Introduction, problems and approaches in sediment transport measurements
1. INTRODUCTION, PROBLEMS AND APPROACHES
1.1 Introduction
An important phase prior to the actual field survey is the selection of the most appropriate instruments, which usually is a rather difficult problem because a wide range of instruments has been developed from simple mechanical samplers to sophisticated optical and acoustical samplers. The selection of instruments is largely dependent on the variables to be measured, the available facilities (boat, winch) and the required accuracy. Especially, the required accuracy should be considered carefully. For example, a reconnaissance study requires the use of much less sophisticated instruments than a basic research study.
This manual (600 pages; detailed information is available as PDF.files at site:.......)provides information of all relevant aspects related to sediment transport measurements such as:
- measuring principles and statistics,
- type and accuracy of the instruments,
- selection of the instruments,
- analysis of the samples,
- elaboration and presentation of the measuring results.
1.2 Sedimentation and erosion problems in rivers, estuaries and coastal seas
1.2.1 Introduction
Sedimentation and erosion engineering problems in rivers, estuaries and coastal seas are discussed as well as practical solutions of these problems based on the results of field measurements, laboratory scale models and numerical models.
1.2.2 Sedimentation and erosion problems
Human interference in hydraulic systems often is necessary to maintain and extend economic activities related to ports and associated navigation channels. Often, engineering structures are required: 1)to stabilize the shoreline, shoals and inlets, 2) to reduce sedimentation, 3) to prevent or reduce erosion, or 4) to increase the channel depth to allow larger vessels entering the harbour basin. Coastal protection against floods and navigability are the most basic problems in many estuaries in the world. Sedimentation problems which generally occur at locations where the sediment transporting capacity of the hydraulic system is reduced due to the decrease of the steady (currents) and oscillatory (waves) flow velocities and related turbulent motions, are discussed.
1.2.3 Approach of sedimentation problems
The general approach to solve sedimentation and erosion problems is discussed. The topics are: A) Identification of the problem and wider context,B) Formulation of general objectives and desired state of knowledge, C) Determination of problem dimensions and analysis of physical system, D) Formulation of hypotheses related to the problem, E) Generation of alternative solutions and cost estimates, F) Selection of optimum solution.
The tools available for solving problems are discussed: existing databases, measurements and monitoring (field studies), numerical and or physical modelling. The manual focuses on measurements and monitoring.
