Informatics Publishing Limited

E. Shaji ¹, N. Vinayachandran ², D. S. Thambi ²

Affiliations
1 Department of Geology, University of Kerala, Kariavattom, Trivandrum - 695 581, IN
2 Central Ground Water Board, Kerala Region, Trivandrum - 695 004, IN

Abstract

Hydrogeochemical characteristics of groundwater in phreatic aquifers of Alleppey district were studied. Factor analysis has been applied to the chemical analysis data of 32 water samples collected from dug wells to extract the principal factors corresponding to the sources of variation in the hydrochemistry. 12 hydrochemical parameters were correlated and statistically examined. Varimax rotation was used to define the factor scores and percentage of variance in the hydrogeochemistry. A four-factor model is extracted and explains over 80.394% of the total groundwater quality variation. Factor-1 has high loading values of Electrical Conductivity (EC), Ca⁺⁺, and Cl^-, and reflects the signature of saline water. Similarly strong correlation exists between F3 score and pH. The correlation coefficient matrix between EC and Na⁺, Cl^-, SO^--₄ is significant. The mineralogy of coastal aquifers and the marine aerosol are playing significant role in the hydrogeochemistry of groundwater in the phreatic aquifer system.

Keywords

Factor Analysis, Groundwater, Coastal Aquifer, Marine Aerosol, Kerala.

Full Text

     

K. Md. Najeeb ¹, N. Vinayachandran ¹

Affiliations
1 Central Ground Water Board (SWR), Bhujal Bhavan, 27th Main, 7th cross, Sector-1, HSR Layout, Bengaluru-560 102, IN

Abstract

This paper discusses the unique hydrochemical environment of Lakshadweep Archipelago, a cluster of coral islands, where groundwater exists in the form of a thin freshwater lens over the saltwater, having restricted lateral movements. The influence exerted by the shape of these tiny islands on the stability of the water in the lenses and the tendency of this water to mix with seawater are elucidated. The factors which influence the chemical evolution of groundwater in these islands, such as the geochemistry of the coral aquifer, mixing of sea water, dissolution of CaCO₃, marine aerosols and cation-exchange processes are discussed. Mixing of seawater was found to be the predominant process controlling the configuration of freshwater lenses in these islands, as reflected in the ion-ratio studies and the major ionic species observed. The hydrochemical facies, identified with the freshwater lens, represents various phases of mixing. Metabolism of the biological organisms and diagenesis of the lime shells in the corals are responsible for the relatively higher concentration of trace metals, such as strontium and iodide in this aquifer system.

Keywords

Kavaratti Island, Coral Island, Aquifer System, Aspect Ratio, Hydrochemical Facies, Diagenesis.

Full Text

   

Najeeb K. Md. ¹, N. Vinayachandran ¹

Affiliations
1 Central Ground Water Board, Bangalore - 560 102, IN

Abstract

There are 36 islands in Lakshadweep archipelago, of which 10 are inhabited. The study focuses on the hydrogeological conditions prevailing in nine of these inhabited islands. Groundwater is the major source of fresh water and the well density is high in the range of 296 to 620 per km². The aspect ratios of these islands indicate that the shape of the islands have significant role on the stability of fresh water lens. The changes in water level do not reflect the real changes in the water resources as it is greatly influenced by tides. Moreover, the Ghyben-Herzberg relation in its ideal form does not hold good in these tiny oceanic islands. Hence, the rainfall recharge in the islands was assessed based on daily water budgeting. A relation between water surplus and annual rainfall could be established. This approach of recharge estimation could be applied for similar oceanic islands.

Keywords

Groundwater, Oceanic Islands, Coral Islands, Aspect Ratio, Lakshadweep.

Full Text