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This chapter examines the application of general international law on international groundwater issues. It analyses state practice with regard to the utilization of international groundwater to determine whether there is evidence of any applicable legal principles. It evaluates the application of the notion of ‘emergent customary law’ and the principle of hydrological cycle to the resolution of disputes concerning the use of groundwater.

We see them in our everyday lives. They make skies and sunsets even more beautiful, inspiring painters all over the world. But what are clouds? What are the physical processes occurring within a cloud? Do they all look alike, or are there different types of clouds? Why? Beyond our small human scale, how are clouds distributed at large, planetary scales? How do they couple and interact with the large-scale circulation of the atmosphere? What do the physics of cloud formation tell us about the hydrological cycle, including mean and extreme precipitation, in our current climate and in a warming world? What role do they play in the global energetics of the planet, for instance by reflecting the incoming shortwave radiation from the Sun, and by reducing the outgoing longwave radiation to space, because of their high altitudes and thus cold temperatures? These are the questions that will be addressed in these five lectures.

Navigators visiting the Amazon during the fifteenth century provided the earliest descriptions of aquatic systems in the region, but it was not until mid twentieth century that systematic studies of the limnology of Amazon waters began (Sioli 1984). The inclusion of vegetation as an important part of the aquatic biota was only possible after the relatively recent change from traditional potamic limnology to wetlands limnology (Sioli 1975). The first studies of the vegetation of Amazon wetlands consisted mainly of species descriptions, and it is only recently that studies of floodplain vegetation have attained a level of importance equivalent to that of studies dealing with water chemistry, phytoplankton, zooplankton, and fishes. For the past thirty years, fertile floodplain systems along Whitewater rivers (várzea) have been focal areas of colonization. This fertility also supports high rates of primary production within the higher plants, especially of the herbaceous vegetation (Piedade et al. 1991, Junk and Piedade 1993a, 1997). Quickly turning-over pools of nutrients (Junk and Furch 1991, Furch and Junk 1992, 1997a) and direct connections with contiguous terra firme forest and river channels (Alves 1993, Furch and Junk 1997b) are also characteristic of these floodplain systems. As a consequence of the annual floodpulse (Junk et al. 1989), floodplain vegetation is subjected to aquatic and terrestrial phases, which hold important ecological implications for both the plant populations and related aquatic and terrestrial biota. Life cycles of the species and the time available for growing depend upon the duration of inundation and drought periods and the habit of the species. During the year, pulses of growth and dormancy occur and herbaceous vegetation changes its species composition according to the phase of the hydrological cycle. In this chapter we discuss the distribution and the development of plant communities in floodplain areas, mainly of the big Whitewater rivers, focusing on factors such as diversity, species composition, biomass and primary production. Based upon these factors, we also discuss the annual dynamics of bioelements stocks and their turnover through herbaceous and floodplain forest communities. Finally, we examine the implications of such nutrient dynamics and turnover for the aquatic biota.