Zambezi River Basin

Environmental Dynamics

Over the years, the Zambezi River Basin has slightly become warmer, while the frequency of floods and droughts has increased. These environmental changes are partly blamed for land degradation, habitat changes and drying or inundation of important ecosystems such as wetlands. Temperature The Fourth Assessment Report of the IPCC states that global greenhouse gas emissions due to human activities grew by 70 per cent between 1970 and 2004 (IPCC 2009). The emission of greenhouse gases in one regionmay result in a temperature rise, with associated effects, in another region. Thus the high rate of greenhouse

gas emissions across the world is partly the cause of the temperature rise of at least 0.5 ° C in southern Africa over the past century. Partly as a result of this temperature increase, the 1990s were the warmest and driest years in the Zambezi basin in recent times (SARDC and HBS 2010). Floods Over the last two decades, the Zambezi River Basin has experienced extreme floods and droughts (SARDC and HBS 2010). Most of the flooding in the basin is associated with active cyclones that develop in the Indian Ocean. The IPCC predicted that tropical cyclones will become more intense, with higher peak wind speeds and heavier precipitation associated with increases in tropical sea surface temperature (IPCC 2009). Major floods were recorded in parts of the Zambezi basin during the rainfall seasons of 1999-2000, 2005-06 and 2007 (SARDC and HBS 2010). While flooding in some areas, such as the Barotse plains, is a regular event providing vital water for irrigation and replenishing soil fertility, the frequency, timing, intensity and duration of floods are changing in the basin (SARDC and HBS 2010). The extent of flooding has intensfied due to poorly maintained embankments and structural measures, while in urban areas poor land use planning and inadequate drainage worsen flooding. In addition to destruction of homes and infrastructure, and loss of crops and livestock, flooding also inundates land, decreases soil fertility and destroys fodder resources, limiting agricutural production.

Annual Mean Temperature Changes for Kariba

30.0 Percentage of total land mass

29.0

28.0

27.0

26.0

© Ara Zambeze

25.0

24.0

23.0

1970 1975 1980 1985 1990 1995 2000 2005 2008

Source:SARDCandHBS2010

Figure 2.4

Zambezi River Basin flood areas

TANZANIA

DEMOCRATIC REPUBLIC OF CONGO

Z a m b e z i

L u n g w e b u n g u

MALAWI

K a b o m p o

L u a n g w a

C u a n d o

ZAMBIA

ANGOLA

K a f u e

S h i r e

Z a m b e z i

M a z o e

NAMIBIA

S h a n g a n i

ZIMBABWE

MOZAMBIQUE

BOTSWANA

Area flooded between 1997 and 2007 Sources: SADC and ZRA 2007. Rapid Assessment Report: IntegratedWater Resources Management Strategy for the Zambezi River Basin. SADCWater Division. Gaborone Figure 2.5

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