The world economic forum in 2016 has ranked the water crisis as the highest concern over the next decade. We in Sri Lanka are beginning to sense this crisis and the uncertainties in weather pattern further aggravate this issue. Different parts of the country experience shortages of water for day- to-day activities including drinking and for agriculture whilst the entire country is affected economically and environmentally by depleting levels of capacity to generate hydroelectric power. It’s a global concern and this has led the entire world to be more vigilant about water use. So much so that various tools are being developed to estimate the water consumed to manufacture different products and also to provide different services to the mankind.
Water footprint
One such tool or a methodology is the calculation of water footprint. Water footprint refers to the amount of water used to produce different products or provide different type of services to the human beings. For example, the amount of water used to produce a shoe or a shirt is the water footprint of that particular article. It can be estimated for a product, a service, an individual, a country and even the whole world. An individual’s consumption of fresh water based on the products and services he or she uses or consumes per year is that person’s water footprint.
We use a lot of water in ways that we would never anticipate often referred to as hidden water in everyday products, such as in the production of clothing, i.e., the production of one cotton suit might require over 14,000 liters of water and almost 3,700 liters for a cotton shirt. The water required for manufacturing a cell phone may be as much as 916 liters. This includes the water necessary to make the raw materials /components of the product, the water needs of the human resources used during the manufacturing process and also water required to treat waste generated during the production process.
An individual may not drink, feel or see all the water he or she uses or consumes. This is called, “Virtual Water” and it actually makes up the most of our water footprint. The combined total of direct and indirect usage of water in the lifecycle of products and related services all play a role in the overall footprint calculation. Knowledge on the water footprint of a particular product or a service would enable us to make processes more efficient so that we could control the use of this valuable and limited resource.
There are three different types of water footprint, namely Green, Blue and Grey. Green Water Footprint refers to the amount of soil water, which is recharged by rainwater, required to produce a product. It is mainly relevant for forestry, horticultural and agricultural products. Blue Water Footprint refers to the amount of groundwater or surface water required to produce a product. Domestic water use, industry and irrigated agriculture can each have a blue water footprint component. The amount of freshwater required for incorporating and diluting the pollutants/waste water to meet a particular water quality standard as required by environmental regulatory institutions, e.g., Central Environmental Authority, is the Grey water footprint.
Water footprint of plantation crop produce
The plantation industry of our country is more than 150-years-old and the land extent utilized at present is around 1,000,000 hectares when crops found in home gardens are also taken into account. The families dependent on the industry both directly and indirectly is not well documented but could easily exceed a million. Since the water is a basic need in cultivation, processing, manufacturing and waste management the water footprint of the plantation industry has been a significant aspect in making decisions on the plantation economy.
Accordingly, the water footprint for different commodities and products of plantation crops has been calculated worldwide and well documented. This information could be of immense value to all stakeholders of the plantation industry today, since there is a debate on which crop consumes more water and hence whether such crops are suitable to be included in to the crop mix of the plantation industry in a country.
The concept of water footprint therefore provides more scientifically valid information for policy makers to take environmentally sound decisions on the development projects of the plantation industry which is still a vital industry in the Sri Lankan economy. Also, such information is of much use for each and every responsible citizen and organisation of the country that supports the development of the plantation sector to decide on sustainable development projects and to maximize community engagement in such projects through creating awareness with correct facts.
The green water component is the water received from precipitation that is stored in the root zone of the soil and evaporated, transpired or incorporated by the plants. When it is expressed in terms of cubic metres required for producing one metric ton of the crop produce, water use efficiency of the crop (i.e crop productivity per unit of water used) is also factored in to it.
Accordingly, among the different plantation crop produce, the green water component is lowest in Sugarcane and is followed by coconut, oil palm, tea and rubber. Hence the green water usage of 1,184 m3t on-1 for sugarcane is the lowest and this could be attributed to the fact that plant species having the C4 mechanism of photosynthesis for which the sugarcane belongs is much more efficient in water use than the plants with C3 mechanism of photosynthesis. Amongst the crops being discussed in this report the highest Green water footprint, i.e. soil water recharged by rain water, was shown by the natural rubber which is around 12,964 m3/ton. This is almost 300% higher when compared with crops like coconut and oil palm.
The government of Sri Lanka has taken a policy decision to plant 20,000 ha of oil palm as an import substitution strategy. If well managed this extent has the potential to produce 80,000 MT of palm oil annually. With a total water footprint of 4,970 cubic metres per metric ton the total water footprint for 80,000 MT will be 397.6 million cubic metres of water annually. A similar extent of natural rubber plantations has the potential to produce 50,000 MT of raw rubber. With a total water footprint of 13,747 cubic metres per metric ton of natural rubber the total water footprint for 50,000 MT will be 687.4 million cubic meters of water. Hence for similar land extents, the total water footprint is 173% higher in rubber when compared to oil palm.
The stakeholders of the entire plantation industry should make a concerted effort to adopt a more scientific approach towards the use of an invaluable natural resource like water more effectively and efficiently. Research and development can play a key role. Crop improvement for water use efficiency is one long term approach.
Genetic engineering to incorporate the gene responsible for the C4 photosynthetic pathway to all plantation crops would be the best ultimate solution though the progress of global research and development in this aspect is still slow. If such genetically modified plantation crops are cultivated in areas having favourable environments for them, e.g., the intermediate zone of the country, the crop water use will be less with no decline in production. In the short term we need to adopt new and correct technologies in management of plantations and in manufacturing industries.
Measuring water footprint and taking all the necessary steps to keep that level as low as possible is extremely important for mankind. This balance is urgently required because freshwater is vital to our daily life while the supply of freshwater is limited.
As the world population is growing, the need for fresh water is growing too. Experts predict that by 2030 the demand for global freshwater will exceed supply by 40 percent. And if we don’t take measures to keep water footprint in the agricultural and manufacturing sectors at a low level, soon, we will be running short of drinking water.
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