Sanaa’s Water Crisis: How Unchecked Drilling Overwhelmed an Ancient Water System

Running out of water is a gradual process, not a single event.

Before the pump, none of these systems could be over-drawn.

Common accounts portray Yemen as careless with its water. The historical record suggests the opposite. On the mountainsides, farmers built stone terraces in their thousands. Some highland systems were first laid in the Bronze Age and are still in use. In the wadis, they practised spate irrigation, diverting the brief, violent floods that follow a storm across fields prepared to receive them.

All these systems share a design principle: each can use only water that has recently fallen as rain. A flood cannot be over-drawn. The rules that governed them, upstream before downstream and older fields before new ones, were enforced locally; in many spate systems that was the responsibility of the sheikhs of the wadi.

The well was, for each farmer, an entirely rational decision.

In the 1970s and 1980s, Yemeni men worked in the Gulf in very large numbers and sent billions of dollars home. Some of that money bought a diesel pump and a borehole. This is the crux of the account: for an individual farmer, the well was an unambiguously sound decision. It freed him from waiting for rain that might not come, allowed him to grow a cash crop rather than subsistence grain, and made his family more secure.

The resource he drew on, however, was shared and invisible. Customary rules addressed wells, including spacing and protection zones, but provided no precedent for unlimited extraction and sale from deep aquifers. What followed is the most familiar sequence in groundwater management and one of the hardest to arrest. As the water table falls, shallow wells fail. Those who can afford to drill deeper keep their water; those who cannot lose theirs. Depth becomes a proxy for wealth. Each new deep well lowers the table further, making it more necessary, rather than less, to drill deeper.

Qat provides income throughout the season, and is grown where water must be lifted.

The war did not cause the crisis. It removed every remaining buffer.

Solar pumping removed the fuel bill that had limited extraction.

When fuel for pumps became scarce and expensive after 2015, Yemeni farmers adapted in a notable way: they turned to solar power. Markets for panels expanded rapidly, and solar pumping spread across the farms that could afford it. By most conventional measures, this was a positive development. Solar pumping is clean and resilient, and it works when fuel deliveries do not. It has kept water flowing through a war.

A diesel pump limits its own use: every hour of running costs money, so every farmer has a reason to stop. A solar pump, once installed, costs essentially nothing to operate, so the rational course is to run it whenever the sun is up.

Without the discipline of a fuel bill, solar pumping can exceed what diesel ever extracted, and local authorities do not regulate it. Yemen has thus replaced a polluting constraint on extraction with no constraint at all.

An optimistic conclusion would not be warranted. Groundwater is being drawn at more than twice the rate at which it refills, in a country whose real GDP per head has fallen by 58 per cent since 2015, with public institutions that can no longer deliver services and an unfinished war. But the picture is not uniform. Terrace rehabilitation restores rainwater capture and is labour-intensive, which, in a collapsed economy, is an advantage rather than a cost. Spate irrigation still functions in the wadis. At a local level, water management is often in the hands of water user associations, which are recognised by and under the authority of the state.

The underlying conclusion is that Yemen’s water problem is not, at root, hydrological. The country knew how to manage scarce water and did so for thousands of years, and the physical evidence of that knowledge still stands on its mountainsides. What broke was the link between the rules and the resource, when a technology arrived that allowed individuals to reach water that no rule covered.