معرفي گوشه اي از معماري ناشناخته ايران: ساختمان آب انبارها

Introducing some Aspects of Iranian Vernacular Architecture: Construction of Ab- anbar or Underground Cistern

A large part of central Iran is in hot arid zone. Living in these areas depends on existence of water. In order to keep water in an Iranian city or a village, different ways have been adopted. Iranian people have used an important architectural element which is called ab-anbar. Ab-anbar or underground cis- tern is a place to keep water for different users in a settlement during hot seasons. We can depict an overall picture of their building elements. Generally, all ab-anbars consist of tanks or cistern, dome or vault, steps, and badgir or wind-catchers. In most ab-anbars, access to water is provided by a long staircase with a steep slop reaching the tank. There is "pashir" (small underground hall) at the end of the staircase in which a bronze tap is arranged to take from cistern which is a water reservation tank located deeply under the ground. The vaulted covering on top of the tank holds wind-catchers which ventilate the area and make the drinking water cool. The main aim of this paper is to concentrate on structural elements of ab-anbar. This building must be built very precisely. Any mistake means leak- ing water which is so vital for habitants. We can consider constructional methods for different elements such as roofing, tank, staircase and wind-catchers. The first section of the paper is devoted to materials used for construction of ab-anbar. Different materials are used such as brick, stone, gypsum mortal and some composition of lime mortar. Application of these materials is very crucial in maintaining water in the tank. Covering the cistern is a useful act to prevent water evaporation contamination and warming. In Iran, the most common type of roof is the vault and in central parts of Iran, due to shortage of timber materials vaults are common. Another reason for superiority of vaults over timber roofs is the weakness of the latter against dampness. Furthermore, penetration of insects and small animals in wood fabrics may contaminate water resources. In addition due to the fact that it was not possible to repair and control ab-anbars continuously their covering structures need firmness and durability. Types of vaults in each place are different on the basis of typology of ab-anbars and what determines the type of each covering in different places is the type of the tank plan. In ab-anbars with circular cistern plan domes are also located on circular surfaces without using squinches. In the cases of sizeable rectangular tank plans the main solution is application of domes. Different vaults are used for small rectangular tanks. For columned plans various vaults have been used like crossed vaults, small domes and barrel vaults. Cisterns are containers for water reservation. Water reservation idea is materialized by the tank construction and performance. In order to access water in ab-anbars we can identify two methods in different parts of Iran. Both these elements have been built with high quality materials in order to preserve the entire building for long time use.