Hydro Geological Conditions                                     [Home]

    Kerala State lies as a narrow stretch of land bordering the Lakshadweep Sea on the western side and Tamil Nadu & Karnataka on the eastern side.  It lies between north latitudes 8⁰18' and 12⁰48' and east longitudes 74⁰52' and 77⁰22' .

       The occurrence and movement of ground water is mainly controlled by the physiography/ geological setting and is briefly discussed below.

 Physiography 

       The State is divided into three major physiographic units viz. The coastal plains, the midlands and the hill ranges (Fig.1). The coastal plains have an elevation of less than 6m. whereas the elevation of the midland ranges from 6 to 80 m and that of the hill ranges is more than 80 m above mean sea level (amsl). Along the hill ranges two distinct plateau regions are seen, the important being the Wayanad plateau, which covers major part of Wayanad district, the general elevation of which is above 700 m-amsl.  The other one is the Munnar plateau, which is seen along the northern part of Idukki district with a general elevation of about 1000 m amsl.

Geology

        Geologically 88% of the State is underlain by crystalline rocks of Archaean age comprising schistose formations, charnockites, khondalites and gneisses. All these formations are intruded by dykes of younger age.  The sedimentary formations of Tertiary age occurring along the western parts of the State comprise four distinct beds viz. Alleppey, Vaikom, Quilon and Warkali (Fig.2).  The crystalline and the Tertiary formations are lateritised along the midland area.  Alluvial deposits of recent origin are seen along the coastal plains.  The general stratigraphic sequence is given in Table 2.1.

 Table 2.1 :      Stratigraphic succession of Kerala