Despite record rainfall in the Yemeni capital Sana'a and other areas this summer, very little is being done to harvest this water to mitigate water shortages, experts say.
In May at least seven people were killed in what officials described as the worst flooding to hit Sana'a in a decade. Flooding has brought large parts of the city to a standstill on a number of occasions.
Attempts by the government to harvest rainwater are very limited, according to Ramon Scoble, a consultant for Germany's Technical Cooperation Committee (GTZ).
"The government is doing very little," he said. "Very little funding is dedicated to rainwater harvesting for water supply and groundwater recharge. There are a number of ineffective dams in Yemen and none are supplying significant water to cities, agriculture or groundwater recharge."
Sana'a is predicted to be the first capital in the world to run out of economically viable water supplies by 2017. Experts say this is due to a rapid increase in Sana'a's population in recent years because of rural-urban migration, and to the widespread planting and inefficient irrigation of 'qat', a water-thirsty plant believed to consume 40 per cent of all irrigated water.
Local authorities say this increased demand for water is causing Sana'a's water table to fall four to six metres a year.
According to Salem bin Shueb, head of the Water Resources Department in Sana'a Municipality, a study carried out with the Ministry of Agriculture and Irrigation concluded that dams needed to be built to harvest rainwater to prevent water shortages.
Roadmap to nowhere
In an attempt to feed the Sana'a water basin, which is shrinking by five per cent a year, and provide drinking water to the city, a 2008 plan entitled A Road Map to Harvesting Rainwater in Yemen was designed to ensure that 70 per cent of city rainwater was harvested by 2012, and 100 per cent by 2020.
The plan envisaged harvesting through the building of water barriers, small dams, concrete tanks in valleys, and water harvesting systems in or on houses.
Shueb explained that the government is encouraging people in areas with higher rainfall, such as Sana'a and Taiz, a city 256km south of Sana'a, to erect water collection devices on the roofs of their houses, schools and government buildings to harvest rainwater.
Recently a committee issued a decree that rainwater roof harvesting should be compulsory, said Shueb, adding, "these plans are moving ahead slowly because of the limited technical capacity, expertise and poor information."
Shueb said water shortages had been exacerbated by the widespread use of private wells and water pumps for domestic and agricultural use.
"Something has to give"
However, Shueb said rainwater harvesting was not the ultimate solution; what was required was the more efficient treatment of waste water and the reduction of water consumption, especially for irrigation, he said.
But even these measures might not be enough.
A 2007 study by the Japanese International Cooperation Agency (JICA), the National Water Resources Authority (NWRA) and the Ministry of Water and Environment (MWE) suggested that even the most aggressive measures to improve efficiency, conservation and recharge, would at best delay water depletion in Sana'a by a couple of years, perhaps until 2020 at the latest.
Calling for more funding for rainwater harvesting, GTZ's Scoble said that in the 1940s only 60,000 people lived in Sana'a whereas today there are close to two million. "Rainfall has probably varied from year to year, but the population has increased. Something has to give, and it will probably be the donors, not the clouds, nor the crowds of Yemenis."