Title Page
Contents
ABSTRACT 14
Chapter 1. Introduction 16
1.1. Background and Research Necessity 16
1.2. Objectives and Scope 20
1.3. Study Procedure 20
Chapter 2. Literature Review 23
2.1. Stream drying phenomenon and contributing factors 23
2.2. Watershed based hydrological and water quality model 25
2.3. Wasterwater reuse and treatment 27
Chapter 3. Assessment of stream drying phenomenon using SWAT 28
3.1. Study area 28
3.2. Building a dataset of factors contributing to stream drying phenomenon 29
3.2.1. Groundwater use 29
3.2.2. Forest growth 31
3.2.3. Urban development 34
3.2.4. Soil erosion 35
3.3. SWAT application and modification for stream drying phenomenon 42
3.3.1. Model description 42
3.3.2. Model modification and application 47
3.3.3. Model calibration 54
3.4. Assessment of stream drying phenomenon based on DSI 67
3.4.1. Drying Stream Index (DSI) 67
3.4.2. DSI result 68
3.5. Detailed modeling approach for small-scale watershed 71
3.5.1. Study area 71
3.5.2. Detailed modeling approach 75
3.5.3. Model calibration and the evaluation for modification 78
3.6. Comprehensive analysis on stream drying phenomenon 87
3.6.1. Evaluation based on DSI and field survey 87
3.6.2. Influence of stream drying factors 93
3.6.3. Contribution rate of stream drying factors 107
Chapter 4. Recovery by the diversion of retreated sewage 112
4.1. Environmental improvement flow 112
4.2. Wastewater reuse plant and beneficiary stream 117
4.2.1. Wastewater reuse plant 117
4.2.2. Beneficiary stream 126
4.3. Determination of EIW discharge scenario 130
4.3.1. EIW discharge scenario 130
4.3.2. Recovery from stream drying by the diversion of retreated sewage 135
4.3.3. Adjustment of treatment efficiency for EIW discharge 141
Chapter 5. Conclusion 145
5.1. Summary and conclusion 145
5.2. Recommendations for future work 150
References 152
Appendices 159
Appendix A.1. Field survey at the upstream in JR watershed. 159
Appendix A.2. Field survey at the Gwangsacheon in JR watershed. 159
Appendix A.3. Field survey at the Eoduncheon in JR watershed. 160
Appendix A.4. Field survey at the Minrakcheon in JR watershed. 160
Appendix A.5. Field survey at the Buyongcheon in JR watershed. 161
Appendix A.6. Field survey at the Baekseokcheon in JR watershed. 161
Appendix A.7. Field survey at the Shinwoncheon in GA watershed. 162
Appendix A.8. Field survey at the Shindaecheon in GA watershed. 162
Appendix A.8. Field survey at the Yeongmuncheon in GA watershed. 163
Appendix A.9. Field survey at the Geumeocheon in GA watershed. 163
Appendix A.10. Field survey at the Jubukcheon in GA watershed. 164
Appendix A.11. Field survey at the Daedaecheon in GA watershed. 164
Appendix A.12. Field survey at the Yangjicheon in GA watershed. 165
Appendix A.13. Field survey at the Geumhakcheon in GA watershed. 165
Appendix A.14. Field survey at the upstream of Gyeongancheon in GA watershed. 166
Appendix A.15. Field survey at the upstream of Juksancheon in JS watershed. 166
Appendix A.16. Field survey at the Janggyecheon in JS watershed. 167
Appendix A.17. Field survey at the Yongseolcheon in JS watershed. 167
Appendix B.1. Monthly analysis on ET change in JR watershed under stream drying scenarios 168
Appendix B.2. Monthly analysis on surface runoff change in JR watershed under stream drying scenarios 168
Appendix B.3. Monthly analysis on lateral flow change in JR watershed under stream drying scenarios 168
Appendix B.4. Monthly analysis on baseflow change in JR watershed under stream drying scenarios 169
Appendix B.5. Monthly analysis on groundwater recharge change in JR watershed under stream drying scenarios 169
Appendix B.6. Monthly analysis on SS change in JR watershed under stream drying scenarios 169
Appendix B.7. Monthly analysis on T-N change in JR watershed under stream drying scenarios 170
Appendix B.8. Monthly analysis on T-P change in JR watershed under stream drying scenarios 170
Appendix B.9. Monthly analysis on ET change in GA watershed under stream drying scenarios 170
Appendix B.10. Monthly analysis on surface runoff change in GA watershed under stream drying scenarios 171
Appendix B.11. Monthly analysis on lateral flow change in GA watershed under stream drying scenarios 171
Appendix B.12. Monthly analysis on baseflow change in GA watershed under stream drying scenarios 171
Appendix B.13. Monthly analysis on groundwater recharge change in GA watershed under stream drying scenarios 172
Appendix B.14. Monthly analysis on SS change in GA watershed under stream drying scenarios 172
Appendix B.15. Monthly analysis on T-N change in GA watershed under stream drying scenarios 172
Appendix B.16. Monthly analysis on T-P change in GA watershed under stream drying scenarios 173
Appendix B.17. Monthly analysis on ET change in JS watershed under stream drying scenarios 173
Appendix B.18. Monthly analysis on surface runoff change in JS watershed under stream drying scenarios 173
Appendix B.19. Monthly analysis on lateral flow change in JS watershed under stream drying scenarios 174
Appendix B.20. Monthly analysis on baseflow change in JS watershed under stream drying scenarios 174
Appendix B.21. Monthly analysis on groundwater recharge change in JS watershed under stream drying scenarios 174
Appendix B.22. Monthly analysis on SS change in JS watershed under stream drying scenarios 175
Appendix B.23. Monthly analysis on T-N change in JS watershed under stream drying scenarios 175
Appendix B.24. Monthly analysis on T-P change in JS watershed under stream drying scenarios 175
Appendix C. DSI result calculated for standard unit 176
Abstract (in Korean) 181
Table 1. Nationwide forest survey information and forest height analysis result. 31
Table 2. Linear regression equation and correlation value for 16 weather stations. 37
Table 3. Land cover types and their assigned C factor values. 39
Table 4. P factor assigned by land cover type and slope gradient. 40
Table 5. Legends for land use map overlaid with 1980s and 2010s land cover data 52
Table 6. Criteria standard for evaluating model performance. 54
Table 7. Parameters used for model calibration. 56
Table 8. DSI classification and description. 68
Table 9. Sources of agricultural reservoirs in JS watershed. 77
Table 10. The variation of hydrology and water quality in the 2010s scenario at JR watershed. 96
Table 11. The variation of hydrology and water quality in the GU scenario at JR watershed. 96
Table 12. The variation of hydrology and water quality in the FG scenario at JR watershed. 96
Table 13. The variation of hydrology and water quality in the UD scenario at JR watershed. 97
Table 14. The variation of hydrology and water quality in the SE scenario at JR watershed. 97
Table 15. The variation of hydrology and water quality in the 2010s scenario at the watershed of Gyeongancheon upstream. 99
Table 16. The variation of hydrology and water quality in the GU scenario at the watershed of Gyeongancheon upstream. 99
Table 17. The variation of hydrology and water quality in the FG scenario at the watershed of Gyeongancheon upstream. 99
Table 18. The variation of hydrology and water quality in the UD scenario at the watershed of Gyeongancheon upstream. 100
Table 19. The variation of hydrology and water quality in the SE scenario at the watershed of Gyeongancheon upstream. 100
Table 20. The variation of hydrology and water quality in the 2010s scenario at JS watershed. 102
Table 21. The variation of hydrology and water quality in the GU scenario at JS watershed. 102
Table 22. The variation of hydrology and water quality in the FG scenario at JS watershed. 102
Table 23. The variation of hydrology and water quality in the UD scenario at JS watershed. 103
Table 24. The variation of hydrology and water quality in the SE scenario at JS watershed. 103
Table 25. Influence of stream drying factors on Q355 and their contribution rate to stream drying in JR watershed. 109
Table 26. Influence of stream drying factors on Q355 and their contribution rate to stream drying in GA watershed. 110
Table 27. Influence of stream drying factors on Q355 and their contribution rate to stream drying in JS watershed. 111
Table 28. Analysis result of required flow rate, EIW, and retaining day for three target watershed. 113
Table 29. Treatment capacity and reuse information of WTP in JR watershed. 119
Table 30. Treatment efficiency of WTP in JR watershed. 119
Table 31. Validity verification based on the concentration criteria of EIW discharge performed for WTP in JR watershed. 119
Table 32. Treatment capacity and reuse information of WTPs in GA watershed. 122
Table 33. Treatment efficiency of WTPs in GA watershed. 122
Table 34. Validity verification based on the concentration criteria of EIW discharge performed for WTPs in GA watershed. 122
Table 35. Treatment capacity and reuse information of WTPs in JS watershed. 125
Table 36. Treatment efficiency of WTPs in JS watershed. 125
Table 37. Validity verification based on the concentration criteria of EIW discharge performed for WTPs in JS watershed. 125
Table 38. DSI, field survey, and urban area of streams in JR Watershed. 127
Table 39. DSI, field survey, and urban area of streams in GA Watershed. 128
Table 40. DSI, field survey, and urban area of streams in JS Watershed. 129
Table 41. Evaluation of recovery from stream drying under daily discharge and best scenario. 135
Table 42. Periodical variation of EIW discharge under daily discharge and the best scenario in JR watershed. 140
Table 43. Periodical variation of EIW discharge under daily discharge and the best scenario in GA watershed 140
Table 44. Periodical variation of EIW discharge under daily discharge and the best scenario in JS watershed 140
Table 45. Concentration change of water quality in beneficiary stream in JR watershed based on the best scenario and the improvement of treatment efficiency. 143
Table 46. Concentration change of water quality in beneficiary stream in GA watershed based on the best scenario and the improvement of treatment efficiency. 143
Table 47. Concentration change of water quality in beneficiary stream in JS watershed based on the best scenario and the improvement of treatment efficiency. 143
Figure 1. Research framework displaying the study procedure of this study. 22
Figure 2. Description of study area. 29
Figure 3. Periodic groundwater use of the Han River basin: (a) 1980s, (b) 1990s, (c) 2000s, (d) 2010s. 30
Figure 4. Distribution map of periodic forest height of the Han River basin: (a) 1980s, (b) 1990s, (c) 2000s, (d) 2010s. 32
Figure 5. Correlation anlaysis result between forest growth and changes in LAI. 33
Figure 6. Periodic leaf area index (LAI) distribution map of the Han River basin: (a) 1980s, (b) 1990s, (c) 2000s, (d) 2010s. 34
Figure 7. Periodic land cover map of the Han River basin: (a) 1980s, (b) 1990s, (c) 2000s, (d) 2010s. 35
Figure 8. Flow chart of estimating soil erosion and deposition. 36
Figure 9. The regression result of the rainfall energy factor and annual precipitation. 37
Figure 10. Rainfall energy factor map of the Han River basin: (a) 1980s, (b) 1990s, (c) 2000s, (d) 2010s. 38
Figure 11. Periodic sediment yield distribution map of the Han River basin: (a) 1980s, (b) 1990s, (c) 2000s, (d) 2010s. 42
Figure 12. Nitrogen and phosphorus cycling of soil dynamics in SWAT 44
Figure 13. Description of SWAT Input data: (a) gauging stations, (b) DEM, (c) land cover classification, and (d) soil map 46
Figure 14. Schematic description of the concepts for groundwater processes in the original model. 48
Figure 15. Creation of Land Cover Maps Overlaid with 1980s and 2010s Land Cover Data: (a) land use map of 1980s (b) land use map of 2010s (c)... 52
Figure 16. Calibration result of (a) ET, (b) LAI, and (c) soil moisture in SM. 58
Figure 17. Calibration result of (a) ET, (b) LAI, and (c) soil moisture in CM. 59
Figure 18. Calibration result of flow, SS, T-N, and T-P in SYD. 60
Figure 19. Calibration result of flow, SS, T-N, and T-P in HSD. 61
Figure 20. Calibration result of flow, SS, T-N, and T-P in CJD. 62
Figure 21. Calibration result of flow, SS, T-N, and T-P in GCW. 63
Figure 22. Calibration result of flow, SS, T-N, and T-P in YJW. 64
Figure 23. Calibration result of flow, SS, T-N, and T-P in IPW. 65
Figure 24. Calibration result of flow, SS, T-N, and T-P in PDD. 66
Figure 25. DSI result of the Han River basin. 69
Figure 26. Determination of stream drying areas. 70
Figure 27. The description of JR watershed. 71
Figure 28. Periodic condition of (a) groundwater use, (b) forest growth, (c) urban development, and (d) soil erosion in JR watershed. 72
Figure 29. The description of GA watershed. 73
Figure 30. Periodic condition of (a) groundwater use, (b) forest growth, (c) urban development, and (d) soil erosion in GA watershed. 73
Figure 31. The description of JS watershed. 74
Figure 32. Periodic condition of (a) groundwater use, (b) forest growth, (c) urban development, and (d) soil erosion in JS watershed. 74
Figure 33. Beneficiary areas irrigated from three agricultural reservoirs in JS watershed. 76
Figure 34. Calibration points in (a) JR watershed and (b) GA watershed 79
Figure 35. Calibration points in JS watershed. 79
Figure 36. Calibration result of flow, groundwater level, SS, T-N, and T-P in JR watershed. 81
Figure 37. Calibration result of flow, groundwater level, SS, T-N, and T-P in GA watershed. 82
Figure 38. Calibration result of flow, groundwater level, SS, T-N, and T-P in JS watershed 83
Figure 39. Calibration result for storage of (a) Duksan reservoir, (b) Janggye reservoir, and (c) Yongseol reservoir in JS watershed 84
Figure 40. Graphical comparison between original and modified simulation result of groundwater level. 85
Figure 41. Correlation analysis between original and modified SWAT result of groundwater level. 86
Figure 42. DSI result of of tributaries composing JR watershed. 90
Figure 43. DSI result of tributaries composing GA watershed. 91
Figure 44. DSI result of tributaries composing JS watershed. 92
Figure 45. Flow chart of investigating the influence of stream drying factors on water and material cycle based on stream drying scenarios applied to SWAT. 94
Figure 46. Monthly analysis on flow rate change in JR watershed under stream drying scenarios. 104
Figure 47. Monthly analysis on flow rate change in GA watershed under stream drying scenarios. 105
Figure 48. Monthly analysis on flow rate change in JS watershed under stream drying scenarios. 106
Figure 49. Flow duration curves of JR watershed based on stream drying scenarios. 109
Figure 50. Flow duration curves of GA watershed based on stream drying scenarios. 110
Figure 51. Flow duration curves of JS watershed based on stream drying scenarios. 111
Figure 52. Estimation of EIW, required flow, and retaining days in JR watershed. 114
Figure 53. Estimation of EIW, required flow, and retaining days in GA watershed. 115
Figure 54. Estimation of EIW, required flow, and retaining days in JS watershed. 116
Figure 55. Selection of WTPs suitable for discharging EIW in JR watershed. 118
Figure 56. Selection of WTP suitable for discharging EIW in GA watershed. 121
Figure 57. Selection of WTPs suitable for discharging EIW in JS watershed. 124
Figure 58. Determined beneficiary stream in JR watershed. 127
Figure 59. Determined beneficiary stream in GA watershed. 128
Figure 60. Determined beneficiary stream in JS watershed. 129
Figure 61. Identification of watershed-specific value of extreme rainfall using daily precipitation data based on boxplot analysis. 131
Figure 62. Evaluation result of EIW discharge scenarios considering (a) dry day, (b) accumulated rainfall, and (c) accumulated rainfall and discharge... 132
Figure 63. Evaluation result of EIW discharge scenarios considering (a) dry day, (b) accumulated rainfall, and (c) accumulated rainfall and discharge... 133
Figure 64. Evaluation result of EIW discharge scenarios considering (a) dry day, (b) accumulated rainfall, and (c) accumulated rainfall and discharge... 134
Figure 65. Graphical representation of results for daily discharge and the best scenario of EIW supply in JR watershed. 136
Figure 66. Graphical representation of results for daily discharge and the best scenario of EIW supply in GA watershed. 136
Figure 67. Graphical representation of results for daily discharge and the best scenario of EIW supply in JS watershed. 136
Figure 68. Improvement of DIS through EIW discharge in JR watershed. 137
Figure 69. Improvement of DIS through EIW discharge in GA watershed. 138
Figure 70. Improvement of DIS through EIW discharge in JS watershed. 138
Figure 71. Relationship between the improvement of concentration in beneficiary stream and the increase in treat efficiency of wastewater reuse plant for... 144