Archaeological discoveries unveil advanced water supply system in Ancient Gerasa

AMMAN — The bedrock was cut and used as an integral part of the water supply system in ancient Gerasa. More precisely it was the case with the south-western part of Gerasa. The water supply system contains from cisterns that were opened to basin, which was fed through the hole.

This drain is cut into the bedrock and would have supplied water from a feature located farther to the west. 

Further cuts in the bedrock are found both south and north of the cistern and appear to be of a similar type as the basin, implying a series of water related and possibly interconnected features, said Professor Louise Blanke from the University of Edinburgh.

"The plateau that surrounds the area of bedrock cuts contains no evidence of tumbled stones or other structural collapse. This situation resulted from later use of the area, as plough marks document past cultivation, while improvised football goals reveal the area’s most recent use," Blanke explained.

The professor added that both activities require a flat, cleared area, meaning that collapsed building material was removed for a purpose. 

A brief examination of the immediate vicinity explains the current lack of tumble stones and the cistern for example, contains a large number of stones, which were not a result of natural collapse, but rather, because the area provided a convenient and easily accessible dumping ground. 

Similarly, Area A is covered in loose tumble, which clearly does not originate from the collapse of the building, she said, adding that area C is defined on the western and southern sides by long straight bedrock cuts that join at a 90 degree angle. 

The southern cut can be traced over a distance of 19 metres, after which it disappears below an area of dumped soil.

"Combining this archaeological evidence would suggest that Area C was a reservoir intended for the collection and further distribution of water towards [at least] the north and east."

"The sources of water have not been identified to date, but the reservoir could likely have been fed by a combination of rainwater and water from sources that lie beyond the walls of Jerash," Blanke highlighted.

Water from these sources would have been led through channels in the western city wall to be collected and further distributed here, the scholar noted, adding that this solution resembles the water supply from nearby Birkate in that was delivered through a channel in the northern part of the town wall. 

There are no architectural remains to indicate that the reservoir was once spanned by a roof. 

"Alternative water supply strategies can be in the contemporary Decapolis towns of Gadara and Abila, where water was carried through extensive systems comprising a combination of channels that were cut into bedrock and subterranean aqueducts. A total of nine cisterns have been identified in the survey area," Blanke underlined.

"All but two of these are located on, or in the immediate surroundings of the hilltop," Blanke underlined, adding that the largest found cistern at the moment is located about 50 metres south of Area C and is immediately recognisable by the barbed wire that has been piled on top of the opening to repel thrill-seeking visitors.

“This cistern has a large square opening with straight plastered walls that extend for about two metres before it expands in all directions,” Blanke elaborated, noting that the depth of the cistern is at least 7.5 metres. 

"This variety of forms may result from functional considerations – whether the specific cistern served a communal purpose or was storing water for an individual household – or from variations in the dates of construction. It is likely that it was common practice that new structures in Jerash included a cistern to supply the individual building or household and its associated activities," Blanke underscored.