To better understand the options for runoff agriculture, below is a review of some of the imaginative and effective techniques developed for use of runoff and floodwaters in the MENA region and the American Southwest (SW). Experimentation and experience over more than 5,000 years led to remarkable systems that enabled people to live well even in some of the most arid environments. These systems can be built and maintained by local people using available tools.
Two major goals are to hold the water back so it doesn’t run off and to concentrate the water so that even the most arid areas people have enough water to drink and sufficient water to grow a crop. As climate change increases the severity of droughts and floods these techniques may be rediscovered and rebuilt. They will also prove useful in new areas.
Floodwater farming is still practiced in arid and semi-arid lands. Studies in the Middle East, Africa, the American SW, Mexico and many other areas have reconsidered the history and value of runoff farming. Here are a few highlights.
Middle East and North Africa (MENA)
Yemen
The farmers of Yemen have used a wide range of water capture strategies, including extensive terraces to capture runoff and flood water.[i] Floodwater (spate, sayl) irrigation was once common in Yemen.[ii] and involved flooding agricultural plots surrounded by field ridges (bunds, soum). These field bunds are typically 50-60 cm high. Many areas of farm land are also served by diversion canals. The irrigation of most of the agricultural lands in Yemen’s southern and eastern governorates still depends on runoff and floodwater.[iii] Using technologies like those at Ma’rib the neighboring kingdoms of Ma’in, Qatabān, Awsan and Hadramawt captured floodwater runoff from Yemen’s highlands.[iv]
Syria
Syria also relied on runoff and floodwater irrigation. Studies at Hayt al-Suad and Jubabat al-Juruf yielded wheat, barley and other domesticated crops dated to the late 4th to mid-third millennium BCE. This would likely be some of the regions first agricultural terraces.[v] The ancient floodwater harvesting system in Resafa, Syria consisted of extensive embankments, a dam and cisterns to provide water for farming and for a city with no perennial water sources.[vi]
Jordan
The runoff and floodwater systems around Petra, Jordan have been studied in some detail.[vii] Much of the water captured by these systems would have been for people and animals. The amount needed for a family of six with donkeys, camels, sheep or goats would be about 18 m3 year.[viii] For the city of 20,000 people the annual demand might be as high as 90,000 m3. Runoff farming on flatter areas and hill slopes grew food for local use and export. Slopes were terraced or had contour rock/ridge lines. These rock line/ridges were either level or sloped to direct water to cisterns, tanks or fields.
Negev
The Nabatean agricultural systems in the Negev were erected in several phases beginning in the 3rd millennium BCE, and were used and re-built until the Early Islamic Period (7th-11th centuries CE).[ix] The main construction elements in runoff desert agriculture were the floodwater retaining terrace dams that controlled water flow on the hill slopes and in the wadis. Thousands of ancient terraces in the Negev desert show that agriculture was based on the capture and use of runoff and floodwater.[x]
Comprehensive studies of floodwater farms in the Negev highlighted how well these systems worked. The most striking features are the multiple sets of wadi terrace dams.[xi] These were typically spaced from 12-15 meters apart. The heights were set to capture enough water to fully recharge the soil. These irrigation farms developed complex designs with flood bypass and diversion channels.
To increase water capture the farmers deliberately cleared the stones off some of the slopes, smoothed the surface, and exposed finer soil to facilitate the formation of a self-sealing crust that would increase runoff to farm fields. Typical farm units of 0.5-5 hectares were associated with 10-150 hectares of sloping watershed.[xii] The ratio of run-off-contributing catchment to runoff-receiving crop land varied from 20:1 to 30:1. Each plot would receive enough water to produce a crop most years.
The American Southwest (SW)
Anasazi
The Anasazi culture of the SW developed from about 100 CE to 1400 CE. They had highly refined rain water capture management systems with check dams,[xiii] reservoirs,[xiv] cisterns, and canals with diverters. Research showed that the Morefield Reservoir at Mesa Verde persisted across centuries.[xv],[xvi] Detailed soil analysis revealed that its ancient engineers operated it for 350 years and survived 14 major forest fires and 21 periods of high water flow. The community had to work diligently to harvest this water. Runoff included a high sediment load and dams required frequently dredging to maintain adequate capacity.
Tohono O’Odham
In the Tohono O’Odham (formerly known as Papago) territory of southern Arizona the flood run-off of the mountain areas is gathered in streams with well-defined channels that spread out in sheet flow on reaching the undissected alluvial fans. The place where this spreading occurs is called by the ak-chin or arroyo mouth.[xvii] With these ak-chin fields farmers harvested both rainwater and nutrients to grow corn, squash, beans, and melons. Some of the garden terraces at Paaqavi (Bacavi) have been in use since, approximately 1200 CE.[xviii]
Navajo
Similar practices were used by other tribes, including the Navajo.[xix] Formerly, as many as ten fields were continuous in one ephemeral watercourse.[xx] A local community of men shared the responsibility of keeping the watercourse and associated ditches clean and free from brush. They also repaired damage to the water control structures.
The method of planting instead of plowing furrows reduced erosion. Each seed spot was opened with a stick. Cultivars were highly developed to emerge from deep burial. This assured a strong root system capable of resisting drought and to survive some surface washing by subsequent flood flow. By collecting water off mesquite dominated watersheds and allowing nitrogen-rich mulch to flow down into the fields they harvested nutrients as well.[xxi] When Gary Nabhan worked with the last generation of flood-water farmers they were part of a 4,000 year unbroken chain. Soil fertility in their fields was equal to modern Corn Belt corn fields that are treated annually with nitrogen fertilizers.
Hohokam
The Hohokam people lived around the rivers of southwest Arizona (300 BCE–1450 CE). They were gone[xxii] by the time the Spanish arrived about 1600 CE, but the remains of their irrigation systems are still visible.[xxiii] The Hohokam villages were remarkably stable and some were continuously occupied for 1,500 years or more. Their irrigation systems included water collection, main and distribution canals and field laterals. They built more than 483 kilometers of major canals and over 1,126 km of distribution canals. Unfortunately the dynamic nature of these rivers has erased the diversion dams, barrages, headgates, and intake portions of canals. We can’t say how frequently these structures were destroyed or required repair as a result of larger floods.[xxiv]
Zuni
The waffle gardens of the Zuni people are a combination of ridge and strip collectors that look much like a waffle. The ridges are packed smooth and serve as walkways and water runoff areas. The soil berms surround each square planting area. The depressions catch and hold water close to the plant’s roots. Grid gardens are similar, with larger square or rectangular grids bordered with rocks. These stones may have been the base for mud walls as early explorers saw them in the Zuni gardens. Larger versions of grid gardens have been used in the Southwest and also for dryland farming throughout the world.
Rainwater harvesting has been developed and practiced in Mexico since before the Spanish conquest. The Mayan and Aztec cultures captured and distributed rainwater using channels for both drinking and irrigating their crops during the dry season.[xxv] The acequia culture also developed in Mexico.[xxvi]
Lessons for the Future
The ancient masters of runoff and flood agriculture can provide lessons for farmers today. Increases in atmospheric heat retaining gasses are expected to produce an increase in mean global surface temperatures of between 1.5°C and 4.5°C. Warmer temperatures with climate change will increase evaporation, reducing surface water and drying out soils and vegetation.
The Southwestern US has already seen a decrease in annual precipitation since the beginning of the 20th century, and that trend is expected to continue. The Middle East has also experienced growing droughts and heat. Between July 2020 and June 2023, climate change made the drought more intense — mainly due to high temperatures that dried out the soil.[xxvii]
Changes in the amount and distribution (or seasonality) of precipitation have also been predicted, but models are less capable of predicting future changes in seasonal or annual precipitation. We have known that dry places will become drier and available soil moisture in summer may decrease by 15 to 20 percent for decades, but have made little progress in reducing the risk.[xxviii] Expanded water capture and storage before and during drought years is essential. Climate change will also challenge farmers with altered timing of water availability. Warmer winter temperatures are causing less precipitation to fall as snow in many areas, so runoff or flood irrigation will peak sooner and have less water in the late spring and summer.
Climate change with increased drought, reduced stream flow, and the breakdown of infrastructure may make traditional floodwater farming a necessity in some areas. Overdraft of groundwater, failure of electrical grids, lack of diesel fuel, and other problems with industrial irrigation may also make water harvesting for drinking water more important. These changes will also challenge rainwater farmers. Water harvesting doesn’t work if there is no rain. More severe storms will harm dams, canals, and diverters. Hail, intense dust storms (haboobs), and high winds can damage plants. Erosion can remove topsoil and deplete soil nutrients.
The other lesson we can learn from these runoff farmers is the importance of community and cooperation. Keeping runoff and floodwater systems functioning took timely and significant work to repair damage and remove sediment. Working together is essential. A shovel of dirt in the right place, at the right time, might avert a disaster.
Note: The first part of the article is available at this link.
References
[i] Varisco, D. M. 1991. The future of terrace farming in Yemen: A development dilemma. Agriculture and Human Values. 8(1–2):166–172.
[ii] Varisco, D. M. 1996. Water sources and traditional irrigation in Yemen. New Arabian Studies 3:238-257.
[iii]Baquhaizel, S. A., Saeed, I. A. and bin Ghouth, M. S. 1996. Documentary study on models of traditional irrigation systems & methods of water harvesting in Hadramout & Shabwah governorates. Environmental Protection Council.
[iv] Brunner, U. 1997. Geography and human settlements in ancient southern Arabia. Arabian Archaeology and Epigraphy. 8(2):190–202.
[v] Harrower, M. J. and Nathan, S. 2018. Ancient water management in southern Arabia: Creativity, resilience and sustainability in Yemen and Oman. In Sulas, F. and Pikirayi, I. eds. Water and Society from Ancient Times to the Present : Resilience, Decline, and Revival. Taylor and Francis.
[vi] Beckers, B. and Schütt, B. 2013. The elaborate floodwater harvesting system of ancient Resafa in Syria: Construction and reliability. Journal of Arid Environments. 96:31-47.
[vii] Ortloff, C. 2005. The water supply and distribution system of the Nabataean city of Petra (Jordan), 300 BC-AD 300. Cambridge Archaeological Journal. 15:93-109.
[viii] Evenari p150
[ix] Ashkenazi, E., Avni, Y. and Avni, G. 2012. A Comprehensive characterization of ancient desert agricultural systems in the Negev Highlands of Israel. Journal of Arid Environments. 86:55-64.
[x] Evenari, M. 2019 [1981]. Twenty-five years of research of runoff desert agriculture in the MidEast. In Berkofsky, L., Faiman, D. and Gale, J. eds. Settling the Desert. Gordon Breach Science Publisher, NY.
[xi] Evenari et al. p 97.
[xii] Hillel, D. 2: Negev: land, water, and civilization in a desert environment. United Nations University website.
[xiii] Rohn, A. H. 1963. Prehistoric soil and water conservation on Chapin Mesa, Southwestern Colorado. American Antiquity. 28(4):441-455.
[xiv] Earles, T. E. 2005. Mesa Verde Reservoirs: ten years of paleohydrology. Water Resources IMPACT 7(3):9–15.
[xv] Wright, K. R. 2003. Water for the Anasazi: How the ancients of Mesa Verde engineered Public Works. Public Works Historical Society No. 22, June.
[xvi] Wright, K. R. 2024. A summary of 25 years of research on water supplies of the Ancestral Pueblo People. Water. 16, 2462. https://doi.org/10.3390/w16172462
[xvii] Nabhan, G. P. 1986. Papago Indian desert agriculture and water control in the Sonoran Desert, 1697–1934. Applied Geography 6:43–59.
[xviii] Agriculture. https://www8.nau.edu/hcpo-p/AgricFactYth.pdf
[xix] Bryan, K. 1929. Flood-water farming. Geographical Review, 19(3):444–456.
[xx] Nabhan, G. P. 1983. Papago Fields: Arid Lands Ethnobotany and Agricultural Ecology. PhD Thesis. University of Arizona.
[xxi] Stone, T. 2016. Desert Sage: An Interview with Gary Nabhan. Boyce Thompson Arboretum Magazine, July.
[xxii] Some anthropologists think the culture did not die or move, and the descendants are the Tohono O’odham and Akimel O’odham. This is what the O’odham believe.
[xxiii] Caseldine, C. R. 2025. A reevaluation of Hohokam irrigation systems in the Lower Salt River Valley, Arizona. KIVA. January. 1–24.
[xxiv] Woodson, M. K. 2015. The impact of flooding on Hohokam canal irrigation agriculture. pp. 180-216 in Ingram, S. E. and Hunt, R. C. eds. Traditional Arid Lands Agriculture: Understanding the Past for the Future. The University of Arizona Press, Tucson
[xxv] Gleason, J. A., Sánchez, Y. C. and, Flores, C. C. 2020. Mexican rainwater harvesting movement in recent years. In International Rainwater Catchment Systems Experiences: Towards water security. IWA. DOI 10.2166/9781789060584_0073.
[xxvi] Sheridan, T. E. 1996. La gente es muy perra: conflict and cooperation over irrigation water in Cucurpe, Sonora, Mexico. pp. 33–52 In Mabry, J. ed. Canals and Communities: Small-Scale Irrigation Systems. University of Arizona Press.
[xxvii] Tandon, A. 2023. Climate change: Intensity of ongoing drought in Syria, Iraq and Iran ‘not rare’ anymore. Carbon Brief. November 8.
[xxviii] Mitchell, J. F. B., Manabe, S., Meleshko, V., and Tokioka, T. 1990. Equilibrium climate change and its implications for the future. In Houghton, J. T., Jenkins, G. J., Ephraums, J. J. eds. Climate change: The IPCC scientific assessment. Cambridge University Press. pp. 131-172.
