Tuesday, February 21, 2012

Groundwater Is Important In The Himalayas Too

The steep gushing streams of the Himalayas leads one to think of water flow within the Himalayas as primarily a surface phenomenon. Water that falls on the Himalayas is temporarily stored in different types of reservoirs before being discharged into rivers. These include soils, snow, glaciers and groundwater.

A recent paper (behind paywall) in Nature Geoscience by Christoff Andermann and colleagues that has estimated the water budget of the Central Himalayas (Nepal region). I don't have access to the paper but from the abstract I gather that using a combination of river chemistry and models of water budgets the researchers conclude that groundwater contributes more than snow and glaciers to the annual discharge of rivers in that region. The fractured rock of the Nepal Himalayas is an important aquifer.

Last year I was trekking in the Kumaon region of the Lesser Himalayas, west of the study area of this paper. I am not at all surprised that groundwater can be an important component of the water budget of many Himalayan terrains. The rocks are foliated i.e. they are made up of flaky and platy minerals that part and offer passageway to water and further the rocks are tectonically fractured, thus offering a secondary system of conduits for water flow.

I noticed that spring discharge was being used to irrigate just about all the agriculture and personal consumption needs. A couple of pictures from the Mukhteshwar area of the Kumaon Himalayas.

The image below is of a spring. The discharge is quite vigorous .. and soothing for a weary trekker!

The water is channeled into irrigating the fields and orchards you see in the image below.

And here is a useful map of the relative contribution to the annual discharge from various sources. In the westernmost and easternmost Himalayas, the major contributor are snow and ice melt. In the central regions, high rainfall and glacial melt contribute a lot.. In Nepal, groundwater is an increasingly important contributor to rivers.

Source: Hydrology: Himalayan groundwater

I suspect that while comparing across these regions the geographical location of the catchments will matter. In the westernmost and easternmost regions outlined in the figure, larger stretches of the Indus and Brahmatputra catchments lie in very high terrain. Ice and snow melt will contribute significantly here. In Nepal, there is a much broader belt of the lesser Himalayas with relatively less snow and ice.


  1. But consider that - while GW may be a dominant source of streamflow - GW recharge may come primarily from snow/ice melt. So not necessarily direct contribution from these sources, but certainly indirect. This is true of other regions globally - e.g. Okanagan region of southern BC, where upland snowmelt recharges GW that moves through deep fractures to feed lowland stream systems.

  2. Hydro Blogger - I agree.. in the Himalayas it will depend on where you are.. in the high Himalayas the situation you outlined must be holding true.. but for example as i mentioned in the Nepal and adjoining Kumaon to the west there is a broad belt of Lesser Himalayas which see prolonged monsoons and rains, which contribute to groundwater recharge..

  3. Nice Post....Keeping geological features aside , the water resources in the Himalayas are on the verge of extinction and continued and unmindful exploitation. This is alarming .....


  4. Anubhooti- thanks for the link. you have an interesting blog..