NAVIGATE
:

Water for people



article_image

The United Nations General Assembly designated 22 March 1993 as the first World Water Day and It has been held annually since then. This article was written to commemorate the World Water Day which falls on 22nd March.


In Sri Lanka, rainfall is the primary source of water. The annual rainfall is around 1800 mm with areas such as Hambanthota and Mannar receiving only about 900 mm and some areas in the hill country receiving about 5,000 mm. In terms of quantity of water received, it is around 100 billion cubic meters per year. Out of the total water received by the island, around 40% escapes to the sea as run-off, although we often speak of the famous dictum of King Parakramabahu I, according to him which "let not even one drop of water that falls on the earth in the form of rain be allowed to reach the sea"


Sri Lanka is world famous for its water resource management. The dry zone is studded with thousands of ancient tanks of varying capacities to collect water. King Mahasena (274-301) constructed the first giant reservoir, the Minneriya tank which covers nearly 1,900 ha. Since then other large tanks such as Parakrama Samudraya, Mahakandarawa, Kalawewa etc. were constructed to collect rainwater for crop and animal production and various domestic uses. There are around 12,000 small tanks distributed across the undulating landscape in the dry zone. These tanks are not randomly located but occur in the form of distinct cascades each made up of 4-10 small tanks situated with in a single small catchments (meso-catchment) varying in extent from 100-1000 ha,.


Water for crops :


Water for irrigated paddy is obtained from tanks. Rain is the main source of water for upland crops (domestic crops and plantation crops) The cultivable extent from the small tanks has decreased gradually with siltation. Due to low rainfall during Yala season there is hardly any water in these tanks and hence cannot supply any appreciable amount of irrigation water during this season. Crops cultivated with rain water are affected by water shortage as a substantial amount of rain water is not retained in the ground.


Our river basins have tremendous potential to meet our water requirements but we are not managing these effectively. There is a need for an effective approach to water use as populations grow in regions where water is limitied. Water waste in crop production needs to be looked into with implementing appropriate measures to reduce water wastes. Although a crop of paddy needs only 4-5 acre feet of water, farmers in some paddy growing areas use as much as 6-7 acre feet of water. In such areas, it is essential that farmer education programmes are conducted to reduce water consumption. Water use in crop production could be reduced considerably by using methods such as drip irrigation, sprinkler irrigation but these are expensive.


Water for domestic use:


Around 300 million cubic meters of treated water is supplied to about 40% of the population with piped water for drinking and other domestic use by the National Water Supply & Drainage Board. About 3,000 rural piped water supply schemes and 50 small town water supply schemes are managed by Community Based Organizations (CBOs) which are facilitated by the Department of Community Water. The water need of around 4 million people are met by these water supply schemes which use village tanks, protected /unprotected shallow wells, deep wells with hand pumps or motorized pumps and rainwater as water sources.


In spite of the country receiving around 100 billion cubic meters of water, thousands of people, mainly in rural areas do not get a regular supply of water. Hence, they have to walk a few km to collect water and even the water that is available is not pure. Supply of safe water is extremely important . Women are the most affected from lack of access to safe drinking water as in a water scarce situation they spend a large part of their time in accessing water for domestic needs, there by limiting their involvement on other day to day activities.


Shortage of water supply in rural areas could be attributed to inadequate water conservation. Most of the water we get from rain run-off to sea without being retained in the land.


Water Quality


Quality of water used for domestic purposes, is of considerable importance as poor water quality affects human and animal health. Physical, chemical and biological components of water influence its quality. Effluents from factories lower the quality of water chemically and cannot be easily removed unlike physical and biological constituents. A number of chemicals are known to affect the quality of water resulting in the occurrence of a many non-communicable diseases.


In a study conduced covering nearly 1 million people in 20 Ds Divisions, it has been reported that nearly 45%of the people get water considered to be from unsafe water sources. A number of issues have been reported in studies conducted on the quality of water. Among these are a high content of Coliform bacteria, High iron concentration in ground water in Hambantota, Buttala, Kataragama areas, Drinking water in some pats of the Dry Zone has a fluoride concentration ranging from 6-8 mg/liter although the WHO limit is 1.5 mg/liter. High fluoride levels in potable water mostly in the dry zone causes children to have brown decaying teeth. Fluoride at high levels can cause severe skeletal fluorosis and it can disrupt the actions of many key enzymes.


Phosphates present in phosphatic fertilizers tend to get washed into water bodies causing eutrophication. The result of this process cause water quality to decrease. Nitrate is one of the most common groundwater contaminants in agricultural areas. The high nitrate content in groundwater is mainly from run-off from agricultural fields where urea has been used indiscriminately. Ground water in Kalpitiya is reported to contain nitrate levels above 10mg per liter which is the WHO standards for drinking water. The presence of nitrite in the digestive tract of newborns can lead to a condition called Methemoglobinemia, which is the most significant health problem associated with nitrate in drinking water.


Chronic Kidney Disease (CKD)


Chronic Kidney Disease (CKD) widespread in the North Central Province, part of North Western and Uva provinces is attributed to a toxic element/compound present in drinking water . According to separate studies carried out by a number of Sri Lankan Scientists, CKD is attributed to high levels of one or more chemicals in drinking water. Among these constituents are cadmium, fluoride, toxins released by Blue Green Algae, and some pesticides.. As the exact causal factor/s of CKD is not known it is identified as Chronic Kidney Disease of unknown etiology (CKDu)


Rainwater


The amount of water available for irrigation, domestic use etc. can be increased considerably by collection of rainwater in households. Rainwater collection has been practiced since time immemorial. Rainwater is relatively the most pure form of water and if collected properly has no toxic elements in it.. A considerable portion of the rainwater that falls on the roofs of buildings can be collected in tanks in the premises itself. Water that falls on a roof of 1,000 sq m in an area where the average annual rainfall is 2,000 mm, would be around 2,000 cubic meters (i.e 2 million liters or app. 400,000 gallons). Water thus collected could be used for numerous domestic purposes including drinking. For centuries the world has relied upon rainwater harvesting to supply water for households. Before city water systems were developed rainwater was collected (mostly from roofs) and stored in storage tanks and used for drinking and other domestic purposes.


It is because of the importance of rainwater harvesting, Dinesh Gunawardena, in the year 2005, as the then Minister of Urban Development and Water Supply presented the World’s first National Rain Water Harvesting Policy and promulgated the regulations with unanimous consent of the Parliament of Sri lanka . This policy has been approved by the then Cabinet Minister of Sri Lanka. The main objective of this policy is to formalize the practice of rain water harvesting in Sri Lanka and recognize its importance in solving the problems related to water supply in the country.


Sustaining water supply:


The total amount of water received annually in the country remains almost constant, but the increase in demand for water has imposed a considerable strain on the water resources authorities. Lack of access to water in an agriculture based rural economy, will inevitably impact adversely on the socio-economic well being of the community


In view of the fact that around 40% of the water received is lost as run-off water, it is essential that appropriate action is taken to reduce this loss. Strategies for conserving and protecting water sources are well described in the " National Policy on Protection and Conservation of Water Sources, their Catchments and Reservations in Sri Lanka" formulated in Feb. 2014 by the Ministry of Land and Land Development. It is important that these strategies are implemented as early as possible, If we are to effectively address the issue of water shortage in the country.


Dr.C.S. Weeraratna


csweera@sltnet.lk


 
 
 
 
 
 
 
 
 
 
animated gif
Processing Request
Please Wait...