Question

Hydraulics & Hydrology

Problem Statement

The Romans were exquisite water engineers, and that without having at their disposal the modern tools and the knowledge we have today. Remember that Hydraulics and Hydrology as we know it now only came to be in the 1700’ when engineers started to put a fundamental framework together that is/was based on lab experiments and theoretical approaches and principles. Until then, you just “knew”. The Romans build all sorts of hydraulic systems, from irrigation canals, to water supply infrastructure, to the famed “hot baths” of Rome, to sewer systems, you name it. They realized that if you want water for different purposes at locations that were important to you that very often you had to get the water there because it just was not available in close proximity.

One of the marvelous feats they accomplished was to build water supply systems that would run over dozens of miles to convey water from sources to locations of need, typically the towns and cities they founded in their vast empire. They managed to do so by building a lot of infrastructure that withstood time and that, almost 2000 years later, is still in place for us to marvel at. Especially the many bridges that were built to cross valleys and gorges to keep the supply line flowing as an open channel are spectacular in their construction, such as the Pont du Gard, Segovia, and Aquila aqueducts.

Task:

1. Create a small inventory of the 5 most prominent and well-known aqueducts around to this day (you make a decision on what the criteria are for the selection of the 5). Come up with some describing parameters (for sure show an image or two) such as location, total length, capacity, year of built, special features, how many bridges, building materials, etc. Be creative and decide on your own what you want to tell about them.

2. Pick one of them and carry out a hydraulic analysis. I am interested here in typical characteristics such as discharge capacity, slopes, cross sections, but also operation: how did you get the water into the aqueduct, control structures, terminal end structures, Manning’s “n”, ... But also how they were lined, how gaps between construction elements were sealed so no seepage (or losses) would occur. It would also be great if you could treat the aqueduct as a chain of: uniform, rapidly (around controls), and gradually varied flow sections. Carry out a few analyses steps and report on what happens to energy and friction grade lines in these sections, preferably of the entire length of the aqueduct.

Answer 1

5 most prominent and well-known aqueducts

Magdeburg Water Bridge, Germany:

This is the world longest navigable aqueduct with total length of 918 m. The project was started in more than a hundred years ago, in 1905, but it was stopped in 1942 due to WWII. During the Cold War all works on the water bridge were “frozen” and the building process was restored 55 years later, in 1997. After 6 years, 24 000 tons of steel and 68 000 tons of concrete, the aqueduct started operations in 2003. Since then it crosses over the Elbe River and connects the Elbe-Havel Canal to the Mittellandkanal, reducing more than 12 km (7.5 miles) of the distance passed by trading and passenger vessels.

Veluwemeer Aqueduct, Netherlands:

Open since 2002, the Veluwemeer Aqueduct is a stunning work of architecture and engineering. This waterway measures up at a short 25 meters long by 19 meters wide and is located in Harderwijk, Eastern Netherlands. During the design of this unique passage, engineers chose to construct the waterway over the N302 road, where 28,000 vehicles pass each day.While this structure does not set any records, it does stand as one of the shortest aqueducts in the world. Typically thought of as tunnels or bridges used in water supply and irrigation, there is another subset to the aqueduct realm. Navigable Aqueducts, like Veluwemeer, include land bridges and other passages that allow for boat and barge traffic.

Catskill Aqueduct

Construction commenced in 1907. The aqueduct proper was completed in 1916 and the entire Catskill Aqueduct system including three dams and 67 shafts was completed in 1924. The total cost of the aqueduct system was $177 million ($2.4 billion in 2015 dollars).The 92-mile (148 km) aqueduct consists of 55 miles (89 km) of cut and cover aqueduct, over 14 miles (23 km) of grade tunnel, 17 miles (27 km) of pressure tunnel, and nine miles (10 km) of steel siphon. The 67 shafts sunk for various purposes on the aqueduct and City Tunnel vary in depth from 174 to 1,187 feet (362 m). Water flows by gravity through the aqueduct at a rate of about 4 feet per second (1.2 m/s).

The Catskill Aqueduct has an operational capacity of about 550 million US gallons (2,100,000 m3) per day north of the Kensico Reservoir in Valhalla, New York. Capacity in the section of the aqueduct south of Kensico Reservoir to the Hillview Reservoir in Yonkers, New York is 880 million US gallons (3,300,000 m3) per day. The aqueduct normally operates well below capacity with daily averages around 350–400 million US gallons (1,500,000 m3) of water per day. About 40% of New York City's water supply flows through the Catskill Aqueduct.

Colorado River Aqueduct

Stretching 242 miles from the Colorado River on the California-Arizona border to its final holding reservoir near Riverside, California, the Colorado River Aqueduct consists of more than 90 miles of tunnels, nearly 55 miles of cut-and-cover conduit, almost 30 miles of siphons, and five pumping stations. Supplying approximately 1.2 million acre-feet of water a year - more than a billion gallons a day - it helped make possible the phenomenal growth of Los Angeles, San Diego, and surrounding Southern California areas in the second half of the 20th century.

Funded by a bond issue of $220 million approved by voters in 1931, the Colorado River Aqueduct is capable of lifting more than 1,600 cubic feet of water per second to a static height of 1,600 feet as it travels over several desert mountain ranges. Recognizing the project's unprecedented length, cost, pumping rate, lift, and severe climate and terrain, the American Society of Civil Engineers in 1955 selected it as one of Seven Modern Civil Engineering Wonders.

Central Arizona Project

The Central Arizona Project (CAP) is a 336 mi (541 km) diversion canal in Arizona in the United States. The aqueduct diverts water from the Colorado River from the Bill Williams Wildlife Refuge south portion of Lake Havasu near Parker into central and southern Arizona. CAP is managed and operated by the Central Arizona Water Conservation District (CAWCD).[It was shepherded through Congress by Carl Hayden.

The CAP delivers Colorado River water, either directly or by exchange, into central and Southern Arizona. The project was envisioned to provide water to nearly one million acres (405,000 hectares) of irrigated agricultural land areas in Maricopa, Pinal, and Pima counties, as well as municipal water for several Arizona communities, including the metropolitan areas of Phoenix and Tucson. Authorization also was included for development of facilities to deliver water to Catron, Hidalgo, and Grant counties in New Mexico, but these facilities have not been constructed because of cost considerations, a lack of demand for the water, lack of repayment capability by the users, and environmental constraints. In addition to its water supply benefits, the project also provides substantial benefits from flood control, outdoor recreation, fish and wildlife conservation, and sediment control. The project was subdivided, for administration and construction purposes, into the Granite Reef, Orme, Salt-Gila, Gila River, Tucson, Indian Distribution, and Colorado River divisions. During project construction, the Orme Division was re-formulated and renamed the Regulatory Storage Division. Upon completion, the Granite Reef Division was renamed the Hayden-Rhodes Aqueduct, and the Salt-Gila Division was renamed the Fannin-McFarland Aqueduct.

The canal loses approximately 16,000 acre-feet (5.2 billion gallons) of water each year to evaporation, a figure that will only increase as temperatures rise. It loses 9,000 acre-feet (2.9 billion gallons) annually from water seeping or leaking through the concrete.

In modern civil engineering projects, detailed study and analysis of open channel flow is commonly required to support flood control, irrigation systems, and large water supply systems when an aqueduct rather than a pipeline is the preferred solution. The aqueduct is a simple way to get water to other ends of a field.

In the past, aqueducts often had channels made of dirt or other porous materials. Significant amounts of water were lost through such unlined aqueducts. As water gets increasingly scarce, these canals are being lined with concrete, polymers, or impermeable soil. In some cases, a new aqueduct is built alongside the old one because the water supply cannot be shut down during construction.