Assessing Cumulative Watershed Effects by Zig-Zag Pebble Count Method

ASSESSING CUMULATIVE WATERSHED EFFECTS BY ZIG-ZAG PEBBLE COUNT METHOD TIMOTHY NEX BETIN UNIVERSITI TEKNOLOGI MALAYSIA i ASSESSING CUMULATIVE WATERSHED EFFECTS BY ZIG-ZAG PEBBLE COUNT METHOD TIMOTHY NEX BETIN A project report submitted as a partial fulfilment of the requirement for award of the degree of Masters in Engineering (Civil-Environmental Management) Faculty of Civil Engineering Universiti Teknologi Malaysia JULY, 2006 v ABSTRACT Cumulative effects are the combined effects of multiple activities for example such as agricultural activities, logging activities, unpaved roads, grazing and recreation, while the watershed effects are those which involve processes of water transport. Almost all impacts are influenced by multiple activities, so almost all impacts must be evaluated as cumulative impacts rather than as individual impacts. This paper attempts to present and discuss the cumulative effects occur within the Endau watershed, current issues on water resource planning and management and the approaches/strategies required to confront present and emerging critical problems. In this study, the deposition of fine sediment (particle size < 8 mm) are main concern because this can adversely affect macro-invertebrates and fish by filling pools and interstitial spaces, decreasing inter-gravel dissolved oxygen concentrations, and inhibiting fish fry emergence. The bed material particle-size distribution is believed to be one of the first channel characteristics to change in response to management activities. This study was carry out on Jasin River as reference stream while Mengkibol River and Sembrong River and as study stream. The method for assessing these CWEs is by using Zig-Zag pebble count method. As result, the sediment loading is in the order of Sembrong River > Mengkibol River > Jasin River. As the Sembrong River is heavily silted, sediment transport process is expected to be more active here compared to the Mengkibol River. For the Jasin River, due to the presence of much larger material, movement of fine particles is impeded thus minimizing sediment transport. From the study, it suggests that agricultural erosion is the primary sediment source due to the large areas involved and the land disturbance effects of cultivation. This follows up by urban erosion due to sediment originates mainly from exposed soils in areas under construction and from street dust and litter accumulation on impervious surfaces. vi ABSTRAK Kesan kumulatif legeh adalah kesan terkumpul pelbagai aktiviti penggunaan tanah seperti aktiviti pertanian, pembalakkan, tanah tak berturap dan reakreasi. Manakala kesan legeh pula adalah kesan yang melibatkan proses pengangkutan air. Hampir keseluruhan impak adalah kesan daripada kepelbagaian aktiviti penggunaan tanah. Maka, keseluruhan impak ini haruslah dinilai sebagai satu kesan kumulatif. Tujuan kertas kerja ini adalah untuk membentangkan serta membincangkan kesan kumulatif legeh yang terjadi di Legeh Sungai Endau, isu semasa dalam pengurusan dan perancangan sumber air serta masalah-masalah yang timbul berikutan daripada impak berkenaan. Untuk kajian ini, taburan endapan (partikel bersaiz kurang daripada 8 mm) telah dinilai kerana ia menyumbangkan kesan negetif terhadap hidupan macro-invertebrat serta ikan dengan memenuhi ruangan paya, mengurangkan kandungan oksigen terlarut dalam air serta menghalang kemunculan anak ikan. Kajian ini dijalankan di Sungai Jasin (sungai rujukan) dan Sungai Mengkibol serta Sungai Sembrong (sungai yang dikaji). Kaedah yang digunakan untuk menilai kesan kumulatif legeh ini adalah dengan “Zig-Zag Pebble Count Method”. Daripada hasil kajian, beban endapan adalah dalam turutan Sungai Sembrong > Sungai Mengkibol > Sungai Jasin. Sumber utama endapan ini adalah berpunca daripada kakisan pertanian. Aktiviti pertanian adalah merupakan salah satu aktiviti utama yang menjadi punca endapan di Malaysia, maka banyak kawasan hutan telah giat diterokai serta diusahakan untuk aktiviti pertanian. Seterusnya, ini diikuti dengan hakisan urbanisasi dimana endapan berpunca daripada aktiviti pembinaan di kawasan persekitaran yang sedang dibangunkan terutamanya daripada tanah yang terdedah. Sesungguhnya ini telah menyumbangkan beban endapan yang tinggi terhadap Sungai Sembrong dan Sungai Mengkibol. vii CONTENT CHAPTER SUBJECT PAGE THESIS STATUS VERIFICATION SUPERVISOR VERIFICATION TITLE DECLARATION i DEDICATION ii ACKNOWLEDGEMENTS iii ABSTRACT iv ABSTRAK v CONTENTS vi LIST OF TABLES xii LIST OF FIGURES xiii LIST OF SYMBOLS xiv LIST OF APPENDICES xv viii I INTRODUCTION 1.1 Research Background 1 1.2 Problem Statement 3 1.3 Study Area Description 4 1.3.1 Kluang District 4 1.3.2 Endau Rompin National Park 5 1.4 Objective of the Study 6 1.5 Scope of the Study 7 II LITERATURE STUDY 2.0 Introduction 8 2.1 Introduction to Cumulative Watershed Effects (CWEs) 9 2.1.1 Definition of Cumulative Effects 10 2.1.2 History of Cumulative Watershed Effects 11 2.1.3 Potential Stream Impact by Cumulative Watershed Effects 13 2.2 Erosion, Transport, and Deposition of Sediment in Channels 16 2.2.1 Bank and Channel Erosion 16 2.2.2 Channel Sediment Transport 19 2.2.3 Sediment Deposition in Channels 20 2.3 Impacts on Fisheries Resources and Aquatic Communities 22 2.3.1 Flow Characteristics 23 2.3.2 Channel Morphology 25 2.3.3 Water Quality 28 ix 2.3.4 Food Resources 30 2.3.5 Predation and Fishing Pressure 31 2.4 Assessment of Cumulative Watershed Effects 32 2.5 Local Watershed Management 35 2.5.1 Impact of Landuse Activities on Soil Erosion in Malaysia 36 2.5.2 Malaysia’s Environmental Legislation, Enforcement and Application 39 III METHODODLOGY 3.0 Introduction 41 3.1 Introduction to Pebble Count Method 43 3.2 Experiment Method 44 3.2.1 Zig-Zag Pebble Count Procedure 44 3.2.2 Using the Procedure in a Watershed Assessment 49 3.3 Sampling Location 52 3.3.1 Jasin River 52 3.3.2 Mengkibol River 52 3.3.3 Sembrong River 53 3.4 Sampling Parameter 53 3.4.1 Parameter 53 3.4.2 Measure a Pebble 54 3.5 Sampling Equipment 55 3.6 Summary of Sampling Activity 55 x IV RESULTS AND DISCUSSION 4.0 Introduction 56 4.1 Data and Results 57 4.1.1 Data Collected by Zig-Zag Pebbles Count Method 57 4.1.2 Reference Reach (Jasin River) vs. Study Reaches (Mengkibol River and Sembrong River) 58 4.1.3 Study Stream: Mengkibol River vs. Sembrong River 60 4.2 Discussion 63 4.2.1 Factors Affecting Sediment Delivery 63 4.2.2 Sediment Problem 64 4.2.3 Mitigation Measure: Integrated River Basin Management Approach 66 4.2.4 Zig-Zag Pebble Count Method for Assessing Cumulative Watershed Effects 70 CHAPTER V CONCLUSIONS 5.1 Conclusions 72 5.2 Recommendations for Future Work 74 xi BIBLIOGRARPHY 75 APPENDICES 90 xii LIST OF TABLES TABLE NO. TITLE PAGE Table 2.1 Summary of Potential Stream Impacts from Human Activities 14 Table 2.2 Comparison of General Procedure for Prediction of CWEs. 34 Table 2.3 Malaysia - GDP Contribution by Sector 37 Table 2.4 Mean Runoff and Soil Loss under Different Ground Cover Vegetation 38 Table 3.1 Wentworth Size Class Midpoint Based on A Log Scale 48 Table 3.2 Summary of Sampling Activity 55 Table 4.1 Data of Distribution Particle Size for Jasin River, Mengkibol River and Sembrong River 57 Table 4.2 Percentage Surface Area Occupied by Various Land Uses in the Districts of Johor 61 xiii LIST OF FIGURES FIGURE NO. TITLE PAGE Figure 3.1 Location of Sampling Sites 42 Figure 3.2 Reach Site Selections for Long-Term Channel Monitoring 46 Figure 3.3 Zig-Zag Pebble Count Method 50 Figure 3.4 Field Data Form 51 Figure 3.5 Measuring a Pebble 54 Figure 4.1 Comparison of Distribution Curve at References (Jasin River) Reach and Study Reach (Mengkibol River and Sembrong River) 58 Figure 4.2 Comparison of Particle Size Distribution at References (Jasin River) Reach and Study Reach (Mengkibol River and Sembrong River) 58 Figure 4.3 Comparison Particle Distribution Curve at Impacted Stream 60 Figure 4.4 Bar Graph Showing Percentage of Particle Size Distribution on Impacted Stream 60 Figure 4.5 Stochastic Representation of the Delivery Ratio Process 64 xiv LIST OF SYMBOLS pr - Proportion of Less 8 mm for Reference Reach ps1 - Proportion of Less 8 mm for Study Reach 1 ps2 - Proportion of Less 8 mm for Study Reach 2 nr - Sample Size for Reference Reach ns - Sample Size for Study Reach f - Factor relating Reference reach to Study Reach for Sample Size yr - Year m - Metre km - Kilometre Ha - Hectare % - Percentage mm - Millimetre oC - Degree Celsius < - Less Than Cum % - Cumulative Percentage BMPs - Best Management Practices CWEs - Cumulative Watershed Effects EQA - Environmental Quality Act, 1974 GDP - Gross Domestic Product CEQ - Council on Environmental Quality xv LIST OF APPENDICES APPENDICE TITLE PAGE A Statistical Framework 91 B Sample Size Estimation 93 C Wolman Pebble Count Procedure 96 D Photo 100 CHAPTER 1 INTRODUCTION 1.1 Research Background In Malaysia, 90% of water resources required for domestic, industrial, and other purposes are derived from surface water with naturally defined watershed. Though the rainfall is considered abundant, due to uncontrolled land-use activities and unsustainable development coupled with poor land-use management policies/strategies, our precious water resource has been subjected to continuous degradation and other negative impacts limiting its utility. This has led to disastrous and/or catastrophic socio-economic events nationally (Johari, 1993) Hence, there is a need to seek systematic management approaches/strategies that will support a sustainable balance between land-use activities and the need to protect our precious resource. This is critical in the long term considering the accelerated growth and the impending socioeconomic development of the country against the growing demand and the rising expectation for adequate and sound water supply for domestic and industrial needs (Ramadasan et al., 1999). 2 In United State, the National Environmental Policy Act requires federal land managers to assess the impact on the environment of any proposed management activities (Thatcher, 1990).

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