On 10 April 2008, Dr Gordon Knox gave a public lecture at Din l-Art Helwa entitled ‘Water – a Crisis?’, which focused on the issue of water resources from global and Maltese perspectives. What follows are some of the main points discussed during the lecture:
Malta is heading for a crisis unless attitudes to water management and conservation change drastically. Water is common on the surface of the earth, but only a tiny proportion is in the form of fresh liquid water and it is not equitably distributed. Water is scarce and under severe pressure in the Maltese islands. The natural water resources are over exploited and insufficient for the population of the islands, such that the shortfall is provided by expensive reverse osmosis (RO) plants and virtual water.
Virtual water is water utilised in the production of agricultural and industrial goods. According to a 2004 Unesco-IHE publication Malta imported about 640 million cubic metres per annum of virtual water in the period 1997 to 2001. Thus, elsewhere in the world, around 40 times as much water was consumed as the sustainable yield of the Maltese aquifers, to provide food and goods for the Maltese population. From this perspective Malta is in an unsustainable situation.
Major natural water resources in Malta and Gozo consist of the mean sea level aquifers (MSLA), which essentially consist of fresh water lenses floating on denser seawater. The actual water is situated in fissures and pores within the Maltese limestone layers. Minor resources are situated in perched aquifers lying above the blue clay formation, which manifest themselves as springs.
The actual volume of water resources in place, and producible on a sustainable basis, cannot be measured directly. Geological modelling is required, plus knowledge of the variation of rock porosity and permeability and related flow rates.
In addition, a good understanding is needed of charge rates and depletion rates (natural + artificial). Estimates never consist of a single figure as there are many uncertainties inherent in the estimates. The volume of the fresh water lenses beneath the islands has been estimated at two billion cubic metres several decades ago. However, it is not the water volume in place in the rock, but the sustainable producible volume that is important.
Charge rates are related to rainfall and discounted by surface evaporation, plant transpiration and run-off to the sea. For example, about 160 million cubic metres of rain falls on Malta, of which a range of about 22 to 40 million cubic metres reaches the MSLA on average.
Once in the MSLA aquifers, some depletion takes place by natural processes such as flowage to the periphery of the lenses at the coastlines. Perched aquifers discharge by springs. Artificial depletion is extraction by boreholes and pumping stations by the public utility, and boreholes by the private sector. In the five years up to 2001 the total extraction was of the order of 36 million cubic metres per annum, which included an unreported volume estimated at 16 million cubic metres. Aquifer extraction in no way meets the shortfall for demand as the public RO plants provided about 23 million cubic metres per annum production in the same period up to 2001.
Any aquifer has a maximum sustainable yield that includes natural as well as artificial depletion, beyond which it will suffer irreversible damage such as salinisation and invasion by seawater. The MSLA have been estimated to have a sustainable yield of between 12 and 16 million cubic metres per annum. Thus, 1995 to 1999 both metered and total extraction estimates are well above a sustainable yield. The article, quoting Mepa says that the large share of extraction by private individuals, estimated at 30 per cent of total water production in 2003, highlights the vulnerability of the ground water to multiple private users.
This statement totally misses the point that it is the total extraction (measured and unmeasured, both public and private) beyond sustainable levels which damages the aquifer and in the case of the MSLA aquifer of Malta has resulted in a contraction in the size of the fresh water lens.
According to the MRA estimates in 2004, demand is anticipated to be about 57 million cubic metres per annum in coming years, in which treated sewage effluent and RO pants will provide the bulk, a minor amount to come from rainwater harvesting and about 24 million cubic metres to be provided by the aquifers, again well above the sustainable yield.
In Malta, several issues relate to water consumption: a dense population; a Western paradigm – water/sanitation is a public right provided at public expense; total demand of 57 million cubic metres a year; overproduction from the aquifers; at least 5,000 private registered boreholes, the production of which is unknown; unregistered boreholes with an unknown production; water use is energy/cost sensitive; water production requires six per cent of total power generation; RO water costs five times that of borehole water and has an impact on the balance of payments; meeting EU quality requirements; limited recycling of water; management and capturing of storm water; public awareness/education of issues and pricing is a social and economic balancing act.
What are the consequences of not addressing/addressing these issues? Two extreme scenarios can be postulated, one of which I have called Drift and the other Ruthless Conservation. The real future is likely to lie somewhere in between.
The Drift scenario would describe a world with some or all of the following characters: population density remains high or increases; the water wasteful paradigm is rooted in the population; unregulated water production continues; minimum husbandry of rainfall; limited recycling; depletion and exhaustion of aquifers; near total dependence on desalinisation and energy/price fluctuations and the water supply being hostage to an international crises.
On the other hand, Ruthless Conservation would feature a world with some or all of the following characters: lower population density; the population is highly sensitive to water conservation; a highly regulated sustainable production from aquifers; maximum husbandry/domestic use of rainfall; large to micro scale recycling – state, industry and domestic; desalinisation still prominent; reduced exposure to energy/price fluctuations and a more manageable future with preserved fresh water resources.
What might the Ruthless Conservation world entail?
Government policies, incentives and education campaigns which encourage water conservation. Rainwater harvesting will be at a premium by public and private sectors, including usage of domestic well water and installation of collection tanks. Recycling would be the norm with water saving practices in hotels, homes, industry, agriculture and the public sector.
Meter pricing would severely penalise high usage while being socially sensitive. A full registry of private boreholes, including consumption and charging, would be in place, plus measures and resources for prosecution and penalisation of water theft.
Virtual water practices would be in place, whereby industry and agriculture migrate to production of products which are not water intensive.