Innovative Polygon Trend Analysis Method: A Case Study of the South Gujarat Region

Abstract

The unpredictability of precipitation can have dramatic impacts on agriculture, ecosystems, and water resource manage¬ment. It is needed to study the change in trends of precipitation due to climate change. The present aims to assess the impact of climate change, trend analysis using the Innovative polygon trend analysis (IPTA) method considering monthly precipitation data of 120 years for seven districts of South Gujarat. Further comparison is carried out with the trends predicted by the well accepted Mann-Kendall (M-K) method. IPTA method shows increasing trends during the monsoon season (June and August) but decreasing trends for the monthly precipitation of July for all seven districts. It can be said that over the period of years, less precipitation occurs in the month of July. De- creasing trends are observed for the post-monsoon and pre-monsoon seasons. No trend is observed for the monthly precipitation of Febru- ary which demands preparedness in the water Management system. Interestingly, monthly variation of trends is observed for Dang Dis- trict for both monsoon and post-monsoon seasons. However, a variation in trends in the monsoon season leads to difficulties in the water management system, and sometimes flood events occur. Trends predicted by the Mann-Kendall method show decreasing trends in the post-monsoon season and increasing trends for the monsoon season. Whereas Tapi and Bharuch districts show decreasing trends in the month of June. No trend is predicted in the pre-monsoon season. Comparative analysis of trends predicted by IPTA and M-K method shows similar results for Post Monsoon. IPTA predicts decreasing trends in pre-monsoon season whereas the M-K test shows no trends in pre-monsoon season. The monthly prediction by IPTA may bring useful information for water utility sectors and decision-makers in the study area.

Keywords: climate change, innovative polygon trend analysis, precipitation, Mann-Kendall, rainfall pattern