The melting Himalayas : examples of water harvesting techniques
Abstract: Himalayan glaciers are both growing and shrinking as a response to global climate change. The major trend is a loss of ice sheets, especially among the smaller glaciers. As glaciers retreat there is a change in hydrology and seasonal water availability both upstream and downstream of the river basins. This is most apparent in high altitude and glacierfed areas where meltwater is the main (sometimes only) water supply for agricultural and domestic use. The change in hydrology is most noticeable during the first months of sowing since the amount of meltwater is increasingly unpredictable. This uncertainty increases the risk for crop failure, as the cropping season is limited from March/April to September/October. To deal with water shortages and an unpredictable water supply, high altitude areas have developed water harvesting-methods by storing water as ice. This thesis seeks to explore and explain two techniques, first an indigenous technique called glacier grafting where glacial ice is relocated to shaded cavities where it is left to grow. Secondly, a more recent innovation is described where water is diverted to create icings (also called artificial glaciers) that melt just in time for the sowing season. Both techniques have been developed and incorporated into the agriculture of the western part of the Himalaya (The Karakoram). In order to assess the effectiveness of this water-harvesting technique, a case study has been compiled from a village in Ladakh, north India, where one of the artificial icings is located. Cropped areas are estimated to calculate and establish the water need. In addition to this, the volume of water that the icings are likely to contain is estimated. Thereafter a comparison between water demand and the extra water supply is made possible, to conclude if the artificial icings is an adequate water storage.
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