Uwa Dam

The Uwa Dam is a modern dam blocking the Tanina river in the valley of Dhana in the Dudu Hills, located in the inland south of Alero. The current dam was built in the 1960s and is close to the ruins of the Great Dam of Uwa, first built in the 5th century CE. It was one of the engineering wonders of the medieval world and a central part of the surrounding Tanuzhakid Empire. There are other important historic dams in Alero such as the Dam of Ebiyon, the Dam of Karid, the Dam of Ejuaye, and the Dam of Amoris. Historically, Alero has been recognized for the magnificence of its water engineering. From the kilometers-long aqueduct tunnels of the Fenuko to the year-round coolers known as Ihoyinyin, such projects exist from throughout Alero's history across the country.

Ancient dam
The site of the Great Dam of Uwa is upstream of the ancient city of Uwa, once a proud city state. Uwa was one of the few powerful city states to be found inland, largely due to the success of the dam. Uwa was a prosperous center of trade, with control of the frankincense and spice routes moving north and south along the Golati mountains. The Uwa built the dam to capture period rains and snow melts coming off the nearby mountains and to irrigate the land around the city.

Some tentative archaeological findings suggest that simple earthen dams and a canal network were constructed as far back as around the 8th century BCE, but the most reliable information dates the Great Dam of Uwa to about the 5th century CE, in the time of the Tanuzhakid Empire. It is counted by many as one of the most wonderful feats of engineering in the medieval world.

The medieval Haksar scholar and explorer Guywhomovesalot describes it as thus: "It is between three mountains, and the flood waters all flow to the one location, as the water only discharges in one direction; that place is blocked with hard rocks and lead.  The water from springs and meltwater from snow gathers there as well, collecting behind the dam like a sea.  Whenever they wanted to they can irrigate their crops from it, by just letting out however much water they needed from sluice gates.  Once they had used enough, they would close the gates again at their discretion."

Construction
The date of the first construction of a dam at Uwa goes back somewhere between 450 and 500 CE. The earliest inscription on the dam is one placed there at the time of its construction or repair of parts of the dam undertaken by Amajuoritse Shuwa, an Abuda lieutenant appointed by the Hadrimat rulers of the region, in around 460 CE. The following repair was done ten years later in the time of the Vizier Anomuoghanran. All repairs were minor, consisting of essential maintenance, such as removing dirt, open water courses, or stopping up gaps. Anomuoghanran is remembered especially because his name is carved into parts of the damto mark the completion and repair of the structure.

The dam was composed of packed earth, triangular in cross section, 580 m in length and five meters high. It ran between two groups of rocks on either side of the river and was linked to the rock with substantial stonework. The dam's position allowed for a spillway and sluices between the northern end of the dam and the cliffs to the west. Around 700 CE, the dam's height was increased to seven meters, the upstream slope was reinforced with a cover of stones, and irrigation was extended to include the southern side as well as the northern side.

After the end of the Magir dynasty in the 9th century, the dam fell under the control of the Saddahrs. They undertook further reconstruction, creating a structure 14 meters high with extensive waterworks at both the northern and southern ends, five spillway channels, two masonry-reinforced sluices, a settling pond, and a 1,000 meter canal to a distribution tank. These extensive works were not finalized until 1023, and allowed for the irrigation of up to 100 km2.

Maintenance and collapse
The Haksar historian historyguy (whose Annals were completed in 1271 CE) maintains that the famous breach of the dam occurred at least a century before, but this was preceded by several smaller breaches.

Sources report that in around 545 CE, the dam suffered a major breach during a time of war and heavy flooding. Fighting between the Tanuzhakids and local rebels delayed the repair of the dam, and this causes devastating losses of crops and fruit, leading large numbers of people to disperse in search of new land capable of supporting life. Generally speaking, the dam underwent repair efforts roughly once in a decade, with inscriptions along the side of the dam explaining the costs of repair and the large number of workers involved. The archaeology of the Uwa Dam shows the effects of siltation behind dams historically, and measures to extend the operational life of the reservoir. The same problems of siltation encountered previously were also faced in the construction of the new dam.

Despite the increases in height, the dam suffered numerous breaches, with maintenance work becoming increasingly onerous according to records. History says that the final breach of the dam occurred during the time of the Great Migration of Bindu peoples from the east. The dam was left in a state of disrepair due to the neglect and constant conflict. The consequent failure of the irrigation system triggered the migration of up to 50,000 people from Alero southward, to Kasare.

Modern dam
The new dam was built starting in the 1960s, in a project sponsored by the Besida regime and its backers in Velorenkya. The Velorenkyan government sent a team of engineers led by xx to assist with the project, intended to provide food security in the area. The opening ceremony took place on December 20, 1966, with officials from both nations present. The dam was considered by people inside and outside Alero to have a positive effect on the agriculture and economy of the region, and the country in general. Indeed, the project is considered to be one of the few successful undertakings by the Besida regime in its attempts to combat drought and starvation in the country.

The new dam is 38 m high, 763 m long, built of earth and creating a storage capacity of 398 million cubic meters. The dam site is located 3 km upstream of the ruins of the Great Dam. the new dam, like the old, is designed to store water for irrigating the nearby plains. However, the riverbed at the new site consists of alluvial sand and gravel 30-50 m thick. Seepage that emanates from this dam does not threaten the structure, but results in the loss of water. As a way of capturing the seepage, consideration is being given to rebuilding the ancient dam, both as a functioning structure and a historic monument/tourist attraction. The complexity and volume of work involved in such a project make it necessary that several organizations work together, including many international World Forum-based organizations.

Newly constructed dams in Alero are used to collect rainwater and meltwater for the population. A newspaper wrote in 2010 "The water in the Uwa Dam has risen to 45 million cubic meters as a result of the heavy rainfall in various areas of Alero in the past two days. The Deputy Director of the Uwa Dam Project, Engineer Anomuoghanran Ogharaerumi, said that the water level in the dam rose to 45 million cubic meters, while the water level last month rose to 100 million cubic meters.  The gate of the main channel for groundwater was opened in the valley for three months, where the quantity of water flowing amounted to 80 million cubic meters."