0.02 0.66 1.11
11-Nov-03 54 136 259 0.07 0.03 0.73 0.6
11-Jan-04 85 296 1024 0.91 0.13 8.7 7.3
2-Mar-04 190 675 742 3.9 0.06 7 7.8
4-Mar-04 123 316 259 3.3 0.07 9.12 1.24
6-Mar-04 156 728 374 1.7 0.82 3.6 3.44
12-July-04 68 181 85 6 - 0.37 0.93
8-Sept-04 39 98 152 0.17 - 0.37 4.52
4-Nov-04 47 118 21 3.7 - 0.8 0.01
27-Dec-04 113 320 405 3.1 - 3.7 1.6
SMC 95 311 364 2.4 0.1 3.5 3
Pollutographs and hydrographs in the residential catchment
0
2
4
0.0 0.5 1.0Storm Duration (hr)
Con
cent
ratio
n (m
g/L)
0
20
40
Flo
w (
l/s)
NO3-N
Flow
Residential - 6 March 2004
0
0.5
1 Rai
nfal
l (m
m)
0
100
200
0.0 0.4 0.8Storm Duration (hr)
Con
cent
ratio
n (m
g/L)
0
75
150
Flow
(l/s
)
BOD
Flow
Residential - 8 September 2004
0
2
4
Rai
nfal
l (m
m)
0
300
0.0 0.4 0.8Storm Duration (hr)
Con
cent
ratio
n (m
g/L)
0
75
150
Flo
w (
l/s)
SS
Flow
Residential - 8 September 2004
0
2
4
Rai
nfal
l (m
m)
0
300
600
0.0 0.4 0.8Storm Duration (hr)
Con
cent
ratio
n (m
g/L)
0
75
150
Flo
w (
l/s)
COD
Flow
Residential - 8 September 2004
0
2
4
Rai
nfal
l (m
m)
POLLUTANT LOADING
Calculated by the following equation:
L = V x EMC (2)
where, L is unit pollutant loading rate (kg/ha),
V, total volume of flow over entire event duration (m3)
EMC, event mean concentration (mg/l)
Event pollutant loadings for the residential catchment
Parameters Loading (kg/ha)
Range Mean
BOD5
COD
SS
NO3-N
NO2-N
NH3-N
P
0.5-16.5 4.9
1.2-27.5 9
2.2-22 7.5
0.001-1.5 0.35
0.0003-0.01 0.004
0.013-1.2 0.2
0.002-0.14 0.05
FIRST FLUSH PHENOMENON
L = m(t) / M (3)
F = v(t) / V (4)
where L is dimensionless cumulative pollutant mass; m(t) is pollutant mass transport up to time t (g); M is total mass of pollutant over the entire event duration (g); F is dimensionless cumulative runoff volume; v(t) is flow volume up to time t (m3) and V is total volume of flow over the entire event duration (m3).
LITERATURE REVIEW
Bertrand et al. (1998) defined first flush by the fact that at least 80% of the pollutant mass is transported in the first 30% of the volume.
Meanwhile, Wanielista and Yousef (1993) proposed that 50% of the pollutant mass is transported in the first 25% of the volume.
Mass Volume, M(V) ratios of BOD, COD, SS, NO3-N, NO2-N and NH3-N in the residential catchment
BOD - Residential
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Dimensionless Cumulative Flow rate
COD - Residential
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Dimensionless Cumulative Flow rate
SS - Residential
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Dimensionless Cumulative Flow rate
NO3-N - Residential
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Dimensionless Cumulative Flow rate
NO2-N - Residential
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Dimensionless Cumulative Flow rate
NH3-N - Residential
0.0
0.2
0.4
0.6
0.8
1.0
0.0 0.2 0.4 0.6 0.8 1.0
Dimensionless Cumulative Flow rate
Cumulative load at 20-30% of the runoff volume in the residential catchment
BOD COD SS NO3-N NO2-N NH3-N P
MinMax
Mean
0.20.590.4
0.150.690.42
0.150.780.47
0.140.490.3
0.140.190.17
0.230.530.38
0.230.430.33
CONCLUSION
By comparison to the Interim National Water Quality Standards for Malaysia, the stormwater quality from the urban residential catchment was severely polluted with major parameters generally exceeded the acceptable limits for class V water;
EMC for all parameters were found to vary greatly between storms;
FF phenomena were detected in this study. The relative strength of the first flush was: SS> COD> BOD5> NH3-N> P> NO3-N> NO2-N.
A rain gauge installed on roof top in the residential catchment