|Article 2(a) includes the term ‘watercourse’, which defines the type of waters to which the Convention applies and means both the system of surface and groundwater channels, tributaries, and the water that they contain. This definition highlights the need for an integrated approach to systems of surface and underground waters.
The phrase ‘normally flowing into a common terminus’ has the effect of putting a limit on the geographical scope, for example where two different drainage basins were altered and connected by a canal – this would not make them part of a single ‘watercourse’ for the purpose of the present Article 2(a). This Article is modified by the word ‘normally’ reflecting the seasonal variability and complexity of hydrological systems – e.g. many watercourses will flow into the sea, in whole or in part via groundwater, or as a series of tributaries which may be as much as 300 km apart, or only empty at certain times of the year into a common terminus such as an ephemeral river, with temporary surface flow that varies between seasons and years and which will sometimes end its journey terminating into an inland lake or delta (endorheic), or at other times into the ocean (exorheic).100
100 1994 Draft Articles at 90. For an explanation of ephemeral, exorheic and endorheic rivers see A Turton, P Ashton and E Cloete, Transboundary rivers, sovereignty and development: Hydro-political drivers in the Okavango River basin (African Water Issues Research Unit African Water Issues Research Unit (AWIRU) and Green Cross International (GCI) 2003) at 188.
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