The need for a comprehensive national policy on water resource management is critical if life is to be sustained in the country and for future generations to enjoy the lifestyle that their past generations enjoyed. Of course, strict enforcement of such a policy, free from political interference and self-destructive, short term gain avarice is even more critical
by Raj Gonsalkorale, Janendra De Costa, Vijith Gunawardena and Mohanlal Peiris
In Part 1 of this article that was published, the authors set out to present the view that water resources, and all its composites need to be considered as an integral component of what is referred to as the whole, or the broader context of land, and the anticipation of threats, and what needs to be done to address such threats, and not reactions to threats when they occur. The need for a futuristic, sustainable water management policy for the country within the purview of a broader policy framework for land and land management was stressed. In this second part of the article, the water resource situation in Sri Lanka and challenges faced, and possible remedies is explored.
Threats and challenges to the future of water resources in Sri Lanka
The future water resources that will be available for human consumption, agriculture, hydropower generation and various industrial purposes will depend on a range of factors and processes that influence the inputs, extractions, losses and retention of water. Some of these processes are part of the global macroclimate which is largely beyond human control.
Greenhouse gas-induced climate change is one such process. Increasing air temperatures, one of the clearest signals of climate change, accelerates the hydrologic cycle by increasing evapotranspiration from vegetation and direct evaporation from open water surfaces such as the oceans, lakes, reservoirs, and rivers.
The greater amounts of water vapour, so released to the atmosphere, can increase precipitation in some regions of the world, where the atmospheric processes that cause rainfall are active and operational. This will have a positive impact on water resources if adequate structures and mechanisms, both natural and man-made, are in place to capture the additional input of water from increased precipitation. On the other hand, in regions where adequate rainfall-causing mechanisms are not present, increased evaporation losses due to global warming could diminish the existing water resources. This future scenario is summarized as climatic change causing ‘wet areas to get wetter and dry areas to become drier’.
In the latest assessment report of the Intergovernmental Panel for Climate Change (IPCC-AR6), which was published in 2021, in predictions of future climate using the current state-of-the-art global circulation models (GCMs), Sri Lanka is identified as a region which is likely to experience increased precipitation during this century. However, almost all GCMs predict an increase in rainfall variability and in the frequency of extreme climatic events. This means that increased future precipitation could come through several high-rainfall events, which could cause more harm via floods and landslides than benefits. It is also possible that increased rainfall variability could result in longer rainfree periods between successive rainfall events, thus increasing the possibility of droughts occurring at greater frequency. The recently identified phenomenon of ‘flash droughts’, meaning droughts that develop fast within about a month without much warning could be a manifestation of increased variability in rainfall and overall climate.
While there is observational and anecdotal evidence that such flash droughts may be occurring with greater frequency in Sri Lanka, especially in the wet and intermediate zones, systematic analyses of long-term climatic data are urgently required to verify the observational and anecdotal evidence. This is a critical area that should be covered by a policy framework as proposed in this document.
Furthermore, it is possible that while the overall country-wide precipitation in Sri Lanka may increase in accordance with the predictions of GCMs, the phenomenon of ‘wet areas getting wetter and dry areas becoming drier’ may operate in the different climatic zones of Sri Lanka. For example, rainfall in the wet zone in the South-West part of Sri Lanka and the Central Highlands may increase while the intermediate and dry zones in the rest of the country may experience decreased rainfall. Such changes in future rainfall patterns in Sri Lanka as induced by global climate change will have enormous implications on its water resources and their utilization for different purposes. While increased rainfall in the wet zone and the Central Highlands will increase water availability for drinking, hydropower generation and irrigation (via transfer to reservoirs in the dry zone), it is important to have measures and mechanisms in place to mitigate the adverse impacts of floods and landslides. Similarly, it is important to devise adequate water conservation measures for the dry and intermediate zones to mitigate the possibly increased frequency of droughts, and especially flash droughts.
Future water resources in Sri Lanka will depend not only on changed patterns of water inputs (i.e. rainfall), but also on changed patterns of water extraction and the capacity of land to retain water, many of which are within human control. Increased water extraction, especially from the deep aquifer, for drinking and agriculture in the dry and intermediate zones could deplete the aquifer further. This could threaten the long-term sustainability of both agriculture and human settlements in the dry and intermediate zones.
It is notable in this regard that Sri Lanka contains substantial tracts of water-scarce land areas in all its climatic zones, despite having a high overall rainfall and water availability regime by global standards.
How much water is extracted from the deep aquifer to supply the water demand in these areas will be a crucial factor in determining the magnitude of the future water resource that will be available to Sri Lanka. Of equal importance will be the capacity of the land to retain water, especially in a future scenario of increased rainfall.
Future patterns of land use and land use change will have a crucial bearing in determining the capacity of land to retain water. Presence of a vegetation cover, especially a forest cover, minimizes overland flow of rainwater and facilitates its slow infiltration in to soil to re-charge the aquifer and the water bodies (called the ‘sponge effect’). Deforestation and conversion of vegetated land to other forms of land use by removing the vegetation cover would not only reduce retention of rainwater within the land and the aquifer, but also increase land degradation through soil erosion. Removal of the vegetation cover and subsequent conversion of steep lands, especially at higher altitudes and in the Central Highlands, to either agriculture or human settlement could cause serious adverse impacts on the future water resources. A policy on land use with adequate regulatory measures to control land use change is an urgent need in this regard.
Optimisation of fresh water use for agriculture and potability
Water optimisation is based on reducing water loss, use or waste, avoiding damage to water quality, and improving water management practices that reduce or enhance the beneficial use of water. While pollution renders large quantities of water unusable, treating it for usability requires electricity and chemicals, an added cost. The question that should be asked is what percentage of water is unusable due to pollution and what preventive measures are in place to prevent or reduce such pollution.
The next issue is about the amount of water that has added value downstream prior to flowing into the sea. Ancient rulers of the country saw the need to make maximum use of water for agriculture prior to this eventual flow, and the building of reservoirs was their strategy to achieve such an optimization. While scope for further expansion of large-scale reservoir systems may be limited, potential surely exists to increase smaller systems. While the droughts cause delays in planting seasons and are responsible for crop damages, floods have been destroying mature crops awaiting harvest. The total cultivated area in Sri Lanka is estimated at around 1.86 million ha, while 632,000 ha. of this area or approximately 33% of it, is irrigated and the rest is rain-fed. Excessive rain and droughts impact on both.
Growing less water consuming Rice
While water has played an integral role in Sri Lankan agriculture throughout its 2000-plus years of recorded history, there is a need to re-visit and re-think the way in which water is used in Sri Lankan agriculture. The cultivation of rice in lowland paddies, where water is impounded and maintained as a layer of standing water, is a cropping system with a high-water requirement. This is a system which incurs substantial losses of water due to evaporation from the open water surface and deep percolation due to the high hydrostatic pressure exerted by the layer of standing water. As such, the production of Sri Lanka’s staple food grain, rice, in the lowland flooded cultivation system requires up to 2500 – 3000 cubic meters of water to produce 1 ton of rice grain.
The magnitude of this water requirement of rice can be understood when it is placed within the context of the water requirements of other staple food crops such as wheat, which requires only 1000 cubic meters of water to produce one ton of grain. The International Rice Research Institute (IRRI) made it a priority in the new millennium starting from the year 2000 to find alternative cultivation systems which are able to fulfil the increasing demand for rice while using less water. This change in IRRI’s central mission and priority was summarized by the term ‘more crop per drop’.
This is very much in line with the overall goal that the authors identified in the introductory article on land that utilization of land must be based on a policy of reaping more with less land. Rice scientists in IRRI and other rice-growing countries, including the scientists in Sri Lanka, have devised, and introduced water-saving irrigation technologies in place of the traditional lowland rice cultivation with continuous standing water.
Saturated Rice Culture (SRC), Alternative Wetting and Drying (AWD) and Aerobic Rice Culture (ARC) are three of the major alternative water management systems that have been designed and recommended for rice cultivation in Asia, including Sri Lanka.
Saturated Rice Culture involves maintaining the soil at saturation without maintaining a layer of standing water and thereby aims to reduce water losses due to standing water in the traditional lowland rice culture. Alternative Wetting and Drying is a system which allows the soil to dry below saturation during non-critical periods of the crop’s life cycle and thereby aims to reduce the water requirement even below that of SRC. Aerobic Rice Culture involves growing rice as an upland crop without standing water at any point during its life cycle, which reduces the crop’s water requirement further.
Research on all these alternative water management systems has shown that the rice crops will incur a yield loss in comparison to the traditional lowland rice cultivation. However, importantly, the water use of the rice crop was shown to decrease by a proportionately greater margin than the decrease in rice grain yield, so that the water use efficiency (or ‘water productivity’ as it is called in irrigation and water management), measured as the grain yield per unit of water used, was higher in the alternative systems as compared to the traditional system.
Despite the superiority of alternative water management systems in terms of greater water use efficiency, especially SRC and AWD, they had not been widely adopted by the Sri Lankan rice farmers. Therefore, a substantial effort is needed in agricultural extension to promote these water management technologies. This important research-oriented initiative too should be part of the policy framework that is urgently needed in Sri Lanka.
Similarly, a paradigm shift is needed on the way farmers view and use water in the cultivation of their upland crops such as maize, grain legumes, root and tuber crops, vegetable crops, spice crops, sugar cane etc,. Farmers often perceive water as a freely available, unlimited resource and use excessive quantities for irrigating their crops. As such the predominant method of irrigating upland crops by Sri Lankan farmers has been surface irrigation, where irrigation water is applied along the land, often with very little control on the amount used and the uniformity of application.
The amount of water used for irrigating upland crops can be reduced substantially by using alternative irrigation methods such as drip irrigation. While drip irrigation of upland crops, especially fruit crops such as mango and banana, has been adopted by farmers to a greater extent than the alternative water management technologies for rice cultivation, there is still much more room for improvement in terms of farmer adoption.
While supplementary irrigation is essential to achieve the maximum potential land productivity from agricultural crops, especially in the dry and intermediate zones of Sri Lanka, use of poor-quality water, in which a variety of chemical ions are dissolved, for irrigation could lead to gradual salinization of arable lands. In view of the absence of strong regulatory measures for preventing the pollution of water resources by a variety of institutions and individuals, Sri Lanka should be especially vigilant on the possibility of salinity development in the agricultural lands under major and minor irrigation schemes. Once the process of salinization of an arable land start, it is difficult to reverse it and measures of desalination such as large-scale drainage are expensive. As irrigated lands contribute a proportionately greater share of the national food production, salinization of these productive lands could have serious repercussions on national food security and farmer livelihoods.
Ada Derana report on the 12th June cited the Agriculture Minister Mahinda Amaraweera as saying that uncultivated or abandoned paddy lands across the island are to be acquired for a period of five years for the cultivation of food crops. This indicates that tracts of land that had been cultivated earlier, had not been cultivated for whatever reason. It would be important to enquire why they were not cultivated as a possible reason may be the unavailability or unpredictability of water for cultivation as the demand for water is high in paddy cultivation compared to many other crops. Sri Lanka’s dry zone is the main paddy producing area in the country and it’s been reported that paddy production is set increase by 10% by 2025. While this would require an additional amount of water to the totally irrigated land, some parts of this area may face a serious scarcity of water by 2025 based on present trends.
To manage those challenges, there is a need for a new approach of water resource management to face the rising threat to water security. This calls for a holistic approach where agricultural water management is considered a part of an overall strategy of natural resource management. This thinking falls in line with the premise of interdependency and interconnectedness of all components that the authors have labelled as “land”.
For example, the management of water for Agriculture from an irrigation tank largely depends on the management of the catchment area of the tank. The catchment area will have other crops and even other industries that require water, resulting in pollution of water, and giving rise to numerous challenges to those engaged in activities requiring water. Managing catchment areas is therefore a substantial challenge, leading to the need to have a national water management policy that includes management measures in such catchment areas.
Readers are referred to a very comprehensive research work titled “A review on water governance in Sri Lanka: the lessons learnt for future water policy formulation” (https://iwaponline.com/wp/article/23/2/255/80096/A-review-on-water-governance-in-Sri-Lanka-the) on the subject of water use for agriculture. This study encapsulates the essence of this article in regard to the goal of more with less and more crop per drop in order to maximise the utilisation of this increasingly scarce resource.
In its conclusion, it says, quote,” There are significant efforts by governments over the past few years to establish new infrastructure, rehabilitate or renovate existing dams, reservoirs, and canals, and promote agro wells and micro-irrigation technologies to meet the rising demand for agricultural water. Despite such efforts, however, the problem of water scarcity continues grow. To meet the future demands of agricultural water innovative approaches are needed. The demand for agricultural water has to be balanced with the municipal and industrial water demands. In balancing these demands, the goals of public health, environmental protection, economic viability, and food security need to be carefully assessed. The development of crop varieties that demand less water is one possible strategy to manage competing demands for water.
The selective adoption of technologies appropriate for small farmers is another tool. Planning and coordinating irrigation water is also very important to save the excess use of water. Farmer organizations, local institutes, and state agencies such as the Agrarian Development Department, Department of Agriculture, Department of Meteorology all have an important role to play. They must work closely and share knowledge and information so that irrigation water can be better managed” unquote.
The need for a comprehensive national policy on water resource management is critical if life is to be sustained in the country and for future generations to enjoy the lifestyle that their past generations enjoyed. Of course, strict enforcement of such a policy, free from political interference and self-destructive, short term gain avarice is even more critical thereafter. Such a policy has to consider region-based realities and grass root needs as well.
The policy has to be comprehensive in that it needs to address water resource management from the broader perspective of the “whole”, which includes components such as agriculture, fisheries, hydropower, energy in general including renewable energy, forestry, wildlife protected areas, bio diversity, pollution and importantly, climate change.
It is also strongly suggested that children are exposed from their initial school going age, to an increasing degree of sophistication as they progress towards higher classes at school on issues relating to the broader context of land, as described above and in the introductory article titled A futuristic, sustainable land management policy for Sri Lanka. Formative years are the most important for the next generation and the ones to follow in understanding and appreciating the value of these resources and their finiteness.
Concluded: The authors: Raj Gonsalkorale, MBA, International Management Consultant, Janendra De Costa, BSc (Agric) PhD, Senior Professor and Chair of Crop Science, Faculty of Agriculture, University of Peradeniya, Vijith Gunawardena, BA, Land Management Practitioner, Mohanlal Peiris, BSc(Hons), MSc (Loughborough University), DipWEM, CEng, Regional Water and Sanitation Specialist at UNICEF Regional Office for South Asia (ROSA)
Post a Comment