Abstract
Hydraulic systems were built by ancient civilizations, notably the Persians and Romans, to deliver water to their residences where the water supply was scarce. Qanats were invented by the Persians to transfer water from aquifers to the surface, and aqueducts were built by the Romans to transport surface or underground water from its sources to distribution points in cities. Finding groundwater is a similarity between these two historical systems. This research compares ancient methods used by Persians and Romans to locate areas with abundant subsurface water. The oldest existing historical documents that recorded ancient ways of tracking groundwater, Al-Karaji’s treatise on qanats and Vitruvius’ treatise, were investigated with the qualitative content analysis method. As a result, historical means are divided into two categories in these two treatises including natural indications and practical tests. Natural indications consist of mountains and rocks, features of steppes, plants, vapours and dew, the whistles of the wind, and alluvial fans. An inverted container, a fleece of wool, an oil lamp, and a fire are instances of practical tests. Although these two treatises were authored over a ten-thousand-year interval and the structures of water systems differ, there are commonalities between ancient methods of tracing underground water.
1 INTRODUCTION
Water is a vital natural resource and the lifeblood of our life. Throughout history, due to a lack of surface water in several parts of the world, people built hydraulic systems to transport water to the surface. Persians and Romans, for instance, built two different traditional hydraulic systems known as qanats and aqueducts, respectively. Qanat was made and used earlier than Roman aqueducts.1 Qanats convey groundwater to the surface with a gently sloping subterranean gallery.2 It was first developed in ancient Iran dating back to the early first millennium BCE3 and then was spread throughout the world, including China, Afghanistan, Pakistan, Iraq, Saudi Arabia, Oman, Egypt, Syria, Algeria, Morocco, Jordan,4 Yemen, Libya, Spain, Mexico, Peru, and Chile.5 The relationship between the qanat and the city is depicted schematically in Figure 1.
Schematic section of a qanat6 (Republished with permission from Dr Labbaf Khaneiki)
Citation: Építés - Építészettudomány 51, 3-4; 10.1556/096.2023.00097
The Roman aqueducts consist of pipes, tunnels, canals, and bridges to transfer water to cities for irrigation, drinking, and other purposes7 through gravity alone. Even though Romans did not build aqueducts for the first time,8 the Roman aqueducts are considered the greatest in the ancient world. In 312 BC, Appius Claudius erected the first aqueduct for the city of Rome.9 An aqueduct with an infiltration gallery as the source is shown in Figure 2.
Schematics of an aqueduct with infiltration gallery as the source, by W.D. Schram, Permanent link: http://www.romanaqueducts.info/introduction/ (© 2004 W.D. Schram) (Accessed 18 June 2023)
Citation: Építés - Építészettudomány 51, 3-4; 10.1556/096.2023.00097
While groundwater is the only source of qanats,10 surface water and groundwater are the sources of Roman aqueducts.11 The first step to building these two hydraulic structures is finding a suitable place that contains a significant amount of water. This research reviews and compares ancient ways of detecting where underground water can be obtained to construct qantas and aqueducts. Hence, the oldest extant records on ancient knowledge of identifying groundwater resources to develop these hydraulic supplies, Al-Karaji’s treatise on The Extraction of Hidden Waters and Vitruvius’ treatise on Ten Books on Architecture, were chosen and studied in the following sections.
The history of qanats has caught the attention of many researchers from the 20th century. The oldest document about qanat, according to Goblot’s book Qanat; A Technique for Obtaining Water, is an inscription by Sargon II12, King of Assyria.13 Although this inscription is the oldest remaining document about the existence of qanats, Al-Karaji’s treatise on water engineering is the first historical text that explains the qanat system in detail and provides a practical guide on building qanats. Abu Bakr Muhammed Al-Karaji was a Persian scholar who lived in the late tenth and early eleventh centuries and he is most known for his contributions to mathematics, particularly algebra.14 He was also an engineer and wrote a treatise on water extraction.15
Al-Karaji’s treatise, Inbat al-miyah al-khafiya (The Extraction of Hidden Waters) is a technical treatise on hydrology that is the first of its kind in this field, covering various types of water, techniques for finding groundwater, instruments and methods for surveying, technical issues for building qanats, and their maintenance.16 The original book was written in Arabic (circa 1017 CE).17 In this research, the Persian translation by Hoseyn Xadiv Jam and the English translation by Abigail E. Schade (as an appendix in her Ph.D. thesis)18 of the book were used.
According to Bill Thayer, Frontinus’ book, De aquis Urbis Romae19, is the primary source on the aqueducts of the city of Rome;20 however, Vitruvius explains in his treatise methods to find groundwater to build aqueducts about a century earlier, and Vitruvius’s treatise was selected for this research. Marcus Vitruvius Polli (during the 1st century BC), commonly known as Vitruvius, is a Roman engineer, architect, and author of the treatise De architectura (The Ten Books on Architecture).21 The original text is in Latin and the English translation by Joseph Gwilt (The Architecture of Marcus Vitruvius Pollio)22 was used for this research.
2 RESEARCH METHODOLOGY
This research employed qualitative content analysis (QCA). Content analysis, according to Krippendorff, is “a research technique for making replicable and valid inferences from texts (or other meaningful matter) to the contexts of their use”.23 In this paper, the interference addresses the message itself in two treatises. Researchers use content analysis in both qualitative and quantitative methods to recognize and record the attitudes, viewpoints, and interests of individuals or groups, such as small groups or large and diverse cultural groups.24 Mayring describes qualitative content analysis (QCA) as a setup technique for systemic text analysis.25 This method’s most distinguishing feature is its systematic approach, which starts with creating a coding frame for materials based on the research question(s), then placing materials into coding units where they fit, whereupon evaluating and adapting the coding frame, and after that main analysis, interpreting, and finally presenting findings.26 The qualitative content analysis was used to determine and compare ancients’ knowledge of two different nations to find groundwater based on research questions and two chosen historical treatises as main documents.
The steps of QCA in this study are demonstrated in Figure 3. Due to research questions, a coding frame was created, and then by assigning consecutive pieces of the treatises to the coding frame where they fit, and modifying the coding frame, two categories resulted including natural indications and practical tests. These categories were identified using a step-by-step procedure in the two documents, and each category includes subcategories, and the findings in them were interpreted and compared.
Steps in QCA of this research (by the authors)
Citation: Építés - Építészettudomány 51, 3-4; 10.1556/096.2023.00097
3 ANCIENT METHODS OF GROUNDWATER PROSPECTING
Al-Karaji referred to subsurface water as hidden waters that must be traced beneath the land surface. The treatise’s sections II, III, IV, V, VI, XIII, and XXV detailed historic ways for locating groundwater27 and were studied in the following parts. In book VIII of Vitruvius’ treatise, he states that water is not always obtainable on the surface and that underground water sources must be sought.28 Different chapters in Book VIII cover topics such as where to find underground water, different forms of water and their quality, and how to transfer water via aqueducts. The methods for locating abundant groundwater were thoroughly covered in the first chapter of this book and were discussed in the sections that follow.
3.1 Natural indications
Both treatises listed a variety of natural indicators that show the presence of subsurface water. Al-Karaji points out that becoming a Moqani, a master craftsman of qanats, is meaningless if one does not know how to discern terrain signs.29 If there are no springs, Vitruvius argues, wells must be dug to access groundwater, and they must be excavated with great care and the utmost skill and discernment in evaluating the natural indicators of the location, such as soil kinds.30 Natural indicators in the two documents were placed into the coding frame and the result was six sub-categories counting mountains and rocks, features of steppes, plants, vapours and dew, the whistles of the wind, and alluvial fans.
3.1.1. Mountains and rocks
An alluvial basin in the middle of mountains with a lot of precipitation and covered in snow all year, a basin located in a valley of these mountains, or a steppe that stretches at the foothills of these mountains, according to Al-Karaji, are the best sites to build a qanat, in order, ranked according to their abundance of groundwater.31 Hence, mountains are a natural sign in all three of these places that have a dependable water supply. Al-Karaji reports underground water can be found beneath flat steppes or vast plains that are bordered by mountains. Water from melting snows piled up in the high valleys of these mountains rushes into the sub-soil, especially on the north-facing slopes, which are more humid than other sides and where trees block the sun’s rays, and assuming subsurface barriers do not block water flow, mountains function as natural water reserves for adjacent plains.32 Snowy mountains have been indicated in this part.
In addition, mountains with distinctive features are indeed addressed. Al-Karaji argues, according to ancients’ classification and his opinion, that black mountains which are composed of both layers or stages of soft rocks and soils with a crumbly texture, contain the most water; then, in sequence, according to their amount of water, green mountains, yellow mountains, and red mountains.33 Moreover, mountains with hard and many rocks reserve less water,34 because the snow on these mountains melts too speedily and water cannot pass through the bottom layer. Furthermore, extensive mountain ranges with very smooth, flattened, and wide peaks, and covered with wild plants with tender and full of sap shoots contain an abundance of water.35 The reasoning seems to be that snow stays for a long time in non-isolated mountains wich have innumerable valleys covered in plants. Additionally, if there are many protruding crags or very large rocks standing straight on the mountain, the mountain contains groundwater.36 The reason for this claim was not explained in the text.
Vitruvius37 explains that valleys among the mountains receive a large amount of rain; in addition, the snow is kept there for a long time because of dense forests and the shade of trees and mountains, then melting snow moves through the strata of the ground, and thus arrives at the foot of the mountains and bursts out.38 In other words, mountain ranges are the sign to trace groundwater because of their valleys. He describes the northern slopes of mountains contain more water because the sun’s rays shine diagonally and slopes are sheltered from the sun’s rays by trees and plants, preventing moisture from being carried off.39 Although Vitruvius mentioned finding springheads on the northern slopes of mountains, this can be interpreted as a location with an abundance of subsurface water. Table 1 illustrates the characteristics of mountains with an abundance of groundwater, as documented in treatises. To indicate where to seek abundant groundwater, Vitruvius specifies two characteristics of mountains: sides of slopes and isolated or nonisolated, while Al-Karaji adds three more factors to this list: colours of mountains, characteristics of peaks, and mountain texture.
Features of mountains with the most abundant groundwater sources (by the authors)
| Authors | Features | ||||
|---|---|---|---|---|---|
| Texture of mountains | Colours of mountains | Characteristics of peaks | Isolated or non-isolated | Sides of slopes | |
| Vitruvius | _ | _ | _ | Valleys in the midst of mountains | North-facing slopes |
| Al-Karaji | Composed of both layers or stages of soft rocks and soils with a crumbly texture | Black | Very smooth, flatted, and wide peaks | Extensive mountain ranges with innumerable high valleys | North-facing slopes |
3.1.2. Features of steppes
As reported by Al-Karaji if there are soft, blackish, layered rocks on the steppes’ surface, or numerous diverse rocks on a grains-covered surface, and/or various white rocks on the surfaces, then there is a plentiful supply of water under the ground. According to the ancients, if the throughput of the basin is covered with black soil which is mostly found as soft loam, and at the bottom of chasms, caverns, and ravines, water exists under the surface.40 For this indicator, he cited his observations as well as ancients. In book VIII of Vitruvius’s treatise, it is reported water is abundant in flinty rocks at the foothills of mountains, followed by red stone and red sands, ranked according to their abundance of water if the water does not filter out and leaks out of the pores, and a small amount of water is found in clay, black earth, and gravel.41 The indigenous pedology of steppes was argued by two scholars to search for water in the ground.
3.1.3. Plants
Al-Karaji reports that if a steppe exists far from the mountains, which are under plenty of precipitation and covered in snow all year, and are covered with rich vegetation and tender plants, it indicates the presence of underground water, and the qanat should be drilled there.42 He lists names of twenty-nine plants to determine where groundwater might be found. He explains that if certain plants, for instance, papyrus, the slender common reed, camelthorn, and willow, are fresh and humid and not growing alongside riverbanks43 and/or neither were planted and irrigated by people,44 then they indicate water in that location.
Even though some wild plants from ancient written sources, such as Origanum dictamnus, papyrus, pennyroyal mint, and common sorrel, were recorded, he claims that he never saw them except where there is running or stagnant water, or where water is at a shallow depth or on the surface.46 He did not name the ancient written sources he referred to in this section, but he clarified his observation and the Ancients’ written resources.
In addition, he highlights camelthorn (Alhagi maurorum) and emphasizes the existence of this plant as a certain sign of subsurface water because it sends its roots into the soil until it riches groundwater.47 Figure 4 illustrates the Alhagi maurorum plant which shows the location of subsurface water.
Camelthorn (Alhagi Maurorum), a plant which shows the availability of groundwater. Permanent link: http://www.biolib.de/taubert/bilder_high/fig_123.html45 (no copyright) (Accessed 20 April 2023)
Citation: Építés - Építészettudomány 51, 3-4; 10.1556/096.2023.00097
As stated in Vitruvius’s book if some plants, for instance, reeds, ivy, and wild willows, which need moisture for springing up and generally grow near lakes, are seen in a district where there is no lake nearby, then underground water resources may be found there.48 Both authors cited their knowledge of wild plants that grow naturally in certain areas, hinting at the potential of groundwater. However, due to the varying climate zones of the countries covered in the books, most flora was distinct, and only willows and reeds were identified in both texts.
3.1.4. Vapours and dew
Vitruvius states that where vapours are curling and rising into the air from the surface before sunrise, the beneath of that area is water and he describes a method for tracing this natural indication; a person must lie down on the ground and place his chin on the earth and fix it, then the sight cannot range upper than it ought.49 Figure 5 is a historical illustration from a rare manuscript dating from around 1511 that illustrates this technique of observing vapours.
Illustration of Method of Finding Water (tracing vapours). Permanent link: https://digital.library.cornell.edu/catalog/ss:11177725 (Division of Rare and Manuscript Collections, Cornell University Library)
Citation: Építés - Építészettudomány 51, 3-4; 10.1556/096.2023.00097
In Al-Karaji’s book, it is reported that if every morning the ground is covered with small droplets of water which are in the state of water vapour condenses, namely, dew, fog, and mist, then hidden waters are contained in that location.50 Al-Karaji notes this sign must be seen every morning in the spot, while Vitruvius just mentions seeing it before sunrise. Furthermore, Vitruvius describes the specific way to observe vapours that are rising from the ground, whereas Al-Karaji gives no instructions on how to do so.
3.1.5. Whistles of the wind
If characteristic sounds, such as wind whistling and hissing, can be heard in basins or basins around mountains, especially where plants and morning dew exist, then there is groundwater in that location, according to Al-Karaji.51 To make this natural indicator more trustworthy, he adds two other natural signs, namely dew, and plants.
3.1.6. Alluvial fans
Al-Karaji explains that beneath valleys and their extensions where the spring flood flows and has no way out, water exists.52 This part refers to alluvial fans, which are created as flowing water interacts with steep walls of mountains and foothills, as a natural sign to look for underground water.
3.2 Practical tests
Apart from natural signs, different tests to find places which contain groundwater to build hydraulic systems on were described in the two treatises. Vitruvius notes in the first chapter of book VIII that if mentioned signs, natural indications in this paper, do not appear in a place then a test must be applied.53 In section XIII of Al-Karaji’s treatise,54 five paragraphs of different points are cited and two of them are about tests by Ancients to determine whether there is water in the subsurface.55 Practical tests in the two treatises were divided into the coding frame and four sub- categories resulted, namely, an inverted container, a fleece of wool, an oil lamp, and a fire. Furthermore, findings were interpreted and compared in each sub-category in the following part.
3.2.1. An inverted container
It is stated by Vitruvius that the following plan must be implemented to find groundwater. A hole about 90 cm square, and at least 1.5 m deep must be dug. About sunset, a bronze or lead curved container that is used to hold liquid, such as a basin or a vessel, must be smeared on the inside with oil and put into the hole upside down. Afterwards, the top of the excavation must be covered with reeds or leaves and earth must be thrown over. On the next day, after uncovering the hole, if inside of the vessel there are drops of water or damp, this place contains groundwater.56 If the vase in the pit is made of unburned clay and has been covered in the pit as indicated above, when it is uncovered, it will be humid and possibly ruined by the moisture. Hence, the place contains water.57 Details such as tools and the timing of the examination were explained in this test.
Al-Karaji indicates that Ancients recommended placing a little of wax-coated wool at the bottom of a hemispherical bowl made of copper, ceramic, or lead, putting the bowl inverted in a three-cubit-deep hole (about 1.6 m), covering it with a leaf (indifferent which types of leaves), and filling the hole with soil, leaving it like that from sunset until sunrise, then getting out the bowl in the early morning next day, and if the inside of the container is moist58 then there is water in that ground.59 The existence of moisture in the inverted bowl is a sign of hidden water in that location. Furthermore, Al-Karaji mentions as a precautionary step drying out the hole, first lighting a fire in it, then putting said bowl inside of the pit, if there is any evidence of moisture just like he said, it is safe to assume that there is water in the ground.60 He added an extra measure to the test to make the result more reliable. This procedure described in both treatises has some similar characteristics, such as the lead vessel, the depth of the pit, the test start time, and the length of time required to complete the test.
3.2.2. A fleece of wool
According to Vitruvius, if a fleece of wool is put in the pit, which was explained in detail in the preceding section, and the wool is examined the next day and a few droplets of water come out after squeezing it, then it shows the sub-soil here contains an abundance of water.61 He did not specify whether the wool had to be placed inside the container in the hole and whether the pit had to be covered. Al-Karaji states gluing a little piece of wool with wax at the bottom of a bowl, which is made of lead, copper, or ceramic, and putting the bowl upside-down in a three-cubit-deep pit (about 1.6 m), covering it with a leaf, and covering the hole with earth; the next morning if after squeezing the wool there are drops of water, then there is water in that ground.62 In the treatise, he combined two techniques, an inverted container, and a wool fleece, to provide a more valid result.
He also detailed another test with the fleece. If the examined ground contains caves or passive wells, to determine whether that sub-soil contains water, suspend a fleece of wool, which is well dried or soaked with oil, with a string into the depth of one of those cavities for three hours, without letting the wool touch the bottom or walls of the cave or the well, then take it out and if you see moist in the wool, there is water in that ground. As a precautionary step, leave the wool suspended for a whole night and replace the fleece of wool with a piece of sponge.63 In this examination, it is not explained whether it is needed to cover the cavities or not.
3.2.3. An oil lamp
Vitruvius explains if an oil lamp is trimmed and filled with oil, then put it in a pit, which was explained in an inverted container test, and cover the pit; on the next day if the oil lamp is not burnt out and found to be damp, with some oil and wick remaining, then it shows the place contains water because heat always attracts moisture.64 The reason for the method’s outcome was stated.
3.2.4. A fire
As the last test, Vitruvius suggests making a fire in the pit, and if the ground is sufficiently warm and burned to emit a misty vapour from its surface, then there is water underneath the ground.65 It was not specified how long the fire should be kept going on.
4 CONCLUSION
Vitruvius and Al-Karaji described various historical methods and knowledge in their treatises on tracing the abundance of groundwater to build hydraulic systems, namely, aqueducts and qanats. Table 2 demonstrates two main categories, consisting of natural indications and practical tests, as well as their subcategories, which were addressed in the two books.
Methods to find groundwater in treatises of Vitruvius and Al-Karaji (by the authors)
| Authors | Natural indications | Practical tests | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Mountains and rocks | Materials/texture of the steppes | Plants | Vapours and dew | Whistles of the wind | Alluvial fans | An inverted container | A fleece of wool | An oil lamp | A fire | |
| Al-Karaji | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | ✓ | _ | _ |
| Vitruvius | ✓ | ✓ | ✓ | ✓ | _ | _ | ✓ | ✓ | ✓ | ✓ |
Despite differences in the details of natural signs between the two manuscripts, such as different species of plants, both authors described four identical indications: mountains and rocks, features of steppes, plants, and vapours and dew. In addition, whistles of the wind and alluvial fans were explained by Al-Karaji as two further natural indicators. In the two documents, an inverted container and a fleece of wool were considered as two testing procedures, and an oil lamp and a fire were also described by Vitruvius.
ACKNOWLEDGEMENT
We would like to express our very great appreciation to Dr. János Krähling for his valuable and constructive suggestions during the planning and development of this research work.
Aicher 1995. 2.
Lightfoot 1997. 448.
Lightfoot 2000. 215.
Aicher 1995. 2, 3; Deming 2020. 152.
Matthews 1970. 2.
Maliva–Missimer 2012. 516.
Deming 2020. 152.
(721–705 BC) Laessoe 2017.
Schade 2011. 195.
This book is a description of Rome’s water supply.
The text is available on Bill Thayer’s website: https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Vitruvius/home.html (Accessed 20 April 2023).
Krippendorff 1984. 18.
Schreier 2012. 6.
Vitruvius Pollio1826. 230.
Al-Karaji 1994. 42.
Vitruvius Pollio 1826. 256.
Al-Karaji 2011. 261.
Al-Karaji 2011. 201, 206, 208–209.
Al-Karaji 2011. 208.
Al-Karaji 2011. 208.
Al-Karaji 2011. 201–208.
Al-Karaji 2011. 208.
Vitruvius Pollio 1826. 232.
Bill Thayer, in private communication, notes the Latin phrase ‘erumpunt ructus’ was wrongly translated as a river by Gwilt.
Vitruvius Pollio 1826. 233.
Al-Karaji 2011. 208–209.
Vitruvius Pollio 1826. 231.
Al-Karaji 2011. 261–209.
Al-Karaji 2011. 211.
Al-Karaji 2011. 44.
Taubert 1891. 82.
Al-Karaji 2011. 212.
Vitruvius Pollio 1826. 231.
Vitruvius Pollio 1826. 230.
Al-Karaji 2011. 209.
Al-Karaji 2011. 209.
Al-Karaji 2011. 261–209.
Vitruvius Pollio 1914. 228.
Al-Karaji 2011. 221; Al-Karaji 1994. 60–61.
In this section of the research, practical tests, the Persian translation of Al-Karaji’s treatise was studied because these two paragraphs were described in more detail compared to the English translation.
Vitruvius Pollio 1826. 232.
Vitruvius Pollio 1826. 232.
Also, if the wool is moist and it is explained in the next sub-category.
Al-Karaji 1994. 60.
Al-Karaji 1994. 60–61.
Vitruvius Pollio 1826. 232.
Al-Karaji 1994. 60.
Al-Karaji 1994. 61.
Vitruvius Pollio 1826. 232.
Vitruvius Pollio 1826. 232.
REFERENCES
Abattouy, Mohammed: Muhammad Al-Karaji. A Mathematician Engineer from the Early 11th Century. Muslim Heritage. 2019. https://muslimheritage.com/muhammad-al-karaji-mathematician-engineer/ (Accessed 5 April 2023).
Aicher, Peter J.: Guide to the Aqueducts of Ancient Rome. Bolchazy-Carducci Publishers, 1995.
Al-Karaji, Abu Bakr Muhammed: The Extraction of Hidden Waters. Columbia University, 2011. (Appendix B. Karaji’s Treatise on the Extraction of Hidden Waters, PhD thesis: Hidden Waters: Groundwater Histories of Iran and the Mediterranean). https://academiccommons.columbia.edu/doi/10.7916/D8X3649D (Accessed 20 April 2023).
Al-Karaji, Abubakr Moḥammad enb Al-Hasan Al-Haseb: Extraction of Underground Waters (Istekhraj Abha-ye Penhan-i). Institute for Humanities and Cultural Studies, Iranian National Commission for UNESCO, Iran 1994.
Angelakis, Andreas N.–Christodoulakos, Yannis,–Tzanakakis, Vasileios A.: Roman Aqueducts in Crete, Greece: Learning from the Past. Water 13 (2021) 8. 1–23. (Accessed 5 April 2023).
Ataie-Ashtiani, Behzad–Simmons, Craig T.: The Millennium-Old Hydrogeology Textbook The Extraction of Hidden Waters by the Persian Mathematician and Engineer Abubakr Mohammad Karaji (953 CE–1029 CE). Hydrology and Earth System Sciences 24 (2020) 761–769. (Accessed 10 April 2023).
Deming, David: The Aqueducts and Water Supply of Ancient Rome. Groundwater 58 (2020) 1. 152–161. (Accessed 20 April 2023).
Drisko, James – Maschi, Tina: Content Analysis (Pocket Guide to Social Work Research Methods). Oxford University Press, Oxford 2016.
Encyclopaedia Britannica: Vitruvius. 2019. https://www.britannica.com/biography/Vitruvius (Accessed 15 April 2023).
English, Paul Ward: The Origin and Spread of Qanats in the Old World. Proceedings of the American Philosophical Society 112 (1968) 3. 170–181.
Goblot, Henri: Les Qanats, une technique d’acquisition de l’eau (Qanat; a Technique for Obtaining Water) / Translated from French to Persian 1992. (Translated by Abdolhossein Sarvghad Moghadam – Mohammad Hossein Papoli Yazdi). Papoli, Iran 1979.
Karajī, Muḥammad ibn al-Ḥusayn: Inbāṭ al-miyāh al-khafīyah (Extraction of Underground Waters). 1084. http://hdl.library.upenn.edu/1017/d/medren/9948256513503681 (Accessed 20 April 2023)
Krippendorff, Klaus: Content Analysis. An Introduction to Its Methodology. Journal of the American Statistical Association 79 (1984) 385. 240. https://www.jstor.org/stable/2288384?origin=crossref (Accessed 20 April 2023)
Laessoe, Jorgen: Sargon II King of Assyria. In Encyclopedia Britannica. 2017. https://www.britannica.com/biography/Sargon-II (Accessed 20 April 2023).
Lightfoot, Dale R.: Qanats in the Levant. Hydraulic Technology at the Periphery of Early Empires. Technology and Culture 38 (1997) 2. 432–451.
Lightfoot, Dale R.: The Origin and Diffusion of Qanats in Arabia. New Evidence from the Northern and Southern Peninsula. The Geographical Journal 166 (2000) 3. 215–226.
Maliva, Robert – Missimer, Thomas: Arid Lands Water Evaluation and Management. Springer, Berlin, Heidelberg 2012.
Matthews, Kenneth D.: Roman Aqueducts. Technical Aspects of Their Construction. Expedition 13 (1970) 13. 1 16. 1. 2–16.
Mayring, Philipp: Qualitative Content Analysis. Theoretical Foundation, Basic Procedures and Software Solution. Klagenfurt 2014. https://www.ssoar.info/ssoar/handle/document/39517 (Accessed 20 April 2023).
McElroy, Tucker: A to Z of Mathematicians. Facts on File, 2005.
Nichols, Susan: Al-Karaji. Tenth-Century Mathematician and Engineer. The Rosen Publishing Group, Inc., New York 2016.
Pazwash, Hormoz–Mvrigian, Gus: The Contributions of Karaji–Successor to al-Khwarizmi. National Council of Teachers of Mathematics 97 (1986) 7. 538–541.
Schade, Abigail E.: Hidden Waters. Groundwater Histories of Iran and the Mediterranean. Doctoral thesis, Columbia University. 2011. https://academiccommons.columbia.edu/doi/10.7916/D8X3649D (Accessed 20 April 2023).
Schreier, Margrit: Qualitative Content Analysis in Practice. SAGE publications, 2012.
Semsar Yazdi, Ali Asghar – Labbaf Khaneiki, Majid: Qanat Knowledge Construction and Maintenance. Springer, Dordrecht 2017. https://link.springer.com/book/10.1007/978-94-024-0957-4 (Accessed 20 April 2023).
Taubert, Paul Hermann Wilhelm: Leguminosae. Natürliche Pflanzenfamilien III, 3. Wilhelm Engelmann, Leipzig 1891. http://www.biolib.de/taubert/index.html (Accessed 20 April 2023).
Thayer, Bill: Marcus Vitruvius Pollio: De Architectura, Book VIII. https://bit.ly/VitruviusE8 (Accessed 20 April 2023).
Vitruvius Pollio, Marcus: The Architecture of Marcus Vitruvius Pollio (translated by Joseph Gwilt). Priestley and Weale; Bill Thayer. 1826. https://bit.ly/VitruviusE8 (Accessed 20 April 2023).
Vitruvius Pollio, Marcus: Ten Books on Architecture (translated Morris Hicky Morgan). The Project Gutenberg EBook. 1914. https://www.gutenberg.org/files/20239/20239-h/20239-h.htm (Accessed 20 April 2023).
Wulff, Hans E.: The Qanats of Iran. Scientific American (1968) 218. 94–105.
