Tomasella, 2012 who found that - since all economic activities of these communities depend on the hydrological regime of the main stem - they were heavily impacted by the
droughts. The 2009 flood event caused mudslides and drove nearly 200,000 people from their homes Marengo et al., 2012 and resulted in record discharge being observed for the
Amazon river. Studies into these extreme events conclude that changes in the timing of
positive and negative rainfall anomalies puts river discharges from the northern and southern tributaries of the Amazon river in phase resulting in extreme positive and
negative discharges whereas in normal years, the timing is different attenuating the main-stem flood waves Tomasella, 2010; Marengo et al., 2012. Such unexpected and high
magnitude changes in water availability are therefore likely to have a great impact on
water security in the region.
3. Major changes in land use and their impacts
Land use can affect water security by changing the quantity and quality of supply as discussed earlier but also by changing and concentrating the demand for water. A major
driver for land use change in the Amazon is the global increase in demand for biofuels. With low costs for land and labour and favourable natural conditions temperature, light
and rainfall, the region is very well suited for this production Sawyer, 2008. Fargione et
al., 2008 calculated the so-called biofuel carbon debt for the Amazon basin. The biofuel debt concerns the process of conversion of native ecosystems in order to produce biofuels
which releases more CO
2
than the annual GHG reductions these biofuels would provide. By converting areas of the Amazon rainforest to soybean biodiesel plantations, this biofuel
carbon debt is estimated at more than 280 Mg of CO
2
per hectare, requiring a period of 380 years to be ‘repaid’ by using these biofuels instead of fossil fuels. Lapola et al., 2009
simulated land use changes for the 2020s caused by expansion of biofuel plantations and found that direct land-use changes have little effect on carbon emissions as they tend to
replace rangeland areas rather than forest but indirect land-use changes i.e. biofuels pushing the rangeland frontier into the Amazon forest could offset any carbon savings from
biofuels. The study projected deforestation of nearly 122,000 km
2
by 2020 with sugarcane ethanol and soybean biodiesel contributing in equal measure creating a carbon debt of 250
years. Arima et al., 2011 has shown that the displacement of rangeland into tropical forest between 2003 and 2008 indeed caused deforestation in the forest frontiers as a result of soy
expansion.
Figure 36: Per-cent of major sub-basin converted during the period 2004-2012 according to terra-i
Terra-i Reymondin et al, 2012 uses learning algorithms to identify land conversion from forest using MODIS vegetation index data on a 16-day basis. Data for Jan 2004 - May 2012
are used here Figure 36 to understand the rates of recent forest conversion by major sub- basin. These data may still contain small-scale artifacts resulting from clouds and riparian
flooding but are well validated within this region. Clearly most recent change has occurred in S and E Brazil, Bolivia, upland catchments in Peru and SE Colombia. Deforestation is
as high as 26 on a sub-basin level over the 8.5 years.
4. Mining and oil and gas development
