Sustainability of a viable water management system that depends on eliminating activities that harm the ecological integrity of the region and the catchment area and the social fabric that allows the system to function, without compromising the historical and cultural values of the built environment.
Long-term continuity (sustainability) of the system also depends on the ability of the system to recover from occasional perturbations (resilience). Resilience, in turn, depends on the ability to monitor and anticipate harmful consequences of certain actions (e.g. falling water table) or otherwise unforeseen events.
(e.g., climate change or new marketing opportunities), the ability to innovate to eliminate harmful developments and improve performance (e.g., use of solar energy, change crops, water recycling).
One of the main themes of the SHADUF project is the exploration of how the study of traditional water management systems can contribute to sustainable development. Sustainability is defined in a variety of ways. We use the term in the SHADUF project to refer to the long-term maintenance of a viable water management system which depends on eliminating activities that harm the ecological integrity of the region and the catchment area and the social fabric that allows the system to function, without compromising the historical and cultural values of the built environment.
Long-term continuity (sustainability) of the system also depends on the ability of the system to recover from occasional perturbations (resilience).
A resilient system is robust and has built-in mechanisms to override or militate against occasional setbacks.
A great deal of resilience depends on the ability to monitor and anticipate harmful consequences of certain actions (e.g. lowering water table) or otherwise unforeseen events (e.g., climate change or new marketing opportunities), the ability to innovate to eliminate harmful developments and improve performance (e.g., use of solar energy, change crops, water recycling).
In addition, traditional water harvesting and management systems are rapidly vanishing due to market economics and shift of economic activities, emigration in response to falling revenues from traditional subsistence systems and developing opportunities for wage earnings elsewhere.
This has led to a dramatic disappearance of experts and expert knowledge.
The combination of socioeconomic changes and technological developments are thus rapidly undermining the sustainability of human populations in arid and semiarid regions.
Short-term benefits requiring high input from non-renewable energy sources, capital financial resources, advanced technology, and extra-local managerial control cannot be sustained indefinitely with the probable consequences of creating uninhabitable areas in many parts of the world.
In the course of the SHADUF Project, Fekri Hassan (CULTNAT), introduced a model based on the dynamic interaction of the ecological and cultural variables that influence water supply and demand. The dynamics of demand and supply depend on external ecological parameters that influence local availability of surface, near surface, and groundwater resources. The cultural variables of water management are considered in terms of (1) water harvesting techniques, (2) water lifting, transport and distribution, (3) water uses, (4) water elimination and drainage, and (4) water treatment.
Investigation of sustainability of using the Shaduf water lifting device in Algeria (Abdelkrim, Benammar, USTO) revealed that oases are declining. This is attributed mostly to a decline in trade as well as agricultural activity (which was in part related to the volume of trade). In addition the oases are threatened by sand invasion, a drop in water table, and salinization. Moreover, manual labor for lifting water from wells and irrigation was provided by a caste of slaves from Sub-Saharan Africa. Since slavery has been abolished it is no longer possible to find cheap labor. Furthermore, there is a loss of well digging “know-how” because oral tradition is disappearing.
Joshka Wessels (SUD TIMMI, Algeria) with Robert Hoogeveen provide a navigation tool to consider some of the variables that influence the sustainability of qanats see also foggara, Khettara in Glossary) in the Mediterranean region (Indicators and strategies for sustainable qanat rehabilitation). The tool is based on her work in Syria, independent of the Shaduf Project (see Joshka Wessels, “Reviving Ancient Water Tunnels in the Desert Digging for Gold?” Journal of Mountain Science Vol 2 No 4 (2005): 294~305).
On the basis of her fieldwork, prior to the SHADUF Project, with two communities, she concluded that Syrian groundwater shortage is evident from the various research data on water supply and demand. Irrigated agriculture uses most of the water resources in Syria. The introduction of diesel-operated pumps has contributed to the severe drop in groundwater levels. She investigated how traditional groundwater supply techniques and how these techniques can be rehabilitated using participatory approaches. Her study follows a Participatory Action Research approach in which the social and physical possibilities of renovating a qanat at community level are considered.
In her work she found a total of 91 qanats of which 30 were still in active use in 2001, most of them are located in southwest Syria. A pilot renovation was executed at Shallalah Saghirah, a site where the local community is solely dependent on the qanat water supply. Although her work was technically successful, the participatory approach did not succeed in resolving existing differences between community members. On the contrary, the initial emphasis on equality and democracy was counterproductive and created an untenable social situation for the village supervisor
At Qarah, a town where qanats play an important role in the social organization of the farmer’s community. The hierarchical structure of the traditional qanat organization in Qara contributed to the social success of the project. Wessels project received financial support from the Netherlands Development Assistance; the United Nations University, Tokyo, Japan; the Dutch, German and Swiss Embassies in Damascus, Syria; and the University of Amsterdam, the Netherlands.
Wessels has also produced, on the extensive collection of digital video footage, Joshka Wessels, a television documentary about the pilot qanat renovation for the BBC World Earth Report Series. Her 26-minute program was broadcast in March 2003 and had a rerun on BBC News24 and BBC One in April 2004. More information can be obtained at www.tve.org/earthreport.
In Italy, Ipogea provides a case study based on the study of the measurements of cisterns to explore possibilities for restoration and sustainability (Sassi of Materia). USTO also provides an assessment of the sustainability of traditional water techniques in Algeria (Algeria-sustainability).
Traditional Water Harvesting Techniques
Traditional water harvesting systems in North African and Southwest Asia include some of the oldest sustainable methods of water harvesting in arid lands.
An understanding of these systems which have lasted for millennia is crucial for current efforts to combat desertification and rehabilitate degraded desert habitats at a time when climate change is compounding the threat to many areas in North Africa and Southwest Asia which are extremely vulnerable to shifts in climatic conditions.
At present there are two main classifications of traditional water harvestng systems one by Oweis et al. (2004) and the other by Prinz (1996. 2000).
The classification by Oweis et al. (2004)(see below) starts by subdividing techniques on the basis of the size of the catchment area, which is the area from which water is collected. Small catchment areas (micro-catchment) are then further classifed as roof-top and on-farm techniques. By contrast, techniques that depend on large catchment areas (macro-catchment) are further subdivided into wadi bed and off-wadi systems. Prinz bases his classification initially on the basis of the source of water; namely, rainwater, floodwater, and groundwater.
The current proposed classification follows Prinz in using the source of water as its starting point, however, in the current system a recognition is made of harvesting moisture (dew and air moisture), snow and snow meltwater. In addition, a differentiation is made between ephemeral wadi water and floodwater from perennial water, like the Nile.
Water from surface runoff is also recognized as a category on its own.
In many cases, harvested water is not used immediately and is stored for use later in cisterns, reservoirs, tanks, or wells. These storage facilities are often lined to prevent water loss, and may be covered to minimize evaporation and prevent introduction of unwanted sand or litter. Similar facilities, however, are used to harvest groundwater. Since they depend on seepage from groundwater, they are mostly unlined cavities. In many cases water harvesting, as in the case of surface runoff, is based on either channeling runoff to storage areas or enhancing infiltration to maximize amount of moisture in the ground.
Water harvesting depends not only on the sources of water, but also on bedrock, surface relief, vegetation, evaporation rates, and more importantly know-how. This or any other classification is only a means for exchanging information within a conceptual framework and a standardized terminology. We hope that this contribution will bring to the attention of policy makers, professionals, and the General Public the innovative approaches by which people in Aridlands all around the Mediterranean have been able to overcome the adversity of water scarcities in a fragile environment. These methods may be used as they have been traditionally used, they may be coupled with new technologies and new materials for greater efficiency and better performance, or they may just be a source of inspiration for equally innovative techniques or even just as an illustration of the endemic problems of water scarcity in desert regions and the ingenuity required to survive where water, the source of life, is a rare gift.
Classification Of Water Harvesting Systems Oweis, Hachum and Bruggeman
In 2004, ICARDA issued a monograph (Oweis, Hachum, and Bruggeman, 2004) with case studies from Tunisia, Jordan, Morocco, Syria, Libya, Iraq, Egypt, and Yemen. In the introductory chapter to that volume Oweis et al. (2004) present a classification system after Oweis et al. (2001) and Prinz (1996, 2001).
Oweis, Hachum, and Bruggeman (2004) provide the following description of traditional water harvesting methods:
The microcatchment systems are those in which surface runoff is collected from a catchment area where surface runoff prevails over a short distance. The system, though simple, requires continuous maintenance with a relatively high labour content.
Contour ridges are “bunds”, usually constructed along the contour line at intervals between 5 and 20 meters.
Semi-circular and trapezoidal bunds consist of bunds assuming geometrical winged shapes facing the direction of maximum slope. They are constructed so that they can catch water from a large area to supply water for plants behind the bund.
Small pits consist of holes 0.3-2 m in diameter, and 5-15 cm deep. Manure and grass are mixed with soil and placed in the pits. These pits are excellent for rehabilitation of degraded agricultural land.
Small runoff basins, which are sometimes called “negarim”, are small shallow basins 5-10 m in width and 10-25 m in length. They can be constructed on almost any slope and are suitable for growing trees.
Runoff strips are narrow cropped strips alternating with vegetated [does this mean cultivated?] strips. The strips (1-3 m) facilitate the movement of runoff water to irrigate the cultivated crops.
Contour bench terraces are terraces supported by stone walls and constructed on very steep slopes.
Courtyard and Rooftop systems include systems constructed to harvest water from roofs and courtyards of houses, large buildings, and greenhouses. Water collected is used mostly for domestic purposes.
Macrocatchment and floodwater systems harvest water from very large areas. The catchment area is often outside the boundaries of the farm. Accordingly, they involve problems of water rights and water allocation. They include wadi-bed systems (a wadi is an ephemeral stream) in which water is used from wadi surface water or water infiltrating the wadi bed. Small dams are often cosntructed to store water in reservoirs. Jessourare dams or embankments constructed across steep slopes. Sediments in water stopped by the dams settles to form new farm land. Off-wadi systems make use of wadi water to irrigate areas outside the wadi-bed. The most important off-wadi systems include water-spreading systems which are based on diverting water from its original course to adjacent areas. Large bunds (also called tabia in Tunisia) consist of large V-shaped earthen bunds spaced at a distance of 10-100 m. They can store large amounts of water.
Tanks and reservoirs are often excavated in the ground. They are called hafa’ir in the Sudan, Jordan and Syria.
Cisterns are subsurface reservoirs with a capacity ranging from 10 to 500 cubic meters. They are often used for human and animal water consumption.
Hillside runoff systems also called sylaba or sailaba are cosntructed to direct runoff downhill to flat fields (often before it joins wadis).
Prinz Classification of Traditional Water Harvesting Systems
Another classification has been provided by Prinz (1996, 2000). His classification is as follows:
- Rainwater Harvesting
- Floodwater Harvesting
- Groundwater Harvesting
Conventional irrigation methods use the rainfall after it has infiltrated into the ground, using underground water or the wa�ter of permanent streams and rivers.
Rainwater harvesting techniques collect the rainfall before it enters the soil, i.e. as surface runoff.. The collection and concentration of rainfall and its use for the irrigation of crops, pastures and trees, for livestock consump-tion and household purposes is called rainwater harvesting.
Each rainwater harvesting system requires:
A “runoff area” (catchment) with a sufficiently high run-off yield, and
“run-on” area for utilisation and/or storage of the accumu-lated water. These methods can be subdivided according to their way of water collection and the kind of storage. The greater the aridity of an area, the larger is the required catchment area in relation to the cropping area for the same water yield.
Three types of water harvesting for agricultural purposes are covered by “Rainwater Harvesting”:
Water collected from roofs and courtyards and similar paved, bituminized, or otherwise treated surfaces. The col-lected water is used for domestic purposes, for animal water consumption or for garden crops.
Micro-catchment water harvesting is a method of collecting surface runoff (sheet or rill flow) from a small catchment area and storing it in the root zone of an adjacent infiltration basin. The basin is planted with a single tree or bush or with annual crops.
Macro-catchment water harvesting is also called “water har-vesting from long slopes” or “harvesting from external catchment systems”. In this case, the runoff from hill-slope catchments is conveyed to the crop-ping area located below the hill foot on flat terrain.
Floodwater harvesting is also called Large catchment water harvesting or “Spate irrigation”, and comprises two forms:
In case of “floodwater harvesting within the stream bed” the water flow is dammed and, as a result, inundates the valley bottom of the flood plain. The water is forced to infiltrate and the wetted area can be used for agriculture or pasture improvement.
In case of “floodwater diversion”, the wadi water is forced to leave its natural course and conveyed to nearby cropping areas. These two systems – the catchments being many square kilometers in size – require more complex structures of dams and distribution networks and a higher technical in-put than the other two water harvesting methods. It is difficult to give exact figures on the present total area under the various forms of “Rain and Floodwater Harvesting”.
Groundwater dams obstruct the flow of groundwater or the subterranean flow of ephemeral streams and rivers in a river bed. The water is stored in the sediment below the ground sur-face. The stored water can be used to recharge an aquifer or to raise the level of an aquifer thus making it more accessible for lifting.
There are basically two types of groundwater dams: sub-surface dams and sand storage dams. A sub-surface dam is constructed below ground level and arrests the flow in a natural aquifer. A trench is dug across the valley, reaching down to the bedrock, and a dam is constructed in the trench. Water is extracted at the upstream side of the dam by shallow wells.
This contribution has been conceived and actualized within the SHADUF Project. The use of iconic representation has been initiated by P. Laureano (IPOGEA, Italy), but his descriptions and classification of water harvesting system are not followed here. The graphics are the work of Adham Bakry based on schematic sketches by Fekri Hassan.
A New Classification of Traditional Water Harvesting Systems
A consideration of current classifications of traditional water systems in North Africa and the Middle East led Fekri Hassan to develop an alternative classification.
The proposed system is based on an initial categorization of water harvesting systems on the basis of the source of water (rainfall, surface runoff, river flood discharge, wadi flow, groundwater, and air humidity). Water harvesting systems are then classified on the basis of the nature of –
Modification of the earth surface into subtractive features creating depressions (e.g.,
Reservoirs, pits, holes, conduits, cisterns, wells) and additive features creating elevated landforms (bunds, ridges, mounds, walls, dams). Combinations of these elements create multiplex water harvesting systems (negarim, foggaras, terracing).
The following diagrams illustrate the logic behind the new classification:
The main terms used in discussing traditional water harvesting include:
Bunds. –Permeable Ridges constructed from earth or stones
Catchment Area. –Area from which water is collected (see Micro-Catchment)
Contour. –Imaginary line connecting points of the same elevation in a landscape.
Infiltration. –Water percolating into the ground.
Runoff. –Water movement from rainfall downslope.
Runoff capture. –percentage of rainfall captured by runoff.
Ranging from a few percentages to 50%.
Micro-catchment. –A small catchment area from a few square meters to around 1000 square meters.
Permeable. –A medium that allows water to flow through it.
Soil. — The top part of the ground produced under the effect of vegetation.
Slope. — The inclination of the surface of the ground measured as percent or angle. Slopes are characterized as gentle or steep.
Storage. –Accumulation of water in the ground through infiltration, in natural depressions, or in artificially created reservoirs, pools or cisterns.
Wadi bed. –floor of wadi channel.
I. Direct Rainwater Harvesting
Rainwater harvesting techniques collect the rainfall before it enters the soil, i.e. as surface runoff.
The collection and concentration of rainfall and its use for the irrigation of crops, pastures, trees, for livestock consumption and household purposes is called rainwater harvesting.
Roof & Courtyard Rain Water Harvesting
Water is collected from the rooftop of a house (and sometimes a courtyard). It is then transported though a pipe to be filtered and stored for domestic use. In Greece this technique is called Impluvium.
II. Surface Runoff Water Harvesting
This group of techniques depends on the harvesting of surface runoff water from a small catchment area ranging from a few square meters to around 1000 square meters.
Water accumulates in artificial depressions from direct rainfall and surface runoff to form water pools and ponds. The amount of water and its persistence in the pond depends on the amount and seasonality of rainfall as well as the spacing of rain storms. It also depends on the compaction, pavement or smoothing of the catchment area, which can be artificially enhanced. It also depends on reducing infiltration by sealing the bottom of the pond and lining the pond with stones and plaster. They range in capacity from 1000 to 500,000 cu.m.
In Syria, a Birka is a stone built reservoir.
Semicircular & trapezoidal bunds (permeable structures)
Crescent shaped earth bunds, usually constructed in staggered rows.
Bunds arranged downslope in straight lines to slow surface runoff and increase infiltration.
Crescent shaped earth ridges constructed down-slope from trees to increase water harvesting and infiltration in the ground.
Circular ridges from earth constructed to enhance water retention and infiltration.
Tree retention ring
The construction of a wall around a tree in order to retain moisture and occasional precipitation
Terracing (small-scale and large-scale)
Reshaping the slope by a series of more or less flat steps.
Earthen low ridges arranged to create artificial basins.
Linear ridges constructed along the contour lines at intervals of between 5 and 20 meters.
Contour bench terraces
Often on very steep slopes, the terraces are supported by stone walls. Common in Yemen for growing coffee and qat as well as trees and field crops.
Small stone mounds were used by the Nabateans to enhance surface water runoff by as much as 25%. They are called by the Bedouins Tuleilat el-‘Anab (vineyard hillocks) and might have been used for supporting the cultivation of vineyards (Issar 1990, 181). The system is perhaps analogous to the more substantial “Kroum” of the Egyptian coast.
Small (0.3-2 m in diameter), deep pits (5-15 m). A dyke may be constructed downslope from the pit.
Artificial mounds of earth constructed to allow rainwater to flow into farming area and subterranean cisterns. Used on the coastal area of Egypt in Roman times to irrigate vine and olive orchards. (Photos F. Hassan, Maryut, Egypt)
Used on gentle slopes, one bare strip is used as a catchment while the strip downslope from it is used for growing crops, mostly field crops.
Negarim (small runoff basins)
Small (5-10 m in width and 10-25 m in length) runoff basins, rectangular, elongated or diamond-shaped surrounded by low earth bunds. Suitable for tree crops.
Hillside conduit system
Excavation of water runnels to harvest water and direct it to where it is needed.
A canal to transfer water running along a hillside. A wall may be built to form the outer wall of the aqueduct.
Hillside runoff system (Saliba) Sylaba, sailaba
Water flowing downhill is directed to flat-lying fields by small conduits before it joins the wadi. A spillway may be used to drain excess water for use downstream.
Water tank, Hafi (the Sudan), Kuruf (Karif sing. Yemen)
Large earthen or stone built reservoir dug into the ground downslope from a wadi to collect water.
Stone-lined water tank, Mawajel (Yemen)
Tanks for water storage, often circular with plastered floors for domestic use (Yemen).
Pond with a settling tank
A settling tank is situated so that solid particles in the water are allowed to settle before water enters the pond.
Small subsurface water containers with a capacity ranging from 10 to 500 cu. m. They are often rock-cut. Varieties include pit cisterns, jar cisterns, or built stone cisterns. They receive water from rainfall, water drip in caves, groundwater, or runoff. A settling area may be used to remove solid particles in water.
Underground cistern for rainwater harvesting
Cistern with a settling basin
A settling basin is constructed to prevent solid particles from entering the cistern.
Roofed cistern, Siqayat (sing. Siqaya), Niqb, Greek-type Cistern
Roofed tanks or cisterns below ground with roof above ground.
Abar Romani (Syria)
Cisterns excavated in bedrock, Syria.
Domed Cistern, Kumbet (Iran)
A cistern covered with a dome-like structure, Iran.
Constructed on the coast of Egypt during WWII by the British troops to store water (Photo F. Hassan, Dab’a, Egypt)
III. Wadi Floodwater Harvesting
This system depends on harvesting water from wadis. Water flow in the wadis is seasonal, erratic, and occasionally torrential. Several methods are used to harvest water from the wadi which depends on slowing water flow during peak discharge to allow water infiltration and divert water flow to fields or cisterns.
Jessour(pl.), Jisr (sing.).
Wall built across step wadi (e.g., in Tunisia). Spillways may be used.
Wadi cross walls, dams, dykes (Marbid, Arabic, Yemen),
Stone wall constructed across gentle-sloping wadi bed. Dams are rarely above one meter.
A series of check dams may be used to slow water down and increase infiltration, or for water storage in cisterns or tanks.
A series of dams is constructed in the wadi bed to direct water for cultivation on wadi bank terraces.
Wadi High Dams & Reservoirs
High dams more than 10 meters in height have been constructed since Antiquity. Among the oldest high dams is Sadd el-Kafara in Wadi Garawi, Egypt, the Sadd at Jawa, Jordan, and the Ma’arib dam in Yemen.
Sadd el-Kafara, Wadi Garawi, Egypt (photo Fekri Hassan)
Tabia: Large (semicircular) bunds, Rabat
Term used in Tunisia referring to the use of large earthen bunds in circular, trapezoidal or V-shape, about 10-100 meters in length and 1-2m in height.
They are staggered facing upslope.
Water Diversion Levee & Dam (Water Speeding System)
Water in a wadi is diverted by a dam or dyke to raise its level so that it can be channelled to the banks of the wadi. A levee is used on the side of the wadi to direct the water.
Flat area of wadi where water collects.
Large basins, often at high elevations where water is collected behind dams.
Waterfall Harvesting Cistern
A cistern constructed to receive water cascading from a waterfall.
IV. River Floodwater
Stream Irrigation System
An irrigation system that makes use of water flowing in a natural stream
Basin Irrigation (dykes and levees)
Water is diverted from the river into a feeder canal. Artificial basins are created by a system of levees (a high embankment parallel to the channel) and a series of cross-dykes. The embankment next to the Nile is called Tarad. The cross dykes are called “Salayib” (pl., sing. Saliba). Water is drained back into the river through a drainage canal. Each group of five or six basins constitutes a chain (Silsila). Canals leading to lower parts of the basins are called syialat (pl., siyala, sing.). The canal ?????
Water gates constructed to regulate the flow of water in a stream. They are also used as bridges.
Hod zar’. Small farming basins
Small basins for planting vegetables and other crops are created by constructing low ridges. The basins are fed by water runnels.
Wells may be dug to take advantage of water seepage from irrigation canals and the main streams in areas outside those supplied by canals or to ensure supply of water regardless of the water level in a canal. In the Faiyum, Egypt, a water well dating to the Roman period was found at Karanis, Faiyum Oasis.
V. Groundwater Harvesting
SpringKhazan, Majahir(Syria),’Ain (Egypt)
Water tank to hold spring water.
A pit for collecting water from sand above an impermeable layer.
Drip water Harvesting
Water dripping from seepage in a cave is collected in storage pits. Common in Karstic areas where limestone has dissolved to form sinkholes, solution fissures, subterranean tunnels, caves, and other solution features.
Open galleries or aqueducts
Open, surface channel used to convey and distribute water (photo F. Hassan, Dab’a, Egypt)
Underground Qanats(Qanwat Romani, pl.), Khettara orKahariz (Iraq, Iran, Afghanistan, Pakistan)
A subterranean tunnel connected to a well used to tap and convey water from an aquifer over a fairly long distance down a gentle slope to be used for irrigation and domestic functions. Storage tanks may be used. The first intake well is called a “mother well”. Shafts or wells spaced within tens of meters of one another serve as air shafts and provide access for maintenance. These were already highly developed in western Iran, northern Mesopotamia and eastern Turkey at least 2800 years ago. The system with modifications and regional variants is known from later periods in Greece, Rome, and the under the Arabs in North Africa. The qanats of southern Algeria and southern Morocco are the best developed outside southwest Asia. Introduced into Spain by the Arabs the qanats spread subsequently to Mexico, Peru and Chile. The qanats are also known from the Arabian Peninsula where they are called Aflaj, and are reported from farther east in China.
Coastal perched water qanats (Egypt)
Water is collected from the freshwater layer perched on top of sea water in subterranean tunnels a few kilometres long with manholes spaced about 20 meters apart. The manholes are excavated in porous limestone underlying coastal dune sand. (photos by F. Hassan, Matrouh, Egypt)
Artificial basins, Afreg (Algeria)
An artificial basin is excavated in a dune field reaching close to the shallow water table supplied by local rainfall.
Shallow water wells (Jilban, Iraq)
Shallow well to collect water from sand in a wadi bed
Instead of lifting water by a bucket (with or without a pulley), these shallow groundwater tables are reached either by a ramp which could be also used by animals, or by a staircase, which may be constructed at several levels.
A well drilled to reach a ground water table. Water rises to the surface as a result of an internal hydrostatic pressure.
Artesian well, Egypt (photo F. Hassan)
Agroundwater cistern excavated below ground to harvest water seepage from a shallow water table.
VI. Moisture Harvesting
Moisture Harvesting Mounds
Water harvesting from the condensation of air moisture using a mound of stones. Water drips from the mound into a pit below it.
Moisture Condensation Canopy
A canopy is placed on top of a water tight hole to collect condensed water. Alternatively a plastic sheet with a stone at the center may be placed over a hole where a receptacle is situated below the stone. Overnight dew drips into the receptacle.
Stone slab moisture capture
Arrangement of stone slabs to capture and channel moisture in the air through condensation to the ground.
VII. Snow Water Harvesting
Snow harvesting enclosures: snow captured in low wall enclosures associated with pastoral settlements and animal enclosures (Photo F. Hassan, Morocco).
Snow meltwater is harvested in reservoirs using dams (Photos F. Hassan, Morocco).
Water Transport and Distribution
Mesqa (Egypt, ditch or irrigation canal) , Saqqia (Morocco)(canal?)
A ditch or runnel used to convery water from source to landuse area.
Qanat comb distributary system
System used to allocate shares of water for distribution to users (Photo. F. Hassan, Adrar)
Aqueducts are narrow runnels used to convey water. Where water crosses a low area, structures may be constructed allowing water to flow in a narrow channel at the top of the structures.
Terracotta pipe aqueducts
Terracotta pipes were used in Crete and Jordan in ancient times to transport water. They become widely used under the Romans (Petra, Photo U. Bellwald, PNT, Jordan