World leaders in water management

How does Israel manage to export water when the country has an arid to semi-arid climate? Fresh Quarterly learns more from renowned hydrologist Prof. Eilon Adar of the Zuckerberg Institute for Water Research at the Ben-Gurion University of the Negev. By Anna Mouton.

Q. What is the state of water use in agriculture in Israel?

A. Most of the Middle East is semi-arid to extremely arid land, and water is a scarce commodity. For more than the last 20 years, the agricultural sector in Israel has consumed about 1.0 billion cubic metres of water per year. Agriculture nowadays in Israel contributes less than 4% of our GDP — so in most cases, the agricultural sector cannot accommodate the real cost of water. But it is important for us to keep the agricultural sector alive for food security.

To overcome water scarcity, we started reclaiming municipal effluent in the early seventies by constructing water-treatment plants next to every municipality, all over the country. I would say that nowadays in Israel, about 95% of the villages, towns, and cities treat their sewage water. We treat and reclaim 87%–89% of our effluent, which is the highest rate in the world. Next to us is Spain with barely 30%.

The treated water is supplied to the agricultural sector through a centralised water-distribution system. This reclaimed sewage water serves 68% of what the agricultural sector consumes. Fresh water for specific crops contributes another 25%, and the rest is natural, untreated, brackish water.

Q. Tell us more about your water-distribution system.

A. Our water infrastructure is unique in the world. In South Africa, like in many other countries, you are accustomed to seeing electricity grids going all over the country. In our country, we have water grids next to the electricity grid — actually, we have three types of water grids.

The blue grid is the national water carrier which supplies water from the north, from the Sea of Galilee — the only fresh lake in the entire Middle East. It also gets water from aquifers and from five mega-desalination plants. In parallel to the blue grid, we have the red or purple one, which transmits the treated effluent. We don’t mix the fresh water and the treated effluent. The third one is the green grid which transmits natural brackish water where it is needed.

We are flexible because of our ability to increase water desalination, but also because of our ability to convey water. We became self-sustaining regarding water because we realised that not having enough water will have an immediate negative impact on our economy. Even the agricultural system must have a backup — in the South African case everything is localised, and you don’t have a backup supply system.

Q. Desalination is very energy intensive. How will Israel power desalination in a warming world?

A. I can share the latest news with you. Since Israel is obliged to move rapidly to green energy, and we don’t have much land to produce solar energy, we have signed an agreement with the Hashemite Kingdom of Jordan. They have a huge unused area of desert land where electricity will be produced and also exported to Israel.

Nowadays, Israel has a potential surplus of water, and we supply the Hashemite Kingdom of Jordan with more than 55 million cubic metres per year as agreed in the peace treaty signed with Jordan. Recently, Jordan has asked Israel to extend it, and we shall soon supply Jordan with more than 100 million cubic metres of water, which is the average capacity of a huge desalination plant.

Jordan doesn’t have access to the Mediterranean. So they will be dependent on water produced in Israel, while Israel will be dependent on electricity produced in Jordan, creating a strategic economic balance.

Q. How does Israel abstract and manage groundwater?

A. Groundwater hydrology in Israel is well-known and very much advanced. I would say with all modesty, maybe the most advanced in the world.

Slowly but surely, we have had to go to deeper and deeper water-bearing formations, for which we had to develop water-abstraction technology. Many production wells in Israel are beyond one kilometre deep — we have wells which are 1500 metres below surface and producing a lot of water. These wells are extremely expensive, so in order to make sure you don’t waste your money, you have to map the aquifers very well.

We map the aquifers by their extension, geometry, quality, and volume — what is the expected yield? Beyond that, what is the hydraulic connectivity between water-bearing formations? Each formation contains water of different quality — different hydrochemical composition.

In Israel, one has to have a permit to drill a well. During drilling, a well-sitter has to take records and samples. The samples are submitted to the Geological Survey of Israel. The well is monitored, and all the above-mentioned information gets into the national database. Once the well comes into use, there is a meter on the well, and the water authority knows how much and when water is pumped, what is the capacity, and for many wells, what is the salinity. So the water abstraction can be managed according to availability.

Nowadays, we keep most of our aquifers as our backup reservoirs — this is the best water savings account. Since we have the desalination plants, we have more water recharging the aquifers. Many aquifers in Israel have been slowly recovering since 2004 when we started producing desalinated water.

Q. Israel are leaders in irrigation technology. Tell us more about the move to subsurface irrigation.

A. Subsurface irrigation is drip irrigation, but the drippers are lying a few centimetres below the surface in order to emit the water directly into the root zone. When water drips on the surface, the topsoil is wet, so some evaporation occurs. Not much — most of the water is immediately absorbed by the soil.

I don’t care that much about losing that water. But I do care about what is left behind. When the water is evaporated from the soil, all the minerals are left behind, so a salt crust starts forming on the top of the soil. When you get some rainfall, all these crusts dissolve and it’s washed into the rootzone.

So we’re moving quite fast to subsurface drip irrigation to save on water and to save the quality of the soil. Special subsurface emitters have been developed for that specifically.

Q. Having visited South Africa many times, what are the top three things we should be doing to improve water management?

A. Tough question, because you have more than three things to do!

The first thing you have to do is educate the users about basic knowledge of hydrology, including groundwater management. Streams, rivers, and groundwater are one hydrological entity. Aquifers can be a sustainable source of water. However, it is a delicate source and more expensive to maintain than water diversion from streams.

I have seen South African farmers desperate for extra water drilling into groundwater without prior study of the aquifer. Drilling is very costly, and it is a waste of money to drill too many wells per unit area.

Secondly, you cannot continue developing the water resource as you develop it now with different regulations and rules in every catchment area and every province. You have several reservoirs in a basin, where every reservoir is operated by different associations. In some cases, there is competition for water between the municipalities and farms. It cannot work like this with non-coordinated sectorial water allocation.

As for reclaimed effluents, very little treated effluent water from towns in the Cape area is reused. The farming industry can use it as a primary resource. It is not just because it is not treated appropriately — you also lack dedicated pipelines to convey the treated effluents to the farms, and dedicated reservoirs to store treated effluent for the dry season. Effluents are produced at a constant level. Therefore, it is a sustainable source of water.

Once the systems for water production and supply have been upgraded, and the efficiency of water use in agriculture has been increased, and when all natural water sources have been developed and exhausted, and if there is not enough municipal wastewater for irrigation, it makes no sense to freeze the economy. Logic says that one should consider producing additional water by desalination of brackish groundwater and seawater.

So there isn’t one thing to do. You need a comprehensive system that includes an integrated water-supply and water-treatment system, and it has to be managed by one entity — let’s call it a regional water authority. It cannot be handled by one farm or even a farming association.

Agricultural production in South Africa is more important to the economy than in Israel, so you should have a much higher motivation than we do. Think big, invest, and change the system.

How does Israel manage to export water when the country has an arid to semi-arid climate? Fresh Quarterly learns more from renowned hydrologist Prof. Eilon Adar of the Zuckerberg Institute for Water Research at the Ben-Gurion University of the Negev. By Anna Mouton.