Assessment of precipitation trends in Gilgit Baltistan (Pakistan) for the period 1980−2015: an indicator of climate change
Keywords:
Mann-Kendall test; Sen'sslope; Precipitation; Monsoon; Climate change; Gilgit-BaltistanAbstract
Long-term seasonal and annual precipitation trends are among the effective tools to assess the climate change of a region. In this study, long-term seasonal and annual trends were assessed for six meteorological stations of the Gilgit Baltistan (GB) (a mountainous belt of Pakistan) during 1980−2015. Non parametric Mann-Kendall (MK) and Sen's slope (SS) techniques were applied to find strength and magnitude of trends at
10% significance level. Serial correlation in data was removed by using Trend Free Pre-Whitening (TFPW) technique. Results revealed increasing trends in mean annual precipitation at five stations (significant only at Gupis with a SS of 7.34 mm/year) and decreasing trend at one station (Astore) with a SS of -3.05 mm/year. The evidence of increasing trends in mean annual precipitation in five out of six hydro-climatic stations indicated perennial flow in the Indus River and which ensure sufficient ground water recharge for the downstream plain areas. All stations showed increasing trends in precipitation during monsoon season while in other seasons both positive and negative trends found were non-significant. Precipitation trend in post- monsoon season is decreasing in most parts of the GB that might cause temporary dry condition in the Indus River downstream. Based on the overall mean precipitation analysis for the entire GB, there were non- significant increasing seasonal and annual trends except the post-monsoon season. These seasonal variations in precipitation might affect water supply to the Indus River resulting in less availability of water for agriculture sector and in turn affecting crop production in the downstream plains. Seasonal trends in precipitation could directly affect agricultural activities which is a vital source of livelihood in Pakistan. To be on safe side, construction of water storage structures (dams) is highly needed to avoid possible floods during monsoon season and store most of the precipitation to meet off season demands especially in dry season.
References
Arun, M., Sananda, K.,Anirban, M., 2012. Rainfall trend analysis by Mann−Kendall Test: A case study of North-Eastern part of Cuttack District, Orissa, India. International Journal of Geology, Earth and Environmental Sciences, 2(1), 70 -78.
Atif, I., Mahboob, A.M., Iqbal, J., 2015. Snow cover area change assessment in 2003 and 2013 using MODIS data of Upper Indus Basin, Pakistan. Journal of Himalayan Earth Sciences, 48(2), 117-128.
Chen, H., Guo, S., Xu, C., Vijay, P.S., 2007. Historical temporal trends of hydro−climatic variables and runoff response to climate variability and their relevance in water resource management in the Hanjiang basin. Journal of Hydrology, 344, 171-184.
Christopher, J.M., Jerome, J.M., Martin, F.M., 2012. Trends in precipitation and temperature in Florida, USA. Journal of Hydrology, 452-453, 259-281.
Frich, P., Alexander, L.V., Delaa-Marta P., Gleason, B., Haylock, M., Klein, T.A.M.G., Peterson, T., 2002. Observed coherent changes in climate extremes during the second half of 20th Century. Climate Research, 19, 193-212
Keggenhoff, I., Elizbarashvili, M., Farahani, A.A., King, L., 2014. Trends in daily temperature and precipitation extremes over Georgia (1971- 2010). Weather and Climate Extremes, 4, 75-85.
Khaliq, M.N., Ouarda, T.B.M.J., Gachon, P., Sushama, L., St−Hilaire, A., 2009. Identification of hydrologic trends in the presence of serial and cross correlations: A review of selected methods and their application to annual flow regimes of Canadian rivers. Journal of Hydrology, 368, 117-130.
Khattak, M.S., Babel, M.S., and Sharif, M., 2011. Hydro-meteorological trends in the upper Indus basin in Pakistan. Climate Research, 46, 103-119.
Khattak, M.S., Ali, S., 2015. Assessment of temperature and rainfall trends in Punjab province of Pakistan for the period 1961-2 014. Journal of Himalayan Earth Sciences, 48(2), 42-61.
Messerli, B., Viviroli, D., Weingartner, R., 2004. Mountains of world: water towers for 21st century. Berne (Switzerland): Paul Haupt. Special Report Number 13. The Royal Colloquium: Mountain Areas: A Global Resource, 29-34
Maida, Z., Ghulam, R., 2011. Frequency of extreme temperature and precipitation events in Pakistan 1965-2009. Science International (Pakistan), 23(4), 313-319.
Naheed, G., Kazmi, D. H., 2013. Seasonal variation of rainy days in Pakistan. Pakistan Journal of Meteorology, 9(18), 9−13.
Onoz, B., Bayazit, M., 2003. The power of statistical tests for trend detection. Turkish Journal of Engineering Environmental Sciences, 27, 247–251.
Phillips, W., Sloan, V., Shroder, J., Sharma, P., Clarke, M., Rendell, H., 2000. Asynchronous glaciation at Nanga Parbat, Northwestern Himalaya Mountains Pakistan. Geology, 28(5), 431−434.
Rasul, G., Mahmood, A., Sadiq, A., Khan, S.I., 2012. Vulnerability of the Indus delta to climate change in Pakistan. Pakistan Journal of Meteorology, 8(16), 89−107.
Raza, M., Hussain, D., Rasul, G., Akbar, M., Raza, G., 2015. Variation of surface temperature and precipitation in Gilgit−Baltistan (GB), Pakistan from 1955 to 2010. Journal of Biodiversity and Environmental Sciences, 6(2), 67−73.
Salma, S., Rehman, S., Shah, M.A., 2012. Rainfall trends in different climate zones of Pakistan. Pakistan Journal of Meteorology, 9(17), 37-47.
Sen, P.K., 1968. Estimates of the regression coefficient based on Kendall's tau. Journal of American Statistical Association, 63, 1379–1389.
Theil, H., 1950. A rank invariant method of linear and polynomial regression analysis, Part 3. Netherlands Akademie van Wettenschappen, Proceedings, 5, 1397–1412.
Thelma, A.C., Rusalina, G.D.G., Flaviana, D.H., David, M. W., 2014. Long−term trends and extremes in observed daily precipitation and near air surface temperature in the Philippines for the period 1951−2010. Atmospheric Research, 145−146, 12−26.
Yue, S., Pilon, P.J., Phinney B., Cavadias, G., 2002. The influence of autocorrelation on the ability to detect trend in hydrological series. Hydrological Processes, 16(9), 1807-1829.
