Analysis of Drainage System and Water Canals of Persepolis

Parsa, which we call Takht-e-Jamshid and westerns call it Persepolis, is the most important heritage of the Achaemenids. The complex is a series of buildings and palaces dating from 510 to 330 BC. It has emerged as an administrative, governmental and ceremonial complex on a huge man-made rocky platform. One of the basic measures taken to protect buildings on the platform of the Persepolis from the mountain floods and provide drainage for the buildings is the construction of about two kilometers of water canals under the platform. The canals are partly dug into the rock or built over the bed of the platform and run from north to south and west to east to gather the water of 125,000 square meters of palaces and administrative or service buildings. Sometimes these canals are up to 6 meters deep and are generally not less than one meter wide and covered with thick stone slabs. Various archaeologists, such as Schmidt (1939), Tajvidi (1355 solar), Askari (1383-85, solar) Asadi (1395 solar), and scholars such as Hakim, Reza, and Zare have studied the water canals of Persepolis. However, a study of architecture, construction and spatial features of canals is still necessary. This study, has monograph research method which starts from review of first-hand library resources specifically archeological reports and continues with field surveys. It first attempts to integrate the complex network architecture of the canals in interaction with terrain topography, heights of platforms, and 12 monuments over the ground. It Identifies the function of each canal in relation to roof surfaces, walls and open courtyards. The research has classified the canals based on their different characteristics. Functional canals were first divided into four categories: 1. vertical drainage transfer 2. Over ground water transfer 3. Secondary and short waterways 4. Main waterways. They were then divided into three categories based on their form: 1. Open canals that starts through the Gate of Nation 2. Covered canals with or without ventilating holes. The final categorization was carried out according to the method of stonework of the canals, which is the unified stone with smooth carving or coarse carving. It seems that the smooth carvings belong to the first period of construction in Persepolis in the time of Darius, 515 to 490 BC under Apanada Palace. Some of the canals were created not by digging directly the rocky mountain but by arranging rocks on top of each other. Morphological study of the canals shows that there are two important east-west canals which pass through Apadana palace and residential palaces, reaching to a north-south canal adjacent to the mountain at the east of Persepolis platform. The height difference of the longest canal is -7 meters. The average slope is 2% but some have more than 30 %slope to be able to provide the desired depth and homogeneous system of water flow. As a conclusion, after examining the gradual process of formation of Persepolis, archaeological hypotheses suggested by Hertzfeld and Schmidt on the impact of canals on unified planning of Persepolis from the beginning of construction are reviewed.