Evaluation of Satellite Based Precipitations and Their Applicability for Rainfall Runoff Modelling in Narayani Basin of Nepal

High spatial variability of precipitation over Nepal demands dense network of rain-gauge stations. But to set-up a dense rain gauge network is almost impossible due to mountainous topography of Nepal. Also the dense rain gauge network will be very expensive and some time impossible for timely maintenance. Satellite precipitation products are an alternative way to collect precipitation data with high temporal and spatial resolution over Nepal. In this study, the satellite precipitation products TRMM and GSMaP were analyzed. Precipitation was compared with ground based gauge precipitation in the Narayani basin, while the applicability of these rainfall products for runoff simulation were tested using the LANDPINE model for Trishuli basin which is a sub-basin within Narayani catchment. The Nash-Sutcliffe efficiency calculated for TRMM and GSMaP from point to pixel comparison is negative for most of stations. Also the estimation bias for both the products is negative indicating under estimation of precipitation by satellite products, with least under estimation for the GSMaP precipitation product. After point to pixel comparison, satellite precipitation estimates were used for runoff simulation in the Trishuli catchment with and without bias correction for each product. Among the two products, TRMM shows good simulation result without any bias correction for calibration and validation period with scaling factor of 2.24 for precipitation which is higher than that for gauge precipitation. This suggests, it could be used for runoff simulation to the catchments where there is no precipitation station. But it is too early to conclude by just looking into one catchment. So extensive study need to be done to make such conclusion.Journal of Hydrology and Meteorology, Vol. 8(1) p.22-31

Assessment of Impacts of Climate Change and Adaptation Measures for Maize Production in East Sikkim, India

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.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.15-27

FNEP: Finnish-Nepalese Project for improving the meteorological readiness in Nepal

The Finnish Nepalese Project (FNEP) is a project aimed for the development of infrastructure, education and preparedness to better respond to the increased risks related to the weather-related natural disasters by climate change in Nepal. The project duration was 2010-2012, and the partners were the Finnish Meteorological Institute and the Government of Nepal, Ministry of Environment and Science, Department of Hydrology and Meteorology. The project is financed by the Finnish Ministry of Foreign Affairs. This paper introduces the concept and main results of the project.Journal of Hydrology and Meteorology, Vol. 8(1) 2012, p.72-76

Heavy metals Fractionation in Bagmati River Sediments, Nepal

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.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.119-128

Application of the Snowmelt Runoff Model in the Salang River Basin, Afghanistan Using MODIS Satellite Data

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 485.9km2 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 11.57m3s-1 and 10.73m3s-1, respectively. Similarly, the observed and calculated annual average discharges for the validation year 2010 are 11.55m3s-1 and 10.07m3s-1, respectively and for 2011, the discharges are 9.05 m3s-1 and 9.6m3s-1, 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.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.109-118

Climatic Water Balance of Annapurna, Langtang and Khumbu regions of Nepal Himalaya

For the protection of the environment, climatic water balance studies play key role. This study attempts to assess the potential water availability at the Annapurna, Langtang and Khumbu regions of Nepal Himalaya. Potential evapotranspitration (PET) is calculated by CROPWAT 8 with the help of maximum and minimum temperature, relative humidity, wind speed and sunshine hour. The climatic water balance of water bodies is calculated on the basis of Thornthwait procedure. These calculations help to examine annual water surplus (WS) and water deficit (WD) periods. Potential water surplus at three selected station is calculated by above techniques after averaging the data of time period from 1987 to 2008. The main aim of this study is to compare the obtained result from the climatic water balance for the selected sites of the Nepal Himalaya region. This study will provide climatic water balance information of the given area which will be useful for sustainable management of water resources in local and small area of the Nepal Himalaya.Journal of Hydrology and Meteorology, Vol. 8(1) p.47-57

Spatial analysis of water quality of the Karra River, Hetauda, Nepal

The assessment of water quality of Karra River in Hetauda, Nepal was carried out by determining the changes in the concentration levels of eight physico-chemical parameters (pH, Electric conductivity (EC), bicarbonate, dissolved oxygen (DO), silica, chemical oxygen demand (COD), phosphate and nitrate). The samples were collected from upstream, industrial belt and downstream of the Karra River. The Karra River is the dumping ground for industrial effluents of Hetauda industrial district (HID). On analysis, the concentrations of most of the physico-chemicals parameters were found to be above the prescribed limits for industrial wastewater into inland surface waters. Dissolved Oxygen was found to be in the range of 0.49- 8.47 mg/L while COD, nitrate and phosphate were recorded in the range of 8.3-367 mg/L, 0.35- 78.22 mg/L and 0.01-1.64 mg/L, respectively. Concentrations of most of these parameters were within the prescribed limits in the samples collected from upstream and downstream, revealing the river still in good condition at these points indicating less human interference at the head water region and good self-purification capacity at downstream. However the concentrations of the pollutants’ parameters are higher at the sample points just after effluent discharge.Journal of Hydrology and Meteorology, Vol. 8(1) p.58-65

Investigating the Impact of Climate Change on Future Runoff of River Satluj

Climate change has been emerging as one of the challenges in the global environment. Information of predicted climatic changes in basin scale is highly useful to know the future climatic condition in the basin that ultimately becomes helpful to carry out planning and management of the water resources available in the basin. Climatic scenario is a plausible and often simplified representation of the future climate, based on an internally consistent set of climatological relationships that has been constructed for explicit use in investigating the potential consequences of anthropogenic climate change. This study based on statistical downscaling, provide good example focusing on predicting the rainfall and runoff patterns, using the coarse general circulation model (GCM) outputs. The outputs of the GCMs are utilized to study the impact of climate change on water resources. The present study has been taken up to identify the climate change scenarios for Satluj river basin, India.Journal of Hydrology and Meteorology, Vol. 8(1) p.10-21

UV Index and Total Ozone Column Climatology of Nepal Himalaya Using TOMS and OMI Data

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 >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 (>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.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.45-59

Estimation of Discharge From Upper Kabul River Basin, Afghanistan Using the Snowmelt Runoff Model

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 1633.8km2 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 5.7m3/s and 5.6m3/s, respectively; and in 2011 are 1.33m3/s and 1.31m3/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.Journal of Hydrology and Meteorology, Vol. 9(1) 2015, p.85-94