In the south-eastern area, for example, the reservoir covered about 5 ha (hectare), the largest within the walled area. The walls acted as effective bunds. Both faces of the wall were plastered with fairly water-repelling sticky clay.
Special and vulnerable areas, mostly on the exterior face, were vencesed with hammer-dressed stones. Keeping in mind the general slope of the city, several bunds were constructed across the width of the tanks to reduce the pressure of the stored water body on the city walls.
The bunds also served as causeways for easier movement. In times of scanty rainfall, they enabled the water to get stored in selected tanks instead of being spread out over a large area and reduced quickly by evaporation and seepage. In the area designated as the citadel, an interesting networks of drains, both small and large, was discovered.
Most of the drains intersect each other and ultimately link up with an arterial drain. The entire drainage system could have been set up to assiduously conserve every drop of rainwater that fell in the city.
The water must have been a treasured commodity in an area lacking in perennial source of surface water and where the ground-water, largely brackish and saline, tends to dry up during droughts”.
The importance of water for agricultural societies during the Vedic period must have increased. Flow of water in channels for irrigation purpose was practiced. There are references to artificial waterways kulya and khanitrima apah in Rig Veda. These perhaps refer to irrigation channels. The other expressions used for the same device are Sushira and Soormi. Wells avat were dug up.
Lifting devices to draw water from the wells were also in use, called ansatrakosh and ashmchakra. These were probably composed of a leather bucket drawn over a pulley for lifting water from the wells. Mauryans, as the founder of one of the earliest empires, gave special importance to water resources.
On the authority of Kautilya we know that the building of reservoirs by damming streams was an important public work the king was encouraged to construct. Similarly, Ashoka refers in his edicts to the construction of wells and watering-places along the major routes.
The epigraphic evidence testifies to the construction of a big reservoir of water by damming a stream in the Junagarh district of Gujarat by Pushyagupta, the governor of the region during Chandragupta Maurya’s reign. The reservoir was named as Sudarshan. Under Ashoka his Greek governor Tushasf maintained the dam and the reservoir.
In AD 150 there occurred a breach in the dam which was repaired by Rudradaman. The dam seems to have been maintained till the fifth century AD when the last known repairs were carried out by Parndatt during the reign of Skandagupta, in AD 457-8.
Since medieval India was also a largely agricultural society, the resource-use practice with regard to water was basically geared at providing irrigation to the fields. Besides using most of the prevalent methods, a few new techniques were introduced during this period. The prominent among them were arghatta and arhat (Persian wheel), which improved irrigation significantly. In the 14th century a very elaborate network of canals was constructed by Firuz Tughlaq.
The rivers from which the canals were cut were Yamuna, Sutlej and Ghagghar. An additional water tax was levied on the farmers of the irrigated areas. Due to greater and more secure availability of water, production of cash crops had increased.
The same concern for the use of water resources was shown by the Mughals. They also promoted irrigation facilities by providing loans to farmers to install irrigational devices. There was a general concern for better use and regulation of water resources.