Climate variability, climate change and water resource strategies for ...
Climate variability, climate change and water resource strategies for ...
Climate variability, climate change and water resource strategies for ...
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<strong>Climate</strong> <strong>variability</strong>, <strong>climate</strong> <strong>change</strong> <strong>and</strong> <strong>water</strong> <strong>resource</strong> <strong>strategies</strong> <strong>for</strong> small municipalities<br />
case of the Richtersveld Local Municipality, the only representative town is Lekkersing which has a<br />
largely interrupted data set. Calvinia, Leliefontein, Steinkopf, Lekkersing <strong>and</strong> Sutherl<strong>and</strong> all fall into<br />
the winter rainfall region while Pofadder, Van Wyksvlei <strong>and</strong> Kenhardt all receive predominantly<br />
summer rainfall.<br />
Namakwa<br />
Table 8: Representative towns <strong>for</strong> each local municipality<br />
District municipality Local municipality Representative town<br />
Hantam<br />
Kamiesberg<br />
Nama Khoi<br />
Richtersveld<br />
Karoo Hoogl<strong>and</strong><br />
Khâi-Ma<br />
Calvinia<br />
Leliefontein<br />
Steinkopf<br />
Lekkersing<br />
Sutherl<strong>and</strong><br />
Pofadder<br />
Karoo Kareeberg Van Wyksvlei<br />
Siy<strong>and</strong>a !Kai! Garib Kenhardt<br />
Precipitation displays a high degree of interannual <strong>variability</strong>, with single extreme events skewing<br />
simple analyses, <strong>and</strong> hence precipitation is difficult to analyse in terms of trends (Midgley et al.<br />
2005). This is demonstrated in the selection of graphs below where the linear regression does not<br />
have a very good correlation coefficient (R 2 ). (Although not presented here, the logarithmic<br />
regression does not yield better results). Whilst the trend lines may indicate an decrease in<br />
precipitation over the period <strong>for</strong> most cases, the extreme highs <strong>and</strong> lows greatly influence the<br />
determination of any true trend in the data.<br />
What is particularly evident from all the graphs however, is that rainfall is highly variable from year<br />
to year, with periods of more plentiful rainfall followed by periods of drought. This makes planning<br />
<strong>for</strong> times of drought difficult yet essential, since with large interannual variabilities there are no<br />
rainfall guarantees in any year.<br />
The recorded summer <strong>and</strong> winter rainfall records <strong>for</strong> each of the eight towns <strong>for</strong> the past 30 years<br />
can be found in Appendix A. All the towns exhibit <strong>variability</strong> in rainfall.<br />
Calvinia Rainfall - Winter<br />
Rainfall mm/month<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
R 2 = 0.05385<br />
1971<br />
1972<br />
1973<br />
1974<br />
1975<br />
1976<br />
1977<br />
1978<br />
1979<br />
1980<br />
1981<br />
1982<br />
1983<br />
1984<br />
1985<br />
1986<br />
1987<br />
1988<br />
1989<br />
1990<br />
1991<br />
1992<br />
1993<br />
1994<br />
1995<br />
1996<br />
1997<br />
1998<br />
1999<br />
2000<br />
2001<br />
2002<br />
2003<br />
2004<br />
year<br />
Figure 7: Winter rainfall trends <strong>for</strong> Calvinia between 1971 <strong>and</strong> 2004<br />
14
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