Pakistan Flooding

Pakistan late Summer 2010

Source: NASA Earth Observatory

For a variety of reasons I have been a little obsessed with the floods of the 2010 summer monsoon season in Pakistan. My original idea had been to use Pakistan, a country very much in the news, as a central case study in the water resources course with the idea that the country is chronically short of water and subject to political pressures internally and from India related to water supply and use. Then a few months before the course began Pakistan was hit with excess rainfall and flooding of catastrophic levels. I decided it was wisest to severeky curtail the use of Pakistan as a case. Should I teach the course again, I will have the prospective of time to examine the issue of 2010's flooding, its potential links to global climate change, and the meaning of it to a country usually suffering from drought, or worried about a lack of water. Meanwhile, NASA's Earth Observatory has posted a fine view of the flooded area from space and a brief, but as almost always concise and informative description of that photo in "Flooding in Pakistan," well worth a look!

Pakistan Flooding - the Aftermath

Flood waters on the Indus at Kotri, barrage 19 August 2010

Source: NASA Earth Observatory

The Pakistan floods came just after I collected material on the problems of water supply in that predominantly arid country. The plan was to discuss Pakistan's problems resulting from a growing demand for water in the face of a diminishing supply. Instead of suffering from the problems of drought, in 2010 Pakistan was inundated by record rainfall with the Indus and its various tributaries flooding much of its best agricultural land, washing away crops and soil in productive agricultural areas and drowning parts of several large urban places and countless towns and villages. The lives of millions were disrupted, and the wet season crops of 2010 will be a small fraction of the expected yields in some of the more productive farming areas as flooding washed soil and growing crops off the fields and devastated irrigation facilities.

The flooding has now subsided, and post-flood recovery in Pakistan is largely absent from the world's news media. Today's (30 October) Guardian newspaper from Britain has a fine piece on the problems of recovery by Mohamed Hanif "Forgotten but not gone." Even as in the recent past the US has promised Pakistan's military about $2 billion in military aid, it is contributing a vastly smaller amount for food aid and reconstruction of infrastructure damaged and destroyed in the flooding. Yesterday the BBC reported "Pakistan Flood Food Running Out." With crops far below usually production, the country will need food supplies to carry it through to the next harvest. In addition a huge amount of resources will be needed to reconstruct houses, warehouses, transportation facilities, irrigation canals, and the other elements of life the flooding destroyed.

Discussions of a world water crisis rightly emphasize problems of water supply, and in most of the countries where a water crisis looms, the availability of adequate quantities of water is the key issue. With global climate change, some regions will be faced with additional rainfall and others will suffer from irregular and occasionally excessive precipitation - likely to be the case in much of the Indian subcontinent. A not inconsiderable portion of the subtropics may face wild fluctuations in precipitation year to year. They may then have occasional years like 2010 in Pakistan with damaging and dangerous flooding followed by numerous years with precipitation inadequate to meet basic water needs.

Related articles

• Pakistan faces long-term damage to irrigation system (nature.com)
• Report: Aid shortage in Pakistan leaves flood victims in limbo (cnn.com)

Climate Change and Drought

Source: NCAR

Yesterday 19 October 2010 the Universities Corporation for Atmospheric Research (UCAR) issued a press release describing its work on the water supply aspects of climate change:  Climate change: Drought may threaten much of globe within decades.  The release and the research on which it is based provide yet more evidence, as if such were needed, of how critical climate change is to the human future. No, agriculture cannot simply move from Iowa to northern Manitoba for all to be well! The drying out of middle latitude zones is ominous indeed and does not bode well for maintaining a decent standard of living for the world's increasing human population. The online version of Scientific American has an interesting article based on the UCAR report.

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Smoke, Trash and Dams

Three Gorges Dam, Yangtze River, China under construction below and nearly complete top

Source: NASA Earth Observatory

When it was proposed and during construction of the Three Gorges Dam, many commentators said it would fail to stem the floods for which the Yangtze is notorious. Since its completion the rains of summer 2010 mark the first season of precipitation greatly in excess of long-term averages, and events of the past two months would seem to prove their point. There has been substantial flooding both above and below the dam. Although the Chinese authorities claim the dam itself is sound,  it has been able to hold back only a small part of the additional flow of the massive river. Devastating flooding has wiped out towns and villages, farm fields, and transportation facilities both up and downstream from the world's largest barrage. Built for all four of the magic goals of dams, for the foreseeable future the Three Gorges Dam may fail at three of them, flood control, navigation, and hydroelectric generation, while the rains make the final one, irrigation, unnecessary.

Much of the detritus caused by the flooding, it turn, has washed into the river, and the dam has blocked that material coming from upstream in much the same way that it blocks silt in periods of normal flow. Upstream of the dam the accumulating trash in the reservoir, already about a meter thick and strong enough to form islands capable of supporting a person, could clog a floodgate and threaten the integrity of the dam itself, but more likely is blockage of the navigation locks (right hand side of the pictures) and fouling of the water flowing over and through the dam with trash that makes downstream use difficult. There are dire predictions about navigation dangers on the river, a crucial route for Chinese commerce, due to the accumulated trash. Upstream, the immense city of Chongqing (Chongqing (重庆; Chóngqìng formerly spelled Chungking), may have to draw water into its public supply that has been fouled by industrial and agricultural chemicals, farm waste, and human sewage. Rapid flow would serve to dilute those pollutants if the river had been left undammed, but the slack water behind dams results in far less mixing of waters and dilution of pollutants.

Meanwhile, at the opposite end of the rainfall spectrum, the severe drought and excessive heat that have plagued European Russia for most of the summer of 2010 have resulted in some serious problems of heat and smoke in the capital. Moscow, a city where air conditioning is rare because in the past it has been needed infrequently, has suffered multiple days with 35+ degrees Celsius. In addition to the heat, Muscovites are breathing air with dangerous levels of smoke, soot and other pollutants, a consequence of field, brush and forest fires, some of them burning down into the layers of peat beneath birch woods and brush lands surrounding the city. Peat, used as a fuel in several parts of the world, can smolder and burn for a long time once ignited, and until drenching rains or the winter cold begins, smoke will continue to plague Moscow even when temperatures moderate.

Most Russian grain is rain-fed with no supplemental irrigation, and the combination of drought and fires have devastated the 2010 crop. World grain prices have soared because analysts expect the grain crop in Russia to be far smaller than usual, and that country has banned grain exports. Increases in grain prices could spark serious food problems worldwide.Should the Argentinian and Australian grain areas suffer serious drought in the 2010-11 growing season, the year of 2011 could have a food crisis.

Temperature anomalies in Russia, Summer 2010

Source: NASA Earth Observatory

As always one must remember that the events of a single summer say nothing about climate change, but the flooding in Pakistan and China and the drought and heat in Russia are precisely the kinds of conditions that warmer earth temperatures point toward. Those include long spells of hot weather in many northern hemisphere cities, redistribution of precipitation with increases in some areas and deficits in others, and an increasing frequency of extreme weather events including both drought and torrential rainfall.

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Droughts and Floods

Navy Memorial Fountain, Pennsylvania Avenue NW, Washington, DC 2010

©EOP

Todays feed from Huffington Post includes a rather apocalyptic piece by Toby Barlow "Let's Call it Climate Chaos." I have enough experience with both climatology and statistics to realize that the current nexus of climate related issues worldwide is in itself neither proof nor disproof of climate change—only trends over a longer period can serve that purpose—but current conditions give powerful reasons to fret about the future of a warmer world. Those of us unfortunate enough to live in the Mid-Atlantic states have experienced a prolonged spell of very hot and uncomfortable weather, though neither New York nor Washington, DC actually set new records for the month of July, merely matching older ones. Just the discomfort of hotter summers is adequate to make one hope global warming is limited to only a few degrees at most. It is clear that warming has many effects, most of them much scarier than simple discomfort.

Source: Novosti Infographics

Much of European Russia has had one of its hottest and driest summers ever. It seems that Moscow is posting new heat records almost daily even as its residents are forced to breathe smoke filled air from countless brush, field, and forest fires in the surrounding region. In addition to the dessicating heat, rainfall in the breadbasket areas south of Moscow are far below long term norms with some areas receiving only a tiny fraction of the precipitation expected. Grain yields are in turn now expected to be well below long-term averages, and it will soon be too late, if it is not already, for additional rainfall to benefit the current year's crop. The expected deficit in grain production is likely to raise world grain prices, for it has already raised grain futures.

The drought in Russia points to the changes in the global distribution of precipitation during a hotter Northern Hemisphere summer. The summer of 2010 is entrain to be the hottest ever recorded (just as the 2009-10 winter was the warmest recorded). Common to post el Niño seasons, the southwestern United States, including Southern California and the lower Colorado River Basin has enjoyed above average rainfall, somewhat breaking the years long drought. That has started to refill the various reservoirs, though it is unlikely to leave Lake Mead, Lake Powell or the others anything close to bank-full. For the moment at least, a drought has been broken in an area where water supplies are historically very limited.

In Asia excess rainfall is the issue with deadly flooding in both Pakistan and China. Pakistanis wish for rain in the wet part of the monsoon in mid to late summer, but this year has brought rainfall far in excess of long term averages, and 1,000 or more people have been killed by flood-related causes even as bridges, roads, and rail lines have been severed, towns destroyed, and agricultural areas devastated as rushing waters was away topsoil and growing crops. Instead of providing needed water for crops, the monsoonal rainfall of 2010 has caused massive damage. The situation in southern China is similar to that in Pakistan, though it is a function of typhoon circulation rather than the Asian Monsoon. 

The combined effects of these weather conditions, especially droughts and flooding, could have substantial impact on food prices throughout the world. European Russia and southern China export food to other parts of those countries and to world markets. Pakistan is a net food importer, and destruction of good agricultural land is likely to lead to greater demands for imported food. The combination of reduced production and demand from those areas made unproductive by drought and flood is almost certain to led to increased prices for at least some commodities. Those price increases are already apparent in world agricultural markets.

Once again it is important to note that the current summer is not in itself evidence for climate change, but it offers us a shocking preview of what warmer global temperatures portend. From the point of view of water supplies, a massive global redistribution of precipitation will be making some areas much drier than they have been in the past while other areas suffer from excessive precipitation. Severe storms are likely to become much more common, and 100-year floods may become 10-year floods. Instead of being expected not more than once in a century, those water levels will be expected once a decade. Some presently habitable areas will be erased from the map by flooding (granted other areas currently uninhabitable may be added to the ecumene but a net loss of usable land is the most likely outcome), while others will become too dry to use for crops. The world's food supplies are likely to be reduced and food prices increased by the combined effects of drought, flooding, and loss of land accompanying an increase in average world temperatures. It is all quite scary to contemplate!

Image via Wikipedia

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Notes III

Carhenge, Alliance, Nebraska

©EOP

In the posting about dams, I failed to note one major issue, the possibility of failure. Well-engineered dams rarely fail, but poor engineering, extreme weather events and lack of proper maintenance can lead to failures. In a few cases so can bad water management as illustrated by the first pages in Powell's Dead Pool, where the author describes what could have been a catastrophic failure of Glen Canyon Dam on the Colorado River.  Under the worst of circumstances, a catastrophic failure can lead to hundreds or even thousands of casualties. The most famous dam failure in the United States was at Johnstown, PA in 1889 when a badly maintained dam broke and killed 2,200 people. (That same benighted city had further floods in 1936 and again in 1977, devastating to property but not nearly as deadly for people, and neither was the consequence of a dam failure but rather of extreme weather.) Two days ago a small dam in Iowa collapsed after torrential rains. Knowing the failure was likely, deaths were apparently avoided, but several downstream towns had to be evacuated, and there was substantial property damage.

The St. Francis Dam, a water supply dam built in the early 1920s and designed by the famed California water engineer William  Mulholland, catastrophically failed on 12 March 1928 due to an engineering error. The ensuing flood killed 450 people and washed away towns and farms in the Santa Clarita Valley NW of Los Angeles.  Another badly engineered dam failure was the collapse of the irrigation retention  Teton Dam in Idaho in 1976 leading to 11 deaths and tremendous property damage downstream (see some pictures of the collapse on the website of a civil engineering faculty member at San Diego State University. Driving through the area later that summer, I stopped in Rexburg, Idaho to witness some of the devastation, but I have not scanned my slides as yet).

Shortly after posting the piece on glaciers yesterday, I read the New York Times (NYT) Sunday 25 July issue. While I am no fan of their regular columnist Thomas Friedmann,  he has an interesting op-ed  on global warming worth a read. This has been one of the hottest summers ever recorded in the eastern United States, and if current trends continue it could be the hottest yet recorded. Despite that heat (which it must be noted may be completely unrelated to climate change) the Senate has killed even the feeble climate legislation pending before it. Perhaps that is all to the well, for sometimes half measures like those in the bill now dead are worse than no action at all, but the lack of attention to the matter of climate change and the overuse of petroleum products in a hot summer with the Gulf oil gusher only temporarily capped is quite disturbing. It would seem those topics should be the subject of a national frenzy and demand for action. This morning's NYT has a good piece by their regular columnist and Nobel laureate Paul Krugman bemoaning the Senate's action, or or more exactly their lack of action placing a substantial share of the blame on the unprincipled ex-presidential candidate McCain and showing how the demands of the coal and petroleum oligopolies have trumped the public interest.

More water woes in the DC area. The drought may have broken for a time with heavy rains and strong winds accompanying a thunderstorm yesterday afternoon. The storm led to numerous electrical supply problems, and one facility loosing power was a major filtration facility of the Washington Suburban Sanitary Commission causing it to once again issue mandatory water usage limitations for Montgomery and Prince Georges Counties. While water supply systems are often discussed in the abstract and without reference to other elements of urban infrastructure, storms and other catastrophic events illustrate how interdependent those elements are.

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Climate Change - Glacial Retreat

Receding glacier, Upper Joffre Lake, British Columbia, Canada

©EOP

Any discussion of world water supplies over the next century must take into account climate change or what is frequently termed "global warming." The scientific consensus has long since concluded that an increase in global temperatures of several degrees over the next century is nearly certain. The only remaining debate is on how great and how fast the warming will be. That is an important debate, but a little outside our purview. What is important is the impact of increased temperatures on world water supplies. The worst case scenarios for that issue are, to use a very bad pun, chilling indeed.

One early sign of the increase in global temperatures is the recession of glacial ice in the Northern Hemisphere and of mountain glaciers in tropical areas. Glaciers are an important part of the water supply equation as well as a key variable in world climates. Glacial ice acts as a natural reservoir helping to keep runoff in streams constant over the year and from wet years to dry ones. Many perennial streams would run dry for several months a year, and for several years in succession in a severe drought, were it not for glacial melt. Exotic rivers in North America and Asia depend on glacial melt for a sizable part of their flow. The disappearing glaciers of the Rockies are major suppliers of water to the great American Rivers of the west. As a sad example, Glacier National Park is rapidly loosing its namesake features and may have no glacial ice in less than a century. In the Coast Range of British Columbia many glaciers are rapidly melting, like the one feeding Joffre Lakes, one of the most stunning sets of glacial lakes in the world. Not long ago that glacier reached the water of the upper lake. Now the melting glacier is more than 100 meters higher than the lake surface.

Highland glaciers are found in several tropical areas where there is clear evidence of rapid melting. Much of highland tropical South America, including populated parts of Ecuador, Peru, and Bolivia, has permanent streams only because of the water released when glaciers in the high mountains melt. Urban water supplies and irrigation are dependent on that water, for the region is characterized by a division between a wet season and a dry season. There is disturbing evidence of glacial retreat in that area as there is in New Guinea. Kilimanjaro has one of the few glaciers in Africa, and the debate is not if the glacier will disappear but when with the best guess being in about 10 years.

Outside the tropics there is rapid glacial melting in the Himalaya. An unfortunate error in a major climate report concerning glacial melting in the Himalayas has been used as "evidence" by those opposed to the idea of global warming, persons who believe, against all evidence, that global warming is a myth being perpetrated by greedy scientists to get more research funding. The elected Attorney General of the antediluvian Commonwealth of ole Virginny is among those anti-scientific Luddites. Almost all of them are slavishly repeating the propaganda generated by the coal and petroleum industry, an industry which does not want to have any limits placed on coal and oil consumption, the major source of the most important greenhouse gas carbon dioxide. It is clear the glaciers are less important as sources of water in major Asian rivers than the report indicated, and the rate of melting is slower than the alarmist information in the report. But glacial melt in the world's highest mountains is crucial to the flow of the Indus and significant in several other streams. The retreat of those glaciers portends catastrophe in an area where water supplies are already seen as inadequate to meet increasing demands.

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Drought II Cycles and Climate Change

 Kenya’s Ewaso Nyiro River Dries

The river, important for wildlife on the plains of Kenya, has ceased to flow in this October 2009 aerial photograph.

Source: NASA Earth Observatory

Drought in the preceding post was called an absence of adequate wet season water to meet dry season demand, and severe drought follows several years of inadequate precipitation. Seasonal drought is common in many climates. Equally common are climate cycles with a series of wet years followed by a series of dry years. Early humans were acutely aware of these cycles, witness the biblical seven fat years and seven lean years. Not a little effort was expended on trying to foresee conditions in the coming season. There is some evidence that Inca seers used stargazing conditions to predict crop conditions for the coming season. If the sky was clear enough to see certain stars, then the season was likely to be a good one, while years when those stars could not be seen meant bad crops. While the record is difficult to interpret, especially as the Inca had no recorded language as far as we know, it is quite possible these observations were based on El Niño conditions off the nearby coast.

While they are considerably more difficult to prepare for than annual variations in precipitation, longer term climatic cycles have also led to human efforts to minimize drought effects. In Kenya water from more humid higher elevations can take the place of local precipitation in drought periods. If there is advance warning of drought conditions, then the crops planted can be adjusted and the number of stock grazed on land can be reduced. Large storage dams are another response, storing water in a wet period to use in a dry one. All of the responses are premised on the expectation that the dry period will be limited to only a few years. When the dry spell is extended over many years, responses become much more difficult.

Climatic cycles occur over various time periods from a single year to five years or so in the case of the El Niño to a decade even to centuries and perhaps even millenia. The essence of a cycle is the expectation that at some point conditions will return to "normal," that is to levels of precipitation suitable for agriculture and human settlement. Generally humans can only adjust to cycles of a decade or less with temporary measures. Longer term cycles can lead to complete changes in activity or even abandonment of land and settlements.

Now there is evidence that some recently observed climatic shifts that are unlikely to be cyclic but rather are probably permanent. Overall this is often called "global warming," for the general movement is toward higher temperatures across the earth's surface. Related to those warmer temperatures are higher rates of evapo-transpiration and in many, but not all, arid and subhumid areas diminished precipitation. Some marginal areas where precipitation has been barely adequate for agriculture are likely to become unusable.