Low-Scale foreshore morphodynamic processes in the vicinity of a tropical estuary at Honnavar, Central West Coast of India

Abstract

Low-scale foreshore morphodynamic processes in the vicinity of the Sharavati estuary at Honnavar, central west coast of India, are discussed in this paper based on the wave refraction analyses, sediment characteristics, and foreshore morphological changes. In general, the foreshore is composed of medium- to fine-grained (1.12–2.68ϕ), well-sorted to poorly sorted sands (0.18–0.86σ). Beaches experience two periods of accretion, one during September to December (postmonsoon) and another during February to April, followed by two periods of erosion, one during second half of May to early September (monsoon) and another a minor phase of erosion from December to February. The study indicated two distinct trends of geomorphic process on either side of the river mouth. Nearshore coastal process and wind largely control shoreface modification of the beaches to the south of the river mouth, whereas islands in this region modify geomorphic processes of the beach to the north of the river mouth. Northerly drift prevailing during the postmonsoon season favors spit growth across the river mouth from south to north, whereas the southerly drift during December to February is responsible for erosion of the portion of the beach to the north of the river mouth. The growth of a spit is at the expense of the beach to the north of the river mouth. However, during the westerly wave approach (March–April), littoral cells developed in the vicinity of river mouth provided stability to the beach.