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The Impact of Climate Change on Water Availability in Eastern Nepal: A Presentation of the Project Methodology taking into Account the Various Origins of Water O. Aubriot J. Smadja Y. Arnaud P. Chevallier F. Delclaux O. Aubriot, J. Smadja, Y. Arnaud, P. Chevallier, F. Delclaux, P. Laj, L. Neppel, O. Puschiasis, M. Savéan and J. L. Seidel P. Laj L. Neppel O. Puschiasis M. Savéan J. L. Seidel Abstract: The paper refl ects the main methodological aspects of the PAPRIKA Project based on the following objectives: (i) to contribute to a more accurate assessment of glacier retreat, snow cover and climate change in Koshi Basin, Nepal; (ii) to have a better understanding of the contribution of glacier and snow melting to water availability; (iii) to correlate the results with local people's perceptions of climate change and their socio-economic impact. For this, the paper: • highlights the fact that the water used by the population comes from different origins (glacier melting, snow melting, frost, rain) the combination of which varies between the four main landscape units: high, middle and low mountains, and fi nally the Terai plain; • describes the methodology adopted to observe and analyse current as well as future environmental changes in the atmosphere, cryosphere and hydrosphere; • shows that, for each origin, different reasons may explain the changes in water availability, and thus the impact on agriculture and the different water usages. Key words: Water resources, water uses, climate changes, precipitations (snow and rain), Eastern Nepal Introduction already recorded data in the Everest area at the Italian ne of the aims of the PAPRIKA project (CryosPheric research centre, Pyramid (located on the path to the Oresponses to Anthropogenic Pressures in the Hindu Everest base camp), we have decided to choose sites south Kush-Himalaya regions: impact on water resources and of Mount Everest along the Dudh Koshi: a high-mountain society adaptation in Nepal) is to assess the effects of site in Pangboche, at an altitude of 4,000m; a middle- climate change on water availability and consequently on mountain site in Juving Village Development Committee the populations’ activities and practices. In a mountainous (VDC), at 2,000m, both situated in Solu Khumbu district; country such as Nepal, ranging from the sub- tropical Gangetic plain to the high snow- capped mountains, the impact of climate change (which in itself is a complex process involving many variables) on water obviously varies from one place to another. Some studies related to the consequences of climate change for Himalayan populations do exist; they are based on case studies chosen among various climatic and topographic conditions (Dixit, Upadhya et al 2009; Manandhar, Vogt et al 2011). However, these studies do not situate the results in an analytical framework that would take into account the geographical characteristics of the selected sites and their related water issues. In this project we set out to show how the impact of climate change on water use varies according to geographical units and therefore according to the water's origin. In this respect, we have decided to focus on four units, which correspond to four parallel Figure 1. Topographic Map of the Koshi River Basin and Loca on of the belts ranging from the high mountains to the Terai plain Studied Villages (Red Squares). The Green Lines Correspond to the Limits (cf. Smadja 2009 [2003]), and to choose one reference of the Main River Basins and Sub-basins, the Light Green Circles to the site in each belt. Since the project is a pluri-disciplinary Hydrological Sta ons Quoted in the Text, and the Magenta Triangle to the project, and since glaciologists and air chemists have Pyramid Observatory. 12 HYDRO NEPAL SPECIAL ISSUE APRIL 2012 a low-mountain site in Khotang district, at 1,000m, and Water Usages and Geographical Units a last one in the plain, in Sunsari district of Nepal, with The water resources used by people come either: two reference villages, one getting its water from the a. from the direct use of precipitations, such as in Koshi River, the other from another source (Figure 1). The rainfed agriculture, current project started in mid-2010 and will last until the b. from the local discharge of water in a stored form end of 2013. As we are still at the data collection stage, here (soil humidity from permafrost thaw or snow we only present the methodological approach. The results melting), and of the modelling and the analysis of the social sciences fi eld work will be available at the end of the project. c. from the fl ow of water, the origin of this fl ow being Since 84 percent of the Nepalese population live in rural either the discharge of stored water (glacier and area, we have decided to focus on rural activities. Agriculture snow melting, groundwater outfl ow, etc.) or the and animal husbandry are the main occupations of people run-off of rainwater; however, in this case, large living in villages, and tourism is an added seasonal activity valley rivers must also be distinguished from in trekking areas, which is the case for our two reference springs and water courses on the slope. sites in the high and middle mountains. At the four Uses of water will differ according to its origin in the sites, we study the conception people have of water as a four geographical units (Figure 2 and Table 1): resource, their perception of changes in its availability and consequently the measures they may take. We consider two types of water: (1) diffuse water in various states (snow, frost, humidity etc.) necessary for vegetation growth (cultures, pastures…); (2) concentrated water from sources and torrents which is used for domestic activities, for irrigation and to supply water mills or hydroelectric power stations. It is worthwhile noting here that in Nepal- except for religious activities (ablution, cremation) and fi shing-people do not use water directly from the main rivers for various reasons including the high level of turbidity, the rapid variation in the water level and in the fl ow, and the wide range of variation, which are estimated to be Figure 2. North-South Profi le of the Nepalese Himalayas, Focusing on the too dangerous during the monsoon to install hydraulic Four Main Geographical Units: High Mountains, Middle Mountains, Low intakes or other devices. Only when equipped with large Mountains and Hills, Plain (Terai). infrastructures (dam with hydroelectric power station, (Source: Smadja, 2009 [2003] adapted from Ramsay 1986) embankment and canal diversion for irrigation), do • In the high mountains (ranging from over 8,800m rivers have some productive use. Finally, and in order to to 4,000m) characterised by the signifi cant presence understand the consequences of possible changes, we will of the cryosphere in the headwaters, water is either analyse these data and their variations according to the in an icy state (glacier, frozen torrent, permafrost), in origin of water in the different geographical units. the form of snow (falling during winter, beginning of spring or even monsoon High Mountains Middle Mountains Low Mountains Plain season at high altitude) Precipita on in the Koshi Basin 500 to 800 mm 1,500 to 2,600 mm 1,000 to 2,000 mm 1,000 to 2,000 mm or liquid fl uid when the temperature or stream Spring storms (March- May) + ++ + + turbulence permits. Monsoon (June-Sept) + +++ +++ +++ Thus, the streaming Winter precipita ons + ++ +water used comes either (Nov-Feb) (snow) from the melting of a Water fl owing in torrents and Rivers coming from Other rivers glacier, the melting of rivers is due to high mountains or streams snow, resurgence of Mel ng of glaciers + + groundwater, or rainfall May-Sep May-Sep (800mm per year in Mel ng of snow + + + Pangboche). Any change Apr-May Apr-May Apr-May in one of these parameters will have some impact Discharge of groundwater Year round various quan es on the discharge of Rain run-off ++ ++++ +++ ++++ +++ streams and therefore Jun-Sep Apr-Sep Jun-Sep Apr-Sep Jun-Sep on the operation of mills Table 1. Main Origin of Water in the Four Geographical Units of Nepal Examined Here. (only water mills in HYDRO NEPAL SPECIAL ISSUE APRIL 2012 13 Khumbu) and of hydroelectric power stations, on the face major water supply issues since most rain falls consumption of domestic water, on the irrigation of during the monsoon. Thus, any change in the rainfall barley fi elds (in Khumbu, irrigation of such fi elds is pattern but mainly in the monsoon fl ow would have still practised only in Dingboche, an alluvial terrace on signifi cant consequences in this belt. the Dudh Koshi). Due to tourism, new usages (shower in lodges, watering of vegetable plants, purifi cation of • In the Terai plain at the foothills of the Himalayas, drinking water, bottled water) and an increase in the two areas can be identifi ed: (1) one that benefi ts from demand for water supplied by springs and streams, the rivers fl owing from the high mountains - only four have led to social pressure on accessing the resource outlets of such river basins exist in Nepal. In this case, in some places. As far as precipitation distribution and glacier and snow melting would have consequences pattern (either snow or monsoon rain) or temperature on the river fl ow and would directly impact irrigation (infl uencing permafrost thaw, snow melting or frost and hydroelectricity generation; (2) one that is watered creation) are concerned, they have a signifi cant impact by rivers coming from the fi rst or second range of on plant growth and cropping activities such as potato mountains (Churia or Mahabarat), but not from farming and grass harvesting.

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