The Seti River originates from the Annapurna Massif in the Higher Himalaya of Nepal and flows through the Pokhara valley in the Lesser Himalaya. The Seti River witnessed a disastrous flash flood on May 5th, 2012 causing the death of 72 people, obliterating dozens of homes and damaging infrastructures worth millions of dollars. Despite the 2012 flood event and several warnings by scientists for more yet bigger scale future floods in the Seti valley, fluvial risk is being aggravated by anthropogenic activities such as unplanned human settlement, encroachment of riverbanks, haphazard construction of road, drinking water, and hydropower projects in potential flood hazard areas in addition to the increased impacts of climate change on geological and hydro-metrological hazards as in other parts of Hindu Kush Himalayan Range. Covering some 40-km distance from the Seti headwater (Sabche Cirque) down to Pokhara city, the study is carried out based on hydro-geomorphological mapping, analysis of land-use and land-cover change, hydrological analysis including HEC-RAS modelling, historical archives, and interviews with local people. The study shows a significant change on the land use and land cover of the Seti catchment, mainly the urban/built-up area, which is increased by 405% in 24 years period (1996 to 2020) and by 47% in 7 years period (2013 to 2020). Further the study reveals that anthropogenic activities along the Seti valley have increased fluvial risk and are likely to invite more disasters. From the HEC-RAS analysis, two motor bridges built over Seti River were found to have insufficient freeboard to safely pass the highest flood discharge for 100 years return-period. Instead of relocating people to safer places, the government and local authorities rather seem to have encouraged people to live in the floodplain by providing basic amenities such as drinking water, electricity and access road. Given the context of climate change and Pokhara valley and the Seti catchment being in a high-seismic gap zone, there is a strong possibility of similar flood to the scale of 2012 or even greater in Seti River. Though the fluvial risk can be managed in a sustainable way through the application of functional space concept, i.e., by allowing more space (freedom) for rivers, this economic and environment friendly approach of the fluvial risk management has not been implemented yet in the Seti valley nor in Nepal. Rather the encroachment of floodplains by anthropogenic activities along the Seti valley is on an increasing trend. Many settlements and infrastructures along the valley have been identified vulnerable to hydro-torrential hazards, therefore it is utmost necessity to implement functional space river concept, land use and land plan policy, early warning system and public awareness education in order to mitigate and manage the future impact of fluvial hazards along the Seti valley.

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Soil-reinforcement pull-out tests are essential for evaluating the strength, integrity, and effectiveness of the soil-reinforcement system. In this paper, a new pull-out test model that calculates the soil-geosynthetic reinforcement interface shear stress for highly extensible geosynthetic reinforcement is proposed. Based on a new bilinear interface shear model, the geosynthetic pull-out test results are calculated with regard to the variation of the mobilised geosynthetic tension with distance, geosynthetic pre-yield and post-yield behaviour, and the effective and extended length of the geosynthetic reinforcement. The resulting nonlinear equation for the soil-geosynthetic interface shear stress pull-out mechanism is nondimensionalised, expressed in a finite difference form, and solved numerically using the Gauss-Siedel technique. A parametric study is carried out for a range of relative stiffness values and interface shear stresses. The normalised load-displacement relationship and the variation of the pull-out force and reinforcement displacements, with distance along the reinforcement, are presented. The values calculated using the proposed model are compared with experimental pull-out test results for a needle-punched, nonwoven geotextile, polyester fibres coated with polyethylene, and nylon reinforcements.

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A theoretical model is presented for the pull-out response of strip anchor reinforcement based on a nonlinear elastic (hyperbolic) shear stress-displacement relationship for the soil-reinforcement interface. The interface pull-out mechanism has been simplified by formulating the boundary conditions for the anchor section. Additional terms for the soil-reinforcement interaction, which incorporate the anchor section, are also introduced. A new concept of an anchorage factor (anchor-to-strip reinforcement capacities), the relative stiffness, and the displacement parameters are defined to explain the pull-out behaviour. A parametric study is carried out for a range of relative stiffness values, interface shear stresses, and anchorage factors. The normalised load-displacement relationship and the variations of pull-out force and displacements with distance along the reinforcement, at different anchorage factors, are presented. Experimental pull-out test results for planar reinforcements are also examined/compared with the model using a zero anchorage factor. The model helps to evaluate the pull-out displacements, stresses, and strains along the length of the strip anchor reinforcement.

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SUMMARYA formulation for the analysis of pullout test on highly extensible planar reinforcement is presented. The non-linear di!erential equation for pullout mechanism was expressed in non-dimensional form and solved numerically using the Gauss}Siedel technique. Parametric study was carried out for various ranges of relative sti!nesses, and relative bond resistances. Normalized load}displacement relations and the variations of pullout force and reinforcement displacements along the length of reinforcement are presented graphically. A method for the estimation of the interface interaction parameters from a pre-failure test is also given. The numerical predictions compare well with the available experimental pullout test results for various geotextiles, polymers and nylon geosynthetics.