Vegetation Health Index (VHI) analysis during drought season in Brantas Watershed

Abstract

The Brantas Watershed located in East Java has the vulnerability of drought as one of hydrometeorological disasters. The Vegetation Health Index (VHI) as one of remote sensing index was used to analyse drought. VHI can be derived based on both the Land Temperature Surface (LST) and Normalized Differenced Vegetation Index (NDVI). This research aimed to determine the influence of LST and NDVI, respectively, to VHI, especially in dry season of 2008-2017. The data used were MODIS Vegetation Indices (MOD13A1) and MODIS Land Surface Temperature (MOD11B1). The influence of LST and NDVI to VHI in the Brantas Watershed was analysed using correlation and regression testing. The LST-NDVI correlation of Brantas Watershed was negative (-0.73). The high temperature distribution was dominantly located in the low-density vegetation areas. The LST-VHI correlation was 0.35, and NDVI-VHI correlation was 0.63. This illustrated that the influence of land surface temperature to the vegetation drought was weak. Drought indicated by VHI was more likely to be influenced by internal conditions of vegetation and other environmental elements.