Satpula is a remarkable ancient water harvesting dam or weir located about 800 m (2,625 ft) east of the Khirki Masjid that is integral to the compound wall of the medieval fourth city of the Jahanpanah in Delhi, with its construction credited to the reign of Sultan Muhammad Shah Tughlaq (Muhammad bin Tughluq) (1325–1351) of the Tughlaq Dynasty
The objective of building the weir was for providing water for irrigation and also, as a part of the city wall, to provide defense security to the city against attacking armies, Satpula is a usage in Urdu and Hindi languages, which literally means "seven bridges
During the second decade rule of Sultan Muhammad Shah Tughlaq, the economic conditions of the Delhi Sultanate was in distress due to very high expenses incurred on the war campaign in South India (Deccan) and also due to the Sultan establishing his southern capital at Daulatabad. Both these acts necessitated increasing taxes to enhance the treasury coffers to meet large expenses. But people were dissatisfied and distressed with these developments. Some tribal groups, such as the Chaghatai tribes, had rebelled, launched raids on many places in North India and even posed serious threats to Delhi, when the Sultan was on his south Indian campaign. In the period between 1334 and 1344, repeated droughts had caused famines that were further compounded by the Black Plague. These two natural calamities had added to the suffering of the people in the country. Urgent solutions had to be found to remedy the distress conditions. One of the viable options planned was of building the Satpula, the seven arches bridge or gate controlled weir/dam, to tap the water resources of the local nallah (stream) feeding the Yamuna river, which could be used to bring large areas of flat land in the vicinity under controlled irrigated agriculture to grow food crops to stem the famine conditions. This solution was also thought to provide the much needed defense to the walls of the newly built city of Jahanpanah
The location of the Satpula, which is a part of the east–west wall protecting the southern part of Jahanpanah, drains a catchment comprising a series of low hills on the south, east, and west. The stream draining the catchment area, known as Barapulla Nallah was planned to be tapped to store the run–off water of the catchment. Command area for irrigation was identified in a large open plain on the northern side for providing water supplies from the proposed storage behind the Satpula, to grow irrigated crops to sustain a large population
Thus, a reliable water storage reservoir in the arid region of Delhi, which has the Thar desert on its west, was built as the headworks or weir across the Barapulla Nallah. Even though no epigraphic evidence is available to date the Satpula, a reasseacrh study report has conjectured that it could be dated to the same time as the four–eyyan Mosque (first of its kind in India) called Jami built by Muhammad bin Tughluq in 1343
The Satpula across the stream was built as a gate controlled weir. The total length of the structure is 79.5 m (261 ft). It has been constructed in stone masonry. The eleven bays of the weir controlled by sluice gates cover a total length of 54.5 m (179 ft). These eleven bays consist of eleven water tunnels (sluices), each 14.6 m (48 ft) in length, 3.2 m (10 ft) in height, and 2.2–2.9 m (7 ft 3 in–9 ft 6 in) in width. These are located at different levels, with seven main bays at the lowest level. The balance two additional bays on each bank, on the far east and west sides, are at a higher level. The control arrangements seen now are in the form of gate grooves to operate vertical slide gates. When built, wooden vertical sluice gates made of heavy boards of size 16 cm (1 ft) in thickness, 3 m (10 ft) width, and more than 3 m (10 ft) in height, were operated by a rope and pulley arrangement to control flow of water; the wooden gates have since disintegrated but the gate groves are visible in each bay.
The gates of the sluices were closed as a defensive measure against possible attack in the dry season when no storage remained in the dam. Each bay of the weir has an arched opening. On both banks of the weir identical towers (defensive bastions, projecting on the south and north sides) of 5.97 m (20 ft)) diameter, but with octagonal shape chambers, are built, which once functioned as madrasa (Islamic school of learning). Hence, the Satpula is also known as "Madarsa". The second level sluice bays on both banks lead to arched corridors. The walls of the octagonal chambers have graceful decorations. The stream tapped by this weir, has been diverted now further east. The indication of the use of the sluices of the structure, either as a dam or for defense purposes, could be gauged from the platforms provided at the appropriate levels. Silt deposition in the storage area of the reservoir side at the southern end is also seen now
This Article By wikipedia