Innovative polygon trend analysis of monthly precipitation (1952–2015) in the Hindukush‐Karakoram‐Himalaya river basins of Pakistan

Abstract

The Hindukush-Karakoram-Himalayas (HKH) mountainous range supplies water to 10 river basins serving eight countries. The present study focuses on the river basins located within the HKH region in Pakistan. The modified Soil and Water Assessment Tool (SWAT+) was used to split the research region into 13 subbasins. The Mann-Kendall, Sen's slope, innovative polygon trend analysis (IPTA), and innovative trend analysis (ITA) methods were used for the monthly precipitation time series. The Shyok sub-basin (central Karakoram) experienced rising trends for all seasons, while the southwestern Karakoram (Hunza) showed a rising trend only for the winter. The Hindukush Mountain Range feeds five subbasins (Gilgit, Chitral, Swat, Kabul, and Kurram). The Gilgit and Kurram subbasins observed an upward trend for all seasons. A falling trend in spring and transition from spring (falling) to summer (rising) was observed for the Swat and Kabul sub-basins. The Chitral sub-basin received rising precipitation in spring, summer, and autumn, whereas no trend was observed during winter. In the southern Himalayas (Kanshi and Jhelum), no trend was observed in winter and autumn and a falling trend in spring and summer. The Kunhar sub-basin (southern Himalaya) showed rising trends in winter, spring, and autumn. In contrast, the Soan sub-basin (eastern Himalaya) has no trend in spring, and other seasons show rising trends. The sub-basin Upper Indus experienced a rising trend for autumn, winter, and summer, while a downward trend was observed in spring. The IPTA and ITA approaches are much more sensitive than the Mann-Kendall method in detecting trends. Although the innovative methods are mostly compatible with each other (90%), the IPTA presents additional information about trend transitions between successive parts of the time series. The results presented in this study are an advancement in the investigations made so far in this region and will help to understand the climate and hydrology of this region.

Spatiotemporal Runoff Analysis and Associated Influencing Factors in Chitral Basin, Pakistan

“…Similar to Hussain, et al [27], we observed significantly increasing runoff trends in CRB on a seasonal and annual scale, except in autumn. Overall, precipitation increased in the region, except in annual and spring during 1964-2012 in the CRB, as these findings agree with those of [73]. Annual precipitation and mean annual runoff displayed increasing trends, and [26] attributed the increase in precipitation and snow cover to the possible reasons for increased runoff in the CRB.…”

Cross Comparison of Traditional and Innovative Trend Methodologies to Understand Climate Change Process

“…This method has been developed recently (Şen et al, 2019). Compared to ITA, IPTA detects trends in time series, visualizing the increasing/decreasing trend and the transition between months/seasons as polygons (Ahmed et al, 2022). IPTA offers several advantages over other conventional methods, including:…”