Statistical Analysis for Change Detection and Trend Assessment in Climatological Parameters

Abstract

Considering the importance of climatic variability on availability of water, irrigation demand, crop yield and other areas of life, an assessment of change detection and trend on monthly, seasonal and annual historical series of different climatic variables of Raipur, a capital city of newly created Chhattisgarh state of India, have been carried out. The change detection analysis has been conceded using Pettitt’s test, von Neumann ratio test, Buishand’s range test and standard normal homogeneity (SNH) test, while non-parametric tests including linear regression, Mann-Kendall and Spearman rho tests have been applied for trend analysis. The annual series of minimum temperature, wind speed, sunshine hour showed significant change points, while evaporation indicated a doubtful case and maximum temperature confirmed the homogeneity at 95 % confidence level. The change point analysis results of meteorological variables indicated different change points from year 1990 to 2000, with maximum change points in and around 1995. This was due to the industrialization and urbanization in this period as this city was selected as capital of Chhattisgarh state. Based on the results of change point analysis and development scenarios in and around Raipur city, trend analysis was applied for three different time periods namely: P-1 from 1971 to 1995, P-2 from 1986 to 2012, and P-3 the whole series from 1971 to 2012. The significant rising trend in the summer and rainy months in case of minimum temperature, and the winter months in case of maximum temperature during the periods P-2 and P-3 may affect water availability and water demands in the region. The relative humidity showed a significant rising trend in few summer and rainy months series of all three periods under investigation, while sunshine hours and evaporation indicated random distribution prior to 1995 (P-1), but a significant falling trend in few winter months and annual series during period P-3. Although the annual minimum, maximum temperatures and relative humidity showed a rising trend, the falling trend of pan evaporation may be due to strong declining trends in wind speed and falling trend in sunshine hour series on a long term basis.