Hillslopes may be regarded as conveyor belts transferring water and sediment and nutrients to other parts of the geomorphic system. This chapter examines the mechanisms of, and the factors controlling, how far and how fast water, sediment and nutrients move along this conveyor belt, discussing water movement in and on hillslopes, fluid-gravity and sediment-gravity movement of sediment and nutrient movement. Hillslope processes do not operate in isolation, and the interaction, of connectivity among processes is also important. This interaction is particularly significant when assessing the importance of connectivity to understanding hillslopes within the context of landscape evolution. A full description of the connectivity of hillslope processes will require combined knowledge of both the magnitude–connectivity relationship, the probability distribution of event magnitudes and, to explain specific cases of functional connectivity, the actual sequence of events. In recent years there has been a growing recognition of the importance of connectivity in understanding the effects of hillslope processes. At best, however, that understanding remains patchy and incomplete.

The concept of connectivity appeared in several disciplines in the 1950s and 1960s, but did not enter geomorphology until the 1980s. The concept has led to profound insights into the behaviour of systems, and has had significant applications in management. Connectivity may be defined as a structured set of relationships between spatially and/or temporally distinct entities), or as the degree to which a system facilitates (or impedes) the movement of matter and energy through itself. The former definition focuses on the structure of the system, and the latter on the functioning of it. The two definitions give rise to the separate concepts of structural and functional connectivity. A fundamental difference between structural and functional connectivity lies in the fact that, whereas the former can be relatively easily measured, and a variety of tools exists to do so, the latter tends to be inferred from system behaviour, so that measurement is somewhat indirect. Notwithstanding the compelling arguments in favour of studying connectivity, the ability to apply the ideas of connectivity science in any discipline requires a number of challenges to be addressed.

In this chapter, the history and development of the concept of connectivity in geomorphology is presented. It further provides an overview of connectivity terminology, the underlying concepts and identifies the benefits of connectivity thinking for geomorphological research and applications. We further pursue the question of whether connectivity can be considered as key concept in geomorphology and address general key challenges in using connectivity to understand complex geomorphic systems.

The Governments of Argentina, Australia, Belgium, Chile, the French Republic, Japan, New Zealand, Norway, the Union of South Africa, the Union of Soviet Socialist Republics, the United Kingdom of Great Britain and Northern Ireland, and the United States of America,

Recognizing that it is in the interest of all mankind that Antarctica shall continue forever to be used exclusively for peaceful purposes and shall not become the scene or object of international discord;

Acknowledging the substantial contributions to scientific knowledge resulting from international co-operation in scientific investigation in Antarctica;

Convinced that the establishment of a firm foundation for the continuation and development of such co-operation on the basis of freedom of scientific investigation in Antarctica as applied during the International Geophysical Year accords with the interests of science and the progress of all mankind;

Convinced also that a treaty ensuring the use of Antarctica for peaceful purposes only and the continuance of international harmony in Antarctica will further the purposes and principles embodied in the Charter of the United Nations;

Have agreed as follows:

Article I

1. Antarctica shall be used for peaceful purposes only. There shall be prohibited, inter alia, any measure of a military nature, such as the establishment of military bases and fortifications, the carrying out of military manoeuvres, as well as the testing of any type of weapon.

2. The present Treaty shall not prevent the use of military personnel or equipment for scientific research or for any other peaceful purpose.