Hydro-meteorological Analysis of Langtang Khola Catchment, Nepal Tirtha R. Adhikari 1, Lochan P. Devkota 1, Suresh.C Pradhan 2, Pradeep K. Mool 3 1 Central Department of Hydrology and Meteorology Tribhuvan University 2 Department of Hydrology and Meteorology, Nagpokhari, Nepal 3 International Centre for Integrated Mountain Development, Lalitpur, Nepal
Contents Introduction and Background Objective of the study Study area Meteorological information Hydrological information Old snow survey information Methodology for flow simulation by SRM Future work
Introduction and Background Water is main natural resource of Nepal, socio-economy of the country through hydro-electricity and irrigation depends on it The current global mean temperature is projected to rise by 0.3 to 4.8 C by the late-21st century ( IPCC, 2013) Due to increase of temperature water cycle is intensified causing an increase in global mean precipitation (IPCC, 2013) At the same time, there is redistribution causing some areas to receive more or less precipitation depending on the season (IPCC, 2013) 9/11/2015 3
contd High variability in climate, lack of data, large uncertainties in climate change projection by models and uncertainty about the response of snow and glaciers 9/11/2015 4
Objective The main objective: Impact of climate change on flow simulation specially to understand the contribution of snow melt at Langtang Khola Hydrological Station
Data collection Hydro-meteorological data are collection from DHM, government of Nepal, DHM is initiated snow and glacier hydrological activities in the year 1987 with the GTZ, Germany as a pilot project for 2 years. Full fledge project was started in the year 1990 and completed in 1997. During the project period: 6 hydroclimatic stations were established in high Himalayas of Nepal Introduced tracer technology for determination of river discharge and Established a tracer laboratory
Location of High altitude Hydro- meteorological Stations in Nepal Langtang 3800 m. Langtang Khumbu 4335 m Annapurna 3470 m Makalu 3980 m Kanjiroba 3770 m Humla 4220 m Imja Modi Barun Sanu Bheri Humla Karnali C HI NA Kanjuroba Annapurna Langtang Kathmandu Mt Everest Legend: Trans-Himalaya Higher Himalayas Central Hills Mahabharat Range Siw alik Terai Simara 0 100 200 Kilometers
Study Area Meteorological station: Latitude: 28 0 12 43 Longitude: 85 0 31 34 Hydrological station Latitude: 28 0 13 41 Longitude: 85 0 34 28 Area: 361 Km 2 8
Meteorology of Langtang Khola Kyangjing
PPT (mm) Coeffe. of variation Precipitation data information Kyangjing Average Monthly PPT and its Variations (1988-2014) 200 180 160 Avarage PPT (mm) 166 Coeff of Vearation 200 180 160 140 140 120 120 100 100 80 80 60 60 40 40 20 0 3 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 20 0 Month
Percentage of Seasonal PPT (1988-2014) 76 % of PPT occurs in monsoon season 5% of PPT occurs in winter season 5 % 4 % 15 % DJF MAM JJAS 76 % ON 11
1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 PPT (mm) Kyangjing Annual PPT (mm) (1988-2014) 1200 1000 y = 11,477x - 22299 800 600 400 200 0 Year
Rainy Days Monthly Average Rainy Days (1988-2014) 30 25 26 20 15 10 5 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month
1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Rainy Days Kyagjing Annual Rainy Days (1988-2014) 160 140 120 100 80 60 40 20 0 Year
Tempreature( 0 C) Monthly Average Temperature (1988-2008) 15,0 Warmest is July, the average TMAX is 12.3 0 C 10,0 5,0 Coldest is Feb, the average TMIN is 7.2 0 C 0,0-5,0-10,0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Mean Temp. 0C -1,9-2,4 0,5 3,4 6,0 8,3 9,9 9,4 7,9 4,5 1,8 0,2 Maximum Temp. 0C 3,1 2,4 5,2 8,0 10,0 11,4 12,3 11,9 10,7 8,5 6,4 5,2 Minimum Temp. 0C -7,0-7,2-4,2-1,3 1,9 5,2 7,5 6,9 5,0 0,5-2,8-4,8 15
Sunshine Duration (Hour) Monthly Average Sunshine duration situation (1988-2008) Lowest sunshine duration Jun and July due to monsoon cloud activity 8 7 6 5 4 Highest sunshine duration occurs in April 3 2 1 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Sunsine Duration (hour) 6 6,5 6,5 7,5 7 3 3 3,5 3,5 6,5 6,5 6 16
Historical Snow Measurements in Langtang valley Snow measurements work in Feb,1991 Department of Hydrology and Meteorology, Governments of Nepal
WE = D* h* 10 Density = WE/(h*10) Historical Snow Measurement Data Date: 25 Feb 1991 Height 4980 m Exposition SE Slope Gentile Plce Tsergo-Ri Langtang Time15 PM Air Temperature -8 0 C Weather Cloudy Level 1 Height cm 1 WE (mm) 2 Height (cm) 2 WE (mm) 2 Height (cm) 3 WE (mm) 4 Mean density (g/cm 3 ) 1 28 59 29 62 29 60 0.21 2 47 198 47 202 47 194 0.42 3 40 170 42 180 40 172 0.42 Sum 115 427 118 444 116 426 0.37
Hydrology of Langtang Khola
Gauge Height (m) Validity Rating Curve No. From To 1 01.01.1991 13.06.1993 2 14.06.1993 08.10.1993 1 09.10.1993 29.04.1997 2 30.04.1997 05.04.1999 1 06.04.1999 04.06.2002 3 05.06.2002 13.09.2002 2 14.09.2002 31.12.2006 3 2,5 2 1,5 Rating Curve - 1: Q = 2.429(H+0.568) 2.126 Rating Curve - 2: Q = 0.632(H+1.562) 2.716 Rating Curve - 3: Q = 0.654(H+1.889) 2.530 Rating Curve of Langtang Khola 1 0,5 0 0 5 10 15 20 25 30 35 Discharge (cumec)
Stage Height (m) Rating Curve of Langtang Khola (2006-2013) 3,00 2,75 Q = 1.943(H + 0.501)^2.188 2,50 2,25 2,00 1,75 1,50 1,25 1,00 0,75 0,50 0,25 0,00 2,50 5,00 7,50 10,00 12,50 15,00 17,50 20,00 22,50 25,00 Discharge (m3/s)
1-Jan-13 11-Jan-13 21-Jan-13 31-Jan-13 10-Feb-13 20-Feb-13 2-Mar-13 12-Mar-13 22-Mar-13 1-Apr-13 11-Apr-13 21-Apr-13 1-May-13 11-May-13 21-May-13 31-May-13 10-Jun-13 20-Jun-13 30-Jun-13 10-Jul-13 20-Jul-13 30-Jul-13 9-Aug-13 19-Aug-13 29-Aug-13 8-Sep-13 18-Sep-13 28-Sep-13 8-Oct-13 18-Oct-13 28-Oct-13 7-Nov-13 17-Nov-13 27-Nov-13 7-Dec-13 17-Dec-13 27-Dec-13 Water level (m) Langtang Khola Stage Height (m)_2013 2,50 2,00 1,50 1,00 0,50 0,00
Maximum Discharge (m 3 /s) Monthly Maximum Discharge in Langtang Kola 25,00 23,09 20,00 15,00 10,00 5,00 0,00 3,87 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
1988 1990 1992 1994 1996 1998 2000 2002 2004 2006 2008 2010 2012 2014 Discharge (m 3 /s) Annual Observed Discharge Trend (1988-2014) 10,00 9,00 8,00 7,00 6,00 5,00 4,00 3,00 2,00 1,00 0,00
Methodology for flow simulation by Snowmelt Runoff Model (SRM)
Flow simulation year After pre-processing and analyzing the hydro-meteorological data of Kyangjing 2000-2006 will be taken as parameter calibration year 2007-2013 will be taken as validation year
Introduction to Snowmelt Runoff Model (SRM) Developed by Martinec in 1975 in Swiss Snow and Avalanche Research Institute Estimation of daily stream flow in Mountain basins Based on degree day method, can be used to simulate/forecast Simple and Efficient
Snow cover map of Langtang Catchment 25 Feb 2015
Snow Cover Mapping of Langtang MODIS Daily Snow products Preprocessing and processing of MODIS snow products using : MODIS Reprojection tool Which includes; Mosaicking Spatial and temporal filtering Generation of daily snow cover area of Langtang Catchment
Basic snowmelt runoff model Q n+1 = [c Sn. a n (T n + T n ) S n + c Rn. P n ] (A.10000/86400) (1-k n+1 ) + Q n k n+1 Snow melt Rainfall Flow Recession Q : Basin discharge n : Day indicator T : Air temperature P : Precipitation falling as rain S : Snow covered area A : Zonal area k n+1 : Recession coefficient a n : Degree day factor c sn,c rn : correction for losses due to snowmelt and rainfall
Cont. Variables (Inputs) Temperature Precipitation Snow Covered Area % Meteorological Stations MODIS Snow product Measured Forecasted
Cont Runoff Coefficients (c s,c r ) Degree Day Factor (a) 7Parameters Temperature Lapse Rate ( ) Critical Temperature (T crit ) Rainfall Contributing Area Time Lag (L) Recession Coefficient
Future work Calibration and Validation of SRM Simulate daily discharge Calculating runoff components in Langtang Catchment The research is still going on
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