Journal of Hydrology and Meteorology Official journal of the Society of Hydrologists and Meteorologists - Nepal. en-US (Jagat K Bhusal) (Sioux Cumming) Tue, 30 Aug 2016 18:29:59 +0000 OJS 60 GCMs Derived Projection of Precipitation and Analysis of Spatio-Temporal Variation over N-W Himalayan Region <p>The ensembles of two Global Climate Models (GCMs) namely, third generation Canadian Coupled Global Climate Model (CGCM3) and Hadley Center Coupled Model, version 3 (HadCM3) are used to project future precipitation in a part of North-Western (N-W) Himalayan region, India. Statistical downscaling method is used to downscale and generate future scenarios of precipitation at station scale from large scale climate variables obtained from GCMs. The observed historical precipitation data has been collected for three metrological stations, namely, Rampur, Sunni and Kasol falling in the basin for further analysis. The future trends and patterns in precipitation under scenarios A2 and A1B for CGCM3 model, and A2 and B2 for HadCM3 model are analyzed for these stations under three different time periods: 2020’s, 2050’s and 2080’s. An overall rise in mean annual precipitation under scenarios A2 and A1B for CGCM3 model have been noticed for future periods: 2020’s, 2050’s and 2080’s. Decrease, in precipitation has been found under A2 and B2 scenarios of HadCM3 model for 2050’s and slight increase for 2080’s periods. Based on the analysis of results, CGCM3 model has been found better for simulation of precipitation in comparison to HadCM3 model.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.1-14</p> Dharmaveer Singh, R.D. Gupta, Sanjay K. Jain Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Assessment of Impacts of Climate Change and Adaptation Measures for Maize Production in East Sikkim, India <p>An investigation was carried out to assess the impacts of climate change on rainfed maize yield using a yield response to water stress model (AquaCrop) and to identify suitable adaptation options to minimize the negative impacts on maize yield in East Sikkim, North East India. Crop management and yield data was collected from the field experimental plots for calibration and validation of the model for the study area. The future climate data was developed for two IPCC emission scenarios A2 and B2 based on the global climate model HadCM3 with downscaling of climate to finer spatial resolution using the statistical downscaling model, SDSM. The impact study revealed that there is an expected reduction in maize yield of 12.8, 28.3 and 33.9% for the A2 scenario and 7.5, 19.9 and 29.9% for the B2 scenario during 2012-40, 2041-70 and 2071-99 respectively compared to the average yield simulated during the period of 1961-1990 with observed climate data. The maize yield of same variety under future climate can be maintained or improved from current level by changing planting dates, providing supplement irrigation and managing optimum nutrient.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.15-27</p> Proloy Deb, S. Babel Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Impact of Climate Change on the Snow Hydrology of Koshi River Basin <p>Koshi river basin which is one of the largest river basins of Nepal has its headwaters in the northern Himalayan region of the country covered with perennial snow and glaciers. Increased warming due to climate change is most likely to impact snowpack of this Himalayan region. Snowmelt Runoff Model, a degree day based method, was used in this study to assess the snowmelt hydrology of the five sub-basins, viz. Tamor, Arun, Dudhkoshi, Tamakoshi and Sunkoshi of the Koshi river basin, with and without climate change impacts. The model has been fairly able to simulate the flow. Daily bias-corrected RCM data of PRECIS-ECHAM05 and PRECIS-HadCM3 for the period of 2041-2060 were used for future projection. A period of 2000-2008 was set as baseline period to evaluate changes in future flow. In climate change scenarios, magnitude and frequency of peak flows are expected to increase and snowmelt contribution to total river flows are likely to be more. Simulated flow results indicate that the annual flow would still be governed by monsoon flow even in the future under the climate change impact. A high probability of having more flows and snowmelt in 50’s decade than that in 40’s decade is seen. The estimated future flow by ECHAM05 is found more than those estimated by HadCM3 both seasonally and annually.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.28-44</p> A. Khadka, L.P. Devkota, R.B. Kayastha Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 UV Index and Total Ozone Column Climatology of Nepal Himalaya Using TOMS and OMI Data <p class="Default">Ultraviolet index (UVI) and Total Ozone Column (TOC) climatology of six stations of Nepal Himalaya using ground measurement, and OMI / TOMS satellite data is presented. The positive bias found in the OMI UV index from previous study is corrected empirically using a ratio factor using the clear sky coincident data of OMI and ground measurement from NILU UV multi-band filter radiometer (MBFR). UV index &gt;3 in the winter months (e.g. December) and more than 9 during the summer months (May-August) are common in most of the stations. High altitude stations even have more extreme values (&gt;11) during the summer months. Under some meteorological conditions, UV index often found more than 16 at the high altitude station (latitude 28o, altitude 2850m) during a clear sky day in the monsoon season. Diurnal and altitudinal variability is also highlighted. Monthly average TOC climatology from November 1978 to March 2012 using TOMS (Nimbus 7, Meteor3 and Earth Probe) and OMI is also presented. The ozone column data follows the annual cycle, minimum in November/December and maximum in April/May. In addition, slight negative trend of TOC is found in the data from 1978 to 2012.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.45-59</p> R.R. Sharma, B. Kjeldstad, P.J. Espy Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Impact of Climate Change on River Discharge and Rainfall Pattern: A Case Study from Marshyangdi River basin, Nepal <p class="Default">Climate models have predicted increase in monsoon precipitation for Nepal and expected to enhance further in scenario of deforestation and global green house gas emission which induces extremes resulting risk of flood, landslide during monsoon while water shortage in dry season. In this study, the impact of climate change on water resource for glacierized Marshyangdi River is evaluated using HBV light hydrological model with available hydrological data (1988-2009) to predict the future water availability and change in rainfall pattern based on available rainfall data (1981-2009). The results for Marshyangdi basin with 4104.59km<sup>2</sup> area with average discharge of 204.03 m<sup>3</sup>/s (1988-2009) suggested decrease in rainy days while increase in frequency of intense rainfall, and the projected rainfall based on downscaling showed increase in rainfall for 2050’s. The model performance is adequate and able to simulate accurate result with estimated average discharge of 224.82 m<sup>3</sup>/s (1988-2009). The simulated result provided good fit with model efficiency 0.86 for first calibration and 0.81 for second calibration, while total volume difference of 1.43% and Nash-Sutcliffe Efficiency of 0.80 between observed and simulated discharge.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.60-73</p> Achut Parajuli, Lochan Prasad Devkota, Thirtha Raj Adhikari, Susmita Dhakal, Rijan Bhakta Kayastha Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Impact of Climate Change on Water Resources in View of Contribution of Runoff Components in Stream Flow: A Case Study from Langtang Basin, Nepal <p class="Default">Observation and model-based studies suggest substantial hydrological flow pattern changes in mountain watershed where hydrology is dominated by cryospheric processes (IPCC 2007). The response of cryospheric processes to warming climate in mountain areas can be analysed by examining the responses in the seasonal and annual hydrologic regimes of rivers where snowmelt contributes significantly to the runoff. This study is carried out in Langtang basin, which aims to assess the impact of potential warming on snowmelt contribution and river discharge utilizes a Snowmelt Runoff Model (SRM), which is one of a very few models in the world today that requires remote sensing derived snow cover data as a model input. In this study, snow cover and hydrometric data were derived from Moderate Resolution Imaging Spectro-radiometer (MODIS) snow product and Snow and Glacier Hydrological Unit (SGHU) of Department of Hydrology and Meteorology, Government of Nepal. The model is calibrated for the year 2006 and validated in 2005. Different climatic scenarios are used (only change in temperature) to run the model in order to understand the impact of changing climate on runoff component and river discharge. In 2006, snow and glacier melt component contributes 35% in winter, 18% in summer and 19% annually in the stream flow. In this study, model predicts that snow and glacier melt contribution in stream flow will increase approximately at the rate of 2% in winter, 5% in summer and 4% in annual flow per 1°C temperature rise. Due to increase in snowmelt contribution, river discharge will also increase at the rate of 2% in winter, 6% in summer and 5% in annual flow under the projected temperature rise of 1°C.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.74-84</p> Bikas Chandra Bhattarai, Dhananjay Regmi Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Estimation of Discharge From Upper Kabul River Basin, Afghanistan Using the Snowmelt Runoff Model <p class="Default">In this study, we estimated discharge from Upper Kabul River basin in the Hindu Kush Mountain (Paghman range) in Afghanistan. The Upper Kabul River basin covers an area of 1633.8km<sup>2</sup> with a maximum elevation of 4522 m and minimum elevation of 1877 m. The Kabul River is one of the main rivers in Afghanistan and sustains a significant flow of water in summer months due to the melting of snow. In this study, daily discharge from Upper Kabul River basin, west of Kabul basin, for 2009 and 2011 is estimated by using Snowmelt Runoff Model (SRM) (Version 1.12, 2009), originally developed my J. Martinec in 1975. Daily precipitation, air temperature, discharge and snow cover data are used in the model as input variables. We calibrated the model for 2009 and validated in 2011. The observed and calculated annual average discharges in 2009 are 5.7m<sup>3</sup>/s and 5.6m<sup>3</sup>/s, respectively; and in 2011 are 1.33m<sup>3</sup>/s and 1.31m<sup>3</sup>/s, respectively. The model results are in good agreement with the measured daily discharges. With an increase of 1°C in temperature and 10% precipitation, the increase in discharge in winter, summer and annually relative to 2009 discharge are 39%, 18.5% and 17.9%, respectively. Similarly, with an increase of 2°C in temperature and 20% in precipitation, modeled discharge increases by 51.2%, 40.8% and 47.3%, respectively. The results obtained suggest that the SRM can be used efficiently for estimating discharge in the snow fed sub-catchment of the Upper Kabul River basin and other mountain basins in Afghanistan.</p><p class="Default">Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.85-94</p> Hafizullah Rasouli, Rijan B. Kayastha, Bikas C. Bhattarai, Ahuti Shrestha, Hedayatullah Arian, Richard Armstrong Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Influence of a Debris Layer on the Melting of Ice on Lirung Glacier, Langtang Valley, Rasuwa, Nepal This paper provides information about the variation of ice ablation rate underneath the highly heterogeneous debris layer on Lirung Glacier in Langtang Valley, Rasuwa district, Nepal. Ice melt under a debris cover has been commonly modelled using two approaches: physically-based energy-balance models and more empirical temperature-index models. Energy Balance Model (EMB) was used at the point scale to calculate melt under a debris-covered glacier. Because of the high heterogeneity of the surface layer, the ablation rate varies throughout the glacier. The average value of thermal resistance (R) in association with the meteorological variables is found to be sufficient enough to give the consistent value of ablation of glacier ice underneath the debris layer. Solar radiation is the only dominant heat flux which contributes to melting of ice under the debris cover with a little contribution of sensible heat flux in dawn because of the heat storage phenomenon of the debris. In spite of several simplifications, the model performs well and modelled melt rates give a good match to observed melt rates. Thus for accurate distributed melt modelling at different locations of the debris covered glacier it is important to considered the effects of both the external variables and the physical properties of the debris material, which in turn gives estimates of the amount of discharge from the glacier, an important component of the local water resources. Sonika Shahi, Rijan B. Kayastha Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Application of the Snowmelt Runoff Model in the Salang River Basin, Afghanistan Using MODIS Satellite Data <p class="Default">This study is carried out on the Salang River basin, which is located at the northern part of the Kabul River basin, and in the south facing slope of the Hindu Kush Mountains. The basin drains through the Salang River, which is one of the tributaries of the Panjshir River. The basin covers an area of 485.9km<sup>2</sup> with a minimum elevation of 1653 m a.s.l. and a maximum elevation of 4770 m a.s.l. The Salang River sustains a substantial flow of water in summer months due to the melting of snow. In this study, we estimate daily discharge of Salang River from 2009 to 2011 using the Snowmelt Runoff Model (SRM, Version 1.12, 2009), originally developed by J. Martinec in 1975. The model uses daily observed precipitation, air temperature and snow cover data as input variables from which discharge is computed. The model is calibrated for the year 2009 and validated for 2010 and 2011. The observed and calculated annual average discharges for the calibration year 2009 are 11.57m<sup>3</sup>s<sup>-1</sup> and 10.73m<sup>3</sup>s<sup>-1</sup>, respectively. Similarly, the observed and calculated annual average discharges for the validation year 2010 are 11.55m<sup>3</sup>s<sup>-1</sup> and 10.07m<sup>3</sup>s<sup>-1</sup>, respectively and for 2011, the discharges are 9.05 m<sup>3</sup>s<sup>-1</sup> and 9.6m<sup>3</sup>s<sup>-1</sup>, respectively. The model is also tested by changing temperature and precipitation for the year 2009. With an increase of 1°C in temperature and 10% in precipitation, the increases in discharge for winter, summer and annually are 21.8%, 13.5% and 14.8%, respectively. With an increase of 2°C in temperature and 20% in precipitation, the increases are 48.5%, 43.3% and 44.1%, respectively. The results obtained suggest that the SRM can be used as a promising tool to estimate the river discharge of the snow fed mountainous river basins of Afghanistan and to study the impact of climate change on river flow pattern of such basins.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.109-118</p> Hedayatullah Arian, Rijan B. Kayastha, Bikas C. Bhattarai, Ahuti Shresta, Hafizullah Rasouli, Richard Armstrong Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000 Heavy metals Fractionation in Bagmati River Sediments, Nepal <p class="Default">The aim of this work was speciation of heavy metals on the level of the geochemical background; in bottom sediments of the Bagmati River in Kathmandu valley. The distribution and accumulation of heavy metals in the sediments of the Bagmati River were investigated. Sediment samples from six locations were collected and characterized for metals content (cadmium, lead, copper and zinc). The determination of extractable heavy metals such as, Cd, Pb, Cu and Zn, in the sediment samples was carried out by atomic absorption spectrometry. The study has been conducted using five steps sequential extraction procedure described by tessier. Apart from total concentration, the distribution of the above metals into five fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter, and residual, was studied by means of an analytical procedure involving sequential chemical extraction. The result obtained showed total metal concentration to be in the range of Cd 0.89-2.29 mg/kg; Pb 57.58-221mg/kg; Cu 52.2 -198.17 mg/kg and 78.23-362.90 mg/kg in all the areas studied. The fractionated toxic metals like Cd, and Pb were observed to be in the range of 15-36%, and 11- 29%, respectively, in mobile or bio-available fractions of sediments. This potentially mobile fraction could pose a serious threat, with respect to contamination of waterways and aquatic environment.</p><p>Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.119-128</p> Sadhana Pradhanang Kayastha Copyright (c) 2016 SOHAM-Nepal Tue, 30 Aug 2016 00:00:00 +0000