First Phase Results:
After the introduction of Qeshm Island, we attempt to recognize the historical structures located there and their distribution relying a qualitative research method and through deep interview with key informants to find a good knowledge about main problems of these structures.
- Study area
Qeshm Island is the largest island in Persian Gulf with about 122 km length and average width of 18 km. Its total area is about 1445 square kilometers. Qeshm is located at about 22 km, south of Bandar Abbas and is separated from the mainland by the straits of kuran. Hormoz Island is located at about 16 km distance southeast and Hengam Island at about 1 km distance at south of Qeshm Island. The closest part of Qeshm to northern beach is Laft village with distance of about 2 km from pol village in mainland.
The island has a warm and dry climatic pattern. For this reason, there is no stream flow in the island. Thus, reservoirs and other historical water structures can play an important role in island’s freshwater supply.
- Spatial Distribution of Structures
Qeshm island water structures nominated “Borke” are predominantly related to later Islamic periods, specially late and early Pahlavi period. Because of their usage and special effects on island resident daily life, Borkes have been repaired and rebuild several times.
Borkes are places for harvesting rain water due to their special architecture characteristics and have play a critical role in Qeshm island water supplying because of limited rainfall event and water deficit problem in the area and are used still now. Results of pilot study showed that there are 29 Borke in the island, mostly located in north and northeastern parts of the island and south and west south in some cases. Results of census report conducted in 1390 suggested that there are 69 village and city in Qeshm Island that a number of Borke is belonged to each one of them for supplying their water needs. These structures have been conducted by residents and local government by considering population settled in the region. Some of these structures were constructed by government after Islamic republic revolution of Iran in 1357 and others were constructed by people in different years. Location of constructing these reservoirs is mainly in foothills to facilitate run off entering to reservoir of structures.
Pilot study showed that structures with bigger reservoirs are located in more populated villages.
- Problems related to historical water structures
Deficits and problems related to these structures were investigated in pilot study. From hardware point of view, these problems can be categorized into two main group namely qualitative and quantitative. The quantitative dimension is related to lack of attention to these structures, their reservoirs and conveying structure, which have made problems for these structures. Many of silting ponds, gates and channels have been filled by concrete and have caused many problems. Obstructing water way caused reservoirs being empty. channels ended to these reservoirs have been filled by cement making the reservoirs useless. Furthermore, because of lack of conservation practices such as dredging, structures have been filled by sediments and more problems have been generated. It’s considerable that without resolving quantitative problems, qualitative problems could not be addressed.
Because of direct relationship between structures and people’s livelihood, lack of attention to attention in qualitative and quantitative dimensions whether by government or people, can exacerbate occurred risks and problems and can lead to becoming the reservoirs useless, which can impose critical damages to history, culture and welfare of cities and villages including these reservoirs.
The aforementioned hardware problems have been resulted from software problems such as lack of attention to repairing and resuscitation of these structures by communities.
By becoming the island free zone area and population growth as its consequence, desalinization units were developed in many parts of island beach and it’s water supplying pattern undergoes critical changes.
- Structures variety and hardware characteristics
In the second phase, based on a qualitative research method and in order to identifying engineering dimension of structures and their hardware variety, a pilot study was conducted by water structure and resource engineers and through implementing measuring tools , quantitative variable and characteristics were measured. Historical water structures of the island, in terms of structural shape are categorized into two main group: dome-shaped structures which have domed roof and overall shape of structure is circular, and rectangular structures , which have half-cylindrical roof and overall shape of structure is rectangle. In terms of dimensions, these structures can be categorized in two main group: structures with small reservoirs and structures with large reservoirs. It’s notable that the reservoir volume was chosen based on population settled nearby. Most of these structures are made of mortar and mud; thatch cement and plaster have been used for repairing and rebuilding.
The following classification is suggested for better assessment of structures components: a) water conveying structures b) conservation structures or reservoirs c) protective structures
Water conveying structures: these structures are mainly channels ended to reservoirs in form of some parallel open channel which covert water to desired way by gates located in certain distances along the channel. The channel coverage is from mud and mortar which has demolished during time due to lack of dredging that has caused leak and resulting head drawdown along the way. Furthermore, because of neglecting free board, risk of water overflowing is very high. The established channels in some cases are too long. In another case, no structure were built to transfer water and run off had created a path by itself over time; which ended to reservoirs.
Conservator structure or reservoirs
Historical reservoirs of Qeshm Island in different dimension and structural shapes, have their own specific characteristics. For example, in some reservoirs, a number of gates had belonged to woman a just them was allowed to extract water from them. Some reservoirs have had multiple entries indifferent dimensions, which had increasing risk of sediment entering to the reservoirs and decrease required time to fill the reservoir. Reservoirs were dogged in different depth to prevent thermal pollution and conserve the stored water quality. These depths was chosen based on the structure shape and its location. The structure were enclosed to prevent evaporating, polluting and warming of stored water.
- Conservational structure:
For sedimentation control and reservoirs conservation, sediment tanks and settling basins was designed for every structure. Furthermore air valves was devised for air transferring to the reservoirs. The aforementioned sediment tanks was designed based on reservoirs volume and dimensions of structure in different width and depth. Furthermore, settlement basins was designed in different dimension at the entry of each gate, which was filled over time and required to dredging.
In the pilot study, we tried to identify key informants in conducting these structures, especially people whose ancestors were involved in the construction of these structures or have any information about them. The information obtained from these people include information about maintenance and dredging methods in past, building material and locationing of structures. This information have been transferring through … .for example dredging is undertaken in the spring and reservoirs get cleaned from sediment and contamination and get ready for rainfall in next year. Dredging is conducted in spring from past to present. The architecture of the structures has been training to others by specialists and builders, who tackle repairing and rebuilding of structures during their life. Cultural dimension also can be mentioned: every year in an specified time, residents get together and address to conserving and repairing of these reservoirs. This ceremony is due to necessity of maintaining continuity of structures. Because of lack of attention to these educations, related traditions have been forgotten. It is notable that the average age of these people is high. This matter made lagging in the process of taking advantage of them for educating goals.
Local government played an important role in this part, through financial support of key informants for repairing, rebuilding and educating processes.
effectiveness of educational practices
After spending four years from the beginning of the project on 23 and 24 January 2017, and after occurrence of an rainfall event with appropriate intensity and duration, an extensive inspection was conducted and water depth in reservoirs was measured and by adding results to GIS layer prepared in recognition phase, water depth of every reservoir and it’s spatial distribution was analyzed and performance of proposed educational activities was assessed. This time period was chosen for two reasons: educational issues need to a long-term interval to achieve stability. In this way all items in every discussion is analyzes and strengths and weaknesses are identified. After analysis and assessment of available data and conducting several pilot study, identification of key informants and related organization and conducting deep interviews the project steps was determined. Second reason was related to lack of an rainfall event with appropriate intensity and duration to perform the evaluation in more accuracy; because the data collected after multiple urinals were not helpful in performing measurements.
After this time period a rainfall event occurred with 37 mm rainfall depth and 2 days duration. This rainfall event made it possible to perform an appropriate measuring in selected reservoirs. The GIS layer of rainfall data in selected stations was prepared and after drawing rainfall accumulation curves, average rainfall in the area of structures was measured.
Results od visiting developed urban area and conducted measurements suggested that in result of urbanization, population growth and desalinization technologies, requiring to Borkes has lost its necessity and for this reason, local communities are not intended to repairing or resuscitation of them.
Most of borkes are empty; have lost their nature or their usage has been changing. In these cases urban development through prevailing run off entering to reservoirs have a clear role in preventing borkes to be restored. In addition to usage change, in some cases architecture change was observed among them so that some had lost their symbolic nature.
Despite urban area, in plains and rural area, the borkes which had not experienced topography and environmental change, had harvested run off surface generated from rainfall. It’s considerable that local residents use the water harvested from these structures and believed in better quality of harvested water rather than desalinated water and also the importance and effectiveness of restoring these structures. (Borkes are so important from the aspect of residence’s traditional and intellectual thoughts)