Journal of the Institute of Engineering Volume 16, No. 1 Published: April 2021 ISSN: 1810-3383 © TUTA | IOE | PCU Printed in Nepal Critical Review and Improvement of Bank Protection Methods in Nepalese Rivers Mukesh Raj Kafle Department of Civil Engineering, Pulchowk Campus, Institute of Engineering, Tribhuvan University, Nepal Corresponding Author: mkafle@pcampus.edu.np Received: 2020-08-07 Revised: 2021-01-26 Accepted: 2021-02-05 Abstract: This paper reviews performance of bank protection works constructed over the last decades along the major rivers in Nepal. The study reveals main reasons of early spurs failure in five major rivers - Koshi, Narayani, West Rapti, Karnali and Mahakali. The overview finds design deficiency as the main reason of failure of bank protection works. The methodology incorporates a combination of field visits and a review of design reports, master plans. The study finds bank protection works along the major rivers in Nepal consist almost exclusively of spurs often combined with revetments in between, made of gabions filled with boulders. Also, the launching aprons are constructed of gabions. The lifetime of these bank protection works is less than 10 years and often much shorter. Designs are based on standard designs from Indian standards, developed for normal alluvial rivers. The study recommends initiating a bank protection pilot project to identify the cause of failure of the bank protection works and to test remedial measures for the sustainability enhancement of river protection works in future. Keywords: Rivers, protection works, spurs, Indian Standards, master plan 1. Introduction Nepal is one of the worst flood-affected countries and frequently suffers from different kinds of water-induced disasters like landslides, debris flow, flooding and sedimentation [1]. Floods are the recurrent phenomena of Nepal. Every year, the records of extensive damage to infrastructure, environment, economy and devastation of human settlements are soaring. These floods are mainly occur due to mechanisms of continuous rainfall and cloudburst, glacial lake outburst floods (GLOFs), landslide dam outburst floods (LDOFs), floods triggered by the failure of infrastructure, and sheet flooding or inundation in lowland areas due to an obstruction imposed against the flow [2].The rivers that cause much of flooding in the Terai plain are Mechi (Mahakali), Karnali, West Rapti, Narayani, Bagamati and Koshi. All these rivers are perennial and snow fed originated from high mountains and Himalayas. The most common planform types of rivers are meandering and braided, because of the high sediment loads and the subsequent steep slopes. More downstream, the rivers change in meandering ones they reduce their slope after depositing part of their sediment load. Those rivers attain their stability by changing its course. The morphology of a river is a strong determinant of flow, and can thus serve to intensify or mitigate flood waves and torrents. At the same time, when rivers flow in an alluvial plain they often become meandered or braided, and at times of flood, this morphology leads to excessive bank cutting which can destroy agricultural land and human settlements. To improve a river and its banks structural measures are applied and termed as river training. River training is an important component in the prevention and mitigation of flash floods and general flood control, as well as in other activities such as ensuring safe passage of a flood under a bridge [3]. River training measures also reduce sediment transportation and thus minimize bed and bank erosion. Different techniques can be applied to protect eroding riverbanks. River-training structures can be classified into two main categories: transversal protection structures and longitudinal protection Pages: 15 – 25