MAPPING OF SALT WATER INTRUSION DURING THE DRY AND WET SEASONS IN THE FIRST COASTAL AQUIFER OF TUMPAT KELANTAN, MALAYSIA

The most prominent threats to the main water resource in north east Kelantan, is the intrusion of salt water especially in the second aquifer and part of the third aquifer. The main purpose of this work was to evaluate the salt water intrusion into the first aquifer. It was investigated using physical and chemical characteristics of ground water, which revealed that. A range of pH from 4.95 7.63, electrical conductivity (EC) 70  ̶ 2561 µs/cm, salinity 0.02 ̶ 1.21, and total dissolved solids 0.025 ̶ 1.73 mg/l. A range of calcium (Ca), sodium (Na), chloride (Cl) and sulfate (SO4) 1.51  ̶ 37.41, 2.11  ̶ 78.92, 2.84 ̶  575.2 and 0.92  ̶ 172.82 mg/L respectively. The values of Na, Ca, SO4, Cl and EC were decrease gradually from the sea towards inland and vice versa. A variation in ground water levels between the dry and wet seasons which were in the range of 0.2 ̶ 1.97 m. Moreover, the freshwater/saltwater interface was located on the shoreline in the dry season and retreated in the wet season. Generally, the salt water intrusion was discovered in the first coastal aquifer; however, it has affected a small area.   The ground water in this aquifer is fresh (except the three wells 11, 19 and 20) that considered as salty due to the high average of chloride, salinity, total dissolved solids, and electrical conductivity.