Resources Research

Making local sense of food, urban growth, population and energy

Posts Tagged ‘water

An erratic monsoon with late spikes

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RG_IMD_rain_deficit_chart_20140924From the first week of June 2014 until the middle of September 2014, there have been floods and conditions near drought in many districts, but for India the tale of monsoon 2014 comes from individual districts and not from a national ‘average’ or a ‘cumulative’.

The weekly rainfall variation table for Maharashtra's districts. The period of the last week of August and the first two weeks of September is the only period during which these districts received rainfall at or above normal. But overall, the second deficient category, coloured light rose, dominates (this table uses my modified monsoon measure methodology, see text for link)

The weekly rainfall variation table for Maharashtra’s districts. The period of the last week of August and the first two weeks of September is the only period during which these districts received rainfall at or above normal. But overall, the second deficient category, coloured light rose, dominates (this table uses my modified monsoon measure methodology, see text for link)

This revealing chart tells some of that tale. It shows that for the first six weeks of monsoon 2014, most districts recorded rain below their normals for those weeks.

The lines are percentile lines; they tell us what percent of districts recorded how much rainfall in a monsoon week relative to their normals for that week. This chart does not show how much rain – it shows distance away from a weekly normal for districts.

The left scale is a percentage – higher percentages indicate how much above normal districts recorded their rainfall, negative numbers show us how much below normal their rainfall was.

The dates (the bottom scale) are for weeks ending on that date for which ‘normals’ and departures from normal were recorded. The P_01 to P_09 lines are the percentiles (10th to 90th) of districts in every week.

The typical IMD map of 'normal' rainfall measured by the meteorological sub-divisions. The detailed weekly tables give us a very different picture.

The typical IMD map of ‘normal’ rainfall measured by the meteorological sub-divisions. The detailed weekly tables give us a very different picture.

The district weekly normal is an important measure for matters like sowing of crop and issuing water rationing instructions in talukas and blocks. In the week ending 23 July for example, we see that the 60th percentile line spiked above normal, and this means that in that week only four out of ten districts all over India received the amount of rain it should have based on the average of the last 50 years.

The districts overview chart is distilled from the detailed weekly tables I have assembled (see the image of the Maharashtra table). For the whole country, what the districts tell us about the monsoon so far is a very much more detailed and insightful tale than the typical offering by the Meteorological Department (see India sub-divisional map). These weekly district tables are coded using my modified monsoon methodology, geared towards aiding decisions for local administrations especially for prolonged arid conditions leading to drought.

Written by makanaka

September 24, 2014 at 10:06

Where the big rivers are

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RG_IGBP_deltas_sm

The biggest river deltas are flat and that’s why the cities which occupy some of the have expanded so much, so quickly. The last 50 years has seen a big population expansion on deltas – cities like Dhaka in Bangladesh. Twelve megacities on deltas have expanded in terms of populations from 62 million in 1975 to 153 million in 2010, an expansion that is not slowing.

‘Global Change’, which is the magazine of the International Geosphere Biosphere Programme (IGBP), has brought out a special number of deltas and the risks borne by city administrations that occupy deltas. The IGBP, in its own words, “coordinates international research on global-scale and regional-scale interactions between the Earth’s biological, chemical and physical processes, and their interactions with human systems”.

Flooding both from rivers and the sea is increasing. There was a storm surge in the Irrawaddy in Myanmar in 2008 when 200,000 people were killed. But people are still living on the delta. However, the estimate is that two million people have left the Indus delta in Pakistan to move to higher ground as salt water has invaded the farming zone. [A larger version of the graphic above can be found here (1.4MB). The original IGBP infographic which I have modified can be found here – caution, big file (12.7MB)].

The Po delta (near Venice in Italy) subsided largely because methane was being pumped from underground. They stopped the pumping and the delta is sinking 10 times less fast than it was. But the land surface is not actually rising, and it’s still below sea level. The Chao Phraya River Delta (along which Bangkok is built) subsided because of groundwater being pumped out to supply Thailand’s thirsty capital. So they introduced a tax on water use, such as showers. In Shanghai, the local government slowed the rate of pumping water out of the ground.

However, when countries set up commissions to look at the natural environment, it’s often water/river courses they’re concerned about, like with the Rhine. There is not so much focus on the delta. Where countries have tried geo-engineering, they can scarcely bear the prohibitive costs. It is estimated that China in the 15th to 18th centuries used 12-15% of its historical GDP in attempts to control the Yellow River from spilling out into its floodplain, but these gigantic efforts were never really successful.

Weighing the monsoon winds for El Niño

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Ignoring the torpor of the summer heat, the India Meteorological Department has dusted off the statutory paragraphs that give us in the sub-continent a first indication of what monsoon for the year may be like. The result this year, both scintillating pages, has been made that much more gripping by the inclusion of El Niño. The IMD’s treatment of the normal variables whose interplay determine the nature of any monsoon is perfunctory – which is surprising as the regional and international earth observation networks spare no detail and tend to inundate us with data and analysis.

Clouds and wind, land and farm. The equation that all rural districts make at this time of the year, but which is becoming more difficult with every year that climate change strengthens its grip.

Clouds and wind, land and farm. The equation that all rural districts make at this time of the year, but which is becoming more difficult with every year that climate change strengthens its grip.

But the IMD, especially for the south-west monsoon, has always preferred to be spartan. Perhaps there is some philosophical dictum that us non-meteorologists have yet to grasp, and if so then the only criticism we may be permitted, if the IMD had its way, its to ask for more such teaching. But the IMD does not have its way, and we publics whose monies support its work must continue to demand from the recalcitrant department better, much better, application and communication of its work.

The official release, ‘Long Range Forecast For the 2014 Southwest Monsoon Season Rainfall’, is delivered to us by the IMD, Ministry of Earth Sciences (MoES). There is the usual paragraph claiming a profundity of observation and of the IMD being a standard-bearer of superior method. “Operational models are critically reviewed regularly and further improved through inhouse research activities,” says the IMD. But what we still have, in a tradition that is probably three generations old, is the two stage forecast (one in April, the second in June). [Here is the release in Hindi.]

I think this proves how out of step the IMD – and the Ministry of Earth Sciences (grand title isn’t it?) – is with what citizens of India experience in their villages, towns, fields and hills. For, the south-west monsoon no longer arrives in the first week of June, and it no longer begins to depart by mid-September. Climate change began to alter that comfortable rhythm years ago, but the IMD’s forecasting grindstone is the same, never mind how many new earth observation satellites India pelts into orbit.

IMD_monsoon_2014_probability

With all these provisos, stated and implicit, what has the IMD told us?

First, that the “experimental ensemble forecast based on IMD seasonal forecast model (SFM) indicates that the rainfall during the 2014 monsoon season (June to September) averaged over the country as a whole is likely to be 88% ± 5% of long period average (LPA)”. This means that in places it could be as low as 83% of the average, and no more than 92% of the average. Combine this with the assessments about the 2014 El Niño and we can see why, far from being satisfied that the IMD is considering both the monsoon and El Niño, we ought to monitor independently both and force the IMD to become more responsive.

Second, that “the experimental forecast based on the coupled dynamical model forecasting system suggest that the monsoon rainfall during the 2014 monsoon season (June to September) averaged over the country as a whole is likely to be 96% ± 5% of long period model average (LPMA)”. This is a more hopeful set, but also shows that the IMD, by telling us of two different scenarios from two models, is hedging its forecast, which is not what its job is.

Third, the IMD has said “the experimental five category probability forecasts for the 2014 monsoon season rainfall over the country as a whole using the experimental dynamical prediction system are 33% (deficient), 20% (below normal), 24% (normal), 6% (above normal) and 17% (excess)”. This means, using this ‘probability’, that a normal monsoon for 2014 has only a 1-in-4 chance whereas a deficient monsoon (that is, total rain less than 90% of the long period average) has a 1-in-3 chance.

This is a prognosis that stands between serious and grim, for a 10% drift towards the lower side of an expected average, for any of our 36 agro-meteorological regions, can spell ruin for farmers and severe hardship for water consumers. How have central and state governments prepared for such a forecast? We have no information, most likely because there has been no preparation (there are contingency plans for the chronically drought-prone districts, but these are normally triggered when there is an official declaration by  the state government that there are conditions of drought in parts of the state). Elections or no elections, El Niño cares not, and it is up to the state governments to make preparations for a monsoon 2014 whose delivery of water already looks uncertain.

When the 65 million who live in India’s slums are counted

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The graph illustrates the 30 largest slum populations in India, using the new Census 2011 data. The scale is logarithmic - not proportional, else showing the largest metros would reduce the smaller cities to being unreadable - so as to better display the trend of growing slum populations in urban centres whose total populations are less than a million (like Guntur and Malegaon) and up to two million (like Kota, Gwalior, Srinagar, Raipur, Jabalpur and Meerut).

The graph illustrates the 30 largest slum populations in India, using the new Census 2011 data. The scale is logarithmic – not proportional, else showing the largest metros would reduce the smaller cities to being unreadable – so as to better display the trend of growing slum populations in urban centres whose total populations are less than a million (like Guntur and Malegaon) and up to two million (like Kota, Gwalior, Srinagar, Raipur, Jabalpur and Meerut).

We have now one important basis to consider carefully the consequences of the macro-economics of GDP growth and all the programmes to encourage such ‘growth’.

In 2011, 65.49 million Indians lived in slums in our cities and towns (the number was 52 million when recorded in Census 2001). It is important not to allow the immensity of our population numbers (1,250 million now in 2013) to diminish this extraordinary and disgraceful number in any way.

The 65 million who live in slums are all together a population equivalent to the populations of Thailand or France or Britain. This is also larger than the populations of Italy or Burma, South Africa or South Korea.

In Census 2001 the total number of towns that reported slums was 1,743. In Census 2011 the total number of towns and cities that reported slums was 2,613 out of 4,041 ‘statutory’ towns and cities. Here is the guideline for classifying types of slum settlements from Census 2011:

1. All notified areas in a town or city notified as ‘slum’ by state, union territories’ administrations or local government under any act including a ‘slum act’ may be considered notified slums (22.5 million live in notified slums).
2. All areas recognised as ‘slum’ by state, union territories administration or local government, housing and slum boards, which may have not been formally notified as slum under any act may be considered as recognised slums (20.1 million live in recognised slums).
3. A compact area of at least 300 population or about 60-70 households of poorly built congested tenements, in unhygienic environment usually with inadequate infrastructure and lacking in proper sanitary and drinking water facilities. Such areas should be identified personally by the ‘charge officer’ and also inspected by an officer nominated by the Directorate of Census Operations. This fact must be duly recorded in the charge register. Such areas may be considered as identified slums (22.8 million live in identified slums).

[You can get the Primary Census Abstract for slum populations 2011 here as an xls file. There is a very informative presentation on the data available here as a pdf. Consult the primary pages on Census 2011 – India’s 2011 Census a population turning point, India’s 2011 Census the states and their prime numbers and The data vault of the 2011 Census.]

Water spikes of the 48,000 large dams that humans have built

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This is a three-minute film that narrates the impact of humans on the planet and on the water cycle. The global footprint of human habitation – built-up regions, water extraction, industrial agriculture, mineral and fossil fuel extraction – has driven Earth into a new geological epoch: the Anthropocene.

Human activities such as damming and agriculture are changing the global water cycle in significant ways. The film quickly and dramatically describes Earth’s changing global water cycle, why it is changing and what this means for the future. The vertical spikes that appear in the film represent the 48,000 large dams that have been built. The film is part of the first website on the concept of humans as a geological force and was made for the the International Geosphere-Biosphere Programme.

The 6 June water event that our planners have missed

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This was in January 2013, in Mysore district, Karnataka. Can these women even reach the little island today?

This was in January 2013, in Mysore district, Karnataka. Can these women even use their coracle today?

In just under six weeks from today, the water available per head in India from our major reservoirs will drop under the 100 litres per day mark. This will happen on or around 06 June 2013, give or take a day.

Two charts with water levels for half the 84 major reservoirs, early February to late April 2013. Data taken from CWC

Two charts with water levels for half the 84 major reservoirs, early February to late April 2013. Data taken from CWC

For India’s 59 cities with populations of over a million (this will be so in mid-2013, see ‘India in 2015 – 63 million-plus cities’) this will mean an ever more frantic and dangerous race to secure water stocks by urban water mafia, who plunder public water storage and groundwater aquifers alike.

In the largest of these cities, their water boards claim to supply between 160 and 200 litres per capita per day (lpcd). This amount is roughly in line with what residents in comparably large East and South-East Asian cities are supplied, and is well above the lower end (100 lpcd) offered by the World Health Organisation as the minimum ‘optimal’ daily water stock required by an individual to maintain health and hygiene (100-200 lpcd is the band).

That’s the WHO view, but even in the Tenth Five Year Plan (2002-07) it was recommended that in India’s largest metropolitan cities the minimum must be 150 lpcd and in large non-metro cities the minimum must be 135 lpcd.

But six weeks from now, judging by the rate at which water has been used in 2013 from the 84 major reservoirs, we are not going to have, per head per day, even 100 litres of water. (Also see ‘Big dams, scarce water, thirsty India, uncertain monsoon’.)

Two more charts with water levels for the rest of the 84 major reservoirs, early February to late April 2013. For both sets of charts, the trendlines describe water volume as a per cent of the full reservoir volume. Data taken from CWC

Two more charts with water levels for the rest of the 84 major reservoirs, early February to late April 2013. For both sets of charts, the trendlines describe water volume as a per cent of the full reservoir volume. Data taken from CWC

How did we get here, so quickly and so dry? On 14 February 2013, the total water stored in the 84 major reservoirs was 68.718 billion cubic metres (bcm). Over the next ten weeks, until 25 April 2013, that total has dropped steeply to 42.304 bcm.

The Central Water Commission monitors the levels of and volumes in these 84 reservoirs, which if they all were full would store 154.421 bcm. These 84 reservoirs, says the CWC, represent 61% of the country’s water stored in reservoirs, which is altogether 253.388 bcm.

Judging by the same rate of water drawal from these 84 reservoirs, we have used over 43 bcm from all reservoirs in ten weeks, depleting our reservoir stock from 112.6 bcm to 69.3 bcm. This also means that in early February 2013, each of us were (notionally) holding a water stock of about 247 litres per day, a stock that was shrinking at a rate of about 1.3 litres per day to reach 152 litres per day in late April. And remember this is notional water stock per head from reservoirs, water that is used for agriculture and industry too.

What will happen between now and 06 June, when that individual stock drops under 100 lpcd? The Indian Meteorological Department has claimed (the usual bland and bored claim, as if monsoon was just another filing cabinet) that we will have a normal monsoon. As usual, the IMD has made no effort to link water with our alarming depletion of litres per head per day (it does link monsoon with GDP though, typically correct politically, typically unconcerned about human, animal and ecosystem need).

And what if the monsoon is late, scanty or erratic, as has happened with every monsoon since 2009? The IMD doesn’t know, your city’s PWD and municipality don’t know. But the water mafia do, and they’re getting very busy.

Written by makanaka

April 27, 2013 at 18:06

Big dams, scarce water, thirsty India, uncertain monsoon

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India's largest major reservoirs by volume. Indira Sagar (MP, 9.745 bcm), Srisailam (AP, 8.288 bcm), Nagarjuna Sagar (AP, 6.841 bcm), Gandhi Sagar (MP, 6.827 bcm), Ukai (GUJ, 6.615 bcm) and Bhakra (HP, 6.229 bcm).

India’s largest major reservoirs by volume. (from top left to bottom right)) Indira Sagar (MP, 9.745 bcm), Srisailam (AP, 8.288 bcm), Nagarjuna Sagar (AP, 6.841 bcm), Gandhi Sagar (MP, 6.827 bcm), Ukai (GUJ, 6.615 bcm) and Bhakra (HP, 6.229 bcm).

Why did India’s Ministry of Water Resources not start rationing water use at the beginning of 2013? Data on the water levels of the 84 major reservoirs in the country (kept by the Central Water Commission) show an alarming rate of withdrawal over the period January to March 2013.

Over seven weeks, these reservoirs disgorged 20.525 billion cubic metres (BCM) of water – for industrial, commercial, residential and irrigation purposes. By 14 March 2013, the combined water stock in these 84 major reservoirs was 57.355 BCM – on 24 January 2013 that total had been 77.869 BCM. At this rate of water use, by 09 May 2013 – seven weeks hence – there will be a perilous 36.8 BCM in the major reservoirs, and with the possible first onset of the 2013 south-west monsoon still a month away.

The major reservoirs that have disgorged the most water during this period are: Srisailam (Andhra Pradesh) 2.353 bcm; Hirakud (Orissa) 1.808 bcm; Indira Sagar (Madhya Pradesh) 1.652 bcm; Nagarjuna Sagar (Andhra Pradesh) 1.082 bcm; Ukai (Gujarat) 0.976 bcm; Pong (Himachal Pradesh) 0.913 bcm; Gandhi Sagar (Madhya Pradesh) 0.899 bcm; Rihand (Uttar Pradesh) 0.734 bcm; Bhakra (Himachal Pradesh) 0.668 bcm and Koyna (Maharashtra) 0.598 bcm.

Energy, climate, growth, China, India – the World Energy Outlook 2012

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Inputs to the power sector to generate electricity accounted for 38% of global primary energy use in 2010, the single largest element of primary demand. In the New Policies Scenario, this share rises to 42% in 2035. Demand for electricity is pushed higher by population and economic growth, and by households and industries switching from traditional biomass, coal, oil and natural gas to electricity. The fuel mix within the power sector changes considerably, with low- and zero-carbon technologies becoming increasingly important. Graphic: IEA, WEO-2012

In four parts, 18 chapters, four annexes, illustrated by around 300 figures, the chapters supported by about 100 tables, a separate set of data upon which scenarios rest, the World Energy Outlook 2012 of the International Energy Agency (IEA) is a 690-page behemoth. I can only sketch its merest outline here, and in a fleeting way touch upon the knowledge and information it contains.

Drawing on the latest data and policy developments, the World Energy Outlook 2012 presents projections of energy trends through to 2035 and insights into what they mean for energy security, the environment and economic development. “Over the Outlook period, the interaction of many different factors will drive the evolution of energy markets,” said the WEO-2012. “As outcomes are hard to predict with accuracy, the report presents several different scenarios, which are differentiated primarily by their underlying assumptions about government policies.” We are told that the starting year of the scenarios is 2010, the latest year for which comprehensive historical energy data for all countries were available. What are these four scenarios?

Based on preliminary estimates, energy-related CO2 emissions reached a record 31.2 gigatonnes (Gt) in 2011, representing by far the largest source (around 60%) of global greenhouse-gas emissions (measured on a CO2-equivalent basis). Emissions continue to rise in the New Policies Scenario, putting the world on a path that is consistent with a long-term average global temperature increase of 3.6 °C above levels that prevailed at the start of the industrial era. Chart: IEA, WEO-2012

1. The New Policies Scenario – the report’s central scenario – takes into account broad policy commitments and plans that have already been implemented to address energy-related challenges as well as those that have been announced, even where the specific measures to implement these commitments have yet to be introduced.

2. To illustrate the outcome of our current course, if unchanged, the Current Policies Scenario embodies the effects of only those government policies and measures that had been enacted or adopted by mid-2012.

3. The basis of the 450 Scenario is different. Rather than being a projection based on past trends, modified by known policy actions, it deliberately selects a plausible energy pathway. The pathway chosen is consistent with actions having around a 50% chance of meeting the goal of limiting the global increase in average temperature to two degrees Celsius (2°C) in the long term, compared with pre-industrial levels.

4. The Efficient World Scenario has been developed especially for the World Energy Outlook 2012 (WEO-2012). It enables us to quantify the implications for the economy, the environment and energy security of a major step change in energy efficiency.

In the New Policies Scenario, global energy intensity (energy demand per unit of GDP) falls by 1.8% per year between 2010 and 2035. Between 2010 and 2035, energy intensity declines by an average of 37% and 49% in OECD and non-OECD countries respectively. Yet average energy intensity in non-OCED countries in 2035 of 0.16 tonnes of oil equivalent (toe) per thousand dollars of GDP is still more than twice the OECD level. Chart: IEA, WEO-2012

I have extracted five important messages from the summary which are connected to the subjects you find in this blog – food and agriculture, consumer behaviour and its impacts on our lives, the uses that scarce energy is put to, the uses that scarce water is put to, the ways in which governments and societies (very different, these two) view food, energy and water.

Five key messages:
“Energy efficiency can keep the door to 2°C open for just a bit longer.” Successive editions of the World Energy Outlook have shown that the climate goal of limiting warming to 2°C is becoming more difficult and more costly with each year that passes. The 450 Scenario examines the actions necessary to achieve this goal and finds that almost four-fifths of the CO2 emissions allowable by 2035 are already locked-in by existing power plants, factories, buildings, etc. No more than one-third of proven reserves of fossil fuels can be consumed prior to 2050 if the world is to achieve the 2°C goal.

“Will coal remain a fuel of choice?” Coal has met nearly half of the rise in global energy demand over the last decade, growing faster even than total renewables. Whether coal demand carries on rising strongly or changes course will depend on the strength of policy measures that favour lower-emissions energy sources, the deployment of more efficient coal-burning technologies and, especially important in the longer term, CCS. The policy decisions carrying the most weight for the global coal balance will be taken in Beijing and New Delhi – China and India account for almost three-quarters of projected non-OECD coal demand growth (OECD coal use declines).

China makes a major contribution to the increase in primary demand for all fuels: oil (54%), coal (49%), natural gas (27%), nuclear power (57%) and renewables (14%). Its reliance on coal declines from 66% of the country’s primary energy use in 2010 to 51% in 2035. Energy use in India, which recently overtook Russia to become the world’s third-largest energy consumer, more than doubles over the Outlook period. India makes the second-largest contribution to the increase in global demand after China. Chart: IEA, WEO-2012

“If nuclear falls back, what takes its place?” The anticipated role of nuclear power has been scaled back as countries have reviewed policies in the wake of the 2011 accident at the Fukushima Daiichi nuclear power station. Japan and France have recently joined the countries with intentions to reduce their use of nuclear power, while its competitiveness in the United States and Canada is being challenged by relatively cheap natural gas. The report’s projections for growth in installed nuclear capacity are lower than in last year’s Outlook and, while nuclear output still grows in absolute terms (driven by expanded generation in China, Korea, India and Russia), its share in the global electricity mix falls slightly over time.

“A continuing focus on the goal of universal energy access.” Despite progress in the past year, nearly 1.3 billion people remain without access to electricity and 2.6 billion do not have access to clean cooking facilities. Ten countries – four in developing Asia and six in sub-Saharan Africa – account for two-thirds of those people without electricity and just three countries – India, China and Bangladesh – account for more than half of those without clean cooking facilities. The report presents an Energy Development Index (EDI) for 80 countries, to aid policy makers in tracking progress towards providing modern energy access. The EDI is a composite index that measures a country’s energy development at the household and community level.

“Energy is becoming a thirstier resource.” Water needs for energy production are set to grow at twice the rate of energy demand. The report estimates that water withdrawals for energy production in 2010 were 583 billion cubic metres (bcm). Of that, water consumption – the volume withdrawn but not returned to its source – was 66 bcm. The projected rise in water consumption of 85% over the period to 2035 reflects a move towards more water-intensive power generation and expanding output of biofuels.

Such is the barest glimpse of the WEO-2012. There are a number of aspects of the Outlook which deserve more scrutiny with a view to learning energy use and misuse, and this will be expanded upon in the weeks ahead.

More than half of continental USA hit by drought

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The national drought summary for the USA at the beginning of July 2012 shows how relentless the advance of the great dry has been in the country. Drought conditions are present in 56% of the continental USA, according to the weekly Drought Monitor. That’s the most in the 12 years that the data have been compiled – it was 55% in August 2003.

The Drought Monitor report said arid conditions intensified in large sections of the country, with only southern Texas reporting some improvement. “Light precipitation (0.5 inch or less) fell on most areas of dryness and drought, with only scattered areas reporting more than an inch, primarily in the northern Plains, lower Mississippi Valley, southernmost Great Lakes region, Appalachians, mid-Atlantic region, and southern Texas,” said the summary. “Unfortunately, where rain did fall (outside southern Texas), it was not enough to make up for blistering heat that covered the Nation’s midsection, reaching the central and southern Atlantic Coast by the end of the workweek.”

Both the number of record highs in the past week, (See ‘Climate change truth wallops USA hard’) and the areas with record and near-record dryness over the last one to three months are numerous. The increasing dryness is beginning to take a significant toll on crops, pastures, and rangelands. In the primary growing states for corn and soybeans (18 each), 22% of the crop is in poor or very poor condition, as are 43% of the pastures and rangelands and 24% of the sorghum crop. In addition, the area burnt by wildfires expanded significantly. Over 1.9 million acres have been engulfed since the start of the year, and an increase of 38% in just the past week. [The Drought Monitor pdf map is available here.]

Will it or won’t it? India’s monsoon forecast gamble

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Assam flood refugees. Photo: Alertnet

The India Meteorological Department (IMD) has released the long-awaited update of its long range forecast for the 2012 monsoon.

Stripped of its scientific jargon, this is what the update has said. There is a July model and an August model. For both months, there are three forecast categories: below normal in which rainfall in less than 94% of the long period average (LPA), normal in which the rainfall is between 94% and 106% of the LPA, and above normal in which rainfall is more than 106% of the LPA. Under the three categories, the forecast probabilities for July are (in the same order) 36%, 41% and 23% and for August they are 42%, 36% and 22%. Under any combination of probability therefore, this means that both July and August are going to be drier than usual, and coming on top of an unusually dry June, the scenarios for water availability and for agriculture come early September are all looking tough.

Arunachal Pradesh district rainfall for three weeks

The volatility of the 2012 monsoon over north-eastern India can be seen in the images of the district weekly rainfall deviations for those states. Please bear in mind that with the late beginning of the 2012 monsoon, the week of June from 07 to 13 was for all practical purposes the first monsoon week. The colours signify major deviations – red for 50% of the average and below, green for 150% of the average and above. In Arunachal Pradesh, for the first week the average rainfall in districts was around 45%, the second week it was 41% and the third week it shot up to 124% – red is evenly scattered through the districts in the first two weeks and green districts appear in the third week.

Assam districts rainfall for three weeks

In Assam, the first week’s average for all the state’s districts was 65% of the long period average, with red dominating. In the second week the average was 103%, with ‘red’ districts declining and a few greens appearing. In the third week the average zoomed to 184% with most districts being ‘green’. In neighbouring Meghalaya, the average for the districts in the three weeks was 63%, then 51% and then a steep rise to 225% in the third week. In stark contrast Nagaland and Manipur have for the duration of these three weeks seen a combined district rainfall average of 33% and if we remove the ‘green’ districts from both states of the third week, we get a dismal 15% average – it is of course quite likely that there are data anomalies in the numbers that IMD has collected from the north-east region, as automated weather stations that actually work are likely to be fewer in number than in ‘mainland’ India. (There is a spreadsheet for this data. If you want the data till date please write to me here: makanaka at pobox dot com.)

The first three weeks of monsoon 2012 in district averages for Nagaland, Manipur, Mizoram and Meghalaya

In the update, there is also a separate set of forecasts and probabilities for four major regions of India – North-West India, Central India, South Peninsula and North-East India. There are small variations for each of these in the definitions of below normal, normal and above normal. Here are the forecast probabilities for the regions:

The list of states in each of these four geographical regions is:
Northwest India: Jammu and Kashmir, Himachal Pradesh, Punjab, Rajasthan, Haryana, Chandigarh, Delhi, Uttaranchal and Uttar Pradesh.
Northeast India: Arunachal Pradesh, Meghalaya, Assam, Nagaland, Manipur, Mizoram, Tripura, Sikkim, West Bengal, Bihar and Jharkhand.
Central India: Gujarat, Madhya Pradesh, Chattisgarh, Maharashtra, Goa and Orissa.
South Peninsula: Andhra Pradesh, Karnataka, Tamil Nadu, Kerala, Lakshadweep and Andaman and Nicobar Islands.

Alarming reds and yellows over southern, central and northern India, threatening blues in north-eastern India (Bangladesh has been hit hard by floods). Graphic: IMD

The first stage forecast for the nation-wide season rainfall was issued on 2012 April 26 and this update was issued on 2012 June 22. The summary of the first stage forecast is:

“Southwest monsoon seasonal rainfall for the country as a whole is most likely to be Normal (96-104% of Long Period Average (LPA)) with the probability of 47%. The probability (24%) of season rainfall to be below normal (90-96% of LPA) is also higher than its climatological value. However, the probability of season rainfall to be deficient (below 90% of LPA) or excess (above 110% of LPA) is relatively low (less than 10%). Quantitatively, monsoon season rainfall is likely to be 99% of the LPA with a model error of ± 5%. The LPA of the season rainfall over the country as a whole for the period 1951-2000 is 89 cm.”

The IMD has said that it has taken into account the experimental forecasts prepared by the national institutes like Space Applications Centre, Ahmedabad, Centre for Mathematical Modeling and Computer Simulation, Bangalore, Center for Development of Advanced Computing, Pune and Indian Institute of Tropical Meteorology, Pune. Operational/experimental forecasts prepared by international institutes like the National Centers for Environmental Prediction, USA, International Research Institute for Climate and Society, USA, Meteorological Office, UK, Meteo France, the European Center for Medium Range Weather Forecasts, UK, Japan Meteorological Agency, Japan Agency for Marine-Earth Science and Technology, Asian-Pacific Economic Cooperation (APEC) Climate Centre, Korea and World Meteorological Organization’s Lead Centre for Long Range Forecasting – Multi-Model Ensemble have also been taken into account.

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