Nature Environment and Pollution Technology

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.

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S. N. Ramaiah ¹, G. S. Gopalakrishna ², S. Srinivasa Vittala ¹, K. Md. Najeeb ³

Affiliations
1 Central Ground Water Board (MoWR, Govt. of India), Kerala Region, Trivandrum, Kerala, IN
2 Department of Earth Science, University of Mysore, Manasagangothri, Mysore, Karnataka, IN
3 Central Ground Water Board (MoWR, Govt. of India), South-Western Region, Bangalore, IN

Abstract

The search for new groundwater resources is essential to sustained economic development in arid environment. The study area is part of Ponnaiyar river basin falling between N latitude of 12°48'24" to 13°07'06' and E longitude of 77°50'30" to 78°08'15" falls in Survey of India toposheets 57 G/16, 57 H/13, 57 K/4 and 57 L/1 covering an area of 645 km2 in Kolar District, which is highly drought prone in Karnataka State, India. In the present paper, by a methodological approach based on remote sensing and GIS, drainage and hydrogeomorphological maps were prepared using the IRS-1 C&1 D LISS-III and PAN merged satellite data and geomorphic units. Denudational hill, residual hill, inselberg, pediment inselberg complex, pediment, shallow weathered pediplain, moderately weathered pediplain and valley fill shallow were identified. The area is characterised by undulating terrain interspersed by low ranges of rocky hills. The elevation ranges from 860 m to 1127 m above MSL. The mean annual rainfall of Malur is 722.0mm. The River Dhakshina Pinakini and Markarda Halla drain the area. The streams exhibit dendritic to sub dendritic type of drainage pattern and comprise of granite and gneissic rock formations of Achaean age. On the basis of different geomorphic units, four categories of groundwater potential zones were delineated as (i) very good to good (ii) good to moderate (iii) moderate to poor, and (iv) poor to very poor.

Keywords

Geomorphic Mapping, Ground Water Prospect Zones, Remote Sensing, GIS, Malur Taluk.

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S. N. Ramaiah ¹, G. S. Gopalakrishna ², S. Srinivasa Vittala ³, K. Md. Najeeb ³

Affiliations
1 Central Ground Water Board, MoWR, Kerala Region, Trivandrum, Kerala, IN
2 Department of Geology, University of Mysore, Manasagangothri, Mysore, Karnataka, IN
3 Central Ground Water Board, MoWR, South-Western Region, Bangalore, Karnataka, IN

Abstract

The study reveals that remote sensing and GIS techniques proved to be the competent tool in analysing various morphometric parameters. The drainage network of Kanamanahalli and Devaraguttahalli sub-basins were delineated using false colour composite (FCC) of IRS-1C/1D merged satellite data on 1:50,000 scale. SOI toposheets were used as reference with limited field work. The study area falls in Ponnaiyar river basin covering an area of 686 sq. km comprising two sub-basins namely Kanamanahalli and Devaraguttahalli having an area of 439 sq.km and 247 sq.km respectively in and around Malur taluk of Kolar district. The morphometric analysis of these two sub-basins shows that the terrain exhibits dendritic to sub-dendritic drainage pattern. Stream order ranges from first to sixth order. Drainage density varies between 1.57 and 1.88 km/km2 and has coarse to fine drainage texture. The relief ratio ranges from 0.0111 to 0.0117. The mean bifurcation ratio varies from 3.51 to 4.86 which fall under normal basin category. The elongation ratio shows that these sub-basins are associated with high relief and steep ground slopes.

Keywords

Kanamanahalli Sub-Basin, Devaraguttahalli Sub-Basin, Morphometric Analysis, Remote Sensing, GIS Technique.

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