Islamic Civilization

Irrigation and Water Management

 A major accomplishment of Islamic civilisation was its legal code around water use and management. As Serjeant points out, a considerable part of most Islamic legal books is devoted to water law, a subject, which incidentally, he notes, has not been studied in Europe to any appreciable extent.[1] This legalistic approach to the resource, once more, derives from the faith itself, the place of water in the Qur’an being one of the most predominant, a great number of verses touching upon it in one form or another. The Prophet himself had said much about rights to water and had settled many irrigation disputes, and from his sayings and rulings, worked over by later jurists, there emerged a substantial corpus of irrigation law which clearly established the rights of the parties involved in all sorts of disputes.[2]

The Shariah, the Islamic system of law, distinguishes three types of water sources which may be the object of use and ownership: water from rivers, from wells, and from springs.[3] In relation to water taken out of rivers, for instance, where it is possible to cause shortage to other users, by e.g. digging a canal to take water from higher up the river, or where damming or the allocation of fixed times is necessary to provide enough water for irrigation, in such case, the river is normally regarded as the joint property of the riparian cultivators, and the question of how much water may be retained by the highest riparian cultivator depends on differing circumstances, such as the season of the year, the type of crop irrigated, etc.[4]  In relation to springs, the Shariah states that if the water supply is limited, the first person to undertake irrigation in the area has the priority, otherwise water has to be shared equally.[5] Throughout, though, Islamic legislation insists on providing water for free to those who are thirsty. Caliph Omar  (Caliph 634-644) made some owners of water pay the diya (blood money) for a man who died of thirst after they had refused his request for water.[6] 

Although this legislation did not always work towards the optimum economic use of land and water, Watson points out, it was a distinct improvement over the water law of pre-Islamic times of many of the regions affected. In much of pre-Islamic Arabia , for instance, water rights were usually established and transferred by force, and in many parts whole tribes exercised collective rights over wells.[7] By enshrining individual rights and spelling these out in detail, Islamic law undoubtedly encouraged private investors.[8] It also gave them the incentive to conserve water due to the benefits that might accrue from this resource.

Throughout the Muslim land, institutions were set up for the purpose of water management and distribution. In Damascus , the management of water was granted to the Sheikhs, that is the trusted and learned, leading figures of the city.[9] In Fes , Morocco , the qwadsiya (workmen devoted to the maintenance of the qadus), that is the system of supply, were placed under the control of the Consul of water.[10] Water  disputes in that same city were the prerogative of a special committee composed of representatives from all groups of such users taking counsel from a mufti (learned religious figure).[11] In Valencia , disputes and violations were the prerogative of a special court chosen by the farmers themselves, sitting at The Tribunal of the Waters on Thursdays at the door of the principal mosque (ten centuries later, the same tribunal was still sitting in Valencia, but at the door of the cathedral.)[12]

Under conditions of water scarcity, Islamic society devised a complex system of distribution, in which technical knowledge played a central role. The division of water between several users was assured by a variety of mechanical devices, distributors, or runnels with inlets of a fixed size, and by the allocation of fixed periods of time.[13] Where water is divided by a weir between a number of villages or users, the size of the weir varies according to the share of the water permanently allocated to the different users.[14] During the period of water distribution, shares were defined in terms of  days, hours, or minutes, and were allocated to the different districts, villages, fields, or plots of lands watered by the source in question.[15] In Spain and North Africa , the measuring was done in a variety of ways. For instance, a copper vessel with a hole pierced in it was placed in a tank filled with water; when the vessel itself was full and sank to the bottom of the tank, a stipulated fraction of the time share in the water was finished.[16] When the water came from a basin with vertical sides, one could use a rule whose length was equal to the basin’s depth and which was graduated, ie, it bore notches whose spacing corresponded to a given volume of water.[17] Other methods are still in use.  In the Beni Abbes region of Algeria, in the Sahara, south of Oran, for instance, farmers use a clepsydra to determine the duration of water use for every farmer in the area.[18] This clepsydra times by the minute water use, night and day, throughout the year, taking into account seasonal variations. Each farmer is in turn summoned for his turn, and has to take necessary action to secure most efficient supply of water to his land.[19] In Iran  and Egypt , similarly, sand glass and water gate systems measured both time and volume of water used by each farmer. Leo the African speaks of the filling of water clocks when they are empty at the end of the irrigation time.[20] In Spain, in the Valencia  region, Glick elaborates on a complex distribution system of the waters of the River Turia, divided into successive stages, each stage representing the point of derivation of one main canal which drew all the water at that stage, or of two canals, dividing the water among them. At each stage the river was considered to hold twenty-four units of water.[21] In times of abundance, each canal drew water from the river according to the capacity of the canal; in times of drought, the canals would take water in turn, for a commensurate number of hours or a proportional equivalent.[22] The same was true for individual irrigators; and herein lies the genius of the Valencia system, Glick notes:  when the canal ran full, each irrigator could open his gate as he pleased, but when water was scarce, a system of turns was instituted. Each irrigator, in turn, drew enough water to serve his needs, but could only do so when every other irrigator in the system had taken his turn, hence insuring a relatively equal distribution of supply, both in times of abundance and of scarcity.[23] In general, the scarcer the water, the more detailed and complicated the distribution, and the greater the fragmentation of ownership of the water, the more meticulous and elaborate the organisation of its distribution.[24] In the case of qanats, the rotation period could be lengthened in periods of water shortages, and the amount of water per share reduced.[25]

A decisive contribution of Islamic civilisation was to seize on the existing, pre-Islamic systems, and bring them to advanced levels, most of which have survived to our day. The old, decayed systems were repaired, and new networks were constructed.[26] Iraq , for instance, on the eve of the Muslim conquest, suffered from neglect of irrigation, exploitative taxation and crippling wars with the Roman Empire.[27] In southern Iraq, before Islam, the irrigation works were allowed to degenerate, and in the years 627-8, on the eve of the Muslim conquest, a major agricultural disaster took place, which was followed by disastrous floods of the Tigris river which burst its dikes.[28] Soon Muslim rule provided stable government and major hydraulic works were carried out, including drying swamped lands, reclamation of salt marshes, and new irrigation schemes put in place in the Upper Euphrates region.[29] There was vast reconstruction work of irrigation systems under the viceroy Hajjaj (d. 714).[30] In the Diyala Plains, at least, and probably over a much larger area, the restoration and reconstruction of Sasanian irrigation works took place through the late 8^th and early 9^th centuries.[31] In Egypt , the work of bringing back into cultivation abandoned lands was begun by Qurra Ibn Sharik in 709-14, and continued throughout most of the 8^th and much of the 9^th centuries, and in Spain, we learn of the same initiatives.[32] At the same time, land, which had never before been irrigated, or cultivated, or which had been abandoned, was provided with irrigation systems.[33] There is evidence for the extension of irrigated farming from practically every part of the Islamic world in the early centuries of Islam.[34]

As they expanded vastly, the surface of irrigated lands, Muslims devised new techniques so as to catch, channel, store and lift the water (through the use of norias (water lifting devices), whilst new ingenious combinations of available devices were put in place.[35] Rainwater was captured in trenches on the sides of hills or as it ran down mountain gorges or into valleys; and surface water was taken from springs, brooks, rivers and oases, whilst underground water was exploited by creating new springs, or digging wells.[36] The Muslims also dammed more rivers, and improved irrigation by systems of branch channels.[37] Engineering expertise remained central indeed to the system, one account telling how a mountainside near Damascus  was tunnelled through to allow the passage of a stream.[38] Distribution of water was also adapted to every soil variety, two hundred and twenty four of these, each with a name,[39] and each with its water requirements. Techniques were also adapted to specific natural conditions.[40] The impact was obviously to make irrigation more economical, and to make lands hitherto unused productive.[41]

Like every dominant aspect of Islamic civilisation, the practical and the scholarly were once more brought together in a vast literature devoted to matters of water, its use, management, storage, and preservation. All Kitab al-Filahat (Book of Agriculture), whether North Africa n, Andalusian; Egyptian, Iraqi, Persian or Yemenite, Bolens says,[42] insist meticulously on the deployment of equipment and on the control of water.[43] Thus, Abu’l Khair (fl early 12^th century) of Seville , the author of a book on farming (Kitab al-Filaha) proposes four ways to collect rain water, and other artificially obtained waters.[44] He recommends such recovery for growing olive trees, and also explains techniques for maintaining soil moisture.[45] In his treatise, Ibn al-Awwam (fl Seville end of 12^th century), speaks at length of the watering process for each crop; in the case of rice, for instance, offering advice for each stage, before planting, after, and also irrigation and drainage once the crop has grown.[46] Ibn Mammati (d. 1209) implied that in areas where year-long irrigation was available summer crops might be grown after winter crops and income would thereby be doubled.[47] Other treatises deal with the same subject, and include Ibn Wafid’s (d.1074) Majmu’ fi’l Filaha (Compodium of Agriculture); Ibn Hajjaj (fl 11^th century) Al-Muqni fi’l Filaha (the Satisfactory Book of Agriculture); and Al-Taghnari (12^th century): Kitab Zahrat al Bustan (Book of the Flowers of the Garden).

The same literature also gives good focus to engineering works aimed at the storage and supply of the resource. Ibn Mammati suggests that the construction of a retaining dam on the Alexandrian canal and the consequent provision of perennial irrigation on lands lying below the dam would achieve an increase in income.[48] A particular interest is given to the Qanat system, that is the underground water system, which conducts water from its source to a distant location.[49] In Iraq  Al-Kharaji (11^th cent) wrote Inbat al-miyah al-khafiyya (The Extraction of Hidden Waters), describing not only the application of geometry and algebra to hydrology but also the instruments used by master well diggers and qanat builders.[50] The work deals with surveying instruments, methods of detecting sources of water and instructions for the excavation of underground conduits.[51] It devotes various chapters to specific issues, such as notes related to underground water (chap 3); description of mountains and rocks which reveal the presence of water (chap 4); study of grounds with water (chap 5); plants that signal the presence of water (chap 6);  description of dry mountains and arid soils (chap 7); on the variety of waters and their tastes (chap 8); how to purify polluted waters (chap 10) etc.[52] There is also an anonymous work, also from Iraq: Kitab al-hawi li l-a'mal al-sultaniyya wa rusum al-diwaniyya (Book Comprising Public Works and Regulations for Official Accounting).[53] Cahen has published the part of this treatise dealing with irrigation.[54] It includes large extracts on norias, gharrafas and other water raising machinery; sections on instruments, techniques of levelling and canals, and their digging, water retention structures, etc.[55]

The Qanat, already mentioned above, consists primarily of a series of vertical shafts, resembling but not acting as wells, constructed along the line of the qanat to allow access for maintenance and removal of spoil.[56] The qanat system allows the sound management and protection of a scarce and precious resource from evaporation. It also helped, Guichard notes, to stimulate the prosperity of whole regions that would otherwise have remained barren.[57] Oliver Asin in this Historia del nombre Madrid seems to have presented a good case for the Muslims having made it possible to develop what has become the city of Madrid by introducing a sort of qanat system to supply the district with water.[58] Parts of this apparently still exist, and Asin links the actual name Madrid to it.[59]

The management of the qanat system was also complex, and like other forms of water uses, followed the same strict rules and regulations. In Iraq , for instance, a whole ‘Water  Service’ was devoted to the task of supervision and maintenance, and an army of functionaries and other personnel was also involved.[60] The qanats were also scrupulously policed, and maintained, with references to skilled personnel, and even of diving teams.[61]

The qanat system has survived to this day in many parts, including in the Algerian Sahara, under the name Fogarras, modern Spain, and diverse parts of the South American continent, where it had a substantial impact on the local farming.[62]

Islamic irrigation and water uses, it must be finally pointed out, are owed to the particular  legacy of the Yemen . Serjeant insists that the Yemen was the province which had the most highly developed irrigation systems, terraced mountain sides running from the top to the foot of high mountains, great masonry cisterns, and skill in the control of flood waters that may be unequalled.[63] The Yemenis who came to settle in Egypt , the Maghrib , and Spain, also brought with them their irrigation laws and administration.[64]  And so many south Arabs, to judge by their names, Tujibi, Himyari, Kindi, Ma’afiri, settled in Spain, that it is attractive also to think that they may have influenced the development of the mountain districts of Spain.[65]

This legacy from the Yemen  and other cultures, developed and advanced by the applications of the summons of the religious text, and the works of a large group of ingenious experimenters and scholars, was passed on to the Christian West. Witness of such impact is the considerable Arabic vocabulary in Spanish irrigation (acequia, alberca, arcaduz, noria etc,) for instance.[66] Another aspect is in the prevalence of Islamic techniques: norias, saquias etc, and not just in Spain and Portugal, but also in their American colonies.[67] In Majorca, there still remain extensive tank irrigation schemes constructed by the Muslims.[68] Remains of Islamic water systems can also be seen in the surviving dams; many such dams as on the Turia River now over ten centuries old, still meeting the irrigation needs of Valencia , and so effective that they require no addition to the system.[69] There was a similar impact in Sicily , where the study of philology clearly highlights the Arabic etymology of Sicilian vocabulary related to irrigation.[70]