Historians believe that the Mareb Dam, a symbol of the great Yemeni civilization, was built in several stages. Construction started around 1,000 BC, and was fully completed over the next 500 years during the reign of King Ali Yanouf Bin Dhamar Ali, whose name is inscribed on some of the dam's rocks. 

Extensive maintenance work was carried out whenever damage occurred, as indicated by rock inscriptions written in the Musnad alphabet. The first repair work was carried out at 100 BC by Yasser Yahanaam King of Sabaa, Dhu Raydan, Hadhramaut and Yemna. Other kings carried out more repairs. The last such renovation was done during the Ethiopian occupation of the country by Abraha Alashram (with a hare lip) in about 557AD. 

"Two Paradises"The Mareb Dam was 18 meters high, 700 meters long, and 20 meters thick. It stores enough water to irrigate farmlands with an area of 10,000 hectares. The area of the lake behind the dam is estimated to had been about 8 square kilometers with a storage capacity of about 55 million cubic meters. 
As mentioned in the Holy Quran, the lands on both sides of the dam prospered greatly and were called the "Two Paradises." Farmlands irrigated by water from the Mareb Dam were able to support 30,000 to 50,000 people. Farmers used to grow maze, millet, barley, sesame, lint, grapes, dates, etc. 

Final Collapse 
The collapse of the Mareb Dam was quite a momentous event with far-reaching consequences. The incident probably took place just before the emergence of Islam. What was once a green and pleasant land became desolate. Large waves of emigrants from Yemen flooded other parts of the Arabian Peninsula and beyond. 
Big Rat 
The Mareb Dam did not only become part of Yemeni mythology, but also entered Arab and Islamic lore. Legend has it that a prophecy by the people of Sabaa said the dam would be destroyed by a big rat. Therefore, cats were placed on every floodgate in the dam. However, a huge red rat with iron teeth and claws attacked one of the cats and started digging underneath the dam. The whole edifice then collapsed under pressure of the water stored behind it. 

Unique Site 
The ancient Mareb Dam was built in the Wadi Adana between the Northern and Central Balaq mountains. They form the last ridge of the eastern highlands before the desert between Mareb and Shabwa, where many wadis meet at Ramlat Al-Sabaatain. The place is ideal for holding rain water. Wadi Adana is the meeting point of the largest number of wadis in Yemen, making it the best place for a dam. 

How It Was Built 
It was imperative that the dam should be solidly built to withstand the force of torrential rain and flashfloods. The ancient Yemeni builders took optimal advantage of the topography of the place. 
The dam's foundation was dug into the bed of the valley until rocks appeared. A strong stone base was constructed at the bottom of the valley in a narrow straits to facilitate the opening of two floodgates leading into two irrigation channels on the sides. The wall of the dam was made of earth and covered with rock. 

Main Structures 
The Mareb Dam consisted of: 
- the main body or wall 
- two large floodgates on the dam's two sides 
- two irrigation channels emanated from the sides of the dam with a capacity of 60 cubic meter of water per second 
- a big network of small irrigation gutters leading into the surrounding farms and orchards of Wadi Abeeda. 
The purpose of the dam was not to store water for a long time, but to divert the flashfloods' course for irrigation. If the dam were built for holding water over a long period of time, its storage capacity would have decreased gradually due to the accumulation of silt, stones and deadwood. The amount of matter carried by flashfloods every year is estimated at 2.5 million cubic meters. 

Once Every Century! 
Silt, wood and stones accumulating behind the dam were cleared manually every century. That material was later used in construction work. 

Modern Mareb Dam 
A modern version of the Mareb Dam was built in the 1980s a few hundred meters above the location of the old dam. It is constructed up-river in Wadi Adana, with a water storage capacity of 400 million cubic meter. Sheikh Zayed Bin Sultan Aal Nahyan, President of the United Arab Emirates, financed the US$ 80 million project. However, the full potential of the dam has not been realized because the irrigation channels have not been built. 

By Ismail Al-Ghabiry, 
Yemen Times