Persepolis annual rainfalls, sometimes had caused storing huge quantity of water in underground waterways and eventually damaging the waterways and palaces. The main aim of the excavation along the Persepolis canals outlet, (started from April 30, 2012 and continued for 112 days until August 20, 2012) was to open an urgent way ,among the mass of deposited soils of Persepolis previous excavations in south of the terrace, to led the stored water of annual rainfall in the underground canals, out of the PlatformFor the purpose of Excavation, a north - south trench (Started from outlet of the canals to the south where the soils of previous excavation was finished) with about 100 meters and with 4 meters width was designed. It was necessary to finish the operation in just one season of work, before that the annual rainfall of the region get started. With achieving to the main aim of the excavation in the end also a series of interesting findings, including new details on the Persepolis terrace wall and some waterways in the trench was detected.
Though, given the relatively similar levels of identified waterways with other Achaemenid structures in south area of the terrace and also due to the other discovered evidence, they can be dated to the Achaemenid era, it is difficult to understand their function and organization in south area of the terrace. Generally, discovered waterways can be considered as a part of Achaemenid structures system surrounding the Persepolis Platform. Nonetheless, it’s possible to say that Revealed evidence including direction of discovered canals and specially cut off waterways of No 2 and 3, perhaps indicating existence of a pond in south area of the terrace.