Deltas on the move; Making deltas cope with the effects of climate c

KvR report 001/2006<strong>Deltas</strong> on the moveOptional: Should you wish to make more analysis in Excel, you can also click thedownload button. This will allow you to download the full excel database on your PC.Figure 6.7:Ranking of deltas for physical vulnerability based on1/100 yr surge height.Step 5) You can close the application by closing the DELTAS browser window.Check it out at http://ivm10.ivm.vu.nl/deltas,the interactive on-line system for innovative delta management!6.3 Ranking of deltas, an illustrationThe DELTAS system produces a ranking of deltas for indicators according tophysical vulnerability, for stock at risk, and potential for soft measures (Table 5.4).Specific indicators depict the different categories of system-based soft approaches.The next sections aim to show how these rankings should be interpreted, and howthey can be used for innovative system-based delta management.Physical vulnerabilityBoth the one in a hundred year surge height and the area between 0 and 2 m abovemean sea level were identified as prime indicators for physical vulnerability inChapter 5. The latter is also considered useful to indicate the overall potential for softsystem-based approaches. Some deltas are located in areas of high surge (listingbelow and Figure 6.7), whereas others discharge in quieter seas.The following deltas are found in high surge regions:1. Lena;2. Mekong;3. Fraser;4. Fly;5. Ganges-Brahmaputra.The other indicator, area between 0 and 2 m, is important because larger coastalplains with low storm surges, such as Yukon, Mackenzie and Mississippi areprobably less vulnerable. These examples show that, depending on the context,more than one indicator should be considered. The DELTAS system offers thispossibility. When in doubt, we suggest that here you adhere the precautionaryprinciple and consider high-ranking deltas for both indicators to be very vulnerable.LenaMekongFrazerFlyGanges-ZambeziRedChao PhrayaMangokyIndusBurdekinOrinocoParanaMahakamYangtze-KiangMahanadiShatt el ArabPoHuang HeIrrawaddyDneiperGodavariMississippiSao FranciscoKrishnaMacKenzieYukonPechoraSenegalNigerDanubeEbroNileMagdalena0 1 2 3 4 5 6 71/100 yr surge height (m)Stock at riskThe next five deltas have a particularly high stock at risk (when using peoplepotentially flooded in 2000 as an indicator for stock at risk):1. Ganges-Brahmaputra;2. Chao Phraya;3. Godavari;4. Krishna;5. Mahanadi.The first thing to notice is that these five deltas are all Asian. If we, subsequently,compare this ranking to the one for physical vulnerability, we are fortunate that onlythe Ganges-Brahmaputra ranks high in both lists, and is therefore both physicallyvulnerable and has a high stock at risk. This delta, which is one of the largest in theworld, covers some 105.640 km 2 and has one of the highest population densities ofall deltas, and consequently DIVA gives a relatively high number of peoplespotentially flooded (Figure 6.8). The major river floods occur during the months fromJune through September (Coleman & Huh, 2004). The inland part of the tidal plainhas been reclaimed, and the former saline lands have been converted to variousagricultural and marine farming practices (see also Section 7.3.)6061