Growth of Invasive Aquatic Macrophytes Over Tapi River

Abstract

<p><strong>Abstract.</strong> Aquatic macrophytes are important elements of freshwater ecosystems, fulfilling a pivotal role in the ecological functions of these environments and biogeochemical cycles. Although aquatic macrophytes are beneficial, some species can hinder human activity. They can clog reservoirs and reduce water availability for human needs. Surveys of macrophytes are hindered by logistic problems, and remote sensing represents a powerful alternative, allowing comprehensive assessment and monitoring. The objectives of this study was to map temporal changes in the macrophytes using time series multispectral dataset over Tapi River, Surat. The field trip was conducted over the Tapi River on 22nd June 2018, where <i>in-situ</i> spectral response dataset were acquired using ASD Spectroradiometer. Water samples were also collected over three locations, one before entering the city (Kamrej), second at the Sarthana water treatment plant and third at the outer end (causeway). The nutrient concentration was less before entering the city (Ammonical Nitrogen 0.056<span class="thinspace"></span>mg/L and phosphate 0.0145<span class="thinspace"></span>mg/l), while higher concentration (Ammonical Nitrogen 0.448<span class="thinspace"></span>mg/l and phosphate 0.05<span class="thinspace"></span>mg/l) was observed within the city. Maps of aquatic macrophytes fractional cover were produced using Resourcesat-2/2A (LISS-III) dataset covering a period of 2012–2018. Maximum extent was observed in February-March of every year. Although during monsoon, lot of agriculture run-off and nutrients will come into the river, but main flow of water will dilute its concentration. During summer, the same nutrient concentration will boost these macrophytes due to less availability of stream water. Within the area of 16<span class="thinspace"></span>km<sup>2</sup> between Kamrej and causeway, 3.35<span class="thinspace"></span>% was covered by macrophytes during March 2013. This area coverage increase to 36.41<span class="thinspace"></span>% in March 2018. Based on these maps, we discuss how remote sensing could support monitoring strategies and provide insight into spatial variability, and by identifying hotspot areas where invasive species could become a threat to ecosystem functioning.</p>

Application of New Hyperspectral Sensors in the Remote Sensing of Aquatic Ecosystem Health: Exploiting PRISMA and DESIS for Four Italian Lakes

“…In this latter more applied paper category a total of 40 articles were found, and the majority of them were related to lakes (85% of the applied articles). In addition, imaging spectroscopy has been also attracting a wide interest [28] and reference therein since its simultaneous collection of narrower and contiguous bands is improving aquatic ecosys-tem mapping for the retrieval of parameters describing water quality, aquatic vegetation (e.g., biomass [41], invasive species identification [42]) and benthic substrates that might be undetectable with broadband multispectral sensors [15,27,40,[43][44][45][46][47][48]. In such a context, airborne data (e.g., APEX, AISA, MIVIS) have been providing unique data at high spectral and spatial resolution for performing advanced mapping as well to support satellite mission development and verification (e.g., [49][50][51][52]).…”

Tracking Water Quality and Macrophyte Changes in Lake Trasimeno (Italy) from Spaceborne Hyperspectral Imagery

“…The reviews reported in [23,24] highlighted the significant increase in remote sensing studies of inland water quality, due both to improved access to Earth Observation (EO) data and increasing computational capabilities. Particularly, imaging spectroscopy has gained wide interest [25][26][27][28], as the collection of data in narrower, contiguous bands is improving aquatic ecosystem mapping for the simultaneous retrieval of parameters describing water quality and aquatic vegetation (e.g., biomass [29] and the identification of invasive species [30]). In the last few years, hyperspectral spaceborne and airborne images have been providing significant advances in algorithm development and innovative mapping tools [31,32].…”

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

“…24 Its excessive growth causes various environmental (including ecological and socioeconomic) impacts that are hazardous to aquatic systems and disable human uses of surface waters. 25 It causes hypoxia, threatens freshwater quality and availability, 3,8,[26][27][28][29] worsens the quality of freshwater ecosystems, 30 including the quality of the aquatic life, 8,31,32 by causing changes in macroinvertebrate species richness 33 and biodiversity loss, 20,34,35 and promotes breeding grounds for pests and vectors. 36,37 Moreover, the expansion of water hyacinth obstructs river flows and irrigation systems, 38,39 thus increasing flood risk and hindering navigation 40 and recreational water activities.…”