Long term trend analysis of rainfall at heavy rainfall zone of South Gujarat, India

The study of precipitation trends is critically important for a country like India whose food security and economy are dependent on the felicitous availability of water. Present study was carried out using monthly, seasonal and annual rainfall data of 112 years (1901–2012) for Navsari and Bharuch districts of heavy rainfall zone of south Gujarat. The long term changes in rainfall were determined by Mann-Kendall rank statistics and linear trend analysis. The annual rainfall at Navsari illustrated significantly increasing trend (+ 2.72 mm yr⁻¹), while decreasing trend in rainfall was observed at Bharuch location (−0.36 mm yr⁻¹). This, also reflected into their decadal analysis i.e. + 29.22 mm decade⁻¹ at Navsari, while-7.61 mm decade⁻¹ at Bharuch. During pre-monsoon, post-monsoon and winter season, rainfall showed decreasing trend over both locations. The increasing trend of monsoonal rainfall was observed at Navsari and decreasing trend was found at Bharuch. The long term data analysis divulged that at Bharuch station wider variability rainfall was observed as compared to Navsari.