Nepal Hazard Risk Assessment - Asia-Pacific Gateway for Disaster ...
Nepal Hazard Risk Assessment - Asia-Pacific Gateway for Disaster ...
Nepal Hazard Risk Assessment - Asia-Pacific Gateway for Disaster ...
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<strong>Nepal</strong> <strong>Hazard</strong> <strong>Risk</strong> <strong>Assessment</strong><br />
% of stations<br />
% of stations<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
100<br />
90<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<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 />
2005<br />
2006<br />
2007<br />
Year<br />
Figure 3.40. Drought occurrence in premonsoon<br />
SPI and SMI were used <strong>for</strong> drought analysis at seasonal scale. It is found that drought of all category<br />
occur in <strong>Nepal</strong> in all seasons. Moderate drought frequently occurs in all seasons. But severe and extreme<br />
droughts in comparison are less common. All categories of drought show increasing trend in winter<br />
season. During winter severe and extreme droughts were rare in past but it has been observed in many<br />
stations recently. It indicates that winter droughts are getting intense. During the premonsoon season,<br />
moderate drought show slightly increasing trend but the severe and extreme drought both showed<br />
decreasing trend. All categories of drought are decreasing in monsoon. From 2001 to 2007 the extreme<br />
drought was not recorded at all. It was also found that there is little correlation between severities of<br />
drought occurrence from one season to another season during a given period. From this it can be inferred<br />
that drought of extended duration (longer than a season) is not common.<br />
Climatologically drought probably is highest during premonsson and lowest during postmonsoon.<br />
However, winter season showed a large increase in the probability of drought occurrence in the recent<br />
decade.<br />
Western parts of the country are more drought prone specially during winter and premonsoon season.<br />
Analysis of soil moisture index shows that highest moisture surplus occurs during monsoon season<br />
where as there is highest moisture deficit during postmonsoon season. Severity of moisture deficit is<br />
highest in premonsoon season in western Tarai belt. In winter, there is moisture surplus in western half<br />
of the country but deficit in the eastern half.<br />
Figure 3.43 show the percentage of coverage of drought hazard area with respect to district area. Most of<br />
the districts are in moderate and low drought zone. There are few districts in high zone.<br />
Winter<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 />
2005<br />
2006<br />
Year<br />
Figure 3.41. Drought occurrence in monsoon<br />
100<br />
90<br />
% of stations<br />
80<br />
70<br />
60<br />
50<br />
40<br />
30<br />
20<br />
10<br />
0<br />
Winter<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 />
2005<br />
2006<br />
Year<br />
Figure 3.42. Drought occurrence in postmonsoon<br />
Figure 3.43. Percentage of coverage of drought area with respect to district area<br />
74
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