Proposal for a new Green Red Water Index for geo-environmental surface water monitoring

Abstract

One of challenges of today’s world is the long-term geo-monitoring of phenomena and processes that affect our environment after the closure of mining activities. Water resources are one of the components affected by post-mining processes. Moreover, land subsidence can be observed both during and after the cessation of mining activities. This phenomenon has an impact on the entire water management of a region. So far, radar or multispectral images have been used to identify water surfaces. This paper will present a methodology for using drones to detect water surfaces using vegetation indices such as NDVI, GRNDVI and NDWI. During their research, the authors modified the GRNDVI indicator by including the Red Edge band in the calculations. The newly developed Green Red Water Index – GRWI, makes it possible to identify water surfaces. This is important, because the change of water conditions makes it important focus more on the water supply and availability. However, analysis of the spectral bands of the different land-use classes in the Ruhr study area shown that the spectral profiles for water, soils, road and street surfaces have similar spectral characteristics and therefore difficulties may arise in distinguishing between the land-use classes shown. In this article a comparison of the indicators will be presented: NDVI, GRNDVI, NDWI and GRWI together with their statistical interpretation.