ROLE OF ROADS AND WATER CONTROL STRUCTURES ON POLDER WATER MANAGEMENT MD. IBNUL HASAN MASTER OF SCIENCE IN ENVIRONMENTAL ENGINEERING DEPARTMENT OF CIVIL ENGINEERING BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY DHAKA, BANGLADESH AUGUST, 2018 i ROLE OF ROADS AND WATER CONTROL STRUCTURES ON POLDER WATER MANAGEMENT by MD. IBNUL HASAN A thesis submitted for the partial fulfillment of the requirements for the Degree of MASTER OF SCIENCE IN ENVIRONMENTAL ENGINEERING DEPARTMENT OF CIVIL ENGINEERING BANGLADESH UNIVERSITY OF ENGINEERING AND TECHNOLOGY DHAKA, BANGLADESH AUGUST, 2018 ii iii iv Dedicated To My Loving Parents v ACKNOWLEDGEMENT First of all, the author likes to express his deepest gratitude to the gracious Almighty Allah for His unlimited kindness and blessings to fulfill the thesis work successfully. The author wishes to express his heartiest gratitude and sincere thanks to his supervisor Dr. Rowshan Mamtaz, Professor, Department of Civil Engineering, BUET for her proper guidance, invaluable suggestions and continuous supervision at all stage of this research work. The author is indebted to her for his affectionate encouragement and endless contribution to new ideas and helpful co-operation throughout the thesis work. The author also appreciates her sincere effort, which came to a great help to write this thesis. The author also likes to gratefully acknowledge the support and assistance provided by Dr. Cecilia Borgia from MetaMeta, Netherlands and Anika Tahsin from IWFM, BUET. The author also likes to thank Mr. Rahul Dev Paul, Mr. Subrata Paul and Mr. Fahim Hasan for their assistance. The author likes to express a very special indebtedness to his parents whose encouragement and support was a continuous source of inspiration for this work. Finally, the author likes to thank all who helped him in making a successful and a productive completion of the thesis. BUET, Bangladesh Md. Ibnul Hasan August, 2018 vi ABSTRACT Bangladesh is a delta formed by the alluvial deposits of three mighty rivers the Ganges, the Brahmaputra and the Meghna. Bangladesh has been suffering from the twin problem of ‘floods and droughts’ for centuries and it’s also one of the most climate vulnerable countries in the world. From 1960, 19 big cyclones have hit the coast of Bangladesh. To protect the coast from recurrent natural disaster like floods, cyclones and storm surges along with salinity intrusion and sedimentation, the government of Bangladesh constructed 139 polders in the coastal area of Bangladesh. The immediate socio-economic consequences of these polders were very impressive and positive and that positive situation persisted for about two decades. But construction of embankments and unplanned roads within the polder disrupted the drainage system by blocking canals and rivers. This created a massive waterlogging problem within the polders. This study was carried out mainly to find out the opportunity of roads and drainage structures in polder water management within the coastal polders of Bangladesh. To perform the study, two polders were selected. Polder 26 was selected for its massive waterlogging problem within the Polder. Polder 43/2F was selected because it has uneven land elevation within the polder, some areas are high and some low lands. The specific objective for polder 26 was to reduce waterlogging mainly by using roads and water crossing structures. And for polder 43/2F, the specific objective was to find out how roads and water crossing structures can be used to control water flow and store water in high lands for dry season irrigation. A physical survey, several (around 60) House Hold Survey, 2 Focus Group Discussions (FGDs) and 2 Key Informant Interviews (KIIs) were carried out in each selected polder areas. The goals of these surveys were to find out the existing condition of the polders, impacts of waterlogging in farming and other activities, problems related to roads and water within the polder and possible solutions of those problems in priorities. A catalogue of issues and solutions related to road - water interactions is developed based on the survey findings and outcomes of FGDs and KIIs. The study findings show that the overall scenario of road condition and water management within the two selected polders is not good. Most of the roads are earthen or broken. Both polders have waterlogging problem but it has become severe in polder 26. In polder 26, Farmers are facing crop failures (almost every year) and they have to abandon some portions of their cultivable land, in some cases up to 85 percent, because of waterlogging. To solve these problems, this study gives some recommendations such as improve the siting and size of water crossings, re-excavate khals to reconnect drainage ways, use (more) gated water crossings to retain and control water, improve the quality of roads and carpeting, improve collaboration between Bangladesh Water Development Board (BWDB) and Local Government Engineering Department (LGED), improve shelter function of embankments etc. Implementation of those recommendations will free a huge area from waterlogging and will improve the communication vii system. As a result, there will be a positive change in farming activities. And the increased farmland and improved farming activity will increase amount of yields which will bring a big change in the local economy. Finally, a simple design analysis (using rational method) was performed to calculate proper dimensions for internal culverts in polder 26. Rainfall data was collected from Bangladesh Metrological Department and Log Pearson Type III distribution was used to calculate rainfall intensity. From the recommended design dimensions (Table 6.3), it was found that three existing culverts (C2, C5, C7) are of inadequate sizes. To facilitate proper drainage in those locations, at least the recommended size (for 20 years return period and 3 days rainfall) should be provided. Moreover, the Polder needs at least 6 more culverts in stated locations to reduce waterlogging. Implementations of those recommended culverts will improve drainage in 5628 acre agricultural land. And if the improved drainage system can decrease 50% of the current cop loss then the total financial benefit will be USD 290, 823. viii TABLE OF CONTENTS Page No. ACKNOWLEDGMENTS vi ABSTRACT vii CONTENTS ix LIST OF TABLES xi LIST OF FIGURES xii LIST OF PHOTOS xiii LIST OF ABBREVIATIONS xiv Chapter 1 : INTRODUCTION 1-4 1.1 Background 1 1.2 Objective of The Study 2 1.3 Scope of The Study 3 1.4 Organization of The Thesis 4 Chapter 2: REVIEW OF LITERATURE 5-33 2.1 Introduction 5 2.2 Polder 5 2.3 Polders in Bangladesh 6 2.4 Polder Water Management 10 2.4.1 Waterlogging problem in polders 11 2.4.2 Prevention and mitigation of waterlogging 12 2.4.3 Governance and water management structure of 13 polders in Bangladesh 2.5 Roads 14 2.5.1 National road classification 15 2.5.2 Role of LGED in road network development 16 2.5.3 Role Of LGIs in road network development 16 2.5.4 LGED road design standards 17 2.6 Water Crossing Structures 18 2.6.1 Factors influencing effective drainage through culverts 19 2.6.2 LGED design standards for culverts and bridges 22 2.6.3 Hydrological considerations for design of culverts 23 2.7 Role of Roads in Water Management 26 2.7.1 Opportunity of road designs in water management 28 Chapter 3: METHODOLOGY 34-39 3.1 Introduction 34 3.2 Site Selection 34 3.3 Data Collection 36 3.3.1 Primary data collection 36 3.3.2 Secondary data collection 38 ix 3.4 Design Adequacy Test of Culverts 39 Chapter 4: BASELINE STUDY OF POLDERS 40-48 4.1 Introduction 40 4.2 Polder 26 40 4.2.1 Environmental and social baseline 42 4.2.2 Water resources problems 43 4.3 Polder 43/2F 44 4.3.1 Environmental and social baseline 46 4.3.2 Water resources functions and problems 47 Chapter 5: RESULTS AND DISCUSSION 49-97 5.1 Introduction 49 5.2 Survey Findings 49 5.2.1 Polder 26 49 5.2.2 Polder 43/2F 61 5.3 Findings of FGD and KII 72 5.3.1 FGDs (Focus Group Discussions) 73 5.3.2 Findings from Key Informant Interview (KII) 79 5.4 Road – Water Management Issues and Solutions 80 5.4.1 Discussion on Polder 26 81 5.4.2 Discussion on Polder 43/2F 89 Chapter 6: DESIGN OF WATER CROSSING STRUCTURES 98-108 6.1 Introduction 98 6.2 Data Collection and Processing 98 6.2.1 Rainfall intensity 99 6.2.2 Catchment area 100 6.2.3 Runoff coefficient (C) 100 6.2.4 Culvert dimension calculation 101 6.3 Sample Calculation 102 6.4 Recommended Design Dimensions of Culverts 104 6.5 Financial Benefits of Recommended Culvert Implementations 105 Chapter 7: CONCLUSION 109-111 7.1 Conclusion 109 7.2 Recommendations 110 REFERENCES 112-117 ANNEX A Questionnaire (Physical Inventory) 118-126 ANNEX B Questionnaire (House Hold Semi-Structured Interview) 127-134 ANNEX C Questionnaire (Focus Group Discussions – UP/WMGs) 135-136 ANNEX D Questionnaire (Key Informant Interview- BWDB/BG) 137-138 ANNEX E Questionnaire (Key Informant Interview- LGED) 139-140 x LIST OF TABLES Table No. TITLE Page No. Table 2.1 National Road Classification (LGED, 2005) 15 Table 2.2 Bridge Carriageway Widths (LGED, 2005) 23 Table 2.3 RCC Box Culvert Carriageway Widths (LGED, 2005) 23 Table 2.4 Typical gaps by type of road, meters per kilometer (LGED, 23 2005) Table 2.5 Frequency factors to convert rainfall 26 Table 4.1 Water quality parameters of different water bodies in the 43 polder 26 Table 4.2 Water quality parameters of different water bodies in the 47 polder 43/2F Table 5.1 FGDs details for Polder 26, Dumuria, Khulna 73 Table 5.2 FGDs details for Polder 43/2F, Guilshakhali, Barguna 73 Table 5.3 Details of Key Informant Interviews (KIIs) 79 Table 6.1 Rainfall Intensity for different Duration and Return Period 99 Table 6.2 Runoff Coefficients for Rational Formula (From Michigan 100 State Administrative Rules R 280.9) Table 6.3 Recommended Design Dimensions of Culverts for Polder 26 104 Table 6.4 Land Use of Polder 26 105 Table 6.5 Benefits of Culvert Implementation 108 xi LIST OF FIGURES Figure No.