Natural Resources

Practically all our natural water is derived from precipitation, which we shall call rain water even though it is partially in the form of snow in the mountains and, to a much lesser extent, cloud, mist and dew. A popular belief holds that the wells in the Mesaoria are fed from water which comes from the Turkish Taurus mountains, but there is no scientific confirmation of this idea, which is geologically highly improbable.

Rain Water

The average annual rainfall in Cyprus is about 48 cm, with a geographical distribution of most in the Troodos massif, in the Kyrenia mountains and least in the Western Mesaoria (see map). It should be noted that the map and the table of the rainfall in the major towns diverge slightly, as they do not cover the same period. This represents a total annual precipitation of about 4,500,000,000 tonnes (cubic metres) or almost 6,500 tonnes per inhabitant. In reality, the water consumption per inhabitant, including all usage, is less than 300 tonnes per year or about 4½ per cent of the total precipitation. If we are short of water, it means that over 95% or our natural resource goes to waste. By careful conservation measures, we should be able to improve this ratio considerably.

The above graph shows the rainfall between October and April of each year in this century (red line) and the 5 year moving average (dark blue line). It can be seen that the rainfall is quite variable, ranging from just over 200 mm to just under 800 mm in extreme years. The 2008 winter did not reach even 200 mm. Over the winters of 1995/6, 1996/7 and 1997/8, the rainfall has been consistently about 400 mm or about 15% less than average. This does not explain why the dams have dropped to 90% less than maximum: the "drought" has been an excuse for an increased and profligate use and wastage of water. The rainfall situation was far worse in the early 1970s, but there was no real water shortage, then. At the time of writing, the winter of 1998/9 is still in course, but it would appear likely that the rainfall will be somewhat over-average, probably between 500 and 600 mm. This will surely be insufficient to fill the dams to more than a few percent more than they were a year earlier.

It is interesting to note that the 5-year average rainfall is consistently falling over time and has dropped by about 100 mm since the start of the century. It is impossible to draw conclusions as to the cause or causes, but it seems likely that climate change is a major contributory factor. The cause of this change is considered controversial by some but there would seem to be increasing evidence, although no scientific proof, as yet, that it is due, at least partially, by man-made activities, notably fossil fuel combustion, methane production and the use of fluorocarbons. The 2007 IPCC report states that this is "very likely" with a fractile probability exceeding 0.95. These emitted gases which capture the infra-red radiation from the earth's surface and cause "global warming". The following graph shows the average temperature in Cyprus from the beginning of the century (red line) and the 5-year moving average (dark blue line). It can be clearly seen that there has been a temperature rise averaging about 1°C over the century, although there is no correlation between the temperature and rainfall on a yearly basis. This is the difference between weather and climate.

Conservation

Without doubt, there is little likelihood of being able to increase significantly the capture of rain by more large dams. The major valleys suitable for this are already exploited and further development would be environmentally and economically undesirable. Large numbers of small dams (surface areas of water from 1,000 m² to 10,000 m²) could be constructed on seasonal water courses, often in small gullies up to 20 m deep which are unsuitable for agriculture or other development. An average one could be constructed to hold 75,000 tonnes. This seems small but, if it is exploited in late spring to near-dryness, it would save so much water from being drawn off the major dams or from ground water aquifers. This volume is typically that consumed by a village of about 1,000 inhabitants for household use in a year. The dams could be of earth construction, reinforced by boulders and a concrete armature to prevent seismic collapse due to liquescence of the soil under stress, with a typical constructional volume of 5,000 m³ of earth, mostly removed from the flooded part. The most important point to consider is that no single dam should retain more than about 25 or 30 per cent of the inflow at any time and no watercourse should be restricted by more than 50 per cent of the natural water flow at any given place. This would ensure that the impact on the downstream natural ecosystem would be small. Automatic flow-control would be desirable. The water quality may be potable in favourable areas, but may be suitable only for agricultural irrigation in regions where there are free toxic metallic ions or micro-organism contamination from upstream.

There are several other ways that rain water may be conserved for some uses. Over 25,000,000 tonnes of rain fall on metalled roads each year. If just half of this could be collected into reservoirs, the volume would be equivalent to almost the total potable water requirements of Lefkosia in a whole year. It is emphasised that such water, untreated, would not be potable, being polluted with asphalt, oil drips, rubber decomposition products, and organic particles from diesel exhausts, but it could be easily and cheaply rendered suitable for irrigation. As root absorption of water is by osmosis, the weak salts would not be absorbed significantly into edible crops. Such water would not be suitable for pisciculture as the pollutants may enter into phytoplankton which would be at the low end of a food chain, entering via fish into humans. No significant harm would result from their entering the sea, as the dilution would be sufficient that marine life would be unaffected.

Another way that rain could be conserved would be from the roofs of houses. A typical modern villa may have a roof area of 100 m². With the average rainfall figure of 48 cm, the water falling onto it each year would therefore be 48 tonnes. It would be possible to collect at least 25 tonnes of this, which would suffice for at least a quarter of the annual requirements for watering a large (say, 1000 m²) garden. The cost of this would be the guttering and downpiping, in PVC or metal, plus an underground reservoir and a pump. The reservoir could be in an excavated hole of, say, 4 m by 5 m by 2 m deep, lined with 2 mm thick welded polyethylene sheeting with a 10 cm reinforced concrete cap, over which 30 cm of soil could be placed. If such a construction were to become standard in new property, the extra cost would be typically about €1,000. If it saved 25 tonnes per water per year, it would take about 15 years to amortise, not counting interest on the investment, with water at an indicative price of €2/tonne. This would therefore not be viable, if looked at from a strictly economic point of view, but water, if it is lacking, has no price. The government may care to consider the feasibility of offering small subsidies for such constructions to reduce the amortisation period from 15 to 10 years, say €200 per house with 100 m² of roof and 25 tonnes of approved reservoir capacity (pro rata for other sizes), or even to render such conservation as required on new constructions, in an analogue manner to anti-seismic measures. The cost of adding this to existing property would be higher and more difficult, but not impossible to implement. This may also be combined with a grey water system (see later), reducing the overall cost of both.

With new multi-dwelling property developments, the situation would be much more favourable, in that all roof and service road water runoff could be piped to a central reservoir close to the lowest point. It could then be pumped back to the individual houses via a second plastic water pipe system. Amortisation and equitable distribution could be assured by metering the individual consumptions. As a rough estimation, this would cost about 20 per cent less than individual construction for a 20-house development and would conserve almost twice as much water, probably sufficient for the garden requirements of the whole estate, because of the captured road runoff. This would be economically viable for the investment, with a write-off period of 7-8 years, again not counting interest.

Not all rainwater can be made available because of losses through evapotranspiration.