Shoreline Evolution along a Placer Mining Beach of South-West Coast of India

The Chavara coast of 22 km length located along the south-west coast of India is well known for its rich heavy mineral deposits, also called as black sand deposits. Since 1930, the Indian Rare Earths Ltd. (IREL) and its predecessor companies have been engaged in beach sand mining along this coast for the extraction of heavy minerals. The mining of beach sand by the IREL and Kerala Minerals and Metals Ltd. (KMML) has been much beyond the sustainable limits for the past one and a half decades as indicated by different studies, and has caused drastic beach and innershelf morphological changes. In this study numerical modelling is carried out using the LITLINE module of LITPACK to simulate the shoreline evolution along this coast. The model outputs are calibrated and validated using the shorelines derived from satellite imageries and field measurements for the years 2000,2006, 2010 and 2015. The calibrated and validated model has been used for further simulations for the period of 2000-2022 by inserting groins in tally with the field scenarios for different years. The influence of the short and long groins is predominant at the northern end, near to the Kayamkulam breakwater. If the present scenario persists, the deposition at the southern breakwater at Kayamkulam will be stabilized by the year of 2022. Orientation of the shoreline in the groin field area is found to be in accordance with the predominant northerly longshore transport. Due to the impact of intense mining, the recession in the shoreline and caving-in at the mining site will be even up to 300 m during the period of 2000-2022. The simulations show that the observed caving-in at the mining sites will aggravate further in the years to come if unsustainable mining is continued.