Harnessing Floods of the Past: Insights from Egypt and India

Among the myriad wonders we explored in Cairo — including the Pyramids, the Grand Egyptian Museum, the Coptic Museum, the Museum of Islamic Art, and an array of magnificent Mosques — somehow, the Nilometer of Cairo stood distinctly apart for me. Perhaps it is my fascination with understanding water as the essence of past societies, especially the diverse ancient systems that harness floods in specific ways to build and sustain civilisations. Or perhaps it is my research interest in a similar but different ancient system of South India. My mind kept thinking of floods of the past and systems that had developed over time to tackle them, and this blog reflects such thoughts.

Ancient civilisations all began near waterbodies, particularly rivers, as water is essential for sustaining human life and agriculture. Ancient Egypt was no exception, as the Nile River led to the rise of Egyptian civilisation. Harnessing the Nile and its floods was crucial, as sustainable agriculture — and thereby vital food production — depended on effective flood control mechanisms. On the one hand, insufficient inundation can cause drought, leading to acute food shortage and subsequent famine; on the other hand, excessive flooding can be equally disastrous [1]. Thus, Egyptian civilisation developed one of the world’s most sophisticated irrigation and flood control systems, and it is in this context that the Nilometer was unforgettable to me. 

The Nilometer is a device used to measure the water level of the Nile River and thereby predict the annual flood season, particularly from June to September, due to rains in Ethiopia. Multiple nilometers were erected adjacent to rivers or connected by conduits or channels. They came in a range of designs and sizes. Most featured a holding tank or well supplied with water from the Nile, where the water level rose and fell in tandem with the river’s movements. A staircase provided easy access for those in charge of measuring the water. Others had a column of marks regularly spaced, serving as a massive ruler to show the river’s height [2]. The nilometers date back to the Pharaohs’ age; generally, only the rulers or priests were allowed to monitor them, signifying their importance in ancient society.

The most famous among the Egyptian nilometers is the Rhoda Island Nilometer in Cairo. Its design was inspired by renowned astronomer Al-Farghani (or Afraganus in the West) and was built on the site of an earlier nilometer. This Nilometer of Rhoda is now housed inside a modern building with a conical roof, which replaced the older dome destroyed by the French occupation in 1825. Constructed in 861 AD by Abbasid Caliph al-Mutawakkil, it is regarded as Egypt’s oldest surviving nilometer, retaining its original configuration. The mechanism consists of a marble octagonal column, 19 cubits in length, in the middle of a stone-lined well, rectangular at the top and circular at the bottom. Nilometers as flood control devices cannot be viewed in isolation but as part of an extensive flood control system that includes canals, dykes and levees [3]. However, with the construction of the Aswan High Dam in Egypt, nilometers and their connected system of flood mechanisms lost their relevance and became obsolete.

Turning to the irrigation system of South India, my research interest lies in the cascading system of tanks known as the Eri system. I can’t help but observe the commonalities and differences between the Eris and the nilometers of the Nile. The Eris are ancient tank irrigation systems in South India that used traditional technological innovations to irrigate fields and control floods. In Tamilnadu, several rivers are not perennial and often carry an ample water supply during flash floods, particularly during the heavy bursts of the northeast monsoon. Along with heavy rains, soil erosion from the Eastern Ghats is expected as large quantities of water rush down. Such flood waters were designed to be diverted to the Eris from the rivers or streams and stored for irrigation. The Eris have a complex design of interconnections through sluice gates and diversion channels, which eventually drain into the sea.

Thus, soil erosion and damage to property or livelihood were minimised, and irrigation with the harnessing of flood water into the storage tanks led to a rich harvest. The Eris adhere to the region’s natural hydrogeographic principle. What is fascinating is that the system covers almost all of South India, unifying the region via interconnected tanks, and many Eris exist even today despite deterioration and neglect in later times [4].

Dating these Eri systems precisely is challenging, but their origin is traced to the Black and Red Ware (BRW) tradition of the iron-using people. The proximity of many Eris to megalithic sites supports this connection [5]. However, the maintenance and sometimes further construction of these Eris are credited to the Pallavas, Cholas and Pandiyas of South India. Like the nilometers in Egypt, the construction of the Eris enhanced the legitimacy of the rule of the kings amongst the common masses, and both systems were essential for irrigating the fields and managing flood waters to enable agriculture. Notably, the construction of irrigation systems in almost all ancient societies is associated with prestige and sacredness. Just as the Nilometer of Cairo bears Quranic text, emphasising its sacred significance, the Eris of South India possess a similar spiritual dimension. The worship of sluice gates, the deities linked to them, and the water rituals performed vary according to the particular area or region where each Eri is located.

Distinctive features also differentiate the two irrigation systems. Whereas the multiple nilometers are flood-measuring devices, no such devices are installed in the Eri system. Instead, a well-designed cascade system allows an excess surplus of water to outflow (through the sluice gate) into the next tank until it reaches the sea. Caretaking the Eris required a collective effort. Beyond the king and chieftains, an elaborate local social organisation existed to maintain each Eri, including the Neerkatis or Nirpachiis (water turner) and other locals who assisted with desiltation and the upkeep of the flow channels and its overall system. Despite their commonalities, the scales of the nilometers and the Eris are highly contextual and cannot be compared. Each of these systems evolved to suit the needs of the region’s soil, land, hydrology, and settlements (human habitations) in a particular area/region.

Just as the time frames and spatialities of developing such flood control mechanisms to facilitate agricultural irrigation may vary, so can the context and scale of these mechanisms. The need to harness floods to sustain civilisations and ensure food security is a common theme. Often, the building of canals or diversion channels and the creation of embankments to store water at specific points can be found not just in Egyptian and Indian flood control mechanisms and irrigation systems but also in several other ancient irrigation systems. In some instances, the systems of the past can be retrieved or used in different ways to mitigate floods in cities today, as in the case of the Eri system. Floods and human habitation remain a constant concern, especially in the context of climate change. It might serve us well to research the various flood chronologies and the flood control mechanisms of the past to understand better how to deal with present issues.

NOTES

[1] Angelakis, A. N., Capodaglio, A. G., Valipour, M., Krasilnikoff, J., Ahmed, A. T., Mandi, L., Tzanakakis, V. A., Baba, A., Kumar, R., Zheng, X., Min, Z., Han, M., Turay, B., Bilgiç, E., & Dercas, N. (2023). “Evolution of Floods: From Ancient Times to the Present Times (ca 7600 BC to the Present) and the Future.” Land, 12(6), 1211. https://doi.org/10.3390/land12061211

[2] Urbanus, Jason. 2023. “The Limits of the Nile.” The Limits of the Nile. Retrieved May 27, 2024 https://www.archaeology.org/issues/501-2303/features/11203-egypt-thmuis-nilometer.

[3] Abdou, M. (2022, March 18). “Rhoda Island: Egypt’s Medieval Nilometer.” Egyptian Streets. https://egyptianstreets.com/2022/03/18/rhoda-island-egypts-medieval-nilometer/#google_vignette; and AaronNetsky. (2017, May 9). “Nilometer: Cairo, Egypt.” Atlas Obscura. https://www.atlasobscura.com/places/nilometer

[4] Mukundan, T. M. (1988, September). “The ery systems of South India.” PPST Bulletin, 1–37. https://cheyyur.wordpress.com/wp-content/uploads/2013/08/t-m-mukundan-the-ery-systems-of-south-india.pdf

[5]  Gurukkal, R., & Gurukkal, R. (1986). “Aspects of the Reservoir System of Irrigation in the Early Pandya State.” Studies in History, 2(2), 155-162. https://doi.org/10.1177/025764308600200202