# Bridging Mediterranean cultures in the International Year of Soils 2015: a documentary exhibition on irrigation techniques in water scarcity conditions

S. Barontini, Vladimiro Andrea Boselli, A. Louki, Z. Ben Slima, F E Ghaouch, R. Labaran, G. Raffelli, M. Peli, A M Al Ani, N. Vitale, et al.

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## To cite this version:

S. Barontini, Vladimiro Andrea Boselli, A. Louki, Z. Ben Slima, F E Ghaouch, et al. Bridging Mediterranean cultures in the International Year of Soils 2015: a documentary exhibition on irrigation techniques in water scarcity conditions. Hydrology Research, 2017, 48 (3), pp.789-801. 10.2166/nh.2017.113. hal-05452529

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https://hal.science/hal-05452529v1

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# Bridging Mediterranean cultures in the International Year of Soils 2015: a documentary exhibition on irrigation techniques in water scarcity conditions

S. Barontini, V. Boselli, A. Louki, Z. Ben Slima, F. E. Ghaouch, R. Labaran, G. Raffelli, M. Peli, A. M. Al Ani, N. Vitale, M. Borroni, N. Martello, B. Bettoni, A. Negm, G. Grossi, M. Tomirotti, R. Ranzi and B. Bacchi

## ABSTRACT

The paper presents the activity performed at the University of Brescia by students and researchers, belonging to different Mediterranean cultures and different disciplines, to prepare a documentary exhibition on irrigation techniques in water scarcity conditions, on the occasion of the International Year of Soils 2015. Traditional irrigation techniques were identified as a key aspect of soil conservation and agricultural practices, to build living and autopoietic ecosystems, also in adverse climatic conditions, and to adapt to climatic changes. Being a structural source of ecosystem survival, and being based on long-lasting observation of the climate and of the environment, they have deep roots in local cultures and they were identified as a common ground also for multicultural interaction. The core of the exhibition is structured in sections focused on techniques for collecting groundwater, atmospheric humidity and surface water, on water lifting techniques and on water distributive systems. The final section of the exhibition is devoted to the oases which are presented as an equilibrium ecosystem, established upon the alliance between man and nature and founded on the capability of collecting water.

**Key words** | cultural interaction, International Year of Soils 2015, resilience and adaptation, traditional irrigation techniques, transition ecosystems, water scarcity

S. Barontini (corresponding author)

V. Boselli

A. Louki

Z. Ben Slima

F. E. Ghaouch

R. Labaran

G. Raffelli

M. Peli

A. M. Al Ani

G. Grossi

M. Tomirotti

R. Ranzi

B. Bacchi

Università di Brescia, DICATAM,
Via Branze, 43,
I-25123 Brescia, Italy

E-mail: stefano.barontini@unibs.it

N. Vitale

Slow Food Lombardia,
Via Rismondo, 10 (private address),
I-25128 Brescia, Italy

M. Borroni

Università Ca' Foscari,
Dorsoduro 3246,
I-30123 Venezia, Italy

N. Martello

Fondazione Guido Piccini per i diritti dell'uomo
ONLUS, Via Terzago, 11,
I-25080 Calvagese della Riviera (Brescia), Italy

B. Bettoni

Università di Brescia, DEM,
Via San Faustino, 74/b,
I-25121 Brescia, Italy

A. Negm

Università di Palermo, DiSAF,
Viale delle Scienze 12, Ed. 4,
I-90128 Palermo, Italy

## INTRODUCTION

During the 17th World Congress of Soil Science, held in Bangkok in 2002, the International Union of Soil Sciences (IUSS) took a resolution in which worldwide organizations were addressed to install an annual day of the soil, preferably on December 5th (IUSS 2002), to celebrate the soil as a crucial component of natural systems and human

wellbeing. Later, in June 2013, the FAO Conference endorsed World Soil Day (WSD) and proposed the official adoption at the 68th UN General Assembly (FAO 2016a). Finally, on December 20th, 2013, the 68th UN General Assembly recognized the date of December 5th as WSD and declared the year 2015 as the International Year of

doi: 10.2166/nh.2017.113
Soils (IYS), with the purpose of raising awareness world-
wide of the importance of soils for food security,
agriculture, mitigation of climate change, poverty allevia-
tion, and sustainable development; and they recognized
the ‘urgent need at all levels to raise awareness and to pro-
mote sustainability of the limited soil resources using the
best available scientific information and building on all
dimensions of sustainable development’ (UN 2013). During
the celebration of the IYS, on December 7th, 2015, assessing
the achievements and the future challenges of the IYS, the
IUSS together with the Joint FAO/IAEA Division of
Nuclear Techniques in Food and Agriculture drafted the
Vienna Soil Declaration ‘Soil matters for humans and eco-
systems’ and the decade 2015–2024 was proclaimed the
International Decade of Soils (its end being the centennial
IUSS anniversary; IUSS 2015).

Water availability and management are structural for agri-
cultural purposes and therefore for food security. At the same
time, they are key aspects of most soil conservation issues.
Referring in fact to the classification proposed by the Soil The-
matic Strategy published by the European Commission (2012),
water plays crucial roles at least in four of eight main soil
degradation processes (erosion, salinization, landslide, and
contamination) and the water cycle is strongly affected by
three others (decline of soil organic matter, compaction, and
sealing), whereas desertification is regarded as a cross-cutting
issue induced by other degradation processes, namely, ero-
sion, organic matter decline, and salinization. It should be
pointed out that desertification does not necessarily spread
from a desert and arid region, but is a ‘slowly creeping
phenomenon’ (Şen 2008) which can take place in any area,
starting from localized spots, even far from arid conditions,
and essentially due to land degradation.

A cultivated land is an anthropized environment in which
natural resources and anthropogenic activities symbiotically
act to guarantee the food production and ultimately the food
security. According to the interpretative framework proposed
by Laureano (1995 (2013)), after investigations in the Sahara
region, in the Arabic Peninsula, in the Middle East and in
Southern Italy, the symbiotic relationships become structural
in areas in which, due to the adverse climatic or soil con-
ditions, only the alliance between man and nature allows the
building of living and autopoietic ecosystems. An important
case, proposed by the author as the key to understand these

relationships, is that of the oasis. Thanks in fact to this equili-
brium between natural resources and anthropogenic activity,
oases are settled and survive in arid areas, in most of which
the original organic activity of the soil is practically absent
and the preliminary steps of soil development are inhibited
by wind erosion. In these environments, starting from the
Iron Age (third millennium BP), people slowly developed effec-
tive techniques to slow runoff (e.g., the terraces in the Negev
and Sinai), to store monsoon precipitations (the barrages
across the wadis in Yemen) and to collect groundwater
(even if far from the area chosen to become an oasis, as e.g.,
the qanats in the Persian Plateau), which allowed cultivation
of arid and mountain regions (Liverani 1996).

The symbiosis and the alliance between man and nature
leads to a coevolution of environment and society, so that
any change has fallout on both the environmental and
social systems (Laureano 1995 (2013)). The structural role of
the coevolution of water management systems and social sys-
tems was stressed also by Montanari et al. (2013) in the
framework of the Panta Rei decade (2013–2022). Climatic
changes, climatic seasonality, and social changes induce, in
natural and anthropized systems, states of transition (e.g., Rot-
mans et al. 2001), which often become states of continuous
transition, due both to the long time evolution of the external
changes and to the long time required by the system to fully
react to the changes and to move to a new dynamic state of
equilibrium. From an agricultural point of view, a major
source of crisis can be the change of water availability, par-
ticularly in the case of a decrease in availability. In these
scenarios it seems that traditional farming systems, based
on small farms with great biodiversity and selected drought-
tolerant local varieties, are intrinsically resilient and prove
to have a large potential to adapt to climatic changes (Altieri
2009; Altieri & Nicholls 2013).

Taking inspiration from all this information, we ident-
ified the traditional irrigation techniques as a key
instrument for soil conservation in arid and semiarid
areas. Then, in early 2014, we started designing and building
a documentary exhibition to introduce to a large audience
the similarity between these irrigation techniques in arid
and semiarid areas around the Mediterranean Sea. The exhi-
bition was aimed at being displayed for students, both in
secondary schools and universities, and in public circum-
stances, as e.g., local celebrations or congresses. Until now
it has been displayed about ten times and presented in a public lecture given at the Museum of Natural Sciences of Brescia. The project was developed in a multicultural and multidisciplinary framework with the contribution of students, researchers, and independent scholars. On the one hand, the traditional irrigation techniques provided a common ground of investigation and a means for cultural interaction between students linked to both the local community and to the Arabo-Islamic ones. On the other hand, researchers and independent scholars belonging to many disciplines, namely, architects, historians, hydrologists, and philologists, contributed to the project. In the documentary exhibition, which is now available as a technical report of the University of Brescia (Barontini et al. 2016), we concentrated on six main topics: the first three concern water collection, respectively from the groundwater table (qanats), from the atmospheric humidity (cob walls and dry stone walls), and from the surface water (wadis, barrages, and cisterns); the fourth and the fifth topics concern water lifting technologies and distribution in agricultural fields; the sixth one describes some aspects of the oases, as based on the previously introduced techniques.

In this work, after briefly introducing the case of Brescia and its social changes, which underlie the stimulus to the work, we present the concepts behind the exposition and finally the exposition and its structure.

## POPULATION DYNAMICS AND INTERACTIONS: THE CASE OF BRESCIA

Brescia and its province are experiencing a dramatic change in their social and economic structure: in recent years, Brescia has been chosen to be their residence and work place by many foreigners, coming from all over the world, and it has become one of the cities in Italy with the greatest percentage of migrants.

The percentage of resident migrants in the province of Brescia was around 6.8% in 2004 and it grew to 13.2% in 2015 (ISTAT 2015). It is greater than both the national average (8.2% in 2014; Comuni Italiani 2016) and the regional one (11.5% in 2014; Comuni Italiani 2016), and it is comparable with that of the province of Milan (13.7% in 2014; Comuni Italiani 2016). Nowadays, the province of Brescia

has a population of about 1,260,000 people, 167,000 of whom are regular migrants. Among these, about 16% (26,700) come from the Middle East and North Africa (ISTAT 2015). Migrants are not uniformly distributed throughout the province's territory, and are more present in the city of Brescia (19% in the city versus 13.6% in the province in 2011; Chamber of Commerce 2011) comparable to the neighboring province of Milan (18.6% in the city versus 13.7% in the province in 2014; Comuni Italiani 2016).

This change is an important challenge for the city, both from the social, cultural, and economic point of view. Focusing on the cultural aspect, the interaction between cultures is an opportunity for reciprocal enrichment, which, at the same time, requires a deepening of the knowledge and the understanding of both the local and the migrant backgrounds. It is recognized that this process, which requires going back to and reanalyzing the roots of each identity, has positive fallout also on the social aspects, as it contributes particularly to second- and third-generation migrants not to feel rootless. In this context, students from the University of Brescia, both linked with the local and with the Arabo-Islamic communities, constituted a study group named ‘Al-Bīrūnī’, with the objective of cooperating with local students and researchers to investigate and to promote cultural initiatives to explore the differences and the interaction between Arabo-Islamic and European cultures. The name is meant as a tribute to the Persian scientist Abū Rayḥān al-Bīrūnī (about AD 973–1051), who was an engineer, scientist, geographer, astronomer, and historian of the Islamic East. The importance and, to some extent, the exceptionality of al-Bīrūnī lies in the great variety of his production, which covers topics as diverse as pharmacology, astronomy, anthropology, together with engineering and history. He always proceeded according to a method that can be best described in al-Bīrūnī’s own words: ‘Reliance on personal observation and on-the-spot examination enhance the capacity to remember and distinguish the facts and also to identify objects, not only in pharmacy, but in other professions and crafts. Gathering data through direct handling and observation is a greater advantage to be encouraged over mere reading of books’ (Gafurov 1974). Even though al-Bīrūnī’s empiricist approach had a lesser impact on the history of science in the Muslim world, than Galileo’s had on European culture, by choosing the name of ‘Al-Bīrūnī’
for the study group, the students intended to envisage a sort of intriguing parallelism between the two scientists.

## CONCEPTS

The exhibition focused on traditional irrigation techniques in countries surrounding the Mediterranean Sea, because they provide a common cultural background between the different origins of the participants and they are structurally linked with key aspects both of sustainability of the agricultural production and of cultural interaction. In particular these aspects are: (1) mitigation of the fallout of climatic and anthropogenic changes on agricultural systems; (2) management of water scarcity conditions; (3) adaptive capability to changes; and (4) cultural transfer due to travelers and skilled workers' migration. Starting from these concepts the exhibition aimed at disseminating two main ideas: (1) a dense network of cultural and economic relationships, around the Mediterranean Sea, leading to technological similarity of the main water supply systems in countries affected by similar conditions of water availability; and (2) in environments characterized by severely or extremely adverse climatic conditions, an agricultural system can survive only in equilibrium with the surrounding nature. In the following sections the main concepts previously introduced will be briefly detailed.

### Climatic and anthropogenic changes

According to the Fifth IPCC Assessment Report, there is a general consensus about an increase of the global average temperature in the current century (IPCC 2013), even if the magnitude of the warming greatly depends on the scenario of greenhouse gas emissions (FAO 2016b). Temperature increase has the direct effect of exposing the soil to degradation, by means of drawbacks on the main soil processes, namely, organic matter decomposition, leaching, and soil water regimes (WMO 2005). At the same time, an increase in temperature will trigger an increased water demand for evapotranspiration (FAO 2013), which will conflict with the precipitation decrease projected by climate models for the Mediterranean and Southern Africa (FAO 2016b), thus increasing the climate pressure on the soil. Climatic changes are observed to have negative impacts on food production in most cases (Porter et al. 2014) and, in many areas, they are

accompanied by human and social changes. Due to population growth, these lead to an increase of agricultural and sanitary water demand and induce a reduction of the soil capacity of storing water as a consequence of urbanization and bad soil management policies (e.g., Fischlin et al. 2007).

### Water scarcity versus water aridity

In this framework, and to focus on the links between farming and the environment with a sustainability perspective, we chose to stress the concept of water scarcity conditions, rather than that of aridity or drought conditions. Scarcity is an equilibrium concept related to the balance between (water) availability and need (Falkenmark et al. 1989), while aridity and drought are more strongly climate-related concepts, dealing with more or less permanent, or occasional water lack, respectively (Maliva & Missimer 2012). Although aridity often implies water scarcity conditions, scarcity affected regions do not generally coincide with arid ones, or with regions where occasionally droughts occur. A meaningful example is that of mountain ranges. Due to steep slopes, thin soil, and difficulties of storing water, mountain regions can, in fact, be in scarcity conditions even in a humid and temperate climate.

Falkenmark et al. (1989), dealing with microscale approaches to face macroscale water scarcity and aspects of vulnerability in semiarid climates, classified four water-scarcity typologies, according to four main drivers, which in real cases are typically superimposed. Two of them are of natural origin (i.e., arid climate and intermittent drought years), and the other two are man-induced (i.e., land degradation and population-driven water stress). It is here remarked that population-driven water stress is related to a number of aspects which go from increasing water demand, to minimal irrigation efficiency, to water resources pollution. Madulu (2003) and Anand (2004) highlighted as a fifth typology of water scarcity that related to an economic origin, as the lack of investment in water infrastructures or the fallout of conflicts.

### Adaptive capability to changes

The capacity for a territorial system to absorb stresses and to remain functional while facing climatic- or anthropogenic-driven stresses is typically referred to as resiliency.
It is a systemic characteristic which involves all dimensions of social living, both cultural ones and technological and economic ones. Traditional irrigation techniques provide a great contribution to the intrinsic resiliency of traditional farming. According to Laureano (1995 (2013)), who particularly refers to the Mediterranean basin, to the Sahara region and to the Arabic Peninsula, three principal interpretative keys allow this concept to be enlightened: (1) the systems are autopoietic and water collection is in equilibrium with the water availability, thus not impoverishing the available resources; (2) irrigation efficiency is greater, with respect to other conventional irrigation techniques practiced in conditions of water abundance; and (3) the adaptivity of traditional farming is, to some extent, contributed to by the concurrent use of principal and ancillary water collection techniques (see details in the next section). Furthermore, they are structurally linked to the roots and to the culture of local communities, thus contributing to the local cultural identity. Finally, the long-term observation of the climate and of the environment, which underlies both the traditional culture and the irrigation techniques, builds a meaningful capacity of risk mitigation based on reconnaissance of the hazards.

## Cultural transfer and skilled workers' migration

The cultural aspect of these techniques provides a fascinating glimpse into the complexity of the nets of cultural interaction. Most of these techniques are very ancient, the first terraces and barrages belonging to the Iron Age (third millennium BP; Liverani 1996). Afterwards they were diffused along the trade routes by travelers, skilled workers, and treatises. Take, for example, the case of qanats, which originated on the Persian Plateau during the Preachemenid Age, spread throughout many areas of the Middle East and Far East, reaching Chinese Turkestan along the Silk Road, and, with the diffusion of the Arabo-Islamic culture in Northern Africa, reached the central Sahara region, Spain, Cyprus, and Sicily (Tölle-Kastenbein 1990 (1993); Ahmadi et al. 2010). Then, in Spain, the Arabo-Ispanic culture interpolated the Greek-Roman one and allowed the development of Spanish agricultural civilization, which in the Medieval Age reached its greatest development and influenced European agriculture in the early modern age (Ciriacono 1994).

## THE EXHIBITION AND ITS STRUCTURE

The exhibition consists of 20 posters (width 70 cm, height 100 cm) conceived with a modular structure to communicate to a wide public the different techniques classified by their purpose and their hydraulic functioning principle. The presentation of the techniques comes after an introduction which provides the keys to read the posters and it is followed by a closure chapter about the oases. The techniques were classified into ones designed to collect, to lift, and to distribute water. The exhibition is then structured into seven sections: (1) Introduction (2 posters); (2) Systems based on the groundwater (qanat, foggara, khettara; 2 posters); (3) Systems based on the air humidity (cob walls, dry-stone walls; 3 posters); (4) Systems based on the surface water (wadis, barrages, cisterns; 6 posters); (5) Water lifting techniques (3 posters); (6) Water distributing systems (1 poster); and (7) Oases (3 posters). In Figure 1 we present a map of the Mediterranean basin and of the surrounding areas with the location of the sites presented in the exhibition. The cases are classified according to the reference chapter of the exhibition. The map is not exhaustive with regard to the huge occurrence and variability of traditional irrigation techniques in scarcity conditions in the Mediterranean basin, but provides an idea of their spread.

For each module are presented the hydraulic concept, key aspects of the traditional building techniques, some historical examples with the corresponding Walter and Lieth climate diagram and with their geographical position in the Mediterranean basin. The systematic approach is intended to let the audience both read the posters straightforwardly and compare the cases. In Figure 2, as an example of the exhibition, a poster about khettaras and qanats is shown.

The climatic diagram is particularly presented with this aim. It gives a first-sight impression of the local climatology in comparison with that of the city of Brescia, which is commonly experienced by the audience, and is presented in the introduction to the exhibition as a term of comparison. This choice allows the public to perceive the deep differences between the climate of a temperate wet area, as the city of Brescia is, and the ones of arid or semiarid areas. As an example, in Figure 3, the climatic diagrams of Palermo (Italy, semiarid climate) and Kébili (Tunisia, arid climate), where the qanat technique is practiced, are reported together with that of
<figure><img src="image_4.png" /><figcaption>**Figure 1** | Map of the cases of traditional irrigation techniques presented in the exhibition (the map was obtained with an Albers equal-area conic projection with standard parallels at 20°N and 40°N).</figcaption></figure>

Brescia. By this comparison, the audience is led to perceive the different issues for water management that can arise when scarcity conditions may occur throughout the year (Kébili), during some months only (Palermo), or can be a priori expected not to happen at all (Brescia). In the following some details on the presented techniques are given.

## Qanat

A qanat is a draining gallery which, starting from a ground-water table on the mountains, allows the water to flow downstream by gravity until it reaches the soil surface in the plain (Figure 4). The end of the qanat is always located in a village or in an oasis, with a stilling basin and the divisors to distribute the water to the irrigated gardens. According to some historians, qanats were conceived in the Persian Plateau during the Preachemenid Age, introduced in Maghreb by Arab conquests, and spread along the Silk Road as far as Chinese Turkestan. They are, therefore, an emblematic example of a technological solution to mitigate water scarcity issues, spread over a great area by a

complex network of relationships, and subsequently adapted to the local terrain morphology and geology. The qanats are termed in different ways across the world: *kāriz* in some parts of Afghanistan, *qanāt* (pl. *qanāthā*) in Iran (at least in official language), *fouggara* (pl. *fegāgīr*) in Algeria, *falaj* (*aflāj*) in Oman, *gayl* (pl. *guyūl* or *agyāl*) in Yemen, *kārēz* in Western China, *qanāt* (pl. *qanāwāt*) in Syria, and *khettara* in Morocco. The terminology is actually quite fluid in the many languages involved. More details about the subject can be found in de Planho (2012).

A qanat is carved in the rock, starting from downstream up to intercept the inspection well previously dug upstream where the experts, *muqannīs*, detected a water table. The *muqannīs* were able to track down seasonal streams and, according to the geomorphology of the area and to the flora, to find places where the water table was several meters underground. The best area to start digging the inspection well (called *mother well*) was chosen according to their experience. The underground gallery is connected to the surface by regularly spaced ventilation air wells, needed for excavation, which behave as condensers for the
<figure><img src="image_5.png" /></figure>

# Tecniche basate sulla captazione di acque di falda: le khettara

<figure><img src="image_6.png" /></figure>

## Introduzione (1)

Secondo alcuni storici, le khettaras nacquero nell'antica Persia più di 3000 anni fa e furono introdotte in Marocco dagli arabi durante la loro conquista del Maghreb. Altri storici invece sostengono che questo sistema sia una pura creazione degli abitanti del Nord Africa, gli Imazighen. Ciò che è certo è che dalla Persia alla Cina fino ad arrivare all'Occidente, le khettaras hanno lo stesso principio di funzionamento nonostante vengano chiamate con nomi diversi: kiraz in Afghanistan, qanat in Iran, fouggara in Algeria, afaq nello Yemen, karez in Cina e kanawat in Siria.

## Diagramma climatico dell'area (3)

<figure><img src="image_7.png" /></figure>

**Merzouga (Marocco)**

Merzouga ha un clima desertico. Durante tutto l'anno, la pioggia è praticamente inesistente.

La temperatura media annuale è di 21,7 °C.

La piovosità media annua raggiunge i 59 mm.

<figure><img src="image_8.png" /></figure>

**Tindouf (Algeria)**

Tindouf ha una clima desertico.

La precipitazione è praticamente assente in estate.

La temperatura media a Tindouf è 23,4 °C.

Ogni anno, le precipitazioni medie sono di 30 mm.

<figure><img src="image_9.png" /></figure>

**Kebili (Tunisia)**

Kebili ha un clima desertico. Kebili è una città in cui le precipitazioni sono più alte in inverno rispetto all'estate.

Nel corso dell'anno, la temperatura media a Kebili è di 20,9 °C. C'è una media di 98 mm di pioggia all'anno.

<figure><img src="image_10.png" /><figcaption>Fig.3: dentro la khettara (Asfahan)</figcaption></figure>

<figure><img src="image_11.png" /><figcaption>Fig.4: lo schema di funzionamento di una khettara</figcaption></figure>

## Mappa degli esempi (2)

<figure><img src="image_12.png" /></figure>

## Principio di funzionamento (4)

La khettara è una galleria drenante che fornisce acqua dalla falda sotterranea alla superficie, per gravità.

L'uscita della khettara si trova sempre in un paese o in un'oasi. La galleria sotterranea è accompagnato a giorno mediante pozzi d'aria che sono necessari per lo scavo, servono come punti di aerazione e di condensazione dell'aria richiamata da valle. La distanza di questi pozzi dipende da Paese a Paese.

L'acqua drenata da monte uscirà in campagna, poche decine di metri o fino a un paio un paio di chilometri di distanza dalla venuta a giorno, per irrigare i campi agricoli.

Una khettara è più di un sistema tecnico, è ovviamente un patrimonio e rappresenta, dal punto di vista antropologico, una vera e propria cultura.

<figure><img src="image_13.png" /><figcaption>Fig.1: pozzi di una khettara (Marocco)</figcaption></figure>

<figure><img src="image_14.png" /><figcaption>Fig.2: pozzo di una khettara visto dall'alto (Algeria)</figcaption></figure>

## Tecnica idraulica e costruttiva (5)

La khettara è costruita a partire da valle fino a intercettare un pozzo di ispezione a monte ("pozzo madre") ove sia stata riconosciuta la presenza di una falda. Una khettara è composta da:

1. una galleria di captazione che drena la falda e la condensazione.

2. una parte costituita da adduttori, che distribuiscono l'acqua al sistema di irrigazione.

3. un sistema per portare l'acqua ai terreni attraverso i canali di rifornimento che viene chiamato localmente mesraf.

La lunghezza di una khettara varia da poche centinaia di metri a decine di chilometri a seconda della distanza della falda dal punto di venuta a giorno.

La profondità dei pozzi varia in genere tra 10 e 20 m.

La distanza tra due pozzi consecutivi dipende dalla stabilità del terreno e varia dai 10 ai 30 m. I flussi variano a seconda della zona e vanno dai 2 a 20 l/s.

<figure><img src="image_15.png" /></figure>

Tecniche di irrigazione in condizioni di scarsità idrica

Amina Louki, Zied Ben Slima, Fatima Ezzahra Ghaouch, Raisa Labaron, Giulia Raffelli, Marco Peli, Amro Negm, Nicola Vitale, Stefano Barontini

<figure><img src="image_16.png" /></figure>

**Figure 2** | Example of a poster about khettaras and qanats. The numbers explain the parts of the poster: (1) Introduction, (2) Map of the reported cases, (3) Climatic diagrams of the areas, (4) Functioning principle, (5) Building technique.
<figure><img src="image_17.png" /><figcaption>**Figure 3** | Climate diagrams of Palermo (Italy, semiarid) and Kébili (Tunisia, arid) compared with the climate diagram of Brescia (Italy, wet). Source of data: http://en.climate-data.org/ (accessed 11 August 2016).</figcaption></figure>

<figure><img src="image_18.png" /><figcaption>**Figure 4** | Sketch of a qanat.</figcaption></figure>

uplifting wet air coming from downstream. The aeration wells can reach a depth of 20 meters, and the distance between two wells depends on terrain stability and is of the order of magnitude of some tens of meters. The discharge drained by a qanat can vary from 2 up to 20 L/s, depending on the surrounding conditions.

Due to its ancient development and widespread diffusion, a qanat is much more than a simple water drainage technology, it is also a structure of precious cultural and anthropological heritage. As an example, in Iran, the International Center on Qanāts and Historic Hydraulic Structures (ICQHHS) is an institution recognized in 2005 by UNESCO with the mission to promote research and development to restore the qanats and other traditional historic hydraulic structures. Qanats are still used in many areas,

providing an important part of the water needed for agricultural and drinking purposes, even though in some places they were either recently or historically abandoned. As an example, Lightfoot (1996) depicts a map of the usage of Syrian qanats in 1994, evidencing an increasing abandonment rate after the introduction of motor-pumped wells.

A system of qanats, which is reported as a case in the exhibition, was built in Palermo during the Arab domination in Sicily (AD 827-1091), and nowadays 25 of them, located in the hydrological basin of the Palermo Plain, have been identified (Lofrano et al. 2014). Today, three of these qanats (Gesuitico Alto, Gesuitico Basso, and Uscibene), built after the Arab domination, can be explored. They are about 1.5 m high and from 0.6 to 0.8 m wide, with a water temperature around 10 °C. Thanks to its low temperature,
the water was also used to refresh some traditional structures named *Camere dello Scirocco* (south-east wind rooms). These rooms were fixtures of old mansions, carved in the rock and kept fresh by the qanat water.

## Cob walls and tu'rat

Cob walls and *tu'rat* technique were developed on agricultural land to irrigate by means of condensation of the air humidity or of the collection of little drops of fog. Tu'rats are dry stone walls, often shaped as a half moon. This technique allows the creation of conditions suitable for cultivation at the foot of a wall, where the soil is typically shaped as a cone turned upside down to help water and soil-water content to be collected at the bottom. Condensation happens both due to local energy losses related to the complexity of the geometry, as in the case of cob bricks with a trapezoidal section and in dry stone walls, and to the difference of temperature between warm air and cold wall. This structure is very important for many cases of arid and semiarid agriculture as, even if it is not the main water supply technique, it is in most cases used as an ancillary technique. As a secondary effect, the walls also protect the soil from erosion. Examples of this technique, with different shapes of walls, are found all

around the Mediterranean basin. Figure 5 shows an example of a citrus garden at Pozzallo (Sicily): in this case the dry stone walls are high enough to reach the foliage, thus inhibiting the bare soil evaporation. Condensation is traditionally not obtained only by means of cob walls and tu'rats, but also by means of a great variety of both ancient structures and modern prototypes. To give an idea of these, we present the Sussex Downs dew-ponds, which traditionally date back to the Neolithic Age (Martin 1909), the air condenser designed by Knapen in 1930 and built at Trans-en-Provence and a prototype of a water collection tower, the *warka water*, recently designed by Vittori and coworkers (Warka Water 2015). The *warka water* is a tissue structure, held by a wooden frame, built to collect water available in fog. The tower is intended to mimic the behavior of the fogstand beetle (*Stenocara gracilis*), which is able to survive in the Namib Desert by collecting fog water on its bumpy back surface.

## Wadis, barrages, and cisterns

*Wādī* (pl. *widiān*, eng. *wadi*) is an Arabic word meaning at the same time valley and water stream. It is used to indicate mountain streams in arid environments. In desert areas,

<figure><img src="image_19.png" /><figcaption>**Figure 5** | Citrus garden surrounded by a dry stone wall at Pozzallo (Modica, Sicily, Italy).</figcaption></figure>
wadis mostly appear as dry torrent beds where water flows on the surface only during exceptional rainfall events, even if sometimes an hyporeic flow is present below the wadi bed and can seldom emerge in depressed areas. The emergence of a hyporeic stream can nourish the vegetation which can be present at the bottom of valleys even in deserts. The Italian geologist Gian Battista Brocchi (1772–1826) was among the first to notice, during his travels in Egypt and Nubia, that the morphology of wadis indicated a recent geological epoch rich with water and precipitations which modeled the canyons. Starting from the Iron Age, barrages were built in Yemen to let, during the rare precipitations, the water level rise in wadis and the water be stored in reservoirs for irrigation purposes (Liverani 1996). During the time of the Roman Empire, there was a great impetus to build barrages in many semiarid areas, both for irrigation and water supply and for soil protection (Tölle-Kastenbein 1990 (1993)). As reported in Figure 1, wadis and barrages are common in many arid and semiarid areas around the Mediterranean Sea, where also southern Italian *fiumare* have a similar hydrological behavior to that of wadis. Through the ages many barrages lost their original purpose and were reinforced and made higher until they became dams, as in the case of the Ma’rib Dam (Yemen), presented in the exhibition.

Another important structure closely related to the collection of surface water are cisterns. They can be both uncovered reservoirs, as in the gardens of Agdal and Ménara (Morocco), or covered ones, with positive effects on the reduction of evaporation, such as the Justinian reservoir of Constantinople (Istanbul, Turkey, 6th century CE) and the Portuguese cistern of el-Jadida (Morocco, 16th century CE).

## Water lifting techniques

Water lifting is a common problem, already faced in ancient times and which induced populations to develop a great number of different technologies adapted to local contexts. In the exposition we present the *shādūf*, the *cochlea*, the *sāqiya*, the *noria* and some of the water lifting machines designed by al-Jazari (1136–1206), an important mathematician and engineer who served as chief engineer in the Diyar Bakir region. The *shādūf* consists of a lever with asymmetric arms with a weight at the short end and a bucket or a skin bag linked by a jointed perch at the long end. A single man

operating a *shādūf* can lift from 2 to 5 cubic meters of water per day considering a difference in level from 3 to 4 meters. The cochlea (7th century BC) is better known as Archimede’s screw, from the name of the famous mathematician to whom the invention was attributed in the 3rd century BC. According to more recent investigations (Dalley 2003), the cochlea appears described in a cuneiform inscription of the same epoch of the reign of the Assyrian king Sennacherib (704–681 BC). The *sāqiya* (5th century BC) is a device consisting of an articulated chain of buckets to lift water (typically to lift underground water) and by gears to transfer the motion induced by a man or by an animal. This technology was probably developed independently in different regions and is widespread in all the Mediterranean area, in India and in China. In Sicily it is known by the local name of *senia* (Barbera 2007). The *noria* (3rd century BC) is a device composed of a big undershot water wheel with a series of buckets fixed at its lateral side. This technology allows water to be lifted between meaningfully different heights (even more than 20 meters). A big *noria* can lift up to 300 cubic meters per hour. *Norias* are important for facing the lack of terrain slope in the Arabic Peninsula and are spread along the Euphrates in Syria and in Iraq. Finally, the water lifting machines designed by al-Jazari were presented to stress the importance of the treatises and literature to diffuse the knowledge about technical innovations.

## Water distribution systems

Water distribution in irrigated gardens in water scarcity conditions is traditionally achieved by driving the water at the basis of each tree. As an example, we proposed the case of the citrus orchards’ distributive systems around Lake Garda (Alto Garda Bresciano, Italy, Figure 6). Due to the great amount of water required by lemon trees (between 100 and 300 liters per tree every 8 days during the summer season, according to Tedeschi (2006)), the lemon orchards are, in fact, in water scarcity conditions and here a distributive system was developed, analogous to other ones developed in similar conditions in the Mediterranean basin. The cultivation of citrus fruits is such a very old activity along the steep slopes which shape the northwestern shore of Lake Garda, that Renaissance mythology traced its origin to Hercules bringing the citron from the garden of the Hesperides (Voltolina 1574
(2015)). Thanks to the microclimate, induced by the presence of the lake, the cultivation of citrus trees could occur in the ground, more similar to the Mediterranean tradition than to Central Europe orangeries. These *limonaie*, as is the local name, built on artificial terraces filled with soil from the lake's eastern shore, southeasterly oriented to maximize the morning sunlight, closed with wooden and glass panels during winter, allowed the development of a flourishing citrus production in the modern age, whose exports reached as far as Northern Europe. The distributive system consisted of a stilling basin on the course of a small uphill torrent, a channel to convey water upstream of the citrus garden and a system of flumes with a trapezoidal section along the walls to distribute the water at each tree. There was a spillway for each tree, and it was activated by inducing a backwater effect in the flume by means of a sand-filled bag (Figure 6).

## Oases

The last section of the exhibition is devoted to oases. According to Laureano (1995 (2013)), they are presented as the manifestation of the symbiosis between man and the environment,

that can be built only when a suitable system to provide the required water is identified. An oasis is therefore rarely a fully natural environment, but it is mostly the result of a patient process driven by a correct application of the techniques of water collection, storage, and distribution and of many other measures in order to maintain the very complex equilibrium which allows cultivation. In the exhibition we presented cases of erg oases, piedmont oases, and floodplain oases, subdivided according to the main water collection technique. Piedmont oases and floodplain oases mainly base water collection on barrages built across wadis or rivers. On the other hand, erg oases are situated in deserts and mainly base water availability on qanats, on the capability of condensing transpired water and of protecting the soil-water content from evaporation. This capability is typically achieved thanks to the upside down conical space between the dunes.

## CONCLUSIONS

Traditional irrigation techniques are a key aspect of soil conservation and of agricultural practices in scarcity conditions.

<figure><img src="image_20.png" /><figcaption>**Figure 6** | Ancient distribution system in a lemon garden at Lake Garda (Alto Garda Bresciano, Italy). The spilling water was originally accompanied to the bottom of the tree in order to prevent excavation.</figcaption></figure>
In some cases, they allow cultivation of arid and semiarid lands and contribute to an alliance between man and nature to build living and autopoietic ecosystems also in adverse conditions. The coexistence of principal and ancillary techniques of water supply in the same system contributes to the intrinsic adaptivity of traditional farming to climatic changes. Furthermore, being based on long lasting observations of the climate and of the environment, they have structurally deep roots in local cultures. Starting from this information and from the suggestions of the International Year of Soils 2015, we identified the traditional irrigation techniques, practiced in scarcity conditions in countries surrounding the Mediterranean Sea, as a common ground for cultural interaction within a multidisciplinary and multicultural study group of students and researchers belonging to different Mediterranean cultures. The product of this collaboration was a documentary exhibition which aimed at disseminating two main ideas: (1) a dense network of cultural and economic relationships, around the Mediterranean Sea, leads to technological similarity of the main water supply systems in areas affected by similar conditions of water scarcity; and (2) in environments characterized by severely or extremely adverse climatic conditions, an agricultural system can survive only in equilibrium with the surrounding nature.

## ACKNOWLEDGEMENTS

The documentary exhibition was supported by the Department of Civil, Environmental, Architectural Engineering and Mathematics (DICATAM) of the Università di Brescia and by the Fondazione Guido Piccini per i diritti dell'uomo ONLUS which are kindly acknowledged. The Editors of the Special Issue are gratefully thanked for the valuable discussions.

## REFERENCES

Ahmadi, H., Nazari Samani, A. & Malekian, A. 2010 The qanat: a living history in Iran. In: *Water and Sustainability in Arid Regions. Bridging the Gap Between Physical and Social Sciences* (G. Schneier-Madanes & M.-F. Courel, eds). Springer, Dordrecht, Heidelberg, London, New York, pp. 125–138. DOI:10.1007/978-90-481-2776-4.

Altieri, M. 2009 *Agroecology, small farms, and food sovereignty*. *Monthly Review* **61**, 102–113.

Altieri, M. A. & Nicholls, C. I. 2013 *The adaptation and mitigation potential of traditional agriculture in a changing climate*. *Climatic Change* **140**, 33–45. DOI:10.1007/s10584-013-0909-y.

Anand, P. B. 2004 *The political economy of water scarcity and issues of inequality, entitlements and identities*. *International Journal of Technology Management & Sustainable Development* **3** (2), 115–131.

Barbera, G. 2007 Parchi, frutteti, giardini e orti nella Conca d'oro di Palermo araba e normanna (*Orchards and garden in the 'Conca d'oro' (Sicily) between IX and XII centuries*). *Italus Hortus* **14** (4), 14–27.

Barontini, S., Louki, A., Ben Slima, Z., Ghaouch, F. E., Labaran, R., Raffelli, G., Al Ani, A., Borroni, M., Boselli, V., Peli, M., Negm, A. & Vitale, N. 2016 *Tecniche irrigue in condizioni di scarsità idrica (Irrigation Techniques in Water Scarcity Conditions)*. Technical Report No. 1/2016, DICATAM, Università degli Studi di Brescia.

Chamber of Commerce, Industry, Agriculture and Artisanship of Brescia (CCIAA Brescia) 2011 L'imprenditoria extracomunitaria in provincia di Brescia 2011 *Quaderni di Approfondimento (Immigrant entrepreneurship in the province of Brescia 2001 Study Notebooks)*. 9. http://www.bs.camcom.it/files/Studi/Approfondimenti_tematici_2011/imprenditoria_extracomunitaria_al_30_06_2011.pdf (accessed 15 April 2016).

Ciriacono, S. 1994 *Acque e agricoltura: Venezia, l'Olanda, e la bonifica europea in età moderna (Waters and agriculture: Venice, the Netherlands and European Remediation in Modern Age)*. FrancoAngeli, Milan.

Comuni Italiani 2016 *Cittadini stranieri in Italia 2014*. http://www.comuni-italiani.it/statistiche/stranieri.html (accessed 15 April 2016).

Dalley, S. M. 2003 Sennacherib, Archimedes, and the water screw: the context of invention in the ancient world. *Technology and Culture* **44** (1), 1–26.

de Planho, X. 2012 Kāriz. *Encyclopædia Iranica*, sub voce 25 (6), 564–583 http://www.iranicaonline.org/articles/kariz_1 (accessed 15 April 2016).

European Commission 2012 *Report from the Commission to the European Parliament, the Council, the European Economic and Social Committee and the Committee of the Regions. The Implementation of the Soil Thematic Strategy and Ongoing Activities/* COM/2012/046 final *// http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%03A52012DC0046 (accessed 15 April 2016).

Falkenmark, M., Lundquist, J. & Widstrand, C. 1989 Macro-scale water scarcity requires micro-scale approaches: aspects of vulnerability in semi-arid development. *Natural Resources Forum* **13** (4), 258–267.

Fischlin, A., Midgley, G. F., Price, J. T., Leemans, R., Gopal, B., Turley, C., Rounsevell, M. D. A., Dube, O. P., Tarazona, J. & Velichko, A. A. 2007 Ecosystems, their properties, goods, and services. Climate change 2007: impacts, adaptation and vulnerability. In: *Contribution of Working Group II to the Fourth Assessment, Report of the Intergovernmental Panel on Climate Change* (M. L. Parry, O. F. Canziani, J. P. Palutikof,
P. J. van der Linden & C. E. Hanson, eds). Cambridge University Press, Cambridge, UK, pp. 211–272.

Food and Agriculture Organization of the United Nations (FAO) 2013 *First Meeting of the Global Soil Partnership Plenary Assembly, GSPPA – 1/13/Report*. Food and Agriculture Organization of the United Nations, Rome.

Food and Agriculture Organization of the United Nations (FAO) 2016a *World Soil Day – 5th December 2013*. http://www.fao.org/globalsoilpartnership/world-soil-day/background/en/ (accessed 15 April 2016).

Food and Agriculture Organization of the United Nations (FAO) 2016b *Climate Change and Food Security: Risks and Responses*. Food and Agriculture Organization of the United Nations, Rome.

Gafurov, B. 1974 Al-Biruni. A universal genius who lived in Central Asia a thousand years ago. *The UNESCO Courier* June 1974. http://unesdoc.unesco.org/images/0007/000748/074875eo.pdf (accessed 15 April 2016).

International Union of Soil Sciences (IUSS) 2002 Bulletin n.102. IUSS, Vienna.

International Union of Soil Sciences (IUSS) 2015 Bulletin n.127. IUSS, Vienna.

IPCC 2013 *Climate Change 2013: The Physical Science Basis*. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (T. F. Stocker, D. Qin, G.-K. Plattner, M. Tignor, S. K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P. M. Midgley, eds). Cambridge University Press, Cambridge.

Italian National Institute of Statistics (ISTAT) 2015 *Popolazione provincia di Brescia 2001-2014 (Brescia province population 2001-2014)*. http://www.tuttitalia.it/lombardia/provincia-dibrescia/statistiche/popolazione-andamento-demografico/ (accessed 15 April 2016).

Laureano, P. 1995 (2013) *La Piramide Rovesciata (The Reversed Pyramid)*. Bollati Boringhieri, Torino.

Lightfoot, D. R. 1996 Syrian qanat Romani: history, ecology, abandonment. *Journal of Arid Environments* **33**, 321–336.

Liverani, M. 1996 Agricoltura e irrigazione nell'Antico Oriente (Agriculture and irrigation in Ancient East). In: *Storia dell'economia mondiale. Permanenze e mutamenti dall'antichità al medioevo (History of Global Economy. Remainings and Mutations from Ancient Times to Medieval Times)* (V. Castronovo, ed.). Editori Laterza, Bari, pp. 43–59.

Lofrano, G., Carotenuto, M., Todaro, P., Maffettone, R., Sammataro, S. & Giugni, M. 2014 La gestione delle acque a Palermo nel medioevo. Dalla captazione alla distribuzione (Water management in Palermo during middle age. From captation to distribution). *L'Acqua* **6**, 24–35.

Madulu, N. F. 2003 Linking poverty levels to water resource use and conflicts in rural Tanzania. *Physics & Chemistry of the Earth* **28** (20–27), 911–917.

Maliva, R. & Missimer, T. 2012 Aridity and drought. In: *Arid Lands Water Evaluation and Management* (R. Maliva & T.

Missimer, eds), Chapter 2, Springer-Verlag, Berlin Heidelberg. DOI: 10.1007/978-3-642-29104-2_2.

Martin, E. A. 1909 *Some observations on dew-ponds*. *The Geographical Journal* **34** (2), 174–191.

Montanari, A., Young, G., Savenije, H. H. G., Hughes, D., Wagener, T., Ren, L. L., Koutsoyiannis, D., Cudennec, C., Toth, E., Grimaldi, S., Blöschl, G., Sivapalan, M., Beven, K., Gupta, H., Hipsey, M., Schaefl, B., Arheimer, B., Boegh, E., Schymanski, S. J., Di Baldassarre, G., Yu, B., Hubert, P., Huang, Y., Schumann, A., Post, D. A., Srinivasan, V., Harman, C., Thompson, S., Rogger, M., Viglione, A., McMillan, H., Characklis, G., Pang, Z. & Belyaev, V. 2013 ‘Panta Rhei – Everything Flows’: change in hydrology and society – The IAHS Scientific Decade 2013–2022. *Hydrological Sciences Journal* **58** (6), 1256–1275. DOI: 10.1080/02626667.2013.809088.

Porter, J. R., Xie, L., Challinor, A. J., Cochrane, K., Howden, S. M., Iqbal, M. M., Lobell, D. B. & Travasso, M. I. 2014 Food security and food production systems. In: *Climate Change 2014: Impacts, Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects*. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (C. B. Field, D. R. Barros, D. J. Dokke, K. J. Mach, M. D. Mastrandrea, T. E. Bilir, M. Chatterjee, K. L. Ebi, Y. O. Estrada, R. C. Genova, B. Girma, E. S. Kissel, A. N. Levy, S. MacCraken, P. R. Mastrandrea & L. L. White, eds). Cambridge University Press, Cambridge, UK and New York, USA, pp. 485–533.

Rotmans, J., Kemp, R. & van Asselt, M. 2001 *More evolution than revolution: transition management in public policy*. *Foresight* **3**, 15–31.

Şen, Z. 2008 *Wadi Hydrology*. CRC Press, Roca Baton, FL, USA. Tedeschi, P. 2006 *I frutti negati: assetti fondiari, modelli organizzativi, produzioni e mercati agricoli nel Bresciano durante l'età della Restaurazione (1814-1859) (Denied Fruits: Land Structures, Organization Models, Production and Agricultural Markets in Brescia Territory During the Age of the Restoration, 1814-1859)*. Fondazione Civiltà Bresciana, Brescia.

Tölle-Kastenbein, R. 1990 *Antike Wasserkultur (Ancient Water Civilization)*. C.H. Beck, München, Germany.

United Nations (UN) 2013 *General Assembly Resolution No. 68/232*, http://www.un.org/en/ga/search/view_doc.asp?symbol=A/RES/68/232 (accessed 6 April 2016).

Voltolina, G. M. 1574 (2015) De hortorum cultura (About gardens cultivation). In: *De hortorum cultura e altre opere (About Garden Cultivation and other Opera)* (R. Sessa, ed.). Liberedizioni, Brescia.

Warka Water 2015 http://www.warkawater.org/ (accessed 6 April 2016).

World Meteorological Organization 2005 *Climate and land degradation*, WMO No. 989.