Geomorphological Processes in Eastern Nepal as a basis for road design.
This report describes a 8-year study of land forms and land-forming processes as they affect road design
Abstract
This report describes an eight-year study of land forms and land-forming processes as theyaffect road design, carried out in eastern Nepal. The monitoring programme was conducted inthe basin of the Arun River, in association with the alignment and design studies being made forthe Arun Access Road project. The Arun Access Road was a new alignment, proposed as anaccess route to a dam site planned to be built on the river, in the Middle Himalaya some 75km(in a straight line) from the southern plains of Nepal. The terrain is steep, mountainous andcomplex, and presents many difficulties of geometry, poor foundations and unstable ground toroad engineers. The design study for the road was being carried out by Scott WilsonKirkpatrick, and TRL employed SWK under contract to carry out the monitoring survey. Themonitoring was thus separate from the ongoing engineering study but closely connected with it. An appreciation of geomorphological1 processes is important for road design in unstableenvironments. Floods, landslides and erosion episodes occur frequently in the Himalayanfoothills, and gauging their magnitude and likely recurrence interval is central to the design ofroads and associated drainage structures. Predicting the magnitude and frequency of largeevents in regions as little known as the Arun basin is difficult in the absence of quantitative datarelating to rainfall, flood levels, and rates of erosion and slope movement.The original intention was to measure rates of natural slope degradation within the routecorridor before construction began, and then to carry the monitoring into the constructionperiod to see to what extent construction itself affected the natural levels of activity. However,after the research programme had got under way there were several major delays to the startof road construction that continued over a period of four years. During this time, for non-engineering reasons the original ridge-top ‘Hill Route’ had to be re-aligned to a lower
Citation
Hearn, G.J.; Lawrance, C.J. Geomorphological Processes in Eastern Nepal as a basis for road design. (2000). TRL
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Geomorphological Processes in Eastern Nepal as a basis for road design