The opening and closing of Zayandehrud (Zayandeh River) has upset the balance of its historical bridges
The historical bridges of Isfahan have reached their balance during the few hundred years of their life; opening and closing of Zayandeh water flow at short intervals has disturbed the hydraulic balance of these structures and is considered a significant risk for its survival.
Ali Mohammad Fasihi, who is in charge of monitoring the historical bridges of Isfahan, told ISNA: “Zayandehrud has always been a permanent river, but in the last two decades, with opening and closing of the water flow it has lost its permanency”. For the first time in a new decision, this year, in 45 days, the water was opened and closed four times, which, contrary to some estimates, the reopening of the water in a short period, endangers the life of the historical bridges.
Explaining that the life of historical structures and bridges mounted on the Zayandehrud River is directly related to the water of the river, he continued: “We may see the Zayandeh River dry in some periods, by looking at historic photographs, but we should keep in mind that this river has never been completely dry for a long time and in the course of many years. If today it is assumed that the Zayandehrud can only be considered an agricultural water supply canal, such a decision raises the possibility of severe damage to historic structures.
This official of the court of justice, and expert in the field of historical structures, pointed out that the opening and closing of water in a short period of time will cause shock to the historical bridges, and reminded: “Our historical bridges have reached a dynamic balance during their span of life. This dynamic alignment is achieved because the structures have adapted to their existing conditions during the past few hundred years. Now, this balance and adaptability are disturbed by new situation imposed on them, and the structures are now subjected to shock and hydraulic pressure. In this regard, we can take the example of glass or even brick, which sees constant heat and cold in a short period, and will undoubtedly be damaged. Water also penetrates the structure due to its properties. Since the establishment of brick is also receptive to this water, then when water flows for a while and then this flow is interrupted, and this process is repeated several times in a limited period, the phenomenon of expansion and contraction occurs, and when the structure cannot adjust to the new situation, will suffer serious damages.
In response to what should be done to prevent such damage, given the current conditions and challenges of the Zayandehrood River, Fasihi said: “The issue of water is a threat to some historical structures and an opportunity to others.” In research and pathology of structures, we find that some are hydrophobic and water-repellent. Bridges and reservoirs are also waterproof, and water is welcome for these structures. On the other hand, there are two issues about structures and Zayandehrood water. First, the cultural landscape and then the hydraulic balance. If the Meymand or Bam citadel was registered globally, it was because of this cultural perspective. Part of the cultural landscape of bridges and rivers is water, and it cannot be imagined without water, or let part of this landscape be destroyed. Now, let’s consider the effect of water on the bridges as a factor. The discussion of the river’s life and the aquifer’s nutrition is another issue that contributes to the alignment of all structures and, ultimately, the preservation of a city. But, how to prevent such damage to the bridges in the current situation; let us say that the water has to be opened and closed regularly, in a short time, and there is not other way. In this case it is better not to cut off the water completely. The river bed should not be completely dry, and water should flow. There is a minimum of essential support for the structures, which I do not think is impossible.