COMMUNITY-BASED BIO-ENGINEERING FOR ECO-SAFE ROADSIDES IN NEPAL

This manual provides guidance to communities and local government agencies on the occurrence, assessment and mitigation of road construction-induced landslides and erosion. By better understanding the interaction between human activity and natural phenomena we are better able to find solutions and increase our coping capacities to face threats. In Nepal, the number of rural roads has quadrupled over the past two decades as many communities are prioritizing access to markets, health care and education. 
 

We know that haphazard rural road construction in Nepal is one of the leading causes of slope instabilities and severe erosion, leading to the destruction of agricultural land, loss of lives and property. The current way of building roads requires frequent clearing of roads after each monsoon and is much less cost effective as compared to a road constructed  with proper drainage and low-cost vegetative stabilisation, or bio-engineering.

 

It is true  that bio-engineering alone may not suffice to stabilise certain road side failures, while civil  engineering alone and especially - improper  civil engineering - may also be prone to failure.  For small failures, appropriately-scaled civil  engineering structures may be required as  reinforcement to vegetative stabilization to  anchor the soil (e.g. stone walls for reinforcing  slope toes with vegetation on slopes). The  two are most often very complementary since  civil engineering structures often need to be  replaced or strengthened after 10- 15 years,  while bio-engineering benefits accrue over  time. This manual will only consider small  slope failures along roadsides as large failures  require large and costly civil engineering  structures, which fall outside the scope of  community-based stabilisation possibilities.

 

The practice of bio-engineering is not new in Nepal and in fact many very good manuals  exist on this topic [1, 2, 3]. This manual is  however intended for local stakeholders, including communities, civil society groups,  NGOs and local government actors and  those who are involved in or initiating rural  road construction in Nepal. Its purpose is to  better understand the processes and factors  leading to common, small slope instabilities  caused by road construction and low-cost  and appropriate solutions.

 

This manual is  intended as a “ how to guide ” to resolving  common small-scale slope failures, using a  combination of vegetation and simple civil  engineering, or bio-engineering alone. The  manual will answer the following questions:

• What are common slope-stability problems  linked to road construction?

• What locally appropriate bio-engineering  solutions are available for reducing the  negative impacts of rural road construction?

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These are questions that we intend to answer in an easy-to-read language, focusing mostly  on visual content. We have developed a useful roadside slope failure diagnosis tool and bioengineering checklist (see Annex I) that can be used by local government and communities for  better understanding roadside failure issues  and possible, locally appropriate solutions.