National Geoscience Conference 2011 - Department Of Geology ...

NATIONAL GEOSCIENCE CONFERENCE 2011
11 – 12 June 2011 • The Puteri Pacific Johor Bahru, Johor, Malaysia
24
Paper A16
Groundwater contamination in North Kelantan: How serious
Ismail Tawnie*, Anuar Sefie & Saim Suratman
National Hydraulic Research Institute of Malaysia (NAHRIM),
Lot 5377, Jalan Putra Permai, 43300 Seri Kembangan, Selangor
*Email address: ismail@nahrim.gov.my
Groundwater is a major source of public water supply in Kelantan, which constitutes 47% of the total water
supply. In the northern part of Kelantan, groundwater contributes about 90% of the total drinking water demand in the
area. A number of groundwater wellfields and monitoring wells have been established in the area. The groundwater
is mainly used for potable water supply, as well as for agricultural and industrial purposes.
At present, the groundwater consumption is about 146 Ml/d obtained from 94 production wells at 14 wellfields and
treated at 7 groundwater treatment plants (Figure 1 & Table 1). Groundwater from these wellfields is drawn from shallow
aquifer system except in Tanjung Mas, and new wells at Pintu Geng and Kg. Puteh. The demand for groundwater in potable
use is estimated to be 165 Ml/d in 2010 and will increase at a pace of 2.5% per year (Ismail, 2009).
The North Kelantan River Basin is underlain by unconsolidated Quaternary alluvium of marine and fluviatile
origin, with thickness from a few meters to more than 200 m. These alluvial deposits thicken towards the coast.
Bedrock in the south-western part of the Basin consists predominantly of Permian shale, sandstone, phyllite, slate
and volcanic rocks, with granitic rocks are found in the east (MacDonald, 1967).
The alluvium consists mainly of medium to coarse sand with interlayering of gravel, clay and silt. The sand
layers of different thickness occur separated by silt or clay layers locally forming the confining layers. The shallow
sand layers are generally unconfined with areas of confined and semi-confined occurring locally.
The alluvial aquifers in the study area constitute an important source of groundwater for public water supply and
contribute to the 90% of the total drinking water demand. The aquifers consist of two main aquifer systems known
as shallow aquifer which is mostly unconfined but occasionally confined or semi-confined, with thickness normally
2-3 m and may reach up to 17.5 m, usually referred to as first aquifer. The second is deep aquifer which is mainly
confined, with thickness usually more than 15 m. This deep aquifer comprises three different layers, separated from
each other by semi-permeable strata of silt, normally referred to as the second, third and fourth aquifer (Saim, 1997).
These two main aquifer systems are hydraulically interconnected especially the first and the second aquifer as
they are mainly separated by semi-permeable strata of silt. The interconnection between the shallow and deeper
aquifers, or leakage from the lower or upper aquifers depends significantly on the lithology of the aquifer at a
particular location.
The first aquifer is notably productive for development; however, since it is shallow, it is threatened by pollution
as groundwater development is concentrated in the populated area of Kota Bharu town. The second aquifer is
generally not suitable for large-scale exploitation as the groundwater from this layer of aquifer is normally saline.
The third aquifer is the most promising in terms of production and also protected from potential pollution. The
fourth aquifer is not distributed uniformly throughout the entire region as it forms the contact with the underlying
granite or meta-sedimentary rocks. Regionally, the groundwater flows north to north-east.
The population growth heightens the risk of contamination of the groundwater. The unsystematic sewage
treatment and waste disposal expose the water resources to biological contamination such as Coliform and E. coli.
Industrial sectors also contribute to the increase in risk of groundwater contamination. Automobile workshops, for
example, have the potential to cause oil and grease contamination. The same goes with petrol stations when there is
a leakage in the underground storage tank.
Agricultural sectors, on the other hand, contribute to the contamination through the use of fertilisers which
increase the contents of nitrate and nitrite in the soil and subsequently seep through to the groundwater. Heavy
pumping of groundwater during dry season (January to March) for tobacco crop causes groundwater levels to drop
and might induce saltwater intrusion particularly in areas near the coastal line. But in reality, there are no significant
groundwater lowering in the area because during the rainy (wet) season from October to December, complete water
level recovery occurs. If there is a significant lowering of the water levels, it enhances the flow in the aquifer and
increase contaminant transport.
References
Ismail, W. M. Z. W., 2009. Groundwater for Domestic Needs in Kelantan. In Proc. of Groundwater Colloquium 2009, Minerals
and Geoscience Department Malaysia and Academy of Sciences Malaysia, p149-156.
MacDonald, S., 1967. The Geology and Mineral Resources of North Kelantan and North Terengganu. Geological Survey of
Malaysia, Memoir 10, 202p.
Saim, S. 1997. Groundwater Protection in North Kelantan, Malaysia: An Integrated Mapping Approach Using Modelling and GIS.
Ph.D. Thesis. University of Newcastle Upon Tyne, United Kingdom. (unpublished). 362p.