Assessing the potential of Sentinel-2 data for tracking invasive water hyacinth in a river branch

Isabel P De Lima,Romeu Gerardo

doi:10.1117/1.jrs.16.014511

Abstract

Water hyacinth (Eichhornia crassipes) has become a threat to many aquatic environments worldwide. This aquatic weed presents a rapid reproductive capacity and outcompetes other aquatic plant species, forming dense, free-floating mats, which in many instances completely cover fresh-water surfaces. The infestation leads to several serious environmental (including ecological and socioeconomic) impacts that are hazardous to aquatic systems, disables human uses of surface waters, and affects hydraulic infrastructures (e.g., waterways and pumping stations). Our study explores the use of remote sensing tools to monitor and categorize the spread of water hyacinth, aiming at new insights into the detection, observation, and mapping of this invasive plant using vegetation indices and water indices calculated from multispectral data from satellite Sentinel-2, such as normalized difference vegetation index and normalized difference water index. The approach uses spatiotemporal information and has the potential to contribute to inform planners and decision-makers that are concerned with managing the plant by applying integrated measures. The case study deals with a small water course located in the downstream part of the Mondego river valley in Portugal, a country where water hyacinth is widely spread and constitutes a major problem, mainly in the irrigated agricultural areas of the Tagus, Sado, Mondego, and Lis rivers’ basins.

Highlights

Water hyacinth, botanically known as Eichhornia crassipes (Mart.) Solms-Laubach, is a perennial aquatic weed that has become a threat to many aquatic environments worldwide
For the exploratory appraisal of the recurrent presence of the water hyacinth invasive plant in the study area, the normalized difference vegetation index (NDVI) and normalized difference water index (NDWI) were inspected for the period 2017 to 2021 (Fig. 7); the data concern a selected point in the old Mondego River branch, in the vicinity of the Foja Pumping Station
The water hyacinth invasion and Downloaded From: https://www.spiedigitallibrary.org/journals/Journal-of-Applied-Remote-Sensing on 01 Mar 2022 Terms of Use: https://www.spiedigitallibrary.org/terms-of-use corresponding high dominance in terms of water surface coverage is manifested by the higher NDVI values and, correspondingly, by the lower NDWI values

Summary

Introduction

Botanically known as Eichhornia crassipes (Mart.) Solms-Laubach, is a perennial aquatic weed that has become a threat to many aquatic environments worldwide. This aquatic freshwater plant, which is native to the Amazon basin in South America, has spread to other parts of the world since the 19th century,[1,2,3,4] remaining the most troublesome aquatic weed both locally (across the areas affected) and globally.[5,6,7,8,9] The International Union for Conservation of Nature rates water hyacinth as one of the hundred most harmful invasive species.[10]. It presents a rapid multiplicative capacity that enables it to double its biomass in 6 to 14 days under favorable growth (climatic and water) conditions.[19]

Objectives

Methods

Results