Pietro Laureano *
TRADITIONAL TECHNIQUES OF WATER MANAGEMENT A NEW MODEL FOR A SUSTAINABLE TOWN AND LANDSCAPE
From the First Water Harvesting Surfaces to Paleolithic Hydraulic Labyrinths
Water Control and Irrigation Techniques used by Farmers-Breeders
Phenomena of sedentariness without agriculture occurred in Jericho from 12,000-10,000 years ago. In this phase structures supporting soils were realized by building holding walls and clay platforms with coated environments for drinkable water (Cauvin 1994). Since the VIIIth millennium in Africa, in the Middle East, in Anatolia and in the Pakistan-Indian area original ways of cultivation in arid areas developed in places where the broiling sun gave yields that justified the necessary engagement (Childe). Nonetheless, due to the lack of rainfall, it was necessary to develop methods of water management in these areas. Before introducing irrigation techniques, populations used water directly and naturally available that in arid conditions can be found as atmospheric moisture and soil deposits. The first kind of water supply, that is to say the moisture that deposits in the soil, played a key role in the introduction of cultivations organized in small steady gardens in the sites where the phenomenon was more determinant: areas situated near the basins, water courses or geological situations and stone mounds that favoured water steam supply and dew condensation. By observing the best vegetative cycle of naturally-grown plants the most suited areas could be identified. Likewise, it was possible to establish the places where to exploit the second water supply, that is to say the water held in soil deposits. Alluvial soils, the loess, wadi dry courses were the most suitable means to preserve water resources in upper layers, thus allowing the development of the first neolithic societies that from “nomadic cultivation”, relying on spreading seeds in favourable areas where the populations came back only for harvesting, switched to practices of space arrangement.
Caves, characterized by natural water dripping, were excavated to follow the flows and better intercept them, otherwise they were widened and deepened by creating openings on slope walls as well as draining and harvesting cisterns. These practices would then become underground techniques of drainage tunnels and passive architecture, that in suitable geomorphological situations, would allow the troglodytic settlements and the development of stone towns (Laureano 1993). The extraction activity in flint mines allowed the building of the first pit courtyards provided with radial tunnels. The pattern that can be found in Grimes Caves in England and in the mines of Gargano in the South of Italy (Di Lernia 1990) is reproduced in water harvesting devices and in underground dwellings with a central courtyard. These techniques developed in dry karst areas and on calcareous plateaux like the Murge in Puglia, but also in semi-arid clay plains of Northern Africa and loess stretches in China. Steady elliptic or semi-circular settlements, characterized by several perimeters of ditches, established in rainy areas, in poorly drained plains or in karst areas as well as at the edges of high plateaux without water courses. Under climate alternation conditions, they meet many functions linked to water balance: they drain water during rainfalls and preserve it for dry seasons; they are used as drinking troughs and ditches to collect useful sewage and waste to fertilize soils; they symbolically mark the places and strengthen the social cohesion, the group identity and the propensity to sedentariness. Ditches are multi-purpose structures, resulting from the evolution of simple pits used to collect water and waste. This practice was useful to select domestic cultivated species and to identify seeding periods suited to any kind of plant. As a matter of fact, seeds and sewage went into the ditches where they sprouted spontaneously in the most suited season. By sprinkling the fields with the water harvested in pits it was possible to understand the fertilizing capacities of manure. Many traditional techniques, which are still used, show this capacity of using symbiosis with other organisms in the ecosystem management. In Burkina Faso thanks to a method called “zai”, it is possible to regenerate highly degraded soils using water pools, waste and also the combined action of termites. The soil is dug with holes that are filled with water in the humid season whereas during the dry season they are used as dump-sites for rubbish and manure. Such practice attracts termites that digest rubbish which can be easily assimilated by plant roots whereas the tunnels dug in the soil by termites increase soil porosity. The holes are then sown, thus obtaining very high crop yields. Multi-purposeness and polivalency are therefore the successful conditions of typical neolithic structures handed over by traditional techniques. On Murge plateaux in Italy the practice of ditches dug to favour soil collection and plant growing has been preserved up to more recent years. In Daunia in Puglia and on Murge plateaux there are thousands of dug perimeters of neolithic villages (Tinè) which are also found in Germany in the site of Kol Lindenthal along the Rhine Valley and in China in the site of Banpo along the Yellow River that are similar to settlement and water management patterns which are still widespread in Ethiopia. The dwellings are made up of hut-like structures which are scattered outside the perimeters and are equipped with cisterns and ditches to preserve the wheat. The development is realized by repeating the pattern. The construction of the settlement entails the arrangement of the territory at the same time. From both a material and a symbolic standpoint, the organization of the village is the same as the organization of the production area, the image and the functioning and order of the world.
In the 6th millennium the first techniques of canalization and the banks of flow diversion that implemented irrigation by flooding developed in the plains and interfluvial basins of Irak and Anatolia. The settlement structures with an orthogonal texture developed on the matrix of the canals. The first non-circular constructions were realized with water and adobe, the same slime of cultivations, like in the settlements of Çatal Hüyük and of Jarmo, in the plain of Konia in Anatolia and at the foot of Zagros Mountain in Irak, which preceded urban organizations. The squared shape allowed diversified and complex solutions with greater evolution potentials. The dwellings could stretch and cluster gradually without leaving any free areas. In interfluvial plains large clusters grew at the same time as the development of techniques supporting the soil with continuous wall curtains, construction of platforms, banks and canals. Consequently, dwelled and rural areas were organized in a different way. The clustered forms of settlements met building, climatic and defensive needs and were different from the agricultural organization albeit materials, like the adobe, did perfectly integrate in the landscape. These practices allowed to carry out large-scale water management techniques in alluvial valleys such as the Indo, the Nile, the Mesopotamia, the Yellow River which had been developed by important state-owned organizations rightly called hydraulic societies (Witfogel). These were ancient empires built on alluvial deposits of slime, loess and sand along afroasiatic fluvial basins and also in karst areas of Mesoamerican rainforests. The geographic size and the big hydraulic structures led to political despotism, bureaucratic hypertrophy as well as to state militarization. Indeed, in more fragmented landscapes lacking water coming from big rivers, the traditional techniques of water catchment and management developed thanks to the activities of small-scale communities.
Water Catchment and Soil Consolidation Techniques of Agro-Pastoralists Who Used Metals
During the Metal Age the populations organized in familiar clans could easily move thanks to carts and horses, thus widespreading techniques that allow the exploitation of new tillable areas. The agro-pastoral and transhumant economy exploited those areas that had not been previously expanded by structuring paths from mountain ridges towards the sea. Terracings were realized in inaccessible paths whereas hanging gardens were realized in big capitals characterized by interfluvial basins. However, the use of the metal widespread slowly, although it had been anticipated by the significant results achieved by some communities in the neolithic age.
Since the IVth millennium the technique of excavating cisterns and water intakes had developed in order to irrigate the fields from the settlements situated on high hills, thus exploiting the force of gravity. In the same period, in Belucistan (Iran and Pakistan) the civilization preceding Harappa used earthened dams called gabarband to keep water flows in the soil as well as dams accumulating sand that favoured the sedimentation of slime and the control of alluvial sediments and floods. In the IIIrd millennium the civilization of the Indo valley developed in this area. In the centres of Harappa and Mohenjodaro this civilization used water supply systems in dwellings, techniques of sewage disposal and irrigation practices which were similar to those that would be used in Rome after 2,000 years. Moreover, wells equipped with a stone structure that enabled to reach the water tables were introduced.
In the same period, the hydraulic Egyptian and Sumerian civilizations developed the big monumental architecture starting from the experience derived from the construction of banks and canals necessary for irrigating and fertilizing their lands. The first pyramids were made up of adobe, which was the direct evolution of the Neolithic building techniques of banks as well as of mud platforms in Africa, in Mesopotamia as well as in Mesoamerica. The soil left during excavation formed the first holy mounds. Their change into monuments favoured sedentariness, social identity and the transfer of working activities during the standstill of hydraulic works. The powerful state control of hydraulic societies needs these big works that glorified and justified the despotism and the powerful administrative bureaucracy.
Settlements placed on fortified hills developed in rough areas of the Middle East, of Mediterranean Isles and Peninsulae and on coast promontories of arid areas. Towns, citadels and acropolises had to withstand the sieges and to make sure of having drinkable water. In the Bronze Age, in the sites of Arad (Amiran 1962), Jawa and Megiddo, in the north of the Arab desert (Barrois), and of Qana, in the South of Yemen on the coast of the Indian Ocean (Laureano 1995), the area within the walls was used to harvest water and feed either open-air or excavated cisterns that could be reached through tunnels and staircases. Tilled fields or the eventual urban development at the foot of the hill, were fed by pipes that, in case of coast clusters, also supplied the port structures that would thus provide ships with water. During sieges, canals were cut down and defenders, who barricaded themselves on the summit, continued to produce the water that had been denied to attackers. Each rock or wall mass could produce water and protect the soils. The different thermal inertia combined with the atmosphere creates colder surfaces bringing about condensation. The walls intercepted winds and moisture. The interstices between blocks and the stone porosity withhold the water. The shadow protects it from evaporation. The rocks prevent the soils from dismantling, thus facilitating humus formation. As a matter of fact, the majority of dry stone structures widespread in the arid lands of Puglia contribute to water production. In this area the mounds of porous rocks absorb the night frost, thus supplying the soil with moisture. (Nebbia, Cantelli 1994). Therefore, the stones of the most imposing walls are arranged with the slabs bended inside to allow the frost to pass through the filling stony ground. The dry walls preserve the hydromorphic qualities of the soil, thus acting as thermoregulators and moisture balancers both in arid areas and under very cold conditions when water is liquid and can be used by plants, thus hindering the formation of ice. This is the reason why there are dry walls, stone circles and stone arrangement which are generally used as catchers of moisture also in those areas subject to heavy rains such as Ireland and the Orkney Islands. Here, thermoregulation counterbalances soil glaciation and permafrost formation. During this period the circular megalithic structures and conic structures with false vaults developed as the fusion between the African hut and the techniques of wall construction of wells and cisterns. These forms have created the Micenean tholos, the trulli of Puglia, the talayotes of the Baleari Islands and the several rural structures made up of wall masses, harvesting areas and underground cisterns that have increasingly imposing forms like the nuraghis, that is the most outstanding evolution of the possibility of clustering of round forms on the territory and of the use of megalithic structures for moisture condensation.
In arid areas a series of techniques developed ranging from simple stone arrangement, half-moon mounds to dry stones, thus evolving in complex double wall curtain devices equipped with harvesting cisterns. Several archaeologic clues can still be found in the Negev desert, along the Arab wadi and in the Jordan valley. All these areas are completely desert, but thanks to these methods of moisture catchment and soil protection they used to be fertile and rich. Some archaeologic research (Evenari 1971) has shown that century-old olive tree and vineyard wastes were irrigated thanks to a system of small dry walls collecting dew that in Arabic are called teleylat al ‘anab, meaning mounds for the vineyard. The plants grew inside small fences whose stones, arranged with large interstices, caught the wind full of moisture. The vineyard and the olive tree could thus grow even without any source or water table. The walls, the stone mounds, the tombs, the trulli and the calcareous rock called specchie, the talayotes, the nuraghi, the telayet el anab are used as water condensation and preservation structures. The stone mounds carry out their function during the day and at night. In the broiling sun the wind carries traces of moisture which seeps into the interstices of the stone mounds that have a lower temperature inside because it is not exposed to sun rays or it is cooled by the underground chamber if it is present. The decrease in temperature causes the condensation of drops that are absorbed by the soil in case of walls or fall into the cavity. The water collected supply further moisture and coolness, thus amplifying the efficiency of the condensation chamber. Overnight, the process is reversed and the condensation takes place externally, thus producing similar results. The cold surface of stones condenses the moisture and dew slides in the interstices, thus wetting the soil, or it is harvested in the chamber of the cistern. Most of these structures are usually considered as funerary monuments but they can be exploited for hydraulic uses, both for functional or worshipping purposes. In Matera, on Murgia Timone plateau, along the ditch of the archaic neolithic fences, structures formed by a double circle of stones which was crossed by a corridor leading to a central underground area were introduced during the Bronze Age.
Similar devices are found in the neolithic Saharian area, in the Arab desert and in Yemen, the latter being considered as an area where the civilization of hidden waters developed and relied on air hydrogenasis (Pirenne). Moreover, they are widespread all over the Mediterranean area. Their most imposing urban realization is found in Petra that used to be the centre of the two ancient populations (Fauzi) who called them edomite and nabatean agriculture. The contacts with Southern Arabia through the Incense Route explain the similarities with the Sabean hydraulic techniques that, in the so-called Marib dam, which is actually a system of dividers and water intakes (Dentzer), boast the most imposing example of soil formation practices by flooding in complex structures. In the highest sites characterized by rare rainfalls, these devices are associated with surfaces harvesting rainfalls which develop in a terraced or a courtyard architecture organized for this purpose. Temples and worshipping monuments, like successively the mosques, used to catch water. As a matter of fact, in the long run it would be increasingly difficult to identify the functions of the works. Likewise the tombs, the kurgan, the tholos, the holy constructions used the forms of the hydraulic structures for many reasons. Firstly, water was actually used in religious and funerary ceremonies; secondly hydraulic knowledge was often handed over by holy or heroic personalities; finally because the funerary mausoleum reproduced the architecture of the structures producing water, that is the source of life. In small scale societies, the familiar clans celebrated their ancestors through mausoleums and related rites, thus strengthening the identity of the group and highlighting the strategic points to be crossed. In such a way, during this period the territory was meant as an integrated network of centres, that exploited different ecosystems. The practice was already advanced in the middle of the II millennium in central Italy where highland villages got in touch with each other during seasonal transhumance, since they shared paths characterized by water devices, worshipping complexes, stopping areas and pasturelands (Barker).
In hydraulic civilizations the sovereigns gave a monumental interpretation of the techniques of local cultures getting hold of them. Therefore, it is important to remark that in the middle of the 1st millennium, Pharaon Tutmosi I dug “underground rooms in the wadi” on the left shore of Thebes. These were the first monuments of the area that would successively be known as the Valley of Kings all over the world). The localization of underground structures that followed the extensions of the course of the fossile river of the desert, let us think about the reutilization of pre-existing works that were used to intercept the hydrographic network or the monumental use of the experience gained in these activities. The general condition of these areas did not hinder the existence of small-scale family-run agriculture in communities capable of preserving their independence and of handing over the local knowledge within these areas, or in marginal and geographically protected situations. Therefore, adapted knowledge developed within those societies, that compared to hydraulic ones, are called hydroagricultural, hydrogenetic or autopoietic societies. These social forms survive thanks to the isolation and to the geographic harshness in places that had been voluntarily chosen for these characteristics and transformed by clever communities in centres of a particular economic importance by means of commerce or by cultivating rare species, or because of strong cultural reasons relative to the religious faith and to social cohesion.
The separation between small-scale communities and the hydraulic society is highlighted, both from a material and symbolic standpoint, by the construction of the Big Chinese Canal started in the middle of the I millenium b. C. The work is situated at the end of the silk route, that had widespread and exchanged traditional knowledge for hundreds of years, to link the course of the Yellow River of the desert to that of the Blue River of the Chinese Empire. Developed along a northern-southern direction for about 1,700 Kms, it is the most extended canal in the world and due to its geographic imponence and to the impact on society it can be considered as a real artificial Nile. Its realization structures the Chinese area, thus experiencing its territorial, social and administrative changes. During the Ist millennium large-scale irrigation took place in interfluvial basins and water production in deserts through drainage tunnels, qanat, foggara and falaj. The latter widespread the oasis that synthesizes the traditional knowledge capacity of creating autopoiesis and enhances resources in balanced ecosystems (Laureano 1995).
From Oases to Urban Ecosystems towards a Sustainable Future
The oasis is an autocatalytic system whose initial supply of condensation and moisture is extended by planting palm trees that produce shadows and attract organisms, thus forming the humus. The palm grove creates a wet microclimate which is fed by hydraulic catchment techniques such as the drainage tunnels of foggaras, hidden rainfalls, the condensation and the control of underground flows and floods. Adobe dwellings do not lead to the waste of wood to fire bricks, they are cooled by the underground path of water and provide waste for field fertilization. The system manages the water resource according to a cycle of use that is compatible with the renewability of the quantities available and increases them at the same time. In the desert the domestication of the date palm, the foenix dactilifera, is the requirement to plant the oasis. The palm groves extend from the main neolithic poles through the Sahara desert and the other deserts, thus developing the knowledge necessary to create the oasis effect: autopoietic cycles, the hydraulic production and the resource management (Laureano 1987). The techniques widespread also in the Northern Mediterranean area and in southern banks of the desert in places where the date palm cannot ripen. In these situations other plants are used with horticulture in order to guarantee the soil maintenance and the shadow besides the specific fruit like the olive tree in the Mediterranean Basin and the Papaya in Sahel and in South Arabia. An enlarged pattern of oasis is thus created as capacity of creating living situations in difficult and harsh environments thanks to the use of hydroagricultural knowledge: in case of rare resources, urban ecosystems realized in close man-nature relationships trigger vital cycles, autopoietic dynamics which are able to self-reproduce and be sustainable. The urban ecosystem is the stratification of the local knowledge accumulated which therefore takes the characteristics of a town rather than of a village. Irrigating areas are created under favourable geomorphological and precise geographic conditions. A capital dominates each landscape unit: isolated basins in the middle of the desert; large plains between mountain peaks; stripes of oases along hydrographic networks; crossroads of faraway international and or intercontinental roads. However, also the small habitat systems whose urban texture can be explained by analysing the hydroagricultural matrix and the needs of water catchment, become historic centres of regional importance with urban characteristics. They feature different realities that can be found in several situations: adobe oasis-like towns, such as the Saharian or the Yemeni towns that use the organic wastes of dwellers to fertilize the sterile sands and make them suitable to the realization of imposing architectures; stone oases that were excavated since Prehistory in Southern Italy and in the Middle East that are able to condensate the water needed in caves and in dry constructions; religious oases, sculptured in the erosion valleys of Cappadocia, of Palestine, of Thebaid and of Ethiopia or installed along the silk route up to China that are arranged as hermitages and walled gardens, irrigated by drainage tunnels, cisterns and canalizations; sea oases widespread in the arid islands of the Mediterranean Sea and of the Red Sea that are fed by air sources and rainforest oases since Maya architectures that developed in a humid climate can be interpreted by understanding the functions of water collection which is important within a Karst environment without surface courses. Urban ecosystems are the continuity of traditional knowledge that from the first caves, the stone arrangement and the artificial rivers develop and diversify under different environmental conditions up to the realization of increasingly complex hydraulic systems. Likewise the traditional historic centres of Southern Italy and Maghreb, they were dense and concentrated settlement patterns which were used as barns, trade markets and centres for service organization in close relationship with the agriculture landscape. The crisis of traditional agriculture followed the exodus from these centres. Since they were generally situated in harsh and mountainous areas with their traditional architectures, water harvesting systems and soil protection techniques used to be territorial garrisons able to contrast soil degradation.
It is an alternative socio-economic pattern to that of hydraulic civilizations relying on an increasing development supported by the significant demographic growth triggered by the agricultural potential and continued by an imperial policy, by incomes coming from the exploitation of huge quantities of workers and from the waste of resources in monuments or in wars. The consequences of the hydraulic pattern corresponded to those of the unlimited development logic belonging to contemporary affluent societies: hypertrophia and the destruction of the territory, the bureaucratic centralization and the increasing destruction of the environment up to the ecological catastrophe.
The local knowledge continues to be handed over in apparently backward areas or in the advanced society and in places of cultural importance. It is therefore wrong to consider traditional knowledge as marginal compared to current significant economic and technological processes. From a quantitative standpoint their use still supports the greatest part of humanity that is distributed in less industrialized countries. Paradoxically, in these places where traditional techniques are still widely used they are considered from the modernist thought as a backwardness phenomena, whereas in developed countries they enhance their image and their value. As a matter of fact, more modern countries still use traditional techniques, thus consolidating and stabilizing their role within the society and the economy. The values of tradition, the practices of working and the craftsmanship capacities are the key basis of the very high added value of significantly economic productions for many highly developed countries. In the regions of Valais, in Switzerland, of the Loira Valley, in France, of Tuscany in Italy, traditional techniques are still employed in agriculture, thus allowing the highest quality landscapes to stabilize, a vehicule of highly profitable sales of produces. Historic settlements, traditional landscapes and local knowledge offer solutions that have to be safeguarded and that can be recommended and renewed thanks to modern technology. It is not a question of readopting every technique without distinction but to grasp the logic of the traditional pattern that has allowed the society to improve its status and to carry out technical, architectural and artistic realizations which are important in the history of cultures (Laureano 2001). The traditional knowledge has always been a dynamic system capable of integrating the innovation studied for a long time with the local environmental sustainability. It has to be reproposed as the proper and advanced knowledge for working out a new technological paradigm based on the progressive values of tradition: the capacity of enhancing internal resources and managing them at a local scale; multi-purposeness and integration between technical, ethic end aesthetic values; the production which is not considered as a value in itself but it is targeted to the well-being of communities and relies on the principle that each activity shall feed another one without any waste; the use of energy which is based on cycles that are continuously renewed.
Amiran R.1970 The beginnings of urbanization in Canaan , in AA.VV. Near Eastern Archaeology in XXth Century, New York.
(*) Architect and Planner. Professor of Urban History at the School of Architect, University of Bari