Precipitation variability and its trend detection for monitoring of drought hazard in northern mountainous region of Pakistan

摘要

The Standardized Precipitation Index (SPI) is a powerful tool, requiring only precipitation data for calculating the intensity, duration, magnitude, severity and frequency of drought. Moreover, it provides helpful coverage of drought impacts on multi time scales. In this study, the SPI technique was applied to the dataset of 30 years (1986-2015) to detect drought condition in Northern Pakistan, which is a frequent drought-hit area. The coefficient of variability (CV) was used to analyze precipitation trend, while linear regression model was adopted to detect trend. The detected precipitation variability was spatially interpolated by applying the Inverse Distance Weighted (IDW) technique. It is evident from the analysis that there is great variability in precipitation pattern and trend in the study area. During the winter season, a positive trend in the precipitation variability was detected in the Himalaya and Karakorum region. In the Hindukush region, only Pattan weather station has observed a positive variability trend. In contrast to winter variability, pre-monsoon season has observed an increased variability in the Hindukush region, while the Karakorum and Himalayas regions observed a negative trend. The monsoon season has observed a decreased variation in precipitation throughout the study area except for Pattan. In post-monsoon, Skardu weather station of Himalayas, Gupis and Bunji of Karakorum region and Pattan of Hindukush region have witnessed increased precipitation variability. The meteorological stations of Karakoram and Himalaya have noticed a negative trend of precipitation variability, while in the Hindukush region, all the meteorological stations have witnessed a positive trend of variability except Saidu Sharif and Dir stations. The results of SPI also indicated a drought condition in the study area. Similarly, the SPI results of all return periods have shown a significant drought condition in the Himalayas followed by-in terms of frequency and magnitude-Karakoram and Hindukush, respectively. Based on the above findings, it is recommended that the agriculture experts should work on drought-resilient crops in order to cope up with the harsh prevalent climatic condition in Northern Pakistan.