Localized environmental variability within the Hindukush-Himalayan region of Pakistan

Abstract

The Hindukush-Himalayan (HKH) region, known for its eco-environmental importance, has been witnessing transformations in recent years governed by factors such as climate variability, land use shifts, and population growth. These changes have profound implications for regional sustainability, water resources, and livelihood. This study attempts to explore the spatial and temporal variability in selected environmental parameters including land surface temperature (LST), normalized difference vegetation index (NDVI), precipitation patterns, and normalized difference snow index (NDSI), and land use land cover (LULC) from 1990 to 2022 using Landsat imageries (30 m spatial resolution), CHIRPS precipitation data at 0.05° spatial resolution. The study area spans 32,000 km² covering two major political/administrative divisions (Malakand and Hazara) in the HKH region of Pakistan. The study area was selected primarily because of the unprecedented changes over the last three decades. For detailed spatial analysis, the area was divided into five elevation zones and LST, NDVI, NDSI, and LULC analyses were conducted utilizing primarily the Google Earth Engine (GEE) platform and climate engine. The study results revealed a notable rise in LST in the lowest elevation zone. The NDVI and LULC analyses revealed a noticeable decline in vegetation cover from 5988 km² in 1990, to 4225 km² by 2010, followed by a growth to 7669 km² in 2022, since 2010 after the launching of the Billion Tree Tsunami Afforestation Project (BTTAP) in 2013. Likewise, the precipitation patterns exhibit transitioning from low to high precipitation levels. However, the most notable finding of the study is the marked decline in snow covered area 7000 km² to 3800 km² between 1990 and 2022.