Prediction of future hydrological regimes in poorly gauged high altitude basins: the case study of the upper Indus, Pakistan

Abstract

Abstract. In the mountain regions of the Hindu Kush, Karakoram and Himalaya (HKH) the "third polar ice cap" of our planet, glaciers play the role of "water towers" by providing significant amount of melt water, especially in the dry season, essential for agriculture, drinking purposes, and hydropower production. Recently, most glaciers in the HKH have been retreating and losing mass, mainly due to significant regional warming, thus calling for assessment of future water resources availability for populations down slope. However, hydrology of these high altitude catchments is poorly studied and little understood. Most such catchments are poorly gauged, thus posing major issues in flow prediction therein, and representing in fact typical grounds of application of PUB concepts, where simple and portable hydrological modeling based upon scarce data amount is necessary for water budget estimation, and prediction under climate change conditions. In this preliminarily study, future (2060) hydrological flows in a particular watershed (Shigar river at Shigar, ca. 7000 km 2 ), nested within the upper Indus basin and fed by seasonal melt from major glaciers, are investigated.The study is carried out under the umbrella of the SHAREPaprika project, aiming at evaluating the impact of climate change upon hydrology of the upper Indus river. We set up a minimal hydrological model, tuned against a short series of observed ground climatic data from a number of stations in the area, in situ measured ice ablation data, and remotely sensed snow cover data. The future, locally adjusted, precipCorrespondence to: D. Bocchiola (daniele.bocchiola@polimi.it) itation and temperature fields for the reference decade 2050-2059 from CCSM3 model, available within the IPCC's panel, are then fed to the hydrological model. We adopt four different glaciers' cover scenarios, to test sensitivity to decreased glacierized areas. The projected flow duration curves, and some selected flow descriptors are evaluated. The uncertainty of the results is then addressed, and use of the model for nearby catchments discussed. The proposed approach is valuable as a tool to investigate the hydrology of poorly gauged high altitude areas, and to project forward their hydrological behavior pending climate change.

Future Water Availability from Hindukush-Karakoram-Himalaya upper Indus Basin under Conflicting Climate Change Scenarios

“…Thus, it is important to incorporate changes in the future cryosphere that are plausible under anticipated climate change scenario, while assessing the future water availability from a glacerized basin. Since the overall glacial extent of the UIB somewhat remained stagnant since 1980s [28][29][30]65] and particularly since early 21st century [20,22] under the ongoing regional warming, no change in the present-day glacial extent has been assumed for the near-future scenario (2013-2030), as also adopted by several studies [5,9,11] (Table 2). In view of obtaining a far-future climate change scenario, projections for an extreme emissions scenario of RCP 8.5 are considered for the last decade of the 21st century.…”

“…The future climatic changes are likely to change the extent of future cryosphere [10], which in turn can affect the future water availability [9,11]. Thus, it is important to incorporate changes in the future cryosphere that are plausible under anticipated climate change scenario, while assessing the future water availability from a glacerized basin.…”

Modified temperature index model for estimating the melt water discharge from debris-covered Lirung Glacier, Nepal

“…The melt rates of debris-covered glaciers vary significantly compared to other types of glacier (e.g. Scherler et al, 2011;Bocchiola et al, 2011). Debris thickness is a controlling factor that influences melt rates of glacier ice; melt is enhanced with debris thicknesses of a few centimetres, but reduced at greater debris thicknesses (Nakawo and Rana, 1998;Scherler et al, 2011).…”

“…In light of the existing uncertainty in future climatic scenarios, data gaps and glacier mass loss, except in the Karakarom region (Hewitt, 2005), the Himalayan region presents a huge challenge in terms of future water availability and management (Scherler et al, 2011). Modelling is an appropriate tool for places having scarce data (Sivapalan et al, 2003), provided that melt processes can be approximated (Hock, 2003) even in the debris-covered glacier (Bocchiola et al, 2011).…”

Nanga Parbat Revisited: Evolution and Dynamics of Sociohydrological Interactions in the Northwestern Himalaya

“…The sensitive water tower function of the Hindu Kush, Karakoram, and northwest Himalayan ranges, whose meltwaters feed the upper Indus Basin and secure water availability in the adjacent large-scale irrigation network of the Punjab, gained scientific interest and media coverage as a critical issue in climate change scenarios (Viviroli and Weingartner 2004;Archer et al 2010;Immerzeel, van Beek, and Bierkens 2010;Kaser, Großhauser, and Marzeion 2010;Bocchiola et al 2011;N€ usser and Baghel 2014). Such discussions, however, mainly focus on larger scales, neglecting the adaptation strategies of mountain communities that are in close proximity to these glaciers and use ice and snow meltwater for crop cultivation and basic needs (Kreutzmann 2011).…”