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Best Practices on Indigenous Knowledge MOST/NUFFIC (IK-Unit)


Daldal: dams to trap silt and water, an Irob innovation in northern Ethiopia[1]



Crop yield, food security, soil conservation, water conservation


Introducing the practice

The practice was developed by the Irob in northern Tigray in Ethiopia, on the border with Eritrea. The Irob speak Irobigna, which belongs to the Saho group of languages, and are ethnically distinct from the Tigrigna speakers in the Tigray region.

The Irob used to be a pastoral people, moving with their goats and cattle from the mountains on the eastern escarpment of the Ethiopian highlands to the lower plains. It was not until two or three generations ago that the Irob began to pay more attention to cropping, because they could no longer obtain enough cereals in exchange for their livestock products.

The landscape is very rugged and stony, with steep slopes and deep narrow valleys carved out of the plateau by flash floods. There is little land suitable for cropping. Over four decades, the Irob developed site-appropriate methods to capture soil and water for cropping. They built a series of checkdams in the seasonal watercourses and raised and lengthened the walls every year. In this way, they created step-like terraces that are now about 8 m wide and up to 10 m high, with about 20 m between dams. This innovation is known in Irobigna as daldal. It requires year-round effort over many years or even decades.

The practice originated in the community. The idea came from two Irob men: one who was regarded as crazy by his neighbours, and another who had served as a soldier in North Africa in World War II and had observed the traditional water-harvesting methods used there. Both men experimented with building small dams to catch water and silt, thus creating fields on which crops could be grown. They were observed by others, including Zigta Gebre Medhin, the innovator and leader who was also the main informant for this best practice. (See the address below.)

Using their indigenous engineering skills, the Irob have continued to improve the practice. Although building and maintaining the dams and cropping in the small pockets of harvested soil and water is very labour-intensive, it will be necessary for the survival of the Irob for as long as they want to remain in this rugged area, to which they have a strong cultural and emotional attachment.

Content and approach

Irobland is a land of extremes: of depths and heights, of droughts and floods, of frost and scorching sun. The altitude varies from 900 m (Endeli Valley) to 3200 m (Mount Asimba) above sea level; most people live between 1500 m and 2700 m. Rainfall in the main inhabited area is low (200–600 mm per year) and highly variable in space and time. A wet season is expected from mid-June to mid-August. However, water and soil eroded from the highlands, which receive more rain over a longer season, sporadically pour from the Adigrat plateau down through the seasonal streams that flow into two perennial rivers. These flow eastwards towards the Red Sea, but sink into the Danakil depression, 100 m below sea level, before reaching it. 

As is common in tropical highlands, the daily variation in temperature is greater than the seasonal variation over the year. The annual mean temperature in Alitena (at an elevation of 1850 m), the heart of Irobland, is just under 20o C; maximum temperatures can rise above 30o C; minimum temperatures can fall to 5o C. Frost occurs occasionally above 2500 m.

The Irob people, in trying to survive and even to cultivate crops in this harsh environment, have proved to be extremely inventive. Even in the early 1970s, when a Swiss geographer studied land use by the Irob, he marvelled at the ‘grosse Spielbreite an Techniken und Nutzungsformen’ (‘the broad gamut of techniques and forms of land use’) (Strebel 1979). He drew attention to the innovativeness of the Irob, who within an amazingly short period of time and without outside assistance, had developed site-appropriate soil and water conservation methods for crop production.

When the Indigenous Soil and Water Conservation action research programme (ISWC-2) commenced in Tigray in early 1997 and was seeking indigenous innovators in land husbandry, an obvious place to look was Irobland. Zigta Gebre Medhin, a man about 80 years old from Awo village near Alitena, the ‘heart’ of Irobland, told them the story of Ghebray Hawku from Daya village near Awo, who dreamt up a new idea about 50 years ago. In an attempt to catch the soil and water that rushed down the slopes, he had piled stones and earth across the stream’s path in order to make a field for sowing grain. His neighbours saw his hard work and pitied him as they thought he was slightly demented. But Ghebray told them: ‘Tomorrow you will all be as crazy as I am.’ The others laughed but, as Zigta noted, a seed had already been planted in their minds. That seed began to grow when another Irob man, Kahsay Waldu, returned home as an ex-soldier. He had seen traditional soil and water harvesting by farmers near Tripoli. In a valley beside his home, he imitated the North African farmers by constructing a small dam, much like the one that Ghebray had built. Zigta observed this with interest and decided to experiment with the idea himself.

The daldal process

Zigta started in 1957 by fixing a large stone at the bottom of a seasonal watercourse beside his house. Silt collected behind this barrier. He sowed a few seeds on the newly created patch of land and harvested an armful of maize cobs. The next year, he placed more stones to make a somewhat higher barrier, collected more silt and harvested more maize. Over four decades he built a series of checkdams going farther up the watercourse, and raised and lengthened the walls each year. In this way, he created step-like terraces that are now about 8 m wide, with a horizontal distance of about 20 m between dams. Some of his checkdams are filled up to 10 m deep with silt that had been flowing down from the eroding Agridat plateau. Not only has new farmland been created where there had been only rock before, but well-filtered water can now be collected from the foot of the lowest dam during most of the year.

Over the years, Zigta watched how the soil and water flowed within the terraces and over the dams, and learned from these observations. He changed the shape of the dams by curving the walls outwards as he widened them so that more soil collected and the force of the water was spread. He scraped down other patches of soil to help fill in the area behind the newly raised terrace walls so that a larger cropping area would form more quickly. He improved the arrangement of the stones on the top of the dam walls and placed some very heavy stone slabs slanting slightly upwards at the outer edge so as to prevent possible damage to his structures from the overflow. He dug trenches both to increase run-on at some points and to divert excess water at others. He transferred sods of a tough local grass, known as tahagu, on to the deposited silt immediately behind the dam walls. The grass grew down and through the stones, holding them together like gabion wire. An additional benefit is that he can feed the grass to his animals. He planted trees in front of the walls to reinforce them. He did not develop techniques to fertilize the terraced land; he explained that soil fertility is maintained by the continuous addition of soil and litter, including tree leaves, with each flood.


The role of indigenous knowledge

At the time when Zigta began to build checkdams, wealth was measured not in land and crops, but in livestock. He was a skilled livestock keeper and had several cattle, goats and beehives. In the mid-1950s, his family consisted of four persons. He used to sell or trade animals to obtain cereals. However, after some years, as the terraces behind the checkdams became bigger, he was able to produce his own cereals and did not need to sell so many animals. He thus became richer.

His motivation for innovation came partly from necessity and partly from curiosity. When asked why he started the strenuous work of building checkdams, Zigta replied: The geographical conditions of Irobland were not suitable for cropping, and are still not very suitable today. So our main source of livelihood in the past was livestock. We used to travel to faraway towns such as Zalambessa and Adigrat in order to buy cereals which were carried on the backs of donkeys for days, up and down the mountain paths. Some people who did not have donkeys carried the cereals home on their shoulders. While experiencing these hardships, we were not idle in our minds. We were forced by nature to think for ourselves with a long-term view.

Because of the different seasons, wet and dry, we moved from place to place with our animals to seek grazing land. During these movements, I observed some things again and again: when it rains, dried leaves and fallen trees are washed down the valleys with the soil. Seeing what Ato Ghebray and Ato Kahsay (the first two Irob men who tried placing stones to catch the soil) were doing motivated me to start trying it myself, but if I had not noticed the things I mentioned just now, I would not have tried checkdams based only on these two men’s examples. The main question I asked myself when I started was: ‘Would it be possible to catch soil and water to create land and grow crops where this floodwater passes?’

Zigta described the years of developing his silt-harvesting system as a series of experiments: doing something with a vision of the benefits it could bring (in other words, a hypothesis, although he did not use this term himself), observing the effects, analysing the reasons for them, thinking of new ways to improve the technology, trying it out, observing, analysing and so on, in a process that continued until the Eritreans invaded Irobland in May 1998 and he had to flee to Adigrat. Sometimes in his experimentation, he recalled, he tried something and it worked well. Sometimes it did not, so then he reflected and tried something else. This entire development process went on without the aid of extension services. He depended on his powers of observation, his analytical capacity and his own creativity. This practice is thus based entirely on indigenous knowledge and informal experimentation.

Persons involved in the practice

Individual male farmers generally build the daldal in valleys near their dwellings, with the assistance of members of the extended family. These structures to create land for cropping by household members are built up gradually over many years.

When the Adigrat Diocese Development Action (ADDA) project, with support from the Catholic Church, started working in the Irob area in the mid-1970s, it stimulated community action to make larger dams more quickly in order to create more land that could be used in ways determined by the community. Men and women work together in constructing the dams; the work is supervised by older men from the community.

The transfer of knowledge

The practice became more widespread in the community after a small number of individuals who were held in high esteem because of their community spirit applied it successfully to create land and produce food. Zigta, for example, was recognised as a local leader, a rank that is conferred by ability rather than heredity in the Irob culture.

The knowledge behind the practice of building the daldal is now known to all male members of the community, but some Irob men are regarded as more skilful than others in adapting and improving the daldal and in experimenting with different ways of using the niches that they have created for crop, grass and tree production. Not all members of the community actually apply their knowledge by building the daldal for themselves, and it took several years before the practice began to spread beyond the first few men who initiated it.

The practice is already embedded in cultural and religious practices. The majority of the Irob who have settled around Alitena are strongly attached to the Catholic Church. The first Catholic church built in Ethiopia (in 1846) is in Alitena. Some communication about innovation takes place during church meetings, and priests are asked to bless new ideas. For example, when the Irob decided to regulate access to an area used communally for grazing, they invited the priests to say mass in the area and thus to give strength to the regulation agreements in the community.

Portrait of an indigenous innovator

Zigta sees himself as a hard-working and forward-looking man, and as someone who has been blessed with certain aptitudes. Other members of his family and community confirmed this. He is known as a man for whom laziness is next to sin. If he is convinced of an idea, no amount of difficulties and hard work will prevent him from trying to achieve it. His perseverance and conviction that he is right (some relatives also refer to this as his ‘stubbornness’) drive him on, even when others think it is impossible. He is also known as a man who is concerned about the future of the community and its resources. He initiated community action to manage the use of Sangade, a common grazing area in Irob. Upon his suggestion, the boundary was marked, rules were drawn up to regulate land use, and the priests say mass there once a year to ensure respect of the rules. When the community has made such decisions, he is strong in seeing that they are put into practice.

Traditionally, a man who has many ideas, is talented with words and can organize activities well becomes a community leader. Zigta came to be recognized as such a leader. In his opinion, ‘working closely with the other members of the community is the best way to teach them what one knows.’

Zigta’s conviction that he was on the right track and that others should also benefit from his knowledge motivated him to spread his idea. He suggested directly to neighbours who had similar seasonal watercourses near their homes that they try building dams themselves and he advised them how to do so. He tried to encourage individuals, rather than whole groups of people. Zigta explained: ‘at the time when I started building checkdams, community meetings and discussions were not very common. When we visited each other for other purposes, we advised each other in order to achieve better continuity in our farming.’

Some of these farmers, motivated by the results that Zigta achieved with his checkdams, copied his techniques in order to create new land for themselves. However, the spread of dams was initially quite slow. Even though many farmers recognized the potential of checkdams, it was not easy to build them because there were no handtools and it took some years before enough land could be created to grow enough cereals to make a substantial contribution to the family diet. Zigta summed up the reasons: ‘Handtools were not available then. Others saw it as hard work and it was not clear how it would bring benefits. And not everybody has a clear vision of what they want in their lives now and in the future. God makes people who they are and arranges for them to have certain qualifications in life.’

Dissemination and development of the practice

Over time, communication improved between the farmers in Awo and other villages about how to capture more soil and water–for instance, by changing the shape of the dams and reinforcing them. For structural work on the dams, including major repairs, neighbours started to organize themselves into groups. As pastoralists, the Irob had been relatively individualistic, except for some agreements on the use of common pasture, but their growing emphasis on building and repairing dams to allow cultivation led to an increase in mutual assistance. Almost all Irob farmers who live near seasonal waterflows now use the daldal technique.

A rapid increase in the building of such dams began after the small ADDA project financed by the Catholic Church made metal tools available for quarrying stone, and encouraged the Irob to apply their visions for development and their masonry skills to activities that were planned and implemented by the community, such as making cliffside paths and larger communal dams. This project started in 1975. There were therefore important interactions between indigenous innovation and an externally supported project. This helped the new ideas to achieve recognition and to spread, and it also made tools and funds available (in the form of food-for-work).


Achievements and results

The innovative daldal technique is a best practice because it is an indigenous innovation that has been recognised by many Irob people and by others living under similarly harsh conditions as a way of creating land to produce food and obtain a supply of clean water. It can be applied by anyone willing and able to invest the time and labour to build the traps for silt and water and to maintain them. It uses entirely local materials and lends itself to adaptation and experimentation by the agropastoralists. It creates new microclimatic niches in which further local innovation can take place.

The practice is sustainable in environmental terms, as it reduces soil erosion and makes use of soil and water that would otherwise have flowed down into the barren Danakil depression and been wasted. The daldal can be maintained by independent families living in the mountains of Irobland. The larger community dams are being maintained by community groups under their own management but supported by ADDA project funds. However, the larger areas of land behind the community dams built in flatter valleys (as opposed to the staircases of daldal built by individual families in steep and narrow watercourses) are now facing salinity problems.

The very labour-intensive daldal system provides a means of producing food for people who want to remain in the Irob area. However, many young people who have managed (through the Catholic Church) to obtain a formal education seek easier ways of making a living. They emigrate to other parts of Africa and abroad, especially to North America, and send money back to their relatives in Irobland.

Strengths and weaknesses

In the past the Irob’s main source of livelihood was livestock. They used to travel to faraway towns such as Zalambessa and Adigrat in order to buy cereals which were carried on the backs of donkeys for days, up and down the mountain paths. People who did not have donkeys carried the cereals home on their shoulders. Almost all Irob farmers who live near seasonal waterflows now use the daldal technique and grow their own cereals on the pockets of land they have created.

The practice is very labour-intensive and demands rigorous monitoring of the dams during the wet season. If the areas behind the dams become very large, as is the case with some of the community dams supported by the ADDA project, problems of soil salinity may occur.

The development process could be expedited if formally educated engineers with an understanding of local practices and conditions worked together with Irob farmers to improve the innovations still further and to help other farmers to adapt the innovations to other conditions. It is this interaction of formal scientific knowledge and indigenous knowledge and creativity that the Indigenous Soil and Water Conservation research programme is trying to stimulate.


Source of inspiration

The practice is suitable only for farmers living under certain conditions: in steep, rocky areas near a seasonal watercourse with a heavy run-off of silt and water, for example. Farmers living under other conditions may not be able to copy these feats of indigenous engineering exactly, but they could gain some ideas from them and adapt them.

The practice has spread into neighbouring areas of Eritrea. It can also be found in other parts of Ethiopia with very rugged mountainous terrain, but it is not clear whether this has been the result of contact with the Irob. It could also have been a case of simultaneous innovation by farmers facing conditions very similar to those of the Irob.

If you think that this case could be useful in a different context than the one described here, please get in touch first with the contact person listed below (Administrative data). Intellectual property rights could be an issue.


Additional remarks and information

The knowledge is documented in several articles and in a book:

·           ‘How to gain from erosion: catch the soil’ (1997) by Abba (Priest) Hagos Woldu and Asfaha Zigta, in ‘ILEIA Newsletter 13’ (2): 16–18.

·           ‘Local research and higher action’ (1999) by Ann Waters-Bayer, Fetien Abay and Mitiku Haile, in ‘Forests, Trees and People Newsletter 39’: 7–9 and reprinted in Ground Up 1 (1): 11–12, April–June 2000.

·           ‘Displaced and forgotten? The farmers of Irob’ (1999) by Ann Waters-Bayer in ‘Landmark 32’: 6 – 8, and the French translation ‘Chassés de chez eux et ensevelis dans l’oubli: les paysans Irob’ in ‘Agri-Repère 32’: 7–9.

·           ‘Outwitters of water: outstanding Irob innovation in northern Ethiopia’ by Asfaha Zigta and Ann Waters-Bayer: a chapter in the book ‘Farmer Innovation in Africa: a Source of Inspiration for Agricultural Development’, edited by Chris Reij and Ann Waters-Bayer and published by Earthscan, London (2001).

Several photographs have been taken by ISWC-Ethiopia within the context of the ‘Indigenous Soil and Water Conservation in Africa’ programme. A description of the innovation, written in the Tigrigna language, has been distributed through the Farmer Innovator Newsletter of ISWC-Ethiopia.


Administrative data

Organization involved

The Irob farmers themselves are responsible for the practice. They are located in the Irob District or the Tigray Region of Ethiopia and do not have the usual contact addresses and numbers.

Contact persons

Mr Asfaha Zigta

c/o ADDA

P.O. Box 163, Adigrat, Tigray, Ethiopia

Fax +251 4 451829

Tel.: (private) +251 4 451476



Mengistu Hailu

Mekelle University,

P.O. Box 231, Mekelle, Tigray, Ethiopia

E-mail: mengistuhailu@yahoo.com


Person(s) who have described this Best Practice

Ann Waters-Bayer

ETC Ecoculture

P.O. Box 64

3830 AB Leusden

Tel.: +31 33 4943086

Fax : +31 33 4940791

E-mail: ann.waters-bayer@etcnl.nl; waters-bayer@web.de


[1] This case is an adapted version of an article published in: ‘Farmer Innovation in Africa. A source of Inspiration for Agricultural Development’. Chris Reij & Ann Waters-Bayer (eds.), 2001. Publisher: EARTHSCAN, Earthscan Publications Ltd, London (UK) / Sterling, VA. www.earthscan.co.uk

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