A tectono-hydrogeologic investigation on the late medieval Ahom Era ponds of the Brahmaputra Valley, Northeast India

Farha Zaman , Uttam Goswami, Devojit Bezbaruah

Science Vision 25 (1), 34-43 | Published on 27 August 2025 | 10.33493/scivis.25.01.06

Abstract

The Brahmaputra valley was formed by stratified deposits of Palaeo-Proterozoic to Recent sediments that were drained from the Himalaya, Assam-Arakan, and Shillong-Mikir Hill ranges. The underlying hydrogeologic system was developed by alluvium (sand-silt-clay mixtures) layer. Several ancient kingdoms have thrived because of this hydrogeologic environment as a whole prior to the Ahom dynasty (1228-1826 AD). Ahoms were the final monarchs and they made a major impact on Assam’s history, particularly about pond building methods. This study has investigated tectonic and hydrogeological aspects of the major pond series in the Sivasagar District, Assam, using satellite imageries, subsurface lithologic distribution (panel or fence diagram from boreholes data), water table, and surface water variation. The regional groundwater flow is parallel to the east-west linearly aligned major ponds. The moat, or jamuna, that is built around these large ponds plays a vital part in preserving the water level. The sandy clay layer is found on top of the aquifer creating confined aquifers that have kept the water pressure constant, with the foothills having the maximum water pressure. Majority of ponds close to the foothill, therefore, do not need Jamuna surrounding them. The area is controlled by the splaying of the Jorhat Fault, the Naga Thrust zone, and local tectonic features. Conversely, the water from the Jamuna, paleo-channels, and channels has fed the large ponds in the valley. The water level has been sustained by the hydrogeologic environment as well as the link between the Jamuna and the ponds' effluent-affluent groundwater.

Abstract Full Text Download