Amman is a dry city that sits at the nexus of several severe water challenges. It is currently facing a shortfall in sustainable supply to meet demand and expects demand to rise with population growth. It also struggles with infrequent piped supplies which have led residents to resort to other, more expensive sources. All of its major supplies are transnational and face complex geopolitical constraints on expanding those supplies or even adding new ones, like the Red Sea Dead Sea Desalination Project. The Jordanian government has a sophisticated portfolio approach to water management but could benefit from expanding policies that encourage rainwater harvesting to meet potable water needs.
Amman’s Water Context
Amman is the capital of Jordan and the Kingdom’s largest city. It had 3.8 million residents in 2017, which comprised 40% of the country’s residents. It is very hilly, and neighborhoods are often defined by the hills and valleys. Amman hosts a significant number of refugees, around 200,000 from Syria and over 142,000 from Palestine.
Amman has a warm climate and receives 271 mm of rainfall on average each year, with all the rainfall during the winter while the summer months are dry. The amount of rainfall varies dramatically spatially throughout Greater Amman Municipality. Average rainfall in Sweileh in the northwest gets 511 mm of rain, while Al-Muwaqqar and the southeast gets only 153 mm according to a study by the University of Jordan.
Water in Jordan is managed at the national level by the Ministry of Water and Irrigation (MWI). Underneath MWI, the Water Authority of Jordan (WAJ) is responsible for drinking water and wastewater infrastructure. The water utility in Amman is Miyahuna, a WAJ owned company that provides water to domestic and industrial customers in Greater Amman Municipality, as well as Madaba and Zarqa Governorates.
The majority of water supplied to Amman comes from groundwater. Nationally, 589 MCM of groundwater is extracted annually, 160 MCM of which is unsustainable yield. About half of Amman’s supply comes from the Disi Aquifer, which lies in the south of Jordan and has a sustainable yield of only 2-3 MCM, but supplies 100 MCM to Amman and 15 MCM to Aqaba. The Disi Aquifer is also a transnational source – the vaste majority sits in Saudi Arabia.
Surface water is the second largest water source in Jordan and for Amman. Nationally, 259 MCM is abstracted annually. The main source of surface water is the Unity dam on the border with Syria. It holds 110 MCM, and supplies over 70 MCM to Amman via the King Abdullah Canal in the Jordan River Valley. Jordan does not have abstraction rights to the Jordan River beyond an extremely limited amount under the 1994 Peace Treaty with Israel. The Jordan River does effect Jordan because the flow has been reduced through damming and abstraction from 1,200 MCM to 150 MCM annually, which has led a dropping water level in the Dead Sea.
Treated wastewater is the third major source of water for the country. It is primarily used for agriculture – 91% of treated wastewater is used for irrigation. Amman is a major source of this wastewater, which is treated at the As Samra and Wadi Mujib wastewater treatment plants before being sent to the reservoirs behind the King Talal and Kafrein dams, then down into the Jordan River Valley.
In order to expand water supplies, Jordan has engaged in an ambitious scheme to build the Red Sea Dead Sea Desalination Project. It is a multinational agreement between Jordan, Israel, and Palestine to pull water out of the Red Sea near Aqaba, desalinate it, and pipe the brine to the Dead Sea. The Dead Sea has been dropping precipitously, by a meter per year, due to the reduced in-flows from the Jordan River and withdrawals by chemical companies that extract minerals from the Dead Sea water. The plan involves a water swap in which Jordan will supply 50 MCM to Israel in return for equivalent withdrawals from the northern Jordan River. Phase 1 would have a capacity of 100 MCM that would expand to 930 MCM. Later phases would build a pipeline that is almost 300 km to supply the desalinated water directly to Amman.
Amman’s municipal water system has comprehensive coverage with its piped drinking water system. While city-level data was unavailable, UNICEF data showed that over 95% of urban residents in Jordan have improved safely managed or basic drinking water supply. Wastewater coverage is less comprehensive. Only 83% of urban residents have safely managed or basic sanitation service. Despite good coverage, the water system only supplies water an average of 45 hours per week, or 27% of the time.
Total water consumption has steadily increased, with a spike in growth between 2012 and 2014 when Amman was receiving significant numbers of Syrian Refugees. In 2017, water consumption capita was 141 L / day, above the target in the National Water Strategy plan of 120 L / day. Both the actual consumption and the target include industrial water use, meaning domestic water consumption is lower.
Non-revenue water comprises a significant portion of the water supplied to Amman. It is not included in the 141 L per capita consumption mentioned above. Miyahuna has identified reducing non-revenue water as a key target in its 2017 annual report.
Rainwater Harvesting Proposal
Rooftop rainwater harvesting for potable water has a long history in Jordan. The citadel has a 1000 m3 cistern built by the Umayyads around 720 CE and a complex water system solely reliant on rainwater. Today, rural Jordanians continue to harvest rainwater. In fact, in a community-based water demand management program, Mercy Corps found that “people in rural and peri-urban areas in Jordan look at rainwater harvesting as a conventional and indigenous technique to save water… [and] the know-how of establishing a rainwater harvesting system among rural communities is well-known.”
MWI includes rainwater harvesting for non-potable uses in the National Water Demand Management Policy through requirements to build cisterns into all new construction, non-potable plumbing in all new construction, and on-site water treatment and reuse for large commercial and residential developments, as well as for financial incentives. Despite this policy, compliance in new construction is low. According to an MWI spokesperson, “The law stipulates that a cistern for storing rainwater must be built as part of any under-construction building, but contractors are not abiding by this and they pay a fine instead of building the cistern.”
Taking rural methods of rainwater harvesting for potable use by retrofitting existing buildings could create a significant new water supply to meet Amman’s needs. Larger scale distributed cisterns could also supply non-potable water via the non-potable pipe systems mandated for new construction.
Adapting rainwater harvesting to an urban context requires understanding how the different building typologies. There are three major neighborhood typologies in Amman. The first consists of larger, free-standing buildings, often surrounded by a garden. The second has smaller tightly packed buildings. Lastly, there are peripheral neighborhoods or scattered freestanding buildings. The first and third typologies are more suitable for cisterns when retrofitting because of available space surrounding the buildings, while the second is most suitable for rooftop tanks. For all typologies, rooftop tanks provide installed storage capacity due to their prevalence in response to intermittent piped water.
The capacity of a rainwater capture system is a function of rainfall, catchment area, and runoff coefficient, or how much of the water makes it from the catchment area into the tank or cistern. An area of 631 buildings in Jebel Amman was modeled to find the capacity of individual buildings. The area was chosen because it contains neighborhood typologies one and two, and had building footprints available from Open Street Maps. Rainfall data was sourced from Worldclim.org, and the runoff coefficient 0.9 for cement roofs used by the Mercy Corps study was used.
Average rainwater captured per day ranged from 12 L to 855 L, with a mean of 175 L. However because rainfall is seasonal, no water can be harvested from Jun to September. During February, the wettest month, water captured per day ranges from 2,360 L to 33 L, with a mean of 470 L. This means that the average building could supply the 80 L minimum daily per capita consumption for 5 people following the recommendations of the Mercy Corps study.
In order to meet all of Amman’s water needs through rainwater harvesting, 41.6% of the rainfall in Greater Amman Municipality would need to be captured. However in the study area in Jebel Amman, only 34.3% of the land is covered by buildings, and it is denser than average. However, to match the 35% of households water use that Mercy Corps found for rural households’ would only require 15% of Greater Amman Municipality’s land area.
There are several important limitations to the proposed rainwater harvesting scheme. The first is that multi-unit buildings that predominate in urban area have less roof area per resident than individual houses, limiting the impact rainwater harvesting can have on a household’s water supply. If potable rainwater harvesting is a supply augmentation strategy, compliance will likely be an issue as has been seen with rainwater harvesting requirements for new construction because it needs widespread small scale installations. Processes to ensure water quality and maintenance would have to balance Miyahuna or government capacity with the danger of privatizing the cost of water infrastructure and placing the burden on poor households. Special financing and training programs to build on indigenous knowledge could minimize this concern. Droughts also pose a challenge since rainwater harvesting is highly dependent on weather patterns. Pairing rainwater harvesting with climate invariant sources such as the Disi Aquifer and the Red Sea Dead Sea Desalination Project in a water portfolio could help to improve the sustainability and security of water supplies.
Conclusion
Amman faces severe water scarcity issues that have led to unsustainable groundwater extraction, intermittent piped supplies, and limited options given the geopolitical complexity of expanding major supply sources. Applying traditional rural rainwater harvesting practices to Amman’s urban context provides the opportunity to create a new major supply source free of geopolitical constraints. While there are important limitations and concerns that would need to be adequately addressed through policy and program design, the initial case study is promising and warrants further study.