Introduction to open-channel hydraulics

Hydraulics is the study of flows and flow mechanics. The mass balance of hydrology is passed to the field of hydraulics to find how the water passes through the landscape.

Learning Goals

• Become familiar with the concept of open-channel flow

Open-channel flow

Rivers are open channels, meaning that they have a closed bottom and sides, but are open to the air at the surface. Where do you think that their flow moves the fastest? How might this relate to the roughness along their edges and their overall shape? And how do they move sediment and reshape their banks and beds – the purview of fluvial geomorphology? These first few videos will give you a bit of an idea of these systems and how we think about them.

Videos

SAFL main channel

This high-flow discharge is scouring through the sandy bed in the main channel at SAFL. (I’m one of of the onlookers!) You need not watch the whole thing, but I want you to observe and think about what is happening: How is the water picking up the sand? What controls the waves? What does the structure of the flow look like?

Introduction to Open-channel Flow

This video from Kenneth Lamb provides an introduction to open-channel flow for civil engineers. It sets up the general framework that we will follow throughout the course.

Optional supplement: how engineers think through design in the landscape

Geomorphologists often work closely with civil engineers – and indeed often are civil engineers. This video gives you an eye into how engineers may approach the landscape and flows within it.

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