Laser Remote Sensing of Lake Kinneret by Compact Fluorescence LiDAR

Abstract

Harmful algal blooms in freshwater reservoirs became a steady phenomenon in recent decades, so instruments for monitoring water quality in real time are of high importance. Modern satellite remote sensing is a powerful technique for mapping large areas but cannot provide depth-resolved data on algal concentrations. As an alternative to satellite techniques, laser remote sensing is a perspective technique for depth-resolved studies of fresh or seawater. Recent progress in lasers and electronics makes it possible to construct compact and lightweight LiDARs (Light Detection and Ranging) that can be installed on small boats or drones. LiDAR sensing is an established technique; however, it is more common in studies of seas rather than freshwater reservoirs. In this study, we present an experimental verification of a compact LiDAR as an instrument for the shipborne depth profiling of chlorophyll concentration across the freshwater Lake Kinneret (Israel). Chlorophyll depth profiles of 3 m with a 1.5 m resolution were measured in situ, under sunlight conditions. A good correlation (R2 = 0.89) has been established between LiDAR signals and commercial algae profiler data. A non-monotonic algae depth distribution was observed along the boat route during daytime (Tiberias city–Jordan River mouth–Tiberias city). The impact of high algal concentration on water temperature laser remote sensing has been studied in detail to estimate the LiDAR capability of in situ simultaneous measurements of temperature and chlorophyll concentration.

Harmful Cyanobacterial Blooms: Going beyond the “Green” to Monitor and Predict HCBs

“…The interference from clouds, atmosphere and land reflectance at the nearshore zones when using remote sensing can also be surpassed by using imagery from automated unmanned vehicles (AUVs) including drones, boats, underwater vehicles and water samplers that can provide information from spatial or vertical depth profiles, hotspots, nearshore zones or critical health risk areas during the bloom development [174][175][176][177] and help calibrate and validate the algorithms for PC estimation from remote imagery data in lakes and reservoirs [170]. Additionally, data from low orbiting satellites such as CubeSats [178] can also be an interesting alternative.…”

Spatial and Temporal Analysis of Water Quality in High Andean Lakes with Sentinel-2 Satellite Automatic Water Products

“…Therefore, methodologies using optical remote sensing technologies could serve as an alternative and attractive solution. Remote sensing imagery has been widely used for environmental and other studies [9,10], and has proven to be invaluable for water resource management at different scales [11,12].…”