A Guide to Innovations in Irrigation

Animal Skin Bags
Even before primitive man began practicing irrigation, he had devised various means by which to transport water from rivers, lakes and streams to his camps and primitive dwellings.
Because hunting was the principal means of survival, anthropologists believe that early man crafted the remains of his prey into increasingly more useful objects. Bones were shaped into crude tools, and hides were cut or tom and tied inio pouches for carrying food and water. Animal skin bags, like modern day canteens, carried the water needed for hunting outings which olten lasted several days. Sewn leather skin bags called "botas" are still used today to carry wine and other liquids.

Qanats

A qanat is a horizontal well that taps into a natural aquifer from which water is diverted to a desired destination. The first qanats were dug by hand sometime around 700 B.C. in the Middle East. A typical configuration consists of aseries of vertical shafts, usually originating on a mountainside or hillside, whose bases are joined by a tunnel. The tunnel eventually connects to a canal on the surface which carries water into farm lands or municipal water supplies. Qanats represented a milestone in irrigation technology, as a plentiful aquifer could yield a voluminous flow of water for several years. It is estimated that more than 30,000 qanats, some of which are several miles long, have been constructed in the Middle East. Many are still in operation today.

Animal power has been used for centuries to lift water from wells. The cerd, also called a mot, was developed in India. The device consists of a self-emptying animal skin bag connected to a rope and guided by a simple pulley. A har­nessed animal, usually an ox or camel, is used to raise the filled bag to the surface where it empties itself into a trough or canal. The animal is typically rewarded with food or water at the end of each lift. Depending on the water supply and the number of available animals, a cerd could irrigate areas up to several acres in size. The cerd was a considerable achievement in irrigation as it shifted the toil from man to beast.

The shaduf is one of the first mechanical water-lifting devices invented by man. Developed in ancient Egypt, it uses the prin­ciple of the lever to raise a vessel of water from a stream or well to an irrigation canal. A typical shaduf is comprised of a long pivoting pole with either a bucket or leather skin suspended from one end and a weight at the other end of the counterbalance the water being lifted. The operator manually pulls down the rope to lower the bucket into the water supply. When the bucket is filled, the rope is released and the counterweight causes the bucket to rise to the desired height. The pole is then pivoted on its support beam and the water is emptied into a canal or trough. An efficiently operated shaduf, many of which are still used today, can irrigate an area of about two acres.

The Pont du Gard aqueduct is one of the most impressive and best-preserved engineering feats of its time. The structure is more than 900 feet long and rises some 160 feet above the River Gard, 12 miles northeast of Nimes, France. Constructed under the direction of the Romans around 20 B.C., the aqueduct was precision-crafted of cut masonry. The top level of the two-tiered structure supported the enclosed water channel, and the lower tier served as a footbridge. Along with other aqueducts, which comprised a network running throughout the Roman Empire, the Pont du Gard project diverted vast amounts of water for irrigation and local municipal water systems. The concept of applying civil engineering to provide people with clean water was characteristic of the Roman Empire's innovative thinking and advanced technology.

Surface water channels were commonly found on the larger estates and villas of Roman noblemen. These small stone or brick-lined channels irrigated court yards and gardens. Grounds keepers controlled the flow of water through these low-volume irrigation networks by a series of small wooden dams which were opened and closed to divert water to desired locations. Fruit trees, vegetable gardens and various ornamental plants were regularly irrigated by surface water channels.

Introduced in the Middle East, the noria was the first selfpropelled water-lifting device invented by man. A major irrigation advancement of its time, the noria operated without the need for human supervision or animal power. Once installed, the noria steadily lifted water from its river or stream into a trough-day and night-as long as there was enough current to drive it. From time to time, the device's worn or damaged water collectors had to be replaced. Built in configurations up to 75 feet in diameter, noria were also used in conjunction with sophisticated networks of aque­ducts. The noria continues to serve as an important irrigation machine in Asia and many other parts of the world.

The saqia is another irrigation innovation developed by the Egyptians. It is powered by a large animal, usually an ox or camel, yoked to the end of a horizontal beam. Also called the "Persian Wheel," the device utilizes a horizontal, toothed wheel which turns a smaller vertical wheel having compartments or buckets lor lifting water Irom rivers or wells. The compart­ments attached to the vertical wheel disgorged their water near the top of the wheel's arc, where the water flowed into a trough or a canalleading into a cultivated lield. A saqia of average size with a constant water supply could irrigate an area of live to 12 acres.

The Twin Comet, offered for sale in 1897, was among the first gear-driven lawn sprinklers to be mass produced. Developed by E. Stebbins Manufacturing Company, Springfield, Massachu­setts, this innovative irrigation product featured three revolving sprinkler arms and a hose nozzle. When water pressure permitted, the sprinkler's hose nozzle could send a stream of water distances of up to 80 feet. A perfo­rated disc was available as an option al accessory. The disc was designed to produce a light spray or mist when attached at the center of the revolving arms. The fully-assembled sprinkler stood 17 inches high, weighed six pounds, and cost about $5. With the exception of the legs, all parts were solid brass

Orton H. Englehart revolutionized landscape irrigation in the 1930s when he invented the horizontal impact sprinkler. His innovative design had fewer moving parts than most other sprinklers of the time, making it more dependable and less expensive. The impact sprinkler gets its name from the spring-loaded, horizontal rod which causes the device to rotate slowly and incrementally as it repeatedly "impacts" with the stream of water emitted by the nozzle. The rights to Englehart's patented, impact sprinkler were acquired by the Rain Bird Company of Glendora, California, which has become the world's most famous manufacturer of impact sprinklers.

Crop Cultivation & The Beginning of Irrigation

During the period between 7,000 and 5,000 B.C., nomadic tribes settled in the fertile valleys between the Tigris and Euphrates rivers in the Middle East, and man's way of life began to shift! from hunting and gathering to farming and herding. The area's abundance of clean water, grazing wildlife, and thriving vegetation provided an ideal culture for what would later become the flourishing civilization of Mesopotamia. Wheat and barley were among the main staples of this first agrarian society. The soil was cultivated and irrigated by manpower. These early farmers furrowed the earth with hand tools and carried water from the nearby rivers. One of the first innovations in irrigation was a pole with yokes, made from reeds or animal hide, attached to both ends. This simple device enabled irrigators to transport two clay vessels of water into the field each trip.

Early Irrigation Vessels

Early irrigators used a wide variety of hand-made clay pots and buckets to transport water into their fields and dwellings. Yoke buckets (a), which originated in ancient Egypt, were designed to be carried in yokes attached to both ends of a pole five to six feet in length. The device was borne on the neck and shoulders and carried into the fields. The hydria (b) is vessel of Greek origin used primarily by women.1t was filled at a nearby spring or river and carried home resting atop of the head. It is characterized by its elliptical shape, narrow opening and handle. Glay watering pots (c) were used in Medieval Europe to irrigate vegetable and flower gardens. This particular pot was designed with a sprinkler plate at the bottom. A finger placed over a hole in the top of the pot could stop or allow the flow of water as needed. 

Invented by Greek physicist Archimedes about 200 B.C., the water screw is still used in many parts of the world to raise water from rivers and canals. Designed primarily for irrigation, the device was also employed to supply water to municipal and private water storage systems. A typical water screw is approximately 12 to 16 feet long with a diameter of about !wo feet. The device is fixed at both ends by rods seated in vertical support beams; the lower end of the water screw is immersed in water. When rotated, at first by treading and later by cranks, the spiral inner vane propels water up and out the opening at the upper end. The volume of water dis­charged tends to decrease as the angle of inclination becomes more vertical. The water screw is generally used for relatively low lifts of about one to four feet. This ingenious innovation, however, is still used in many parts of the world to irrigate small cultivated areas.

Several tiers supporting two or more shadufs were common along the banks of major waterways such as the Nile River. The tiers, each having its own trough, were carved out of the hillside enabling water to be lifted in increments to irrigation canals several feet above the river level. The shaduf operators, with the aid of the pole's counterweight, lifted the filled buckets to about waist high, then swung the poles and emptied the buckets into the trough of the next tier. Approxi­mately 600 gallons of water per man, per day could be hoisted in this fashion and channeled to nearby farm lands.

Rome's first aqueduct, the Aqua Appia, consisted of an underground tunnel 10 miles in length most of which extended down ward on a slight grade. Its main tunnels were lined with block and mortar to prevent leakage. The Aqua Appia, and similar aqueducts, were built underground to reduce the amount of water lost to evaporation and to protect against water theft. Constructing the aqueduct through hilly areas required the digging of vertical shafts, at regular intervals similar to the qanats of the Middle East. The bases of each shaft were then connected by tunneling. Where necessary, bridges were built to enable the aqueduct to cross rivers and deep depressions. Within a bridge configuration, the Aqua Appia took the shape of a rectangular, blockformed pipe approximately four feet wide and six feet high. Aqueducts contributed immensely to man's ability to irrigate increasingly larger cultivated areas and park lands.

The flood hatch was a signifi­cant innovation in irrigation. With the aid of ropes and pulleys, irri­gators could regulate the water flow in one or several canals from a remote location. Originally designed for small-scale irrigation, such as private farms and orchards, wooden flood hatches were later employed in larger irrigation systems.

A primitive device lor lifting water from wells, the tread wheel bucket chain was utilized throughout the Roman Empire and in the Middle East around 50 A.D. The machine's chief components were a string or chain of wood or leather containers suspended from a drive wheel, which was rotated by one or more men treading inside a con­nected, enclosed cylinder. The tread wheel cylinder typically included a hinged access door and perforations around its circumference to enhance ventilation. The buckets were filled at the bottom of the chain's loop which was continuously being immersed in the well. At the top of the loop, the buckets emptied into a catch basin or conduit from which water was directed to irrigation canals.

The piston pump was invented by the Greek engineer Ctesi­bius around 170 B.C. Modified versions of the pump were later put to use by the Romans for irrigating small parcels. A two-cylinder piston pump, made possible by clapper valves which were already used in the bellows of ironworkers, was introduced in 18th century Europe. Water is drawn by suction into the pump's cylinders through one-way clapper valves. The water is then forced out of the cylinders and into a delivery pipe by the down ward stroke of the pistons which, in this particular pump, were driven by a man rocking from side to side on a beam. Early piston pumps were used for irrigation and to replenish municipal water supplies.

Pop-up sprinklers represent an important advancement in irrigation technology. When not in use, these innovative sprinklers remain either at or below ground level and out the way of lawncare equipment. When activated, however, water pressure causes a riser-tube to "pop up" several inches above ground level allowing the sprinkler's nozzle to emit its spray without interference from surrounding grass and thatch. The earliest pop-up sprinklers, introduced in the 1930s, were fixed-spray sprinklers made of brass because of the metal's resistance to corrosion. Today, "pop-up" sprinklers are the industry standard for most large turf area applications.

In 1963 a U.S. patent was issued to Edwin J. Hunter, founder of Hunter Industries, for the first rotary pop-up sprinkler with plastic internal gears. This development, now a standard in the industry, marked the beginning of a new era of irrigation during which water conservation became an important issue. The plastic componentry of this innovative sprinkler operated on less water pressure than the old-style impact sprinklers, offering a significant reduction of water consumption. In addition, the plastic gear-drive design is self lubricating and more resis­tant to corrosion than brass. Quiet operation and ease of instal­lation contributed to the industry's widespread acceptance of plastic gear-driven sprinklers. Ed Hunter's commitment to the irrigation industry and water conservation has resulted in a full range of top-quality irrigation products for residential and commercial use. He holds more than 150 patents, and his company is a major manufacturer of irrigation products sold throughout the world. Hunter Industries continues to locus its research and development efforts on low ­pressure, low precipitation-rate irrigation systems that save water and reduce operating costs.