ABSTRACT
Testing the significance of observed trends in hydro-meteorological time series has received a
great attention recently, especially in connection with climate change. The changing pattern of rainfall
deserves urgent and systematic attention for planning, development, utilisation and management of
water resources. The daily data on variable were converted to monthly and then computed to seasonal
and annual series. Annual rainfall (mm/yr) was calculated as the sum of monthly values. The missing
values in the data were computed by using average method. The records of rainfall were subjected to
trend analysis by using both non-parametric (Mann-Kendall test) and parametric (linear regression
analysis) procedures. For better understanding of the observed trends, data were computed into
standardised precipitation indices (SPI). These standardised data series were plotted against time and
the linear trends observed were represented graphically. Trend analysis results of rainfall show that out
of 15 annual trends 6 (40%) are increasing and 9 (60%) are decreasing in nature where 1 (6.6%) is
statistically significant (increasing) and 2 (13.3%) are statistically significant (decreasing) at 95%
confidence level. Similarly, the changes were investigated for the four seasons: winter (DecemberMarch), pre-monsoon (April-June), monsoon (July-September) and post-monsoon (OctoberNovember). The analysis of rainfall, annual as well as seasonal, of different gauge stations in Satluj
River Basin showed a large variability in the trends and magnitudes from 1984 to 2010. The rainfall
shows great temporal and spatial variations, unequal seasonal distribution with frequent departures
from normal. Majority of gauge stations have experienced decreasing trends, both on seasonal and
annual scales. Some were statistically significant at 95% confidence level. The sensitivity of rainfall
variations provides important insight regarding the responses and vulnerability of different areas to
climate change. It will further strengthen the formulation of future strategy for management of water
resources.
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