First Largest Masonry Dam in the World

Which is the First Largest Masonry Dam in the World?

The ‘Jawa Dam’ in Jordan is an ancient masonry dam built around 3000 BC. It is the oldest known dam in the world and the largest of its kind. Though, the dam is damaged now due to human intervention; its remnants still remain to testify one of the worlds’s first engineering wonders and a structural feat of its time. The dam was one of the largest water conservation projects of its time in what was then called ‘Mesopotamia’.

It was a masonry gravity dam at the upstream side, wall of which was reinforced with stones on back to provide additional strength against the hydraulic pressure; a constructional marvel ahead of its time. The dam was the largest among the number of dams built in and around the city of Jawa to support its agricultural and settlement requirements.

Location of ‘Jawa Dam’

The ramparts of the dam are located at Jawa in Jordan- an Arab country in Western Asia. Jordan is located on the east bank of the Jordan River. The Jawa Dam lies 90 kilometers east to the city of Al-Mafraq; which is also a military town of Jordan and around 25 km North East to the city of Safawi. Al- Mafraq lies on National Highway 10 connecting the capital of Jordan- Amman to Baghdad.

The Jawa Dam is located at the mouth of a valley or ravine known as ‘Wadi Rajil’ (in local dialects a ravine or valley is called as Wadi). There is no paved road to approach the dam and the site of dam is close to the border with Syria.

No other place could have been better for the location of Jawa Dam than the mouth of Wadi Rajil in an area surrounded by arid desert and warmer winters. The location of the dam has an advantage as the water running down from the north east lying hills gets collected into the dam’s reserve to serve the dry and water scarce Jawa planes.

The Details of Construction

Jawa Dam is a gravity masonry dam built by masonry using its weight to balance against the pressure of reservoir water. The construction of the dam had two masonry walls of mainly Basalt rocks in filled with sand and ash and also used revetments to support the reservoir side of the wall from behind to withstand the hydraulic pressure; a constructional marvel ahead of its time. The dam was an attempt to divert water from Rajil River (a.k.a Wadi Rajil) which flooded during rains; to a reservoir.

The dam was a part of a number of dams and canals built to harness most of the water of the Rajil River and also to collect surface run off during rains. Maximum height of the dam is 4.5 mtr (15 ft) and a length of 80 mtr (260 ft).The width of the dam at base is around 5 mtrs. The total capacity of the Jawa Dam reservoir is 31000 cubic meter.

The Need for the Dam

Wadi Rajil remained dry throughout the year except in rains; when the river got flooded unusually. The river has a catchment area of 300 sq km. It has a huge annual flow during rains of about 2000000 cubic meter/year (2 million cubic meter/year). Such huge amount of water flow resulted in sporadic and destructive flash floods in Jawa, pressing an urgent need to harness the river as well as the runoff water during the rains. The flow of floods ranges from 80-110 cubic meter/second.

 

The town of Jawa was built by nearly 2000-5000 migrants coming from North East. They had some knowledge of hydrology and as well as urban life. The settlement extended over 100000 sq mtr. The flood waters of Rajil as well as surface runoff from the hills lying north east of Jawa had huge potential to meet the water requirements of the Jawa settlement with approximately 5000 inhabitants. The migrants coming from North East would have had to tame the water of Rajil if they had to survive next dry seasons.

This need was the root cause for the construction of world’s first and largest masonry dam. It is researched that if the people of Jawa could have harnessed only 3% of the total flow of 2000000 cubic meter/year; the population and their herds of sheep, goats and cattle can easily make it through the harsh dry seasons. According to the estimates there were around 10000 sheep and goats and 800 cattle with hundreds of horses and dogs.

The water stored in the reservoir was deflected through a network of channels and canals for irrigation as well as domestic use. The water from the reservoir was also used for the irrigation purpose for producing crops like- wheat, chickpeas, barley, lentils and grapes.

The Jawa Water Supply System

The Jawa Dam was a part of a series of dams and canals build to deflect and conserve water from the ‘Wadi’ or valley into a series of reservoirs. The Jawa Dam was the largest of these dams and was having the largest reservoir. The Jawa water supply system was used to deflect water from Rajil River as well as surface run off during rain by using canals and channels especially built for the purpose.

In the valley of Rajil there are remnants of three dams near the settlement of Jawa, two of which were deflection dams; meant to deflect water into the reservoirs. The third of them which was built to block the flow of flood couldn’t survive to see the next season. The other two dams served the people of Jawa for hardly one generation.

The first dam was built to divert the water of Rajil to depressions lying west to the settlement; but, the feat was never accomplished as the dam didn’t withstand the flood long enough. Researchers have speculated that if the dam had withstood the flood for a little longer; some amount of water would have been diverted to the depressions.

Also the rainfall occurring on small catchment area was diverted to the reservoirs through a network of primitive canals.

 

Human Intervention

The Jawa Dam has been fascinating archeologists and researchers from across the world and had always been a location for researches and studies. It is the largest and the oldest water conservation project ever known. It will always be looked upon as the symbol of development of large scale water projects in the world. The Jawa Dam was recently damaged due to an attempt to reconstruct it using cement; it failed to hold water by damaging the dam. Such attempts should never have been permitted without proper studying of their effects and outcomes.

FAQs about Jawa Dam

Q1) Which is the world’s first and largest masonry dam?

Ans- The world’s first known and possibly the largest masonry dam of its time is the ‘Jawa Dam’, Jordan.

Q2) In which country is the ‘Jawa Dam’ located?

Ans- It is located in the Western Asia’s Arab country of Jordan. 90 km east to the town of al-Mafraq.

Q3) When was the dam built?

Ans- The dam was built around 3000 BC.

Q4) Which river flows through Jordan?

Ans- Jordan River flows through Jordan, which got its name from the river.

Q5) How far is the site of Jawa Dam from the town of Al-Mafraq?

Ans- 90 kilometers east to the town of Al-Mafraq.

Q6) On the mouth of which valley was the town of Jawa and the dam located?

Ans- On the mouth of ‘Wadi Razil’ or Razil valley.

Q7) To which international border is the site nearer?

Ans- The site is near to the border with Syria.

Q8) What kind of dam was Jawa Dam?

Ans- The Jawa Dam was a gravity masonry dam.

Q9) How many masonry walls does the Jawa Dam had?

Ans- Two masonry walls with an earth core of thickness 2 meters.

Q10) What was the maximum height of the Jawa Dam?

Ans- Maximum height of the Jawa Dam was 4.5 meters (15 ft).

Q11) What is the length of the Dam?

Ans- The length of the dam was 80 meters (260 ft).

Q12) What is the width of the dam at base?

Ans- The width of the dam at base was approximately 5 meters.

Q13) How much was the total reservoir capacity of the Jawa Dam?

Ans- Total reservoir capacity of the dam was 31000 cubic meters.

Q14) What is the catchment area of Wadi Rajil?

Ans- Catchment area of Wadi Rajil is 300 sq km.

Q15) What was the average annual flow of Rajil River?

Ans- Average annual flow of Rajil is 2000000 cubic meter/year.

Q16) What was the average flood flow of Rajil River?

Ans- Average flood flow of Rajil is 80-100 cubic meter/second.

Q17) Who built the town of Jawa?

Ans- Migrants from north-east.

Q18) What was the approx. human count of the town of Jawa?

Ans- Ranging from 2000 to 5000.

Q19) How much livestock were the part of the settlements?

Ans- Nearly 10000 sheeps and goats, 800 cattle along with hundreds of dogs and horses.

Q20) What was the area of the settlement?

Ans- The area of the settlement was around 100000 square meters.

Q21) How was the water collected in the reservoir and deflected?

Ans- Through a network of channels and small water collection points.

Q22) Name few crops/cereals grown by the people of Jawa?

Ans- Wheat, chickpeas, barley, lentils and grapes.

Q23) How many dams were built in the Rajil valley?

Ans- Three dams.

Q24) What was the purpose of third dam built?

Ans- To stop the flood water directly.

Q24) How long did the two other dams last?

Ans- They served hardly one full generation.

Q25) How were the ramparts of the dam further damaged recently?

Ans- By attempts of local authorities to reconstruct it using cement additions.

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