Permeability refers to the ability of a rock to transmit water. Alluvial aquifers of the Indo-Gangetic plains: These aquifers, found in the Gangetic and Indus plains in Northern India have significant storage spaces, and hence are a valuable source of fresh water supply. The north Indian rivers originating from the Himalayas are perennial as they are fed by glaciers through snow melt and also receive rainfall water during rainy season. The rivers of South India do not originate from glaciers and their flow pattern witnesses’ fluctuations. Dynamic Ground Water Resources of India, 2022 as per the 2022 assessment report, the total annual ground water recharge for the entire country is 437.60 billion cubic meters (BCM) and annual ground water extraction for the entire country is 239.16 BCM. Groundwater is one of the most important sources for irrigation as well as for rural and urban domestic water supply. However, overexploitation of this valuable resource has led to its depletion.

The northern Great Plains region of India has more underground water available due to the geological characteristics of the region. The region is primarily composed of alluvial deposits from the Himalayan rivers, which have created a highly permeable aquifer system. The region also receives relatively low rainfall, which limits the amount of surface water available for irrigation and other purposes. The high permeability of the aquifer system allows for rapid recharge of groundwater, which helps to maintain water levels throughout the year. Additionally, the region is relatively flat, allowing for easier access to groundwater through wells and tube wells. This has made groundwater irrigation a popular choice for farmers in the region, leading to a high demand for groundwater. The rivers in North India have water in them even in summer due to several reasons. Firstly, the northern rivers originate in the Himalayas, which receive heavy snowfall during the winter months. The melting snow provides a continuous source of water for the rivers throughout the year. Additionally, the northern rivers are fed by monsoon rains, which provide an additional source of water during the summer months. Moreover, the northern rivers are also supplemented by water from dams, reservoirs, and canals built for irrigation and other purposes. These structures help to regulate the flow of water and ensure that there is sufficient water in the rivers throughout the year. This has allowed for the development of extensive irrigation networks, which have supported agriculture and other economic activities in the region. In summary, the availability of groundwater in the northern Great Plains and the presence of water in northern rivers even in summer are due to the unique geological characteristics of the region, snowmelt from the Himalayas, monsoon rains, and the development of irrigation infrastructure.

Dear Himanshu Tiwari thank you for your contribution to the discussion

Important rivers of the Northern Plains have water even in summer because the rivers are formed in the Himalayas which are covered with snow and ice. The snow and ice melts during summer and the water flows into the rivers. The north Indian rivers originating from the Himalayas are perennial as they are fed by glaciers through snow melt and also receive rainfall water during rainy season. The rivers of South India do not originate from glaciers and their flow pattern witnesses’ fluctuations. Most of the rivers of North India have their source in The Himalayan Mountains. On the other hand, the rivers of South India are mainly dependent on the monsoon rains and the receding mountains. Thus, due to this the rivers of North India are perennial and those of South India are seasonal. The rivers of the north India are perennial because they are snow fed, owing to the Himalayas. They have a greater water flow and therefore do not dry in the summers. Himalayan rivers have abundant water because rivers rising in this area are perennial in nature. They are either fed by the glaciers from the mountains or by the heavy rainfall. Groundwater Resources the total replenish able groundwater resources in the country are about 432 cubic km. As expected, Uttar Pradesh has the largest ground water resources for irrigation which is as much as 68.95 BCM/year. Groundwater, which is in aquifers below the surface of the Earth, is one of the Nation's most important natural resources. Groundwater is the source of about 37 percent of the water that county and city water departments supply to households and businesses. Even though you may only notice water on the Earth's surface, there is much more freshwater stored in the ground than there is in liquid form on the surface. In fact, some of the water you see flowing in rivers comes from seepage of groundwater into river beds. India is the largest groundwater user in the world, with an estimated usage of around 251 bcm per year, more than a quarter of the global total.