@phdthesis{oai:sucra.repo.nii.ac.jp:00019392, author = {BANIYA, MAHENDRA BAHADUR}, month = {}, note = {xvii, 136p, Sediment yield from a catchment is a complex phenomenon of weathering, land sliding, glacial and fluvial erosion which depends on geological as well as fluvial characteristics. The bed shear stress (τb), specific stream power (ω), and flow velocity (v) associated with maximum boulder size transport were determined throughout years 2003 to 2011 by using derived lower boundary equation from the available data for Kali Gandaki (KG) River at Setibeni, Syangja located about 5 kms upstream from a hydropower dam. The river transported an average of 40.904±12.453 Mega ton (Mt) of suspended sediment (SS) during the period 2006-2011 and the artificial neural networks (ANNs) predicted the daily SS rate and annual sediment load as 35.190±7.018 Mega tons (Mt) satisfactorily compared to multiple linear regression, nonlinear multiple regression, general power model, log transform models including sediment rating curve (SRC). Fluvial discharge is a principal driver of SS transport in Himalaya mountain. The study basin has three hydrometric stations in main river, four hydrometric stations in its tributaries, and a hydropower reservoir site where suspended sediment transport is measured. This study also analysed relationship of specific discharge of main and tributaries rivers with rainfalls of the main basin and its sub basins together with SS transport. Annual anticlockwise hysteresis loops were developed between specific discharge and rainfall at three hydrometric stations of main KG River, whereas its tributaries namely Aandhi Khola, Seti Khola and Modi Khola followed anticlockwise, and Myagdi Khola showed an eight-shaped hysteresis loop. The clockwise hysteresis loop developed between SS concentration and fluvial discharge was eliminated and changed to linear relationship with the direct runoff discharge. The result showed that about 97% of SS was transported during monsoon season (June-September), comprising an annual weathering rate of KG basin estimated to be 4390 tons/km2/yr which is equivalent to 1.66 mm/yr between the period 2006-2017. Particularly, specific direct runoff discharge and monsoonal daily erosion rate of major rainfall events (>30 mm/day) showed linear increasing trend with rainfall in KG basin. Stream flow alteration is one of the most noticeable effects of rainfall change patterns in this catchment. The study also depicted fluvial flow changing patterns of three hydrometric stations of KG River, four hydrometric stations of tributaries due to changing seasonal and annual rainfall trends in twenty-seven rain gauge stations located between the elevation ranges of 700 to 2744 m MSL of this basin over the period of 1957-2018. Monthly rainfall data were used to examine the rainfall and discharge trends. Mann- Kendall trend test (MKT) test along with Sen’s slope and sequential Mann- Kendall trend (SQMKT) analysis on homogenized time series data were used to evaluate the existence of monotonic trends, magnitude of trend and identify shifting of rainfall trend. Finally, the ecological dynamics of riparian area interact with sediment transport in river system, which plays an active role in riparian vegetation growth in the floodplain. Frequently flood disturbance, extreme floods, sediment transport with nutrients and seeds by fluvial discharge, sediment deposition and erosion phenomena which frequently occurred in the floodplain, changed without vegetation land area to vegetative area and vice versa. The sediment grain size (D50) plays important role in riparian vegetation area coverage in the floodplain. Mathematical models describing vegetation growth in flood plain during short period of time available in literature. However, long-term prediction by modelling and validations of riparian vegetation are still lacking. The long-term prediction of riparian vegetation is important in perspective of floodplain management. In order to cover long-term vegetation growth modelling, a Dynamic Riparian Vegetation Model (DRIPVEM) was coupled with Dynamic Herbaceous Model used to establish the interactive relationship of sediment grain sizes (D50) and riparian vegetation in the two rivers: Narayani River floodplain, Nepal and Kuzuryu River floodplain, Japan. In context of Nepal, the calibration of coupled DRIPVEM, observation of species wise herbs and tree biomass, sediment particle sizes with nutrients availability in the floodplain should be conducted. The riparian vegetation observation and calibration of coupled DRIPVEM and prediction of spatial distribution of riparian vegetation in Narayani floodplain, Nepal would be future perspective of this study., Acknowledgements ................................................................................................... iv Preview ............................................................................................................. v Summary ........................................................................................................... vii Publications ........................................................................................................ x List of Figures .................................................................................................... xi Lists of Tables ................................................................................................... xiv PART I- HYDRAULIC PARAMETERS FOR SEDIMENT TRANSPORT AND SUSPENDED SEDIMENT PREDECTION FOR KALI GANDAKI RIVER BASIN, HIMALAYA, NEPAL ..................................................................................................... 1 ABSTRACT ............................................................................................................ 1 CHAPTER 1. GENERAL INTRODUCTION AND LITERATURE REVIEW ............................................................... 2 1.1 Research background ............................................................................................. 2 1.2 Research objectives ............................................................................................. 7 CHAPTER 2.0 MATERIALS AND METHODS ................................................................................... 8 2.1 Observation site ................................................................................................ 8 2.2 Data collection and acquisition ................................................................................ 10 2.3 Analysis of hydraulic parameters for sediment transport ........................................................ 11 2.4 Model development for suspended sediment predictions ........................................................... 12 2.5 Model performance indicators ................................................................................... 13 CHAPTER 3.0 RESULTS AND DISCUSSION ................................................................................. 15 3.2 Shear stress, Specific stream power and Flow velocity relationship with discharge .............................. 15 3.3 Particle sizes and fluvial discharge relationship .............................................................. 16 3.4 Flood return period estimation by Gumbel’s distribution ....................................................... 20 3.5 Boulder movement mechanisms by high gradient river ............................................................. 21 3.6 Suspended sediment quantification and prediction ............................................................... 23 CHAPTER4.0 GENERAL CONCLUSIONS AND RECOMMENDATIONS ................................................................. 30 4.1 Conclusion ..................................................................................................... 30 4.2 Application of study ........................................................................................... 30 4.3 Recommendations ................................................................................................ 30 PART II- EFFECTS OF RAINFALL ON FLUVIAL DISCHARGE AND SUSPENDED SEDIMENT TRANSPORT IN KALI GANDAKI RIVER BASIN, HIMALAYA, NEPAL .................................................................................................... 31 ABSTRACT ........................................................................................................... 31 CHAPTER 1. GENERAL INTRODUCTION AND LITERATURE REVIEW .............................................................. 32 1.1 Research background ............................................................................................ 32 1.2 Research objectives ............................................................................................ 34 CHAPTER 2.0 MATERIALS AND METHODS .................................................................................. 35 2.1 Observation site ............................................................................................... 35 2.2 Data collection and acquisition ................................................................................ 36 2.3 Analysis of direct runoff discharge and quantification of monthly sediment transport............................ 39 CHAPTER 3.0 RESULTS AND DISCUSSION ................................................................................. 40 3.1 Seasonal fluvial discharge of KG River and its tributaries ..................................................... 40 3.2 Fluvial discharge and rainfall relationship .................................................................... 41 3.3 Suspended sediment, fluvial discharge and direct runoff discharge relationship ................................. 44 3.4 Flow and suspended sediment load duration curve and SS quantification .......................................... 50 3.5 Seasonal, monthly sediment transport and rainfall .............................................................. 51 3.6 Specific direct runoff discharge, erosion rate and rainfall relationship ....................................... 55 CHAPTER4.0 GENERAL CONCLUSIONS AND RECOMMENDATIONS ................................................................. 57 4.1 Conclusion ..................................................................................................... 57 4.2 Application of study ........................................................................................... 57 PART III- RAINFALL TREND ANALYSIS IN KALI GANDAKI RIVER BASIN, HIMALAYA, NEPAL ..................................... 58 ABSTRACT ........................................................................................................... 58 CHAPTER 1. GENERAL INTRODUCTION AND LITERATURE REVIEW .............................................................. 59 1.1 Research background ............................................................................................ 59 1.2 Research objectives ............................................................................................ 60 CHAPTER 2.0 MATERIALS AND METHODS .................................................................................. 61 2.1 Observation site ............................................................................................... 61 2.2 Data collection and acquisition ................................................................................ 62 CHAPTER 3.0 RESULTS AND DISCUSSION ................................................................................. 71 3.1 Homogeneity tests results ...................................................................................... 71 3.2 Monthly, seasonal and annual MKT test results .................................................................. 74 3.3 Sequential Mann- Kendall trends analysis ....................................................................... 79 3.4 Rainfall and fluvial discharge comparison ...................................................................... 84 3.5 Rainfall and fluvial discharge hysteresis ...................................................................... 86 CHAPTER4.0 GENERAL CONCLUSIONS AND RECOMMENDATIONS ................................................................. 88 4.1 Conclusion ..................................................................................................... 88 4.2 Application of study ........................................................................................... 88 PART IV- MECHANISM OF RIPARIAN VEGETATION GROWTH AND SEDIMENT TRANSPORT INTERACTION IN FLOODPLAIN .................. 90 ABSTRACT ........................................................................................................... 90 CHAPTER 1. GENERAL INTRODUCTION AND LITERATURE REVIEW .............................................................. 91 1.1 Research background ............................................................................................ 91 1.2 Research objectives ............................................................................................ 94 CHAPTER 2.0 MATERIALS AND METHODS .................................................................................. 95 2.1 Study Site Description ......................................................................................... 95 2.2 Model development .............................................................................................. 97 CHAPTER 3.0 RESULTS ............................................................................................... 106 3.1 Case study (Nepal) ............................................................................................ 106 3.2 Case study (Japan) ............................................................................................ 109 CHAPTER 4.0 DISCUSSION ............................................................................................ 113 4.1 Growth of herbaceous plants in the riparian zone .............................................................. 113 4.2 Growth of trees in the riparian zone .......................................................................... 114 CHAPTER 5 GENERAL CONCLUSIONS AND RECOMMENDATIONS ................................................................. 115 5.1 Conclusion .................................................................................................... 115 5.2 Application of the model ...................................................................................... 115 5.3 Recommendations ............................................................................................... 115 Overall conclusion and recommendation ............................................................................. 116 References ........................................................................................................ 118, 主指導教員 : 藤野毅, text, application/pdf}, school = {埼玉大学}, title = {SEDIMENT TRANSPORT BY RIVER AND SEDIMENT INTERACTION WITH RIPARIAN VEGETATION GROWTH}, year = {2020}, yomi = {バニヤ, マヘンドラ バハドゥール} }