Trend analysis of rainfall and runoff in the Jhelum basin of Kashmir Valley

Abstract

Trend analysis of rainfall and runoff at selected locations of the basin can be good indicator of the flood prediction. In this study, Modified Man Kendall Test (MMKT) was undertaken to observe the existence of significant trends in the rainfall depth of both annual and monsoon periods for a period of 30 years (1980-2009), for six stations in the Jhelum River Basin (JRB) in India (viz. Srinagar, Quazigund, Pahalgam, Gulmarg, Kupwara and Kokernag). Besides this, the maximum and minimum stream flow measured at six hydrologic monitoring stations in JRB (viz. Sangam, Awantipora, Padshibagh, Munshibagh and Baramulla) for a period of 30 years (1980 to 2009) were also subjected to MMKT using a developed interface in MATLAB. It was observed that only Kupawara, Gulmarg and Kokernag stations exhibited significant decreasing trend of annual rainfall depth at 0.05 significance level corroborated by Sen’s slope -12.51, -18.14 and -15.1 respectively. Whereas, the monsoon rainfall depth for only Kupwara showed significant decreasing trend at 0.05 level of significance but the magnitude of decrease was less as indicated by Sen’s slope of -1.94 as compared to the annual rainfall depth. It was also observed that the decreasing trend of annual rainfall is more than that of the monsoon rainfall which indicated low probability of occurrence of flood due to rainfall in the JRB. Moreover, the Awantipora and Munshibagh runoff monitoring stations exhibited decreasing trend in the peak discharge and Baramulla, Awantipora, and Asham showed decreasing trend of minimum discharge at P=0.05. Nonetheless, it was observed that long term trend analysis of rainfall and surface runoff of JRB would serve as a good indicator of flood occurrences under changing climate.