The location of water resources played a role in determining the post-World War I Palestine–Syrian border and presumably will play a part in future negotiations with Syria. Although Syria and Lebanon are upstream riparians on the Jordan basin, the two countries have alternative water resources and are therefore less dependent on the Jordan basin for their water supply. For Israel, Jordan and the Palestinians, however, the Jordan basin offers a primary source of water. The Johnston Plan served as a basis of understanding between Jordan and Israel but without explicit references to international law. The Israel–Jordan peace treaty and the bilateral interim arrangements reached between Israel and the Palestinians deal with allocations of specified quantities of water and not with legal principles. Future negotiations between Israel and the Palestinians will have to find a compromise between two basic tenets of international law, the rule of not causing appreciable harm to existing uses and the inherently contradictory rule of equitable allocations.

This chapter focuses on how flow in rivers shapes channel geometry, particularly the width and depth of river channels. It first examines the concepts of at-a-station and downstream hydraulic geometry, which relate width, depth, and velocity of flow to discharge. At-a-station hydraulic geometry largely reflects the influence of channel form on flow, whereas downstream hydraulic geometry reflects changes in channel geometry to accommodate downstream increases in discharge. A distinction is made between hydraulic geometry and channel geometry, where channel-geometry relations are not restricted by flow continuity constraints. Classic hydraulic- and channel-geometry analyses are based mainly on statistical analysis of empirical data. By contrast, rational regime theory uses optimization algorithms along with physical reasoning to examine relations among flow, sediment transport, bank stability, and channel geometry. The final section of the chapter explores approaches to channel geometry that consider dynamic change in geometry over time.