Up the creek without a paddle: Impacts and Adaptation Prospects for Himalayan Communities

A review of the current literature on changes to Himalayan river discharge due to glacier retreat  indicates that in the short term discharge will increase, followed by a decrease when the glacial component begins to fall. Rivers sourced from the Himalayas, flow into seven countries and support one-third of the world’s population, although this proportion is growing. Therefore, understanding the impacts and potential mitigation strategies available is highly relevant for both policy-makers and scientists and is the focus of this post.

THE CURRENT STATE OF RIVER DISCHARGE

Hasnain (2002) and Xu et al., (2009) suggest that the glacial component can contribute between 70 and 80% of the summer flow of Himalayan rivers during the 'shoulder' season (before and after precipitation from the summer monsoon). Augmenting against  years of low flow due to absence or weakening of the monsoon the glacial component acts a buffer maintaining flow during the summer period when demand for freshwater is highest. It is widely acknowledged that (excluding the Karakoram region) the glaciers in the Himalayas are receding at a greater rate than the world average (Xu et al., 2009). However, the current state of the Himalaya's rivers is largely uncertain. To assess the impact of glacier retreat on Himalayan communities in the next fifty years it is important to place the current discharge levels into the projected bell-shape curve model of discharge predicted by Rees and Collins (2006: 2166)

Hasnain (2002) conducted a six-year study of the Dokraini glacier at the headwaters of the River Ganges in India. Between 1994 and 2000, the total discharge of the river increased from 243 x 10⁵m³ to 1915 x 10⁵m³, of which the glacial component consisted between 82 to 91% (Table 1) It should be noted that no observations were taken in 1998, and that the stated component contributions in 1994 do not add up to the total measured discharge. However, even if the 1994 values are excluded from the analysis discharge in 2000 is over seven times greater than in 1995 suggesting an increase in discharge in the region.

 This rise in discharge is supported by a later study by Hasnain (2008) reviewing the current literature on Himalayan river discharge in the eastern and western Himalayas. General observations from the studies suggest an overall increase in discharge by 3 to 4% due to a 10% and 30% increase in glacial melt in the western and eastern Himalayas respectively. However, Hasnain (2008) argues that attempts to predict future changes in river discharge are limited by the lack of long-term studies in the region. Although remote sensing is now being used to substitute fieldwork data, ground truthing is still required to calibrate and validate the images. However, the current studies available indicate that discharge has already started to rise supported by Rees and Collins (2006) model of hypothesised western and eastern catchments.

ADAPTING TO CHANGING RIVER DISCHARGE

Moors et al., (2011) claim that even if there was no significant change in total water availability by 2050, seasonal changes in the timing of glacial melt and increased variability in the summer monsoon will exacerbate water stress across the Himalayan region. Observed rises in regional temperature alter the timing of the glacial component runoff relative to the monsoon. Removal of this buffer against low flow, is a significant concern for policy makers as it coincides with the period of greatest demand on water resources for domestic and agricultural use (Xu et al., 2009).

Therefore mitigation methods against a projected long-term decrease in river discharge and the hydrological regime are an increasing priority for countries that depend on the Himalayan rivers. Because many rivers cross between countries, trans-boundary organistations such as the International Centre for Integrated Mountain Development (ICIMOD) having been formed. Serving eight regional countries within the Himalayan region, the ICIMOD have been actively promoting water harvesting and increased water efficiency with the former now occurring in five of the eight countries(Chalise, 2002). However, this project is still limited in scale and Xu et al., (2009) argue that rather than disjointed policy approaches, a scale of adaptation needs to be adopted related to uncertainty. Occurring at different scales, Xu et al., (2009) support a pragmatic approach to mitigation, including the local people and recognising the different requirements of urban and rural communities. Essential to successful mitigation against water scarcity is the development of schemes at a river-basin level, focusing on decreasing water demand, modernising irrigation and acknowledging the demands of communities downstream for high quality water (Xu et al., 2009; Moors et al., 2011). Through a pragmatic approach, long-term priorities can be identified and cooperation between countries can minimise conflict due to water scarcity. Numerous examples of trans-boundary conferences such as the Climate Summit of the Himalayas suggest movements towards an international agreement. However, the current state of progress is limited due to substantial gaps in our understanding of basin-specific responses to climate change and uncertainties of future economic and social demands (ICIMOD, 4th December 2011).

CONCLUSIONS

Overall, the significant contribution of the glacier component to river discharge coupled with the rapid retreat (excluding Karakoram) of glaciers in the Himalayas relative to the world average suggests future climate change could have substantial impacts on the 1.3 billion people that rely on Himalayas rivers. Causing both long-term and seasonal changes to river discharge, attempts to reduce vulnerability to water stress will require trans-boundary cooperation managing water resources at a basin scale. According to Rees and Collins (2006) bell-curve, in the short-term discharge may increase in these basins, however countries should utilise this short-term opportunity, improving water efficiency, decreasing demand and researching alternative water sources where possible. Under the business-as-usual scenario, in the long-term river discharge will decrease, and with growing populations and increased demand a robust international agreement on water use will be essential.

Reference:

Hasnain, S. I. (2002) ‘Himalayan glaciers meltdown: impact on south Asian rivers’, FRIEND Regional Hydrology: Bridging The Gap Between Research and Practice, Proceedings of the Fourth FRIEND Conference, South Africa, March 2002, 274: 417-425.

Hasnain, S. I (2008) ‘ Impact of climate change on Himalayan glaciers and lakes’, Proceedings of Taal2007: The 12^th World Lake Conference: 1088-1091.

ICIMOD (2011) 'The Status of Glaciers in the Hindu Kush-Himalayan Region' (www) http://www.icimod.org/?q=5934 (Accessed 4/01/11)

Moors, E. J., A. Groot, H. Biemans. C. T. van Scheltinga, C. Sidevius, M. Stoffel, C. Huggel, A. Wiltshire, C. Mathison, J. Ridley, D. Jacon, P. Kumar, S. Bhadwal, A. Gosain and D. N. Collins (2011) ‘Adaptation to changing water resources in the Ganges basin, northern India,Environmental Science and Policy, 14: 758-769.

Rees, H.G. and D. N. Collins (2006) ‘Regional differences in response of flow in glacier-fed Himalayan rivers to climatics warming’, Hydrological Processes, 20, 10: 2157-2169.

Xu, J., R. E. Grumbine, A. Shretha, M. Eriksson, X. Yang, Y. Wang and A. Wilkes (2009) 'The melting Himalayas: cascading effects of limate change on water, biodiversity and livelihoods', Conservation Biology, 23, 3: 520-529.