XXXI IAHR CONGRESS 1397

SEDIMENT TRANSPORT IN KULIM RIVER, MALAYSIA CHANG CHUN KIAT 1, AMINUDDIN AB GHANI 2, NOR AZAZI ZAKARIA 3 and ROZI ABDULLAH 4 1

Research Student, River Engineering and Urban Drainage Research Centre (REDAC), Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia (Tel: +604-5941035, Fax: +604-5941036, e-mail: [email protected]) 2 Assoc. Prof. & Deputy Director, REDAC, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia (Tel: +604-5941035, Fax: +604-5941036, e-mail: [email protected]) 3 Assoc. Prof. & Director, REDAC, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia (Tel: +604-5937788, Fax: +604-5941009, e-mail: [email protected]) 4 Assoc. Prof. & Lecturer, School of Civil Engineering, Engineering Campus, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang, Malaysia (Tel: +604-5937788, Fax: +604-5941009, e-mail: [email protected]) Abstract Kulim River catchment is located in the southern part of the state of Kedah in the northwestern corner of Peninsular Malaysia. Kulim River slopes are steep and the channel elevation drops from 100m down to 18m average mean sea level at the central area of the Kulim River catchment. Currently, the catchment area is undergoing rapid urban development with oil palm and rubber plantation being replaced by rapid urbanization and this will result in discharge and bed erosion increment or scouring and deposition. Frequently floods that occur in Kulim River Catchment has caused extensive damage and inconvenience to the community especially floods event in October 2003 which exceeds 100 year ARI. Hence, previous studies for Kulim River (DID 1996, Yahaya 1999, Lee 2001, Ibrahim 2002, Koey 2003) were conducted to determine the river behavior and the effectiveness of the flood mitigation projects due to the rapid urbanization development. However, previous results of sediment data and river cross section based on the observed data are up to the year 1999. Thus, this paper describes the analyses and evaluation on sediment transport for Kulim River catchment by using newly observed data in 2004. Keywords: Kulim River; Sediment transport; River behavior; Flood mitigation; Bed erosion 1. INTRODUCTION Effect of rapid urbanization has accelerated impact on the catchment hydrology and geomorphology. This development which takes place in river catchment areas will cause dramatic increase in the surface runoff and resulting in higher sediment yield. When this happens, it not only affects river morphology but cause instability in the river channel and it

1398 September 11~16, 2005, Seoul, Korea may also cause serious damage to hydraulic structures along the river and reduce the channel capacity to convey the flood to downstream. Besides, it has also become the main cause for serious flooding in urban areas. Therefore, it is necessary to predict and evaluate the river channel stability due to the existing and future development. This study proceeds at Kulim River in Kedah state, Malaysia, to determine river behaviors and the effectiveness of the flood mitigation projects due to changes made by nature or human. 2. STUDY AREA The study area is located at the southern part of the state of Kedah in the northwestern corner of Peninsular Malaysia (Fig. 1). It lies within the district of Kulim and upstream of Seberang Perai in Penang. Kulim River catchment consists of 15 subcatchments, with the total catchment area of 130km2. Kulim river tributaries, include Tebuan River, Kilang Sago Monsoon Drain, Wang Pinang River, Keladi River and Klang Lama River drain the urban conurbation of Kulim extending from town to the north. Downstream of Kulim town, the catchment comprises mainly rubber and oil palm estate located mainly at the confluences of Kulim River tributaries. The study reach covers about 15km of Kulim River (Fig. 2), from the upstream (CH 11800) to the state boundary between Kedah and Penang (CH 10) and futher 2.5km downstream at the Ara Kuda gauging station (CH 01). At the headwaters, the Kulim catchment is hilly and densely forested and Kulim River arises on the western slopes of Gunung Bongsu Range and flowing in a north-westerly direction, and joined Keladi River in the vicinity of Kulim town. The river slopes are steep and the channel elevation drops from 500m to 20m average mean sea level (amsl) over a distance of 9km. The central area of the catchment is undulating with elevations ranging from 100m down to 18m average mean sea level. The Kulim Structure Plan, 1990-2010 has outlined development strategies for the region. Currently the catchment area is undergoing rapid urban development with oil palm and rubber plantation being replaced by rapid urbanization especially construction for housing estate and on-going 1450 ha Kulim Hi-Tech industrial Park which will cause impacts to the catchment due to the increase of impervious area. Flooding at Kulim River has been attributed to overbank spill from rivers and tributaries arising from a number of causes, such as undersized river channel and drains to cater flood discharge, high channel roughness, bank irregularity and in-river vegetation, siltation, blockages by debris and refuse. Siltation at study area has been identified as one of the common causes of such flooding brought about by soil erosion at constructions sites. Department of Irrigation and Drainage (DID) Kedah has reported that the rivers have to be desilted typically every 2 to 3 years with removal of one metre thick of silt (DID, 1996). 3. STUDY APPROACH In order to study the sediment transport in the study area, it is important to understand sediment transport process which is important in solving river engineering problem. However, the data including river survey geometry data, sediment data and hydrology data were limited

XXXI IAHR CONGRESS 1399 from the previous studies (DID, 1996, Yahaya 1999, Lee 2001, Koey 2003) in Kulim River. Hence, the result from the present study using newly data up to 2004 will be calibrated and validated with the present condition and used to predict river stability for future development. As a result, the main purpose of the present study is to evaluate river stability over a 13 years period by considering the effect of changes in cross section and sediment size. 3.1 SEDIMENT DATA COLLECTION Field measurements were obtained along the selected cross section at several study sites at Kulim River Catchment by using Hydrological Procedure (DID 1976, DID 1979) and recent manuals (Yuqian 1989, USACE 1995, Edwards & Glysson 1999, Lagasse et al. 2001, Richardson et al. 2001). A summary of data collection including flow discharge, suspended load and bed load during April 1999 by Yahaya is shown in Table 1. Data collection including bed material and bed load have been going on from October to December 2004 and January 2005 for sediment transport analysis. 3.2 RIVER SURVEY GEOMETRY DATA The river survey geometry data in September 1991 is provided by Department of Irrigation and Drainage (DID) Kulim/Bandar Bahru. However, field measurements including bed elevation, thalweg and water surface were carried out at several cross sections during October to December 2004. 4. SEDIMENT TRANSPORT ANALYSIS 4.1 SEDIMENT TRANSPORT EQUATION ASSESSMENT The analysis for a total of 16 set of data from Yahaya (1999) based on average size of sediment (d50) have been obtained for four sediment transport equations including Yang, Engelund & Hansen, Ackers & White and Graf equations. The data were analyzed and evaluated using the above sediment transport equations and the result shows that Graf equation yielded the highest percentage of discrepancy ratio (0.5 – 2.0) with 44% followed by Yang equation at 19% (Table 2). These poor performances can be attributed from the difference in sediment availability from the source, composition of sediment and river configuration in Malaysia. Mathematical model, such as FLUVIAL-12 can be used to study sediment transport for a particular river reach. The model is formulated and developed for water and sediment routing in man-made or natural channel (Chang 1993). The combined effects of river hydraulics, sediment transport and river channel changes are simulated for a given flow period. The accuracy of sediment routing depends on the validity of the sediment transport equation used in the model. In order to select a equation for sediment routing, Graf, Yang, Engelund-Hansen, Ackers-White and Meyer-Peter-Muller equation were tested and computed results were compared with the observed data (DID 1991). The simulation results of FLUVIAL-12 (Manning Roughness Coefficient, n = 0.040) shown in Fig. 3 indicates that revised Ackers-

1400 September 11~16, 2005, Seoul, Korea White equation gives better results which best reproduce the observed river profile for CH 5400 to CH 2600. The study show that the simulation results based on FLUVIAL-12 able to predict sediment transport for Kulim River. 4.2 BED MATERIAL SIZE DISTRIBUTIONS The data for bed material were obtained by grab sampling at CH 1000 and CH 01 on April 1999 for the reach 3.5km as shown in Figure 4. Average bed material size (d50) varies from 3.00 mm to 4.00 mm between CH 1000 and CH 01. Figure 5 depicts the field measurement between October 2004 to January 2005 at CH 11800 (Upstream) and CH 1000 (Downstream). The average bed material size (d50) varies from 0.95 mm to 0.70 mm between CH 11800 and CH 1000 for 11.5km reach. The summary of the mean sediment size of bed material is shown in Table 3. The average mean sediment size (d50) at CH 1000 change from very fine gravel (3.60mm) to fine sand (0.70mm) over 5 years period. Urbanization and the sand mining activities in Kulim River catchment may have affected the river equilibrium and caused variation in sediment distribution along the river. 4.3 TYPICAL CROSS SECTION CHANGES The comparison between cross section provided by DID (1991) and field measurement after November 2004 flood show that there has been a change in cross section (Fig. 6). The channel bed profile has gradually reduced within 13 years period. Thalweg at the CH 11800 has changed from 24.58m to 22.85m and thalweg at the CH 1000 has changed from 15.30m to 12.00m. The results of cross section changes showed that steep slope in Kulim River has induced higher discharge. Besides, it is also associated with the spatial variation in sediment transport. The changes in river bed profile may be attribute to the erosion or deposition along the banks or the channel width. 5. CONCLUSIONS River is a dynamic system governed by hydraulic and sediment transport proccess. Over time, the river response by changing in channel cross section, increased or decreased sediment carrying capacity, erosion and deposition along the channel, which affect bank stability and even morphology changes. As a result, sediment size and cross section in Kulim River subjected to significant changes in a 15km reach over 13 years period. However, in order to study morphological changes of Kulim River, a long term-simulation by using mathematical model, FLUVIAL-12 and InfoWorks RS for water and sediment routing, will be developed and tested with field data up to year 2004. The model, which is applicable to alluvial streams with erodible banks, may be employed to simulate stream bed and width changes. This paper has attempted to give an overview of the channel changes and sediment transport phenomena which cause problems with river bank and bed stability in Kulim River. In general the Kulim River is in equilibrium or slightly degrading, that is, being deepened by erosion. Therefore, it is necessary to predict the river channel stability that will happen due to the existing and future development in Kulim River catchments area. As a result, a design for stable channel

XXXI IAHR CONGRESS 1401 for Kulim River based on the long-term simulation by using FLUVIAL-12 and InfoWorks RS model will be made. ACKNOWLEDGEMENTS The authors gratefully acknowledge Department of Irrigation and Drainage (DID) Kulim/Bandar Bahru for providing river survey geometry data and all information about Kulim River catchment and also DID Hydrology & Water Resources Division for providing hydrology data in this study. The authors would also like to thank all undergraduate and postgraduate students and REDAC’s staff for their involvement in completion of this paper. REFERENCES Chang, H. H. (1993). FLUVIAL-12: Mathematical Model for Erodible Channel. San Diego, California. Department of Irrigation and Drainage Malaysia. (1976). River Discharge Measurement By Current Meter – Hydrological Procedure No. 15 Department of Irrigation and Drainage Malaysia. (1977). The Determination of Suspended Sediment Discharge – Hydrological Procedure No. 19 Department of Irrigation and Drainage Malaysia. (1996). Study on Flood Mitigation and Drainage Master Plan for Kulim and its surroundings, Kedah Darul Aman. Department of Irrigation and Drainage Malaysia. (2003). River Sediment Data Collection and Analysis Study. Edwards, T. K. & Glysson G. D. (1999). Field Methods for Measurement of Fluvial Sediment. U.S. Geological Survey Techniques of Water-Resources Investigations, Book, Chapter C2. Ibrahim, N. A. (2002). Evaluation and Development of Sediment Transport Equations for Kinta River Basins, Kulim River and Kerayong River. MSc. Thesis. Penang : Universiti Sains Malaysia. Koay, B. C. (2004). Evaluation of River Equilibrium: Case Study of Kulim River. Final Year Project Thesis. Penang : Universiti Sains Malaysia. Lagasse, P. F., Schall, J. D. & Richardson, E. V. (2001). Stream Stability at Highway Structures, US Department of Transportation, Federal Highway Administration. Publication No. FHWA NHI 01-002 (Hydraulic Engineering Circular No. 20), 3rd Edition Lee, C. B. (2001). Application of River Modeling (Fluvial-12): Case Studies of Kulim River and Melaka River. Final Year Project Thesis. Penang : Universiti Sains Malaysia. Richardson, E. V., Simons, D. B. & Lagasse, P. F. (2001). River Engineering for Highway Encroachments – Highways in The River Enviroment, US Department of Transportation, Federal Highway Administration. Publication No. FHWA NHI 01-004 (Hydraulic Design Series Number 6). United States Army Corps of Engineers. (1995). Sedimentation Investigations of Rivers And Reservoirs. USACE Engineering and Design Manual. Publication No. EM 1110-2-4000.

1402 September 11~16, 2005, Seoul, Korea Yahaya, N. K. (1999). Development of Sediment Rating Curves for Rivers In Malaysia: Case Studies of Pari, Kerayong and Kulim Rivers. MSc. Thesis. Penang : Universiti Sains Malaysia. Yuqian, L. (1989). Manual On Operational Methods for The Measurement of Sediment Transport. World Meteorological Organisation – Operational Hydrology Report No. 29.

XXXI IAHR CONGRESS 1403

Study Site

Table 1. Range of Field Data for Yahaya (1999) Bed Suspende Total No. of Discharge, Width, d50 Load d Load Load Sample Transport Transport Transport Q (m3/s)

Kulim River

16

1.39 - 11.14

B (m) 14.0 18.0

(mm)

Qb (kg/s) Qt (kg/s) Qj (kg/s) 0.07 0.26 0.34 3.00 - 4.00 0.34 6.78 7.08

Table 2. Summary of Sediment Transport Assessment (16 Data) (Yahaya, 1999). Discrepancy Ratio (0.5 – 2.0) Equation No. of data Percentage Yang

3

19

Engelund & Hansen Ackers & White Graf

0 0 7

0 0 44

Table 3. Summary of Mean Sediment Size d50 (mm) Location No. of data Range Upstream CH 1000 (Apr 1999) Downstream CH 0 (Apr 1999) Upstream CH 11800 (2004) Downstream CH 1000 (2004)

8 8 2 4

3-4 3.55 – 4 0.7-1.2 0.55-0.85

Average 3.60 3.75 0.95 0.70

Peninsular Malaysia

Study Area

Fig. 1 Kulim River Catchment and Subcatchment (DID, 1996)

1404 September 11~16, 2005, Seoul, Korea

CH 01 CH 10

CH 1000

CH 5900

CH 3000

CH 8200 Upstream CH 11800

Fig. 2 Kulim River Study Reach

14.5 14.0

Observed (September 1991) Engelund-Hansen

13.5 13.0

Graph Meyer-Peter Muller

Bed Elevation (m)

Yang 12.5

Ackers-White

12.0 11.5 11.0

Manning’s n = 0.040

10.5 10.0

26 00 27 00 28 00 29 00 30 00 31 00 32 00 33 00 34 00 35 00 36 00 37 00 38 00 39 00 40 00 41 00 42 00 43 00 44 00 45 00 46 00 47 00 48 00 49 00 50 00 51 00 52 00 53 00 54 00

9.5

Section No. (CH)

Fig. 3 Simulated bed profile using FLUVIAL-12 model compared to obseved bed profile

XXXI IAHR CONGRESS 1405

(a) Upstream (CH 11800)

(b) Downstream (CH 1000)

Fig. 6 Typical cross section at at CH 11800 and CH 1000 along Kulim River

1406 September 11~16, 2005, Seoul, Korea

100.00

Percentage Passing (%)

90.00 80.00 70.00 60.00 50.00

01.04.1999 02.04.1999 03.04.1999 04.04.1999 05.04.1999 06.04.1999 07.04.1999 08.04.1999 Average

40.00 30.00 20.00 10.00 0.00 0.01

0.10

1.00

10.00

100.00

10.00

100.00

Partical Size (mm)

(a) CH 1000 (Upstream) 100.00

Percentage Passing (%)

90.00 80.00 70.00 60.00 50.00

01.04.1999 02.04.1999 03.04.1999 04.04.1999 05.04.1999 06.04.1999 07.04.1999 08.04.1999 Average

40.00 30.00 20.00 10.00 0.00 0.01

0.10

1.00

Partical Size (mm)

(b) CH 01 (Downstream)

Fig. 4 Distribution of bed material (Yahaya, 1999)

XXXI IAHR CONGRESS 1407

100.00

Percentage Passing (%)

90.00

08.12.2004

80.00 11.01.2005

70.00 Average

60.00 50.00 40.00 30.00 20.00 10.00 0.00 0.01

0.10

1.00

10.00

100.00

Partical Size (mm)

(a) CH 11800 (Upstream) 100.00

Percentage Passing (%)

90.00 80.00

06.10.2004 (10.00am) 06.10.2004 (02.30pm) 08.12.2004

70.00 60.00

11.01.2005 Average

50.00 40.00 30.00 20.00 10.00 0.00 0.01

0.10

1.00

10.00

100.00

Partical Size (mm)

(b) CH 1000 (Downstream) Fig. 5 Distribution of bed material from field measurement between October and December 2004, and January 2005.