The study looked at groundwater in the northern part of the Yamuna River system in Delhi to find sustainable water sources. They found that the floodplain area receives a lot of groundwater flow, with some of it going into the river. The researchers estimated that about 11 million cubic meters of groundwater flow into the area each year, and around 0.5 million cubic meters contribute to the river's flow. This shows that the aquifer in this region is important for maintaining water levels in the river and could be a valuable resource for the city's water needs.