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It is hard to miss the mountains in Almaty, Kazakhstan. If you look south between the trees and the tall buildings rising all around the city, you can catch a glimpse of the snowy peaks of the Zaiilsky Alatau from nearly everywhere in the city. They rise to nearly 5000 m, and President Nursultan Nazarbayev climbed to the top of one of the highest in 1995. But although the mountains give Almaty a pleasing set of views, a nearby ski resort, and plenty of opportunities to escape the city for the cool alpine air, they are the direct evidence of one of the biggest threats facing the city: earthquakes.
The Zaiilsky Alatau reach such picturesque elevations because of the presence of one (or more) active thrust faults along the base of the range. These faults, which have not been mapped in detail but which must lie close to the city’s affluent southern suburbs, have gradually built up the range through repeated earthquakes. Almaty was destroyed or damaged by earthquakes three times in the last 125 years, most recently in 1911, and while the precise sizes and locations of these events are not known, it is inevitable that future damaging earthquakes will occur. This fact is not lost on the city’s population – conversations over the last few days have shown a sophisticated understanding that earthquakes are a major hazard. Indeed, the threat of natural disasters is one oft-cited reason for the 1997 decision to move the Kazakh capital to Astana, far to the north in a geologically-uneventful location on the steppe. Read more
Dr Alexander Densmore reports from northwestern India on a new project funded by the NERC Changing Water Cycle programme that investigates the effects of past, present and future climate on groundwater systems in this part of the world.
Northwestern India is the country’s breadbasket. The plains of Punjab and Haryana now produce most of the nation’s wheat and rice due to a focused programme of agricultural growth over the last few decades. The semi-arid climate and highly seasonal monsoon precipitation, however, mean that this lush productivity comes at a cost. Northwestern India is also one of the world’s worst ‘hotspots’ of groundwater depletion –- in other words, groundwater is being extracted from the subsurface at a far higher rate than it is being recharged by precipitation and river flow. A key regional-scale study using GRACE satellite data, published by Rodell et al. in Nature in 2009 (‘Satellite-based estimates of groundwater depletion in India‘), showed that across the states of Punjab, Haryana, and Rajasthan, groundwater was lost at a rate of more than 50 km3 per year from 2002 to 2008. This unsustainable deficit poses a grave threat to the continued development of the region, home to more than 100 million people. What’s more, there are indications from regional-scale climate modelling that climate change over the next 30-50 years is likely to decrease summer monsoon precipitation and delay its onset, in precisely the regions that are worst affected by groundwater depletion.
To begin to understand this issue, we are starting a new research project on the aquifer systems of northwestern India, funded by the UK National Environmental Research Council and the Indian Ministry of Earth Sciences. I am working with researchers from the Indian Institute of Technology Kanpur, Delhi University, the National Institute of Hydrology in Roorkee and Imperial College London. Read more
I was recently in Patna, the capital of the state of Bihar in northern India, talking about the ‘Kosi problem’. Bihar shares a border with Nepal and the rivers which flow out of the Himalayas and into Bihar are prone to disastrous floods caused by the enormous volumes of sediment and water that they carry. In August 2008, during one of the most recent floods, the Kosi River burst through one of its levees and flowed back into one of its abandoned channels, following a much straighter and steeper path toward the Ganga River and eventually to the Bay of Bengal. This large-scale shift of the river, called an avulsion, is a frequent occurrence on the Kosi – or at least it was until 1953, when the Indian government began an ambitious programme of dam and levee construction designed to tame the Kosi and ‘train’ it into a straight and well-defined course. Read more
I was thinking the other day about the eruption of Eyjafjallajökull in Iceland, and wondering what the actual levels of ashfall in the UK had been. This was prompted in part by the 30th anniversary of the eruption of Mt St Helens, in the northwestern USA, on 18 May 1980, and my childhood memories of walking through piles of ash and scooping it into jam jars (we lived in Washington state at the time); and also by a question that we received at IHRR about the health effects, if any, of Icelandic ash. After the current eruption began on 14 April, my sons and I put pans out in the back garden to catch any Icelandic ash that fell, and they were disappointed to find only leaves and dead bugs. But there have been a few reports of ashfall at ground level, and I wondered what the concentrations had been.
I should say at this point that I am not doing any research on the health effects of the Iceland ash plume – so what follows is no more than the musings of an interested citizen. I spent some time looking around on the web, and came across the UK Air Quality Archive, which has several good summaries of ground measurements taken during different phases of the eruption:
What those data show pretty convincingly is that the increase in levels of particulate air pollution measured by ground stations (typically expressed as the concentration of particles that are less than 10 microns across – known as PM10) has been nil to minimal, even at times when the plume has been observed over the UK. Any increase – for example, that seen in Northern Ireland on 4 May – is still within the typical daily noise. Read more