Assessment of Soft Computing Techniques for the Prediction of Suspended Sediment Loads in Rivers

Muhammad Adnan Khan,Jürgen Stamm,Sajjad Haider

doi:10.3390/app11188290

Abstract

A key goal of sediment management is the quantification of suspended sediment load (SSL) in rivers. This research focused on a comparison of different means of suspended sediment estimation in rivers. This includes sediment rating curves (SRC) and soft computing techniques, i.e., local linear regression (LLR), artificial neural networks (ANN) and the wavelet-cum-ANN (WANN) method. Then, different techniques were applied to predict daily SSL at the Pirna and Magdeburg Stations of the Elbe River in Germany. By comparing the results of all the best models, it can be concluded that the soft computing techniques (LLR, ANN and WANN) better predicted the SSL than the SRC method. This is due to the fact that the former employed non-linear techniques for the data series reconstruction. The WANN models were the overall best performer. The WANN models in the testing phase showed a mean R2 of 0.92 and a PBIAS of −0.59%. Additionally, they were able to capture the suspended sediment peaks with greater accuracy. They were more successful as they captured the dynamic features of the non-linear and time-variant suspended sediment load, while other methods used simple raw data. Thus, WANN models could be an efficient technique to simulate the SSL time series because they extract key features embedded in the SSL signal.

Highlights

Sedimentation is a nuisance in hydraulic and environmental engineering projects, such as dams, hydropower plants, canals and irrigation networks, wastewater treatment plants and water intakes, requiring sediment management measures for trouble-free operation of the facility
It is considered that the present-day suspended sediment load (SSL) (St) response depends on the present day response of river water discharge (Qt), and the previous one and the response of river water discharge that occurred the day before (Qt−1, Qt−2) and SSL (St−1, St−2)
Sediments carried by water are a nuisance, as they shortens the life of a reservoir, reduce the channel discharge-carrying capacity, especially to tail-end users, etc

Summary

Introduction

Sedimentation is a nuisance in hydraulic and environmental engineering projects, such as dams, hydropower plants, canals and irrigation networks, wastewater treatment plants and water intakes, requiring sediment management measures for trouble-free operation of the facility. Sediment load in rivers has been categorized into two types: suspended sediment load (SSL) and sediment bed load (SBL). The SSL comprises the main part of the river sediment transport and has a complex nature, in contrast with the SBL [4]. The SSL is considered one of the key factors affecting the landscapes [5] and pelagic environments [6,7]. It impacts river morphology, reservoir operation and useful life, as well as the functioning of hydraulic structures [8,9]

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