STABILIZATION OF COASTAL SLOPE AT BAGA HILL KOHIMA DESSAI*, SUMITRA S. KANDOLKAR** *PG student, Department of Civil Engineering, Goa Engineering College, Farmagudi-Goa India 403401. **Associate Professor, Department of Civil Engineering, Goa Engineering College, Farmagudi-Goa India 403401. E-mail Id: kohimadessai10@gmail.com E-mail Id: sumitra@gec.ac.in ABSTRACT The stability of rigid retaining structures in protection of coastal slopes has become a problem in many countries. The main reason for this is failure due to erosion.This paper presents a study of slope failure and suggests possible sustainable remedies to be undertaken at Baga Hill. The study area is a coastal slope popularly known as “Baga hill,” located in Bardez taluka, 18 Km away from Panjim, the capital city of Goa, India. The Baga hill is surrounded by beaches on three sides and an approach road on the entrance sides, leading to the hill's top. During peak monsoon, three consecutive Landslides occurred in August 2020, subjecting this slope to further vulnerabilities. Site visit indicated poor drainage conditions and inadequately designed concrete gravity wall as the basis for failure. This study gives two sustainable alternatives for stabilizing the failed slope; gabion wall and reinforced soil wall. The reinforced soil wall displays better results as compared with gabion wall. Keywords: Slope failure, coastal slope, RE wall, Gabion wall. 1. INTRODUCTION 1.1. General India has a wide range of terrain conditions due to which it is mainly affected by landslides becoming the worst sufferer in south Asia [1]. When triggering processes such as earthquakes, storms, cyclones and human activities act on hilly terrain, it gives rise to slope failures having a long-term or short-term impact on the environment such as soil erosion, change in the profile of land and loss of cultivation. When we compare the typical mountainous slope failures with a coastal slope failure, the only factor that differs is the presence of seawater later, which acts as a fundamental driving force. Driving forces are divided into three sets, depending on the environment. The first set focuses on the marine force, such as water waves, which weakens the slope base leading to landslides. The second set concerns the soil properties of the slope material, which plays a vital role in weathering. Lastly, the third set is climate change, temperature variation and precipitation. The complicated interface between various natural forces, such as marine properties or soil properties, causes coastal slope erosion [2]. The downslope movement of soil mass under gravitational force is known as slope failure [3]. Slope failure is a geological process that occurs when shear stress exceeds the shear strength of the soil. The slope instability can be either due to erosion of slope toe, due to increased seepage forces, surcharge loading, and groundwater table. The soil type and geometric slope conditions also affect slope stability. Various remedial measures for slope protection can be retaining walls, soil nailing, and ground anchors. Traditional retaining walls of concrete, RCC or masonry are used to retain back soil along fill or cut where safe side slopes cannot be provided due to inadequacy of space and requires relatively large space behind the wall to obtain stability [3], [4]. Hence, MSE gabion walls and RE walls can be used with geosynthetic reinforcement, usually geogrid reinforcement is used in steep slopes as it has higher tensile strength than other geosynthetic reinforcements [5] [6], [7]. Geosynthetic reinforcement have enabled the use of local materials and does not require heavy machinery [8]. The RE walls are flexible in nature and is able to withstand large deformations and settlements without any distress. Thus it can be constructed over poor subsoil conditions [9]. 1.2. Geology The geology represents the morphological evolution of the slope. The North Goa zone comprises of metamorphosed schistose sedimentary rocks covered by layer of laterite [10]. After crossing low lying plain of Anjuna, a horizontal hill of length 2 Km and width 700 m is located which separates Baga and Anjuna, this hill is popularly known as Baga hill. The Baga hill is one of the forty coastal cliffs which are found in Goa. This cliff is said to be 88-93 million years old and are said to be formed