Estimation of discharge from Langtang River basin, Rasuwa, Nepal, using a glacio-hydrological model

Pradhananga, Niraj Shankar; Kayastha, Rijan Bhakta; Bhattarai, Bikas Chandra; Adhikari, Tika B.; Pradhan, S.C.; Devkota, Laxmi Prasad; Shrestha, A. B.; Mool, P. K.

doi:10.3189/2014aog66a123

Cited by 42 publications

(21 citation statements)

References 13 publications

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“…Glaciers melt is estimated to contribute 26% and 3% of total runoff in Indus basin and Ganga Basin respectively (Immerzeel and Bierkens, 2012). A few studies, including Alford and Armstrong (2010), Pradhananga et al (2014), andTahir et al (2015) have looked at hydrological impacts on smaller sub-basins. Tahir et al (2011) found that (a) a 1% increase in snow cover area in Hunza under constant temperature will increase summer discharge by 0.7%, (b) an increase in 1 • C mean temperature (keeping precipitation and snow cover constant) is expected to increase summer discharge by 33%, and (c) a 20% increase in snow cover in combination with a 2-4 • C rise in mean temperature is expected to increase future stream flows by 100%.…”

Section: Introductionmentioning

confidence: 99%

Differential Impact of Climate Change on the Hydropower Economics of Two River Basins in High Mountain Asia

Mishra

Veselka

Prusevich

et al. 2020

Front. Environ. Sci.

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Water stored in the form of snow and glaciers in the High Mountain Asia (HMA) region regulates the water supply, and resultant water-based economies, that support the livelihoods of millions of people. Trends in the seasonal and long-term melting of snow and glaciers, governed by initial ice reserves, meteorological factors and geographic features, vary across sub-basins in the HMA region. We examined the economic impacts of climate-led changes in river flow in two drainage basins, one each from the Karakoram and Central Himalaya region. We used an integrated assessment framework to estimate the changes in economic value of the hydropower generation from hydropower plants on rivers fed by snow and glacier melt in the two sub-basins. The framework, developed under a NASA High Mountain Asia project, coupled biophysical models (a suite of climate models, snow/glacier-hydrology, and hydropower model) with economic analysis. We compared the differences in estimated river flow over historic and future time using the water balance model in sixteen scenarios (eight climate models and two emissions scenarios) for rivers upstream of hydropower plants in each sub-basin. Using the hydropower model we developed, we estimated the changes in hydropower generation at the Naltar IV hydropower plant, with an 18 MW capacity, located in Hunza, Karakoram, and the Trishuli hydropower plant, with a 19.6 MW capacity, in Trishuli, Central Himalaya. When compared to their baselines, the estimated impact of climate change and temporal variability were higher for the Naltar plant than for the Trishuli plant. Our sensitivity analysis shows that hydropower plants with water storage facilities help reduce the impact of changes, but the estimated impacts are higher for the higher capacity plants. This study provides an example of the differential impacts of climate change on hydropower plants located in rivers fed by varying amounts of snow and glacier melt at different decades in this century. This type of integrated assessment of climate change impact will support the scientific understanding of hydrologic flow and its impacts on a hydropower economy under various climate scenarios, as well as generate information about water resource management in a changing climate.

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Section: Introductionmentioning

confidence: 99%

Differential Impact of Climate Change on the Hydropower Economics of Two River Basins in High Mountain Asia

Mishra

Veselka

Prusevich

et al. 2020

Front. Environ. Sci.

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“…to 7215 m a.s.l. [20]. The glaciers of this catchment cover an area of 137.5 km 2 while the remaining area of 216.1 km 2 is covered by rock and vegetation.…”

Section: Study Areamentioning

confidence: 99%

Assessment of Sediment Load of Langtang River in Rasuwa District, Nepal

Chhetri¹,

Kayastha²,

Shrestha³

2016

JWARP

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This paper assesses the sediment load of the glacier fed Langtang River, Nepal from April 2014 to March 2015. Water samples were collected from the centre of the river with a frequency of two samples per each sampling day using the Depth Integration Technique (DIT) on daily basis in the monsoon season, weekly in the pre-and post-monsoon seasons and bi-monthly in the winter season. Suspended sediment concentration (SSC) is calculated from the water samples using filtration followed by oven-drying, and a rating curve is used to calculate daily discharge of the Langtang River. The annual sediment yield is 109,276.75 tons and 37.69, 11.52 and 5.54 tons of sediment is transported per day in the pre-monsoon, post-monsoon and winter seasons, respectively. There is a very high value of 872.86 tons per day in the monsoon season, which contributes the highest sediment load among all of the seasons comprising 83% of the total sediment transport. Diurnal cycle of sediment discharge is clearly seen with higher sediment discharge during the evening than the morning and reaching maximum values of 41.1 kg•s −1 and 61.5 kg•s −1 , respectively. A clock-wise hysteresis loop has been obtained for discharge and sediment discharge where sediment flux is higher in the early monsoon than in the late monsoon for a corresponding discharge.

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“…The second method uses a degree day factor adjusted for the elevation effect (Pradhananga et al, 2014) while the third method uses aspect and elevation modified degree day factors. There is variation of degree day factor with respect to the location of glacier cover.…”

Section: Modelling Approachmentioning

confidence: 99%

“…Below 5000 m, DDFs is 5 mm d -1 o C -1 , and DDFi is set to 6 mm d -1 o C -1 . Above 5000 m, DDFs is set to 6.5 mm d -1 o C -1 and DDFi 7.5 mm d -1 o C -1 for ice ablation above 5000 m. These values are calibrated according to the range of degree day factor provided (Pradhananga et al, 2014). For debris covered glacier in the basin, a melt reduction factor of 0.5 is applied (Kayastha et al, 2000b).…”

Section: Modelling Approachmentioning

confidence: 99%

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

Parajuli¹,

Chand²,

Kayastha³

et al. 2015

Proc. IAHS

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In the Nepalese Himalayas, the complex topography, occurrence of debris covered glaciers, and limited data availability creates substantial difficulties for modelling glacier melt. The proper recognition of melt processes governs the accurate estimation of melt water from glacier dominated systems, even in the presence of debris-covered glaciers. This paper presents a glacier melt model developed for the Lirung subbasin of Langtang valley, which has both a clean glacier area, 5.86 km 2 , and a debris-covered glacier area, 1.13 km 2 . We use a temperature index approach to estimate sub-daily melt water discharge for a two week period at the end of monsoon, and the melt factor is varied according to the aspect and distributed to each grid processed from the digital elevation model. The model uses easily available data and simple extrapolation techniques capable of generating melt with limited data. The result obtained from this method provides accurate estimate with an R 2 value of 0.89, bias of 0.9% and Nash-Sutcliffe efficiency of 0.86, and suitable in Himalaya where data availability is major issue.

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Estimation of discharge from Langtang River basin, Rasuwa, Nepal, using a glacio-hydrological model

Cited by 42 publications

References 13 publications

Differential Impact of Climate Change on the Hydropower Economics of Two River Basins in High Mountain Asia

Differential Impact of Climate Change on the Hydropower Economics of Two River Basins in High Mountain Asia

Assessment of Sediment Load of Langtang River in Rasuwa District, Nepal

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

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