Hohokam Canal System Essay
The current research highlights the development of the people of Hohokam and their significance for Arizona particularly and the whole world in terms of the irrigation system construction. The Hohokam engineers created great and complex canal systems, which helped to develop a productive agricultural society. A complex sociopolitical structure was established in order to organize and maintain their canal system. The abovementioned facts pointing out the genius of the Hohokam people were examined and described by Howard (n.d.), Sharp (2014), Hunt et al. (2005), and other authors, whose articles were used for creation of this paper.
Keywords: Hohokam, irrigation system, canal system, sociopolitical structure, mounds, main canal, dam, primitive tools, the Salt River, the Gina River
Hohokam Canal System
The Hokhokams were one of the earliest American cultures. When during the archaic period, the climate became adverse, and the region of modern Arizona became droughty, inhabitants of the Hokhokam people showed a considerable ingenuity and managed to keep both the cultural originality, and a leading position among the areas of distribution of the ancient American cultures. Hohokam culture (approximately 400 AD – 1400 AD) was one of the most progressive cultures of the Southwest of America. Its achievements include an extensive network of irrigational canals in the Salt River basin, stonework of a very high quality, a production of fine textiles and ceramics. In the conditions of the droughty district where they lived, there was no enough water necessary for agriculture, and it generated great difficulties. Therefore, people of the Hohokam tribe created irrigational agriculture and built an extensive network of canals. The Hokhokam were the powerful people, which turned the Sonoran desert into fertile fields. Thus, the construction of canals was a decisive factor for the prosperity of the Hohokam tribe. In this regard, the bases of the culture of this tribe and the principles of construction of canals should be studied in more detail in order to estimate their contribution to the American history and modern irrigation system engineering.
The Hohokam Civilization and Culture
By the early Christian period, the people of Hohokam had already formed small agricultural villages in the vicinities of today's Phoenix, Arizona. Their dwellings were primitive branches. The culture of Hohokam prospered almost up to historical times, having reached the highest point of development in 700-1100 AD. The people of Hohokam inherited the culture of Cochise of the late period, which had a significant similarity with many features of the culture of the Mexican people, who inhabited the south. They grew corn and cotton, collected wild-growing beans and fruits of a cactus, smoked ceremonial cigarettes, and made various types of pottery and jewelry of turquoise, sinks, and stones (Angelakis, Mays, and Koutsoyiannis 385). After about 500 AD, these people built profound courts for a ball game, similar to the courts of the Maya. Unlike Mexicans, they were essentially peaceful people with a social system based on democracy but not class estates. In the conditions of the droughty district where they lived, there was no enough water necessary for agriculture, and it generated great difficulties. Therefore, people of a Hohokam tribe created irrigational agriculture and built an extensive network of canals. The sizes of these constructions (one such network of canals covered over 240 km) meant the high level of organization (Abbott 3-6).
During many hundreds of years, the Hohokam people continued to live in the same area, building one and the same type of dwellings, which was changing in details and remained, in essence, a semi-underground structure with columns, brushwood, and several layers of the ground. This kind of dwelling was widespread in all Southwest. In about 1000 AD, they invented a process of engraving the sinks by means of the fermented juice of a Cereus giganteus and created probably the very first engravings in the world. Today, only few samples of such engravings were found, and the practice of engraving, eventually, disappeared. In the territory of America, similar items were not created anywhere more (Abbott 3-6).
Numerous archaeological researches showed that these farmers were also outstanding artists. The pottery created by them is recognized as one of the most beautiful in the world, and in the art of engraving, they are at least four centuries ahead of European masters of the Renaissance. Among the artifacts created by the culture of the Hohokam Indians, there are sinks with an engraving relating approximately to 1000 AD. They prove that this culture of the southwest had first-ever started developing the art of engraving, which had no analogs in the world during that era. The art of an engraving of Hohokam was not limited by the banal scratching of patterns known in the Stone Age as well, but represented a complicated process. At first, the master put a resin pattern on the shell, then dipped it in fermented cactus juice that was corroding those parts which were not protected by the pitch. As a result, the relief image appeared (Abbott 6-11).
In about 1300 AD, the tribes of Saladoan intruded on this territory from the mountain areas of the east central Arizona. It was the unique case of coexistence of two unrelated groups of people. During several generations, they freely and peacefully communicated with each other and lived in the same settlements, but everyone kept, thus, an own way of life. The coexistence of two groups of people ended after 1400, when the Saladoan tribe left, having moved probably to northern Mexico, and Hohokam kept their traditional way of life. They are considered as ancestors of modern Indians of Pima and Papago. The most known monument of this period is Snaketown in the south of Arizona. Allegedly, the culture of Hohokam faded after 1400 as a result of pressure from semi-nomadic Indians of Apaches (Angelakis, Mays, and Koutsoyiannis 385).
General Characteristics of the Hohokam Canal System
Nevertheless, the Hohokam tribe did not leave considerable traces of architectural constructions. Their greatest achievement, distinguishing them from others, is their irrigating system, covering many square kilometers. Fragments of this labyrinthine network are represented by more than 640 kilometers of canals around the Phoenix, which were found by means of satellites. These evidences serve as the sign of the developed engineering. Canals delivered water from the Salt and Gila rivers to the fields where farmers grew fruit trees, several varieties of maize, pumpkin, haricot, cotton, and other cultures, collecting two crops per year. The remained sites of irrigational canals prove that once, the desert was turned into a flourishing region by skillful hands ("Hohokam Canals: Prehistoric Engineering").
This system, having many kilometers of canals, emerged gradually as a result of work of many generations. One five-kilometer channel was dug manually by means of primitive wooden and stone tools prior to the beginning of our era, in times when locals were still far from their highest art achievements. Channels needed to be adapted for district conditions, it was necessary to monitor the canals constantly, improve and repair them. It was also necessary to build the constructions regulating water inflow, and all this continued throughout many centuries (Abbott 3-6).
Canals were straight and deep: 2 meters in depth and only from 1,8 to 3 meters in width. Thus, surface area was rather small, consequently, the smaller amount of water was evaporated under the influence of hot sunshine. Ironically, floods of these rivers, while giving life, could damage or destroy canals. This irrigational technique is twice more difficult than terrace agriculture and four times more complicated than the usual one, but its productivity covers all expenses and efforts totally (Abbott 6-11).
Approximately in 600 AD, people of the Hohokam tribe started to build irrigation canals. By means of the digging sticks, they excavated 12-feet-deep trenches by their hands. These trenches brought water from the Salt River and supplied it to the network of the smaller canals, which helped to maintain the constant water supply to the fields. By 1450 AD, the Hohokam people constructed about 500 miles of canals, which irrigated almost 100, 000 acres of fields ("Hohokam Canals: Prehistoric Engineering").
The Hohokam canals are featured with a remarkable set of functions, which are still serving as an example of engineering genius. Foremost, the canals were wide at the beginning, i.e. at the mouth, and had a conical form, getting smaller with the distance from the mouth since the numerous smaller canals took water from the main one. In such a manner, by means of narrowing the size of the canal as the flow reduces, the Hohokam people managed to stabilize the water consumption. A steady rate of water flow is a key factor in creation of the functional irrigation system. It is the fact that quickly flowing water carries silt and sand, which lead to the canal block. On the other side, slowly flowing water cannot reach its destination. Nonetheless, the Hohokam people created the canals covering miles of territory based on a steady grade, i.e. avoiding valleys and hills; such a structure could affect the rate of water flow ("Hohokam Canals: Prehistoric Engineering").
The Hohokam Canals Operation and Engineering
The Hohokam engineers clearly understood the features of the local topography, soils and drainages, slopes and dips. They developed a complicated knowledge about the water flow through the canals and found a number of methods for water supply to the fields surfaces. Each developed method was suitable for a certain topographic environment only, for instance, flat river terraces or steep slopes. The Hohokam canal systems were constructed with respects to the characteristics of the environment and the needs of locals. The farmers were usually responsible for letting the water from the canals to the fields and managing the fields surface to ensure the water was flowing to the required places, at the required speed, and at the required times. The farmers had to sculpt the fields surface in order to achieve the aforementioned results. Each farmer had to provide a needed amount of money, materials, and labor proportionate to his water rights (Abbott 6-11).
The Hohokam engineers observed and regulated velocities of the water flow and processes of silting and erosion through the alignment of canals with consistent downhill grades of 1-5 feet in a mile. For this purpose, they, probably, used rudimentary surveying devices. The Hohokam people learned to manage the levels of water through matching canal depth and width to flow volumes. In some districts, engineers managed to reduce losses of water by excavating narrow deep canals, which helped to limit evaporation under the heat of the sun and reduce the surface exposure. In addition, they plastered canal bottoms in order to minimize water absorption by loose soils (Abbott 24-25).
The Hohokam irrigation canals contained a set of physical elements. In the place where the canal was introduced into the river, Hohokam constructors built a weir. The weir is a dam, which is constructed through the river, but does not totally cross it. By means of this construction, the level of river water is raised, and flow of water is directed into the canal. On each side of the canal, there were the headgates constructed. Headgates represented the gates aimed to control the amount of water transported into the canal. As it was mentioned above, the canals had a conical structure. This was caused by the amount of flowing water decreased because of discharge onto fields, seepage, and evaporation; thus, the canal size was reduced. Nevertheless, regardless of the canal reduction, the speed of the water flow remained constant and maintained the golden middle between two critical thresholds. In other words, if the water flow was too fast, it could lead to the bank erosion; and, on the contrary, if the water flow was too slow, particles of soil could fill the water, resulting in the contamination and thus silting up. Finally, both damages required an increased maintenance (Sharp).
The main canal system supplied water to distribution canals, which delivered water to the fields. Besides, distribution canals were used in order to control the relationship between the ground surface and the level of water in the canal. In order to operate the distribution systems, Hohokam people used some kinds of water control features. They constructed diversion gates at the junctions of the distribution and main canals in order to control the water flow. Water control gates were usually settled inside the distribution and main canals. Closed water control gates led to accumulation of water rising in elevation and creating a water column. In their irrigation canals, the Hohokam people used partial dams made of brush and log in order to divert waters of permanently flowing rivers into the canals they built. Within the main canals, the log-and-brush headgates were used for directing the water flow. By means of laterals and distribution ditches, the Hohokam people have learned to deliver water from the canals into their village reservoirs or cisterns. Due to the usage of water control features, the Hohokam tribe managed to create a rather sophisticated irrigation system (Howard).
The Hohokam Canal System Construction
The Hohokam canals construction required large investments of the human force and labor. People removed the soil manually by means of wooden digging sticks for loosening of soil and big wedge-shaped chumps of stone, know as stone-hoes. The soil was removed from the canals by means of the large baskets. For the establishment of the canal gradients, the Hohokam builders used variations on the usual "leveling frame," which was widely used in most preindustrial agrarian societies. During the construction, Hohokam people used to let the water along in the canal for loosing or wetting down the soil. Nonetheless, such a way of construction could have demanded much more time and labor. The flooded canals had to be dammed, and the water in the canal had to be dissipated in full before the works could be resumed (Angelakis, Mays, and Koutsoyiannis 385-387).
Initially, farmers possessed a limited labor and minimal engineering skills. Moreover, oftentimes, farmers faced the problems with materials, especially if scarce materials, for instance, wood, were used extensively when constructing the canals. As a result, the early canal systems were constructed on the lowest terrace, closest to the supplying river. With the further acquisition of additional labor, materials, and engineering experience, the Hohokam learned to build canals away from the rivers, on higher terraces, expanding, thus, their irrigation network. With each expansion, labor, costs of materials used, and engineering skills were increased (Sharp).
The amount of the required work force partially depended on the volume of water in the Silver River. During both Classic and the late Colonial periods of the Hohokam people existence, they faced frequent flooding on the Silver River. Oftentimes, flood waters damaged or destroyed canals, which further were redesigned and reconstructed. The actual time and efforts required for the construction of main canals are difficult to be estimated. Archeologists claim that some of the Hohokam irrigation canals were built by accretion, i.e. one small canal was dug in one agricultural season. The canals could not be widened by accretion; they, however, could be lengthened in this manner. An increase of the canal meant an increase of the command area of the fields irrigated by the canals, that requires more water supply (Hunt et al., 441).
Numerous factors influence the estimates of the expended labor and work force. These factors include the number of working hours in one day, the volume of soils that one worker could remove in one day, and the amount of continuous and discontinuous seasons or days during which the work was performed. Taking into account the fact that one worker could remove 3 cubic meters of soil per day, more than 25,000 person-days would be required for the construction of the majority of the canals. This fact testifies that some canals could take several years for their construction to be completed (Howard).
The construction of new canals did not require the involvement of coordination with already existing lower canals. Nevertheless, expanding from one to more canals, taking water from the same river, caused several problems. The water flow could be essentially reduced, if a new main canal was built upstream on its basis without regulation of the volume of water intake. The construction of dams was a usual practice in the Hohokam community. The dams diverted water from the river into the main canals. Seasonal floods threatened the entire water-works. In this regard, it was rather advantageous to install gates downstream from the intake. When flooding occurred, the farmers had only to close the gates in order to protect all works along the canal from the damages. Diversion dams closed the canals by means of large stones each year in the middle of the falls. In the early spring, the stones were removed out of the canal, and, thus, the dam was reconstructed, letting water into the main canal for the irrigation period (Sharp).
Social Organization of the Hohokam Canals Construction
The construction, exploitation, and the maintenance of the irrigation systems required a significant and well-ordered work. The inhabitants of all villages located along the main canal were involved into the initial construction and constant maintenance of the canals, headgates, and weirs. Each year, a certain amount of water from the irrigation system was appointed to each farmer. Consequently, there were lasting conflicts among the villages and individual farmers because of canal water consumption. Therefore, powerful executives were necessary for quick resolution of such conflicts threatening the wellbeing of the whole settlements (Hunt et al., 436).
Scientists suppose that the Hohokam irrigation systems were combined into irrigation communities, i.e. sociopolitical communities, which played different leadership roles. Each community had its own leadership, which was responsible for the organization of the work processes during the main canal construction and the maintenance of weirs and headgates. Besides, these communities had to allocate and schedule the water consumption and resolve the arising conflicts on the basis of irrigation systems water consumption. Smaller local communities of farmers could organize and control the construction of distribution canals (Howard).
Centralized political control was most pronounced in the Hohokam society when they built more than one hundred platform mounds at the largest settlements. The Hohokam mounds, the construction of which required a labor of numerous supra-household groups, were used as elevated surfaces for both private and public functions. The highest density of the platform mounds was discovered in the intensively irrigated valley of the Phoenix basin. These mounds were equally spaced along the canals in the middle Gila and lower Salt River valleys. Archeologists believe that the local leaders of the Classic period were directly associated with these platforms. The equal spacing of the monuments along the canals is a bright evidence of coordinated leadership, which organized and controlled the irrigation economy. However, scientists concluded that administrative hierarchies became more complex with the growth of the canal systems (Hunt et al, 433-434).
Hohokam Canal System Construction in Modern Conditions
The Hohokam people managed to build such a successful and efficient canal system that the major principles of canals construction are traced even in the modern irrigation systems today. Therefore, one can claim that if the Hohokam built their canals today by means of modern technologies and knowledge, this irrigation system could become one of the most distinguished inventions of the humanity. Modern high technologies could help to simplify numerous difficulties associated with the canals maintenance and operation, transforming them into simple elements. Further, they could be used in the recursive processes, leading gradually to the implementation of new methods of management and the improvement of canals operation in order to promote the movement towards more effective water management and developed water allocation.
One of the methods, for example, which would be obligatory applied in the canal construction today, can be the application of mapping of surface water hydrographical network, including irrigation and drainage system, along with any natural watercourses, if they interact with the canal system or storage reservoirs. This method is aimed at getting information on when and where the water inflow and outflow occur, pertaining to the drain standard, volume, and distribution in terms of time. Such mapping could include all possible constructions, protecting from undesirable consequences. In other words, these constructions could be built for redundant water derivation into the drainage system. Possessing the precise data about all water flow directions could be important for both establishing high effectiveness and finding solutions of such ecological problems as saturation and increase in water mineralization. Consequently, due to mapping, the Hohokam canal system could become more protected from the damages caused by saturations and, thus, could save their structure for centuries.
Moreover, fortification of the canal walls with modern materials, such as concrete, could also prolong their operational period for many years. Canal cementation could also be rather beneficial in economic terms because canals would be less silted, and water losses in the canal through its absorption into the loosened soil could be also reduced significantly. Thus, if the Hohokam canal system was built today, it would be more mechanized and economically efficient. Besides, an automated canal system would require less labor and time expenditures.
Taking into account all the information mentioned above, it should be noted that North America became a cradle of several unique cultures, the most significant of which is Hohokam. People of Hohokam were the first ancient people about whom a lot of archaeological materials were collected, and the leading place in textbooks on archeology is allocated for them. Their system of irrigation canals became one of historical sites which glorified these people. Their canal system turned a desert into the fertile agricultural valleys and rich riparian corridors, supplying tens of thousands of people with water. Due to the fact that the Hohokam did not possess draft animals, this engineering miracle was constructed manually, using only simple survey equipment and stone and wooden tools. Nevertheless, the main principles of the canal construction are widely used in irrigation systems even today. Thus, the Hohokam canal system made a great contribution both to the development and prosperity of the Hohokam and the establishment of modern canal engineering. Such a great and majestic culture could not just disappear eventually without a trace. Possibly, other Indian tribes living in southwest states of the USA have also come from the Hohokam Indians - peaceful farmers, artisans and merchants.