The slow-burn rainfall disaster in China, whilst the monsoon in South Asia is weak so far

Although it has received scant attention in the west, China is currently undergoing a classic slow-burn weather disaster associated with exceptional rainfall.  The scale is remarkable - Xinhua reports that since 1st July, 273 people have been killed and 218 people are missing, 3 million people have been displaced from their homes and 58 million people have been affected directly.  Economic losses are estimated to be about US$8.6 billion.  This means that over 1,000 people have been lost to floods and landslides so far this year in China.  As of 15th July (i.e. before these most recent storms), economic losses from rainfall-induced disasters in China this year were estimated to be US$17.6 billion. A week earlier than that, on 8th July, the Ministry of Civil Affairs estimated that natural disasters (now including earthquakes) in China  in the first six months of 2010 have left about 4,000 people dead or missing, and caused about US$31.2 billion in direct economic losses.

Unfortunately the situation could deteriorate considerably in the next 24 hours as Typhoon Chantu is just making landfall in southwest China, as this Tropical Storm Risk map shows:

Meanwhile, the monsoon in S. Asia is off to a slow start.  Although the weather system progressed northwards more quickly than is normal, the rainfall totals to date are some way short of normal:

Whilst this is good news from a hazards perspective, S. Asia is dependent upon monsoon rainfall.  Very anomalously low years cause water supply issues.  However, there are now signs that atmospheric conditions that generate monsoon rainfall are developing, so expect to see this situation change soon.  The result will inevitably be an increase in the number of landslides in S. Asia, in line with the normal seasonal pattern.

Update on the South Asian Monsoon

The seasonal landslide pattern in South Asia remains very substantively below the long term mean this year - to date at least the monsoon is failing. The level of the problem is illustrated rather well by this map of the monsoon season rainfall anomaly for India, from Monsoon Online:

The result is that the number of landslides in South Asia is very much below average, which is of course good news.

It is interesting to compare this year with 1997. This is part of a press release from 26th June 1997, put out by the Indian Institute of Tropical Meteorology:
"Unfavourable conditions trigger worry over south-west monsoon (26 June 1997)
Weather experts at the India Meteorological Department are keeping their fingers crossed over the performance of the south- west monsoon, as the waters of the Pacific Ocean are getting warmer. Warming of the Pacific is of significance since it means that there is no hope, at least for the time being, for the El Nino factor, which has a important influence on the monsoon, to become favourable. On the contrary, it only meant that it could have a more adverse impact than what was envisaged a month ago. To add to the problem, the Southern Oscillation, which is another global climatological phenomena that influences the monsoon, has also become more unfavourable. While El Nino is a reflection of the warming of some regions in the tropical Pacific Ocean, Southern Oscillation is an index of difference of pressure between the Pacific Ocean and the Indian Ocean. El Nino is considered favourable if the temperatures in the Pacific Ocean, particularly off the coast of Peru are low, and Southern Oscillation is considered to be advantageous if the atmosphere pressure in the Pacific Ocean is less than that in the Indian Ocean. The officials have, however, not given up hope on the ground that there was still a long way to go before the monsoon, which is active for four months, comes to an end in September. "

Interestingly the monsoon was 8-10 days late across most of the country that year. In the end the monsoon rainfall total was slightly above average, but characterised by very heavy rainfall, which caused floods and landslides, in late August.

1997 was of course the start of the largest El Nino in the last 60 years. It is unsurprising that the monsoon is currently showing a similar pattern as a new El Nino develops. The landslide pattern is apparently reflecting this.

Fatal landslides in 2009 so far - a review on the solstice

The summer solstice today seems like a good time to take stock of the position with fatal landslides to date, as collected in the Durham Fatal Landslide Database. Globally the fatal landslide season really starts in early June, the point at which the Asian monsoon starts to generate substantial amounts of rainfall in South and East Asia. Of course the greatest proportion of landslides occur in July and August, so we are before the main event.

So, how does the year look so far. Well, interesting actually. The graph below provides the cumulative number of recorded fatal landslides for 2007, 2008 and 2009, excluding the ones triggered by earthquakes (which obviously don't have a seasonal pattern). Obviously for 2007 and 2008 the full year graph is available.


You should be able to see that for 2007 and 2008 the normal S-shaped curve is clear, with a fairly low rate of increase in the first and last c.120 days. The time before this period, the northern hemisphere summer, shows a much greater rate of fatal landslides (i.e. a steeper line). It is also clear that in 2009 to date the number of fatal landslides is above the previous two years, although it is converging a little of late (of which more below). 2008 was anomalously low - 2007 is far more of an "average" year - although note that this is mostly because of the low number of recorded fatal landslides in the early part of the year.

The second graph, below, shows the recorded number of fatalities (again excluding those caused by earthquake-induced landslides). The coincidence between the patterns in 2007 and 2009 is very striking; again 2007 was very close to an average year on this measure. The comparatively low total at this point in 2008 is notable - but it is also clear that the rainy season resulted in a large number of fatalities (the large step is mostly due to hurricane-induced landslides in Haiti, plus a very active monsoon at this time).

One other aspects of this years data is really interesting. You may have noticed that in both the number of fatal landslides and the number of fatalities the trend in the last few weeks is a little anomalous. In particular, I would expect to see the steepening trend becoming clear as the Asian rainy season starts. However, this is clearly not the case as yet, as the graph below shows more clearly:

Here the blue line is the cumulative total of fatalities and the green line is the trend for fatal landslides. The recent flattening off is clear. This is mostly a clear indication of the rather strange pattern in the development of the South Asian monsoon this year. The northern passage of the monsoon appears to have stalled, as this map from the Indian Meteorological Agency shows:


Here the red lines are the average position of the monsoon front, whilst the green are the conditions observed this year. It appears that the northward advance is two weeks or so late at present - and it appears that this is being reflected in the fatal landslide data. However, the northward advance of the monsoon has apparently restarted this weekend, so the more usual trend may start to be displayed shortly.

Interestingly, there is some evidence that the SW Monsoon is weaker in El Nino years, and conditions are changing from La Nina to El Nino present. We are also recording more fatal landslides in South America than in recent years. However, it is far to early to tell whether the patterns that we are seeing this year are really associated with the possible El Nino conditions. It will be an interesting summer!

Serious landslide in Indian Kashmir - at least 20 people killed

Updated: It appears that May has started with a terrible rockfall in Indian Kashmir (Figure 1). Reports are still rather sketchy, but it seems that the landslide occurred in the Chatroo area Kadiyah,which is about 220 kilometers from Jammu. The rockfall which happened on a road linking Kishtwar and Islamabad, seems to have been caused by blasting. Greater Kashmir online reports:

Eyewitnesses said that the incident took place when some of the labourers were busy in blasting a hanging part of the mountain for widening of the highway this morning. Two tippers, carrying labourers working with the Border Roads Organisation, crossed the same spot from opposite sides when a large portion of the mountain slid down, burying the two tippers and men under several feet of earth.

Figure 1: Greater Kashmir online image of the 1st May landslide, showing one of the buried vehicles. The chances of survival appear to be very limited.

Reports vary on the number of victims, but at least 20 and maybe as many as 30 seems to be the ballpark figure. The outlook doesn't look promising for the victims judging by Figure 1. Understandably, recovery is proving difficult - Greater Kashmir online reported:

“We need to blast the large stones that cannot be moved otherwise,” Kishtwar’s additional deputy commissioner, Riyaz Ahmad Zargar, told Greater Kashmir. “It is difficult to tell how many more are trapped. Fears are that the number could be in excess of 20. Exact details of the causalities can be ascertained only when the rescue operation ends." Zargar said that screams could be heard from under the rocks and efforts were being made to rescue men who could still be alive under the debris.

In an earlier post I highlighted the danger of mountain roads to buses. In a sense these trucks were being used for the same purposes, once again with tragic consequences. Sadly of course with good supervision during construction such rockfalls can be mostly avoided.