1. 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)

2. 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

3. OBJECTIVES Specifically the study will:- i. Quantify loadings of pollution from the residential catchment ii.Determine the first flush phenomenon

4. METHODS I. Measurement of rainfall, streamflow and water qualityrainfall II. Analysis of samples for BOD 5, COD, SS, Nutrients (NO 3 -N, NO 2 -N, NH 3 -N, P).

5. STUDY SITE Taman Universiti

6. N TAMAN UNIVERSITI – JALAN PERTANIAN Study catchment Legend Residential area Rain gauge Pervious areaCatchment boundary Pavement roads Drainage network Monsoon drain Scale 1 : 4,200 Catchment outlet N = 1º 32’ 24” E = 103º 37’ 6” Figure 1: Residential catchment

7. Physiographical conditions of sub catchment Land use Low 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/km 2 ) 78.3

8. Outlet for the residential catchment Sampling point

10. ANALYSIS AND RESULTS

11. Rainfall characteristics of monitored storms Event measured Rainfall (mm) Intensity (mm/hr) Days since last storm (hr) * 8-Nov-03 * 11-Nov-03 11-Jan-04 2-Mar-04 4-Mar-04 6-Mar-04 12-July-04 8-Sept-04 4-Nov-04 27-Dec-04 - 1.52 18.8 2.8 19 6.8 65 8 - 3.5 2.5 16 9.3 16 8.8 27 9.6 - 120 23 45 46.4 24 50 21 - Note:* rain gauge was not installed yet

12. EVENT MEAN CONCENTRATION (EMC) EMC – total constituent mass discharged, during an event, divided by the total runoff volume of the event. EMC = M =  Q i C i /  Q i (1) V Q i is the time - variable flow and C i is the time - variable concentration

13. Event Means Concentration (EMC) SiteEventsBOD 5 (mg/l) COD (mg/l) SS (mg/l) NO 3 -N (mg/l) NO 2 -N (mg/l) NH 3 -N (mg/l) P (mg/l) Residential8-Nov-03732382740.690.020.661.11 11-Nov-03541362590.070.030.730.6 11-Jan-048529610240.910.138.77.3 2-Mar-041906757423.90.0677.8 4-Mar-041233162593.30.079.121.24 6-Mar-041567283741.70.823.63.44 12-July-0468181856-0.370.93 8-Sept-0439981520.17-0.374.52 4-Nov-0447118213.7-0.80.01 27-Dec-041133204053.1-3.71.6 SMC953113642.40.13.53

14. Pollutographs and hydrographs in the residential catchment

15. 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 (m 3 ) EMC, event mean concentration (mg/l)

16. Event pollutant loadings for the residential catchment ParametersLoading (kg/ha) Range Mean BOD 5 COD SS NO 3 -N NO 2 -N NH 3 -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

17. 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 (m 3 ) and V is total volume of flow over the entire event duration (m 3 ).

18. 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.

19. Mass Volume, M(V) ratios of BOD, COD, SS, NO 3 -N, NO 2 -N and NH 3 -N in the residential catchment

20. Cumulative load at 20-30% of the runoff volume in the residential catchment BODCODSSNO 3 -NNO 2 -NNH 3 -NP Min Max Mean 0.2 0.59 0.4 0.15 0.69 0.42 0.15 0.78 0.47 0.14 0.49 0.3 0.14 0.19 0.17 0.23 0.53 0.38 0.23 0.43 0.33

21. 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> BOD 5 > NH 3 -N> P> NO 3 -N> NO 2 -N.

24. A rain gauge installed on roof top in the residential catchment