Impact assessment of drought monitoring events and vegetation dynamics based on multi-satellite remote sensing data over Pakistan.

Drought is a complex hazard caused by the disruption of rainwater balance, and it always has an impact on ecological, farming and socio-economic. In order to protect farming land in Pakistan, effective and timely drought monitoring is extremely essential. Therefore, a regular drought monitoring is required to study drought severity, its duration and spread, to ensure effective planning and to help reduce their possible adverse impacts. In this study, multi-satellite data were used for reliable drought monitoring. For monitoring changing trend of drought in Pakistan, the NVSWI, DSI, VCI, and NAP indices were chosen as a tool incorporated with Moderate Resolution Imaging Spectroradiometer (MODIS)-based NDVI and ET/PET. Due to the low vegetation and significantly high changing trend of drought, NDVI, DSI and TVDI are useful to characterize drought frequency in Pakistan. The yearly DSI index shows that Pakistan suffered of drought with low vegetation during 2001, 2002 and 2006 study years. The seasonal DSI, VCI, NAP, NDVI, and NVSWI values confirmed that 2001, 2002 and 2006 led to severe drought years in Pakistan. The regression analysis between VHI, VCI, NDVI and NVSWI values are significantly positively correlated. The NAP, DSI, and NVSWI showed the positive signs for good drought monitoring indices for agricultural regions of Pakistan. The trend of drought change from 2001 to 2017 also showed characteristics. The results showed that from 2001 to 2017, the drought trend of the whole region changed obviously, and the overall drought frequency showed a downward trend. The good performance of DSI, and NVSWI could, explicitly, contribute progressively towards improving specific drought mitigation strategies and disaster risk reduction at regional and national levels.