Bore-Wells & Salinity In Jaffna
By Willie D. Joshua –March 30, 2016
Willie D. Joshua
Danger of soils becoming saline from bore-wells water in the Jaffna Peninsula
Fresh water supplies and arable land are at risk due to indiscriminate digging of bore wells resulting in saline water extraction. Simple methods for mapping the depth of usable water are proposed that can be used to guide well-depth and prevent significant environment degradation. This information can also be used to estimate the available groundwater for human use.
Recently, there has been a trend in drilling bore wells in the Jaffna Peninsula to extract groundwater for domestic use. This practice is to be implemented for houses being built with foreign aid to settle displaced people in the war torn area. These wells are constructed by drilling about 15cm (6 ins) circular holes right down to the groundwater. The water from these bore wells is used directly by hand pumps or is pumped to an overhead tank and distributed by pipes within the house for domestic use. The groundwater in the peninsula consists of a fresh water layer underlain by salt water. There is a danger that if the bore well goes down to the depth of the saline layer, the pumped out water will be brackish. Thus, there is a possibility of good land becoming saline if this water is used. There have been some instances in Jaffna, where the waters from the bore wells are brackish and not usable even for domestic purposes. Therefore, the depths of the bore wells have to be above the saline groundwater. The Northern Provincial Council has already been informed of this potential problem and remedial measures also have been suggested.
There are three types of wells in use in Sri Lanka namely agro-wells, tube wells and bore wells. Agro-wells, also referred to as dug-wells, are the ones commonly in use in the Jaffna Peninsula and elsewhere in Sri Lanka. Water from these wells are used both for domestic and irrigation purposes. These are large diameter (2-3m) wells whose depths do not go beyond 1m below the dry season water table.
