• R RAMESH

      Articles written in Journal of Earth System Science

    • A critical analysis of processes governing the nutrient profiles in the ocean

      R Ramesh D Lal

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      We have theoretically considered the problem of interpretation of nutrient profiles in the upper ocean (100–2000m). We compare the experimental depth profiles of nonconservative tracers, both stable and radioactive, with solutions of one-dimensional steady state transport equations of increasing complexity including situations not encountered in the real oceans. Apart from gaining insight into the nutrient transport processes, this analysis is useful in offering a way to obtain operational estimates of depth dependent/independent eddy diffusivity and dissolution fluxes in the ocean. These parameters are essential for estimating new production, total production and burial of carbon in the sediments.

    • Numerical modelling approach for the feasibility of shore protection measures along the coast of Kavaratti Island, Lakshadweep archipelago

      T PEARLIN SAM JINOJ SUBBAREDDY BONTHU R S ROBIN K K IDREES BABU K ARUMUGAM R PURVAJA R RAMESH

      More Details Abstract Fulltext PDF

      Erosion along Kavaratti Island has intensified in recent times due to infrastructure development and natural phenomenon. Numerical models were used to identify suitable foreshore protection structures, considering the near-shore coastal processes. For this purpose, shoreline change around the island was obtained from field surveys and results of the DSAS model. Subsequently, model simulations were conducted for the most appropriate use of structural protection measure to understand the change in hydrodynamics and sediment transport, which would ultimately result in stabilization of the Kavaratti Island coast. Based on the prevailing conditions, suitable site-specific coastal protection structures (e.g., groynes, revetment, breakwater, submerged geo-tubes structures and submerged breakwater) were assessed to determine the most feasible and suitable shore protection measure and observed the following: (a) Revetment and submerged geo-tube structure to be the most effective protection measures on the eastern part of the Kavaratti Island, (b) significant decrease in current speed from 0.48 to 0.05 m/s, and (c) significant decrease in wave height (from 2.5 to 0.3 m) and wave energy reduction about 50% from the prevailing conditions were observed. With this intervention, the existing shoreline of the island would at least be maintained, possibly preventing any further loss of land.

      $\bf{Highlights}$

      $\bullet$ Net erosion rate is − 1.2 m/yr and it shows − 1.36 m/yr in the lagoon side and − 2.35 m/yr in the eastern side.

      $\bullet$ Erosion hotspots are identified along the east and west coast. Highest erosion rate of − 4.23 m/yr was estimated in the eastern side of the island and on the southwest side of the chicken neck area (− 2.94 m/yr).

      $\bullet$ Assessment for shoreline change predictions was carried out using Gencade model during 2018–2028.

      $\bullet$ Revetment and submerged geo-tube breakwater are to be the most effective and feasible foreshore protection structure.

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