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DeepSizer 300 for Immediate Sediment Response in Extreme Hydrological Conditions

2025-09-28Application Note

Monitor how extreme hydrological events impact sediment transport using DeepSizer 300 for real-time Suspended Sediment Concentration and Particle Size Distribution analysis.

Product	DeepSizer 300
Industry
Sample	Suspended Sediment
Measurement Type	Particle Size,
Measurement Technology

Introduction

Suspended sediment concentration (SSC) and particle size distribution (PSD) are vital indicators in hydrology, water resources, and ecological protection. During floods and typhoons, SSC can rise sharply, often exceeding 20 g/L. Such short-lived surges drive riverbed scour, reservoir siltation, and pollutant transport, posing risks to flood control, water supply, and ecosystem health. Capturing these events is therefore essential for flood forecasting and sustainable reservoir management.

However, traditional sampling methods are labor-intensive, unsafe during extreme weather, and too slow to capture short-term changes. Automated instruments such as turbidity sensors, acoustic devices, and conventional laser systems exist, but they often face challenges like limited measurement range or frequent maintenance.

In this application note, the DeepSizer 300 is presented as a tool for suspended sediment monitoring that provides accurate, real-time SSC and PSD data across wide ranges, including during flood and typhoon conditions.

Instrument

The DeepSizer 300 is equipped with a 635 nm, 10 mW polarized laser and 80 multi-angle detectors that capture both scattered and transmitted light signals. Its advanced software applies Differential Path Technology and Multiple Scattering Correction to ensure reliable results.

For practical applications, more advantages include:

l Wide measurement range: 0.001–100 g/L for SSC, 0.1–2000 µm for PSD.

l Adaptive path control: Automatically adapts to high, medium, or low sediment concentrations, ensuring accuracy under diverse conditions.

l Self-balancing hydraulic pressure: Automatically adjusts for external water pressure, ensuring stable optical path performance at depths up to 200 m.

l Automatic optical window cleaning: Maintains performance with minimal manual intervention.

l Flexible data transmission modes: Supports wired, wireless (4G), and offline modes, enabling adaptation to different monitoring environments.

Experimental

The DeepSizer 300 was deployed at a hydrological station for continuous in-situ monitoring of suspended sediment concentration and particle size distribution. It recorded data every five minutes and transmitted it via the built-in 4G module, while the instrument also reported its operational status.

Figure 1. On-site installation photo

Results and Discussion

The DeepSizer 300 successfully tracked temporal variations of both SSC and PSD during the monitoring period.

As shown in Figure 2, SSC exhibited significant fluctuations, with multiple events exceeding the threshold of 20 g/L. Peak concentrations reached approximately 33 - 35 g/L, indicating short-term, high-intensity sediment transport processes usually associated with sudden flow changes.

Figure 2. Temporal variations of suspended sediment concentration (SSC)

PSD measurements (Figure 3) revealed stable trends for finer fractions (D10 < 20 µm), while coarser fractions (D50 and D90) displayed higher variability. The median particle size (D50) generally ranged between 50 - 150 µm, while D90 occasionally rose to 600 µm, indicating episodic inputs of coarse particles likely due to localized erosion or bed-material mobilization.

Figure 3. Temporal variations of particle size distribution (PSD)

These results show that the DeepSizer 300 captured short-lived sediment peaks often missed by conventional methods, giving reservoir operators additional lead time for sediment sluicing and flood management. Such timely data also support water-supply protection and ecological monitoring under rapidly changing conditions.

Conclusion

The DeepSizer 300 provided continuous monitoring of suspended sediment concentration (SSC) and particle size distribution (PSD), detecting multiple peaks above 20 g/L with maxima near 35 g/L. PSD data indicated that fine fractions (D10) remained stable, while D50 typically ranged from 50 - 150 µm, and D90 occasionally reached 600 µm.

By delivering synchronized SSC and PSD data at five-minute intervals, the instrument captured short-lived fluctuations often overlooked by conventional methods. These findings validate the DeepSizer 300 as a robust tool for flood forecasting, reservoir operation, and water-quality management under highly dynamic and turbid conditions.