{"id":162352,"date":"2014-12-26T18:17:38","date_gmt":"2014-12-26T20:17:38","guid":{"rendered":"http:\/\/revistapesquisa.fapesp.br\/?p=162352"},"modified":"2017-04-11T13:17:08","modified_gmt":"2017-04-11T16:17:08","slug":"rain-dance","status":"publish","type":"post","link":"https:\/\/revistapesquisa.fapesp.br\/en\/rain-dance\/","title":{"rendered":"Rain dance"},"content":{"rendered":"
\"Changes

L\u00e9o Ramos<\/span>Changes in the volume and frequency of rainfall and misuse of water supplies are among the factors drying up the pipes in parts of BrazilL\u00e9o Ramos<\/span><\/p><\/div>\n

The Amazon is not just the largest tropical rain forest remaining in the world. This endless span of green intersected by winding rivers of varying sizes and colors is also not just the home of an incredible diversity of animals and plants. The Amazon rain forest is also an engine capable of changing the direction of the winds and a pump that sucks water from the air over the Atlantic Ocean and from the soil and circulates it over South America, bringing to distant regions the rainfall that the residents of S\u00e3o Paulo now long for. But how well the pump operates depends on maintenance of the forest, the Brazilian portion of which by 2013 had lost 763,000 square kilometers (km2<\/sup>) of its original area, the equivalent of three states of S\u00e3o Paulo. Antonio Donato Nobre, a researcher at the National Institute for Space Research (INPE), is not pointing a finger at the culprits. What matters to him is to reverse this process and not just stop deforestation, but recover the forest. In the report The Future\u00a0Climate of\u00a0Amazonia<\/a>, <\/em>released in late October, 2014, he makes clear that the only reason not to take immediate action to reduce deforestation is ignorance of what science knows. For him, the way forward is to educate the public. \u201cNow is a good time because the taps are running dry,\u201d he says.<\/p>\n

In the report, drawn from the analysis of about 200 scientific works, he shows that every day the forest of the Amazon Basin gives off 20 billion metric tons of water (20 trillion liters). That is more than the 17 billion metric tons that the Amazon River pours into the Atlantic each day. This vertical river is what feeds the clouds and helps to change the direction of the winds. Nobre says that maps of the winds over the Atlantic show that, in the Southern Hemisphere and at low altitudes, the air moves northwest towards the Equator. \u201cIn the Amazon the forest deviates from that order,\u201d he says. \u201cDuring part of the year, the moisture-laden trade winds come from the Northern Hemisphere and converge to the west\/southwest, entering South America.\u201d<\/p>\n

This circulation pattern violates a weather paradigm that says that winds should blow from regions with colder surfaces to those with warmer surfaces. \u201cIn the Amazon, all year they go from warm, the equatorial Atlantic, to cold, the forest,\u201d he says. A partnership with Anastasia Makarieva and Victor Gorshkov, two scientists with the Nuclear Physics Institute of Petersburg, has helped to explain the meteorological phenomena of the Amazon from a physical point of view. In an article published in the February 2014 issue of the Journal of Hydrometeorology, <\/em>they assert, based on theoretical analyses confirmed by empirical observations, that deforestation is altering the pressure patterns and may be causing a decline in the moisture-laden winds coming from the ocean to the continent. The group analyzed data from 28 weather stations in two areas of Brazil and noted that the winds coming from the Amazon rain forest carry more water and are associated with higher rainfall rates than winds coming from deforested areas and arriving at the same station.<\/p>\n

This happens, the researchers say, because of the biotic pump of moisture, a theory proposed by the Russian duo in 2007 to explain the dynamics of winds driven by forests. This idea complements the description by Jos\u00e9 Antonio Marengo, a climatologist and at the time an INPE researcher, of how the Amazon exports rain to the more southern regions of South America. The biotic pump theory applies an unusual physics to meteorology and postulates that the condensation of water, promoted by transpiration of the forest, reduces the atmospheric pressure that sucks the air currents laden with water from sea to land.<\/p>\n

\"\"<\/a>The reasoning behind the influence of condensation on winds was presented in an article published in 2013 by Anastasia and Gorshkov, in partnership with Nobre and other collaborators, in the journal Atmospheric Chemistry and Physics, <\/em>one of the most important in the field. Through a series of equations, they demonstrated that the water vapor released into the atmosphere through forest transpiration generates, upon condensation, a flow capable of propelling winds over large distances. According to Nobre, the new physics of condensation they proposed generated a dispute among meteorologists even during the review of the article. The matter was furiously discussed on scientific blogs in order to prove that the principal equation of the work was wrong. They failed and the work was published. Nobre can explain the controversy. \u201cThe new physics attributes to condensation a basic and central phenomenon of how the atmosphere operates, an effect contrary to what was previously believed,\u201d he says. \u201cTextbooks on the subject will have to be rewritten.\u201d<\/p>\n

To explain the scope of the problematic dialogue between theoretical physicists and meteorologists, Nobre says that physics develops its understanding of atmospheric phenomena based on the fundamental laws of nature, while meteorology does it largely based on observations of past climate patterns, whose statistical data are absorbed into mathematical models. Such models are very good at representing observations of climate fluctuations, but fail when there are significant changes in the pattern.<\/p>\n

This is now the case, when a new context\u2014caused by deforestation, global changes in climate or other factors\u2014is generating unexpected weather phenomena for certain regions, such as more torrential rains and more extensive droughts. Physical theory gets it right where past extrapolations err, so it is necessary, he says, to build new climate models that collect the physical data at the center of meteorological efforts.<\/p>\n

The timing is now crucial because the Amazon\u2019s climate is changing. Major droughts in this region marked the years 2005 and 2010. \u201cPrior to this, the Amazon had a wet season and a wetter season, but now there is a dry season,\u201d says Nobre. The damage wreaked by these droughts on the forest was not a fatal blow, because the Amazon can regenerate, but the accumulated damage could gradually erode this ability. An important effect already noted, predicted 20 years ago by climate models, is an extended dry season, which has undermined agricultural production in parts of Mato Grosso State. The major concern is when it will arrive at the tipping point, where the forest can no longer produce enough rain to supply itself. Models that take into account climate and vegetation indicate that this point will be reached when 40% of the original forest is lost, a number about which there is no unanimity. According to Nobre\u2019s report, 20% of the forest has been cut and 20% altered to the point of having lost some of its characteristic properties.<\/p>\n

\"Flying

GERARD MOSS \/ PROJETO RIOS VOADORES<\/span>Flying rivers: currents of water vapor that form over the Amazon rain forest export rains to southern BrazilGERARD MOSS \/ PROJETO RIOS VOADORES<\/span><\/p><\/div>\n

If the biotic pump theory is correct, the effects of this tipping point are likely to be more severe than the savannization proposed by Carlos Nobre, also a climatologist and the older brother of Antonio Nobre (see Pesquisa FAPESP <\/em>Issue No. 167<\/a>). \u201cIf the forest loses its ability to bring moisture from the ocean, rain in the region may cease altogether,\u201d says Antonio Nobre. Without water to sustain a savannah, the result could be a desertification in the Amazon. If this occurs, the scenario he envisions for Brazil\u2019s South and Southeast could be similar to other regions at the same latitude: turning them into deserts.<\/p>\n

Antonio Nobre does not say too much about Sao Paulo. \u201cMy report is about the Amazon.\u201d But he believes that the drought in S\u00e3o Paulo is not isolated from what is happening in the North. In his view, it was possible to devastate much of the Atlantic Forest without experiencing a reduction in rainfall, because the Amazon was able to make up for the lack of water in the local atmosphere. But that no longer seems to be happening. His report is an opportunity for him to urge that not only the Amazon rain forest must be immediately recovered, but also almost all of the coastal forest area of Brazil. If for no other reason, the depletion of the dams that feed much of the S\u00e3o Paulo population should suffice as an argument.<\/p>\n

The export of water from the Amazon to other regions of Brazil, especially the Southeast and the South, is a reality, through the phenomenon known as flying rivers (see Pesquisa FAPESP <\/em>Issue No. 158<\/a>). One indication of this direct connection were the heavy rains in southwestern Amazonia in early 2014, almost double the usual volume, while S\u00e3o Paulo experienced the worst of a historic drought. \u201cThe rain was trapped in Rond\u00f4nia, Acre and Bolivia because of atmospheric blocking, something like an air bubble that prevented the passage of moisture. This created an atmospheric stability, inhibited the formation of rain and elevated temperatures,\u201d says Marengo, now a researcher at the National Center for Natural Disaster Monitoring and Alerts (CEMADEN). He is the co-author of a lead article by Jhan Carlo Espinoza, of the Geophysical Institute of Peru, which is slated for publication by the Environmental Research Letters <\/em>and is part of the results of the Green Ocean Amazon (GOAmazon) program, which has the support of FAPESP.<\/p>\n

However, it is impossible to say how much this relationship affects the S\u00e3o Paulo drought. \u201cCalculating how much of the Southeast\u2019s rain comes from the Amazon and how much is brought by cold fronts coming from the South, moisture carried by sea breezes or local evaporation is still an inexact science,\u201d he says. Marengo believes that deforestation may have a long-term impact, but it is still impossible to say if it is related to the current drought. \u201cThe Southeast may not turn into a desert,\u201d he adds, \u201cbut weather extremes may become more intense.\u201d Studies using climate models created by the Marengo group already forecast a redistribution of total rainfall, with a very heavy volume in a few days and longer droughts, something that has already been observed in Brazil\u2019s Southeast and South in the last 50 years.<\/p>\n

In addition to this effect at a distance on a national scale, the relationship between vegetation and water resources also occurs on a more local scale, according to Walter de Paula Lima, an agronomist and professor at the Luiz de Queiroz School of Agriculture (ESALQ) of the University of S\u00e3o Paulo (USP) and scientific coordinator of the Cooperative Environmental Monitoring Program on Microbasins (PROMAB) of the Institute of Forestry Research and Studies. In his studies on the effect of forests (or their removal) on microbasins, he showed that the riparian forest bordering watercourses helps to keep small rivers in good health. \u201cThe Cantareira system, which supplies S\u00e3o Paulo, consists of thousands of microbasins,\u201d he says. \u201cThose that are more degraded do not contribute to the watershed.\u201d This assessment, however, lacks concrete experimental data. According to Lima, to find out exactly how riparian forests affect watersheds, it would be necessary to study an experimental microbasin where the properties of watercourses could be measured with and without forest protection, and absent any other factors\u2014a virtually unattainable scenario.<\/p>\n

A practical experience that reinforces the importance of preserving riparian forests to maintain water resources has been reported by Ricardo Ribeiro Rodrigues, an ESALQ biologist and recovery specialist of native forests. He says that 24 years ago the water disappeared from the microbasin in Iracem\u00e1polis, a city located in S\u00e3o Paulo State. The city sought help from ESALQ, and Rodrigues\u2019 group implemented a soil conservation project for the microbasin and recovery of the riparian vegetation that should be there. \u201cI was there recently and was very surprised,\u201d he says. The level of the dam is a little lower, but it has enough water to continue supplying Iracem\u00e1polis, whose population has tripled since then. \u201cThe whole region is experiencing water shortage problems, but not Iracem\u00e1polis.\u201d<\/p>\n

Forests affect the health of water resources through their influence on rainfall, but are also important when it comes to their relationship with groundwater. Edson Wendland, an engineer and professor in the Department of Hydraulics and Sanitation, S\u00e3o Carlos School of Engineering (EESC-USP), is studying precisely what happens to the Guarani aquifer recharge when the Cerrado is replaced with pasture and crops such as sugarcane, citrus or eucalyptus. The work is being done in the Ribeir\u00e3o da On\u00e7a Basin, city of Brotas, S\u00e3o Paulo State, which has been studied since the 1980s.<\/p>\n

\"In

L\u00e9o Ramos<\/span>In late November the Cantareira system had water in the Paiva Castro reservoir…L\u00e9o Ramos<\/span><\/p><\/div>\n

Through monitoring wells and weather stations, the idea is to detail, before there is no more left of the Cerrado\u2019s original vegetation, how the Guarani aquifer recharges under different land use systems. \u201cIt is impossible to manage what we don\u2019t know,\u201d says Wendland about one of Brazil\u2019s most important groundwater sources. The aquifer is a porous layer of rocks infiltrated by rainwater, which is then slowly released into rivers. This time difference between supply and discharge, a result of the slow path of water through underground means, is what ensures the continuity of rivers, which depend on saving water.<\/p>\n

Wendland\u2019s group has shown, for example, that water availability decreases when the small twisted trees of the Cerrado, which have adapted to living under water stress, are replaced by eucalyptus trees, which consume a lot of water and within a few years reach cutting size. Measurements made \u200b\u200bbetween 2004 and 2007 show that recharge rates are closely related to the intensity of rainfall and the size of the crop in this region where the Cerrado is virtually extinct, according to an article accepted for publication in the Annals of the Brazilian Academy of Sciences.<\/em><\/p>\n

This does not mean, however, that eucalyptus trees are unconditional villains. The impact of large trees depends in part upon the depth of the aquifer at the location where they are planted. According to Lima, trees that PROMAB has continuously monitored for a period of more than 20 years showed that the relationship between forest species and water is not constant. \u201cWhere availability is critical, a new element can dry the microbasins,\u201d he says. \u201cBut where water and climate balance is good, the water reduction is not even felt.\u201d These findings make it clear that a zoning plan is needed to indicate where planting would be good and where the practice would be harmful\u2014something that does not exist in Brazil.<\/p>\n

To Wendland, the importance of understanding the relationship between the Cerrado and the aquifers is crucial because the sources of most of Brazil\u2019s major river basins are in the domain of this biome. In addition to their importance as water resources, some of these basins\u2014Paran\u00e1, Tocantins, Parna\u00edba and S\u00e3o Francisco\u2014are the main providers of water for power generation in Brazil.<\/p>\n

In just over half a century, half of the Cerrado area was cleared and given over to agricultural activities. To evaluate the effect of this change in land use on water availability, Paulo Tarso de Oliveira, a doctoral student in the S\u00e3o Carlos group, did a study using remote sensing data from the entire area of the Cerrado biome. With the sensors, it is possible to evaluate not only changes in vegetation, but also measure rainfall and the evapotranspiration rates of plants and estimate the variation of water storage. According to an article published in the September 2014 issue of Water Resources Research, <\/em>the data indicate a flow reduction because of more intense agricultural activities.<\/p>\n

Deforestation and the agricultural use of soil are important, but Wendland says the biggest problem affecting recharging of the aquifer today is the reduction in rainfall. \u201cThe aquifer can make up for the lack of rainfall for two or three years, but after that it can no longer maintain the base flow in rivers,\u201d he says. In recent years the rainfall of the rainy season has been below average, according to observational data. It also explains, he says, alarming phenomena such as depletion of the headwaters of the S\u00e3o Francisco River, which remained dry for about three months and only returned to water stage at the end of November.<\/p>\n

The challenge of managing groundwater, representing 98% of the planet’s fresh water, has other peculiarities in urban areas, where it can be a crucial resource. According to Ricardo Hirata, a geologist with the Geosciences Institute (IGc-USP), 75% of S\u00e3o Paulo\u2019s municipalities are supplied in whole or part by these waters. This includes major cities of the state, especially Ribeir\u00e3o Preto, where they serve 100% of more than 600,000 residents. Nationwide there are other cities completely supplied by groundwater, such as Juazeiro do Norte (Cear\u00e1 State), Santar\u00e9m (Par\u00e1 State), and Uberaba (Minas Gerais State), according to the book \u00c1guas subterr\u00e2neas urbanas no Brasil<\/em> [Urban Groundwater in Brazil], <\/em>slated for publication by IGc and the Research Center for Groundwater (Cepas).<\/p>\n

Surprisingly in the cities it is the water lost by the public supply that will stop the aquifer. \u201cThe impermeability of the soil reduces rain water penetration, but the losses offset and overcome this reduction and on balance there is greater recharge where there are cities, compared to other areas,\u201d says Hirata. \u201cIf we analyze the water from a well anywhere in S\u00e3o Paulo, half will be from the aquifer and half from Sabesp (waste management company owned by the state of S\u00e3o Paulo).\u201d He estimates that the state capital has nearly 13,000 private wells, many illegal. \u201cThere is a law to manage this resource, but it is not followed,\u201d he says.<\/p>\n

\"...

L\u00e9o Ramos<\/span>… while the drought was evident at the Jacarei and Jaguari reservoirsL\u00e9o Ramos<\/span><\/p><\/div>\n

A problem caused by the cities is groundwater contamination by nitrate due to leaks in the sewer system. As decontamination is expensive, the affected wells end up being abandoned. In cities where the aquifers are used for the public water supply, the solution is to mix the polluted water with water from clean wells so that the overall quality is acceptable. \u201cIn Natal (capital of Rio Grande do Norte State) there is insufficient water to mix,\u201d says Hirata. The underground is the source of 70% of its water.<\/p>\n

Another significant source of pollution comes from industry, such as that caused by chlorinated solvents. Reginaldo Bertolo, an IGc geologist and director of Cepas, studies how this pollutant behaves in the aquifer below Jurubatuba, in the south S\u00e3o Paulo area, which has been an industrial region since the 1950s. \u201cIt is a contaminant with problematic behavior in the aquifer,\u201d he says. In this hard rock, where the water flows into fractures, the compound which is denser than water goes deeper and only stops when it comes to an impermeable stratum. \u201cChlorinated solvents are toxic and carcinogenic products.\u201d Pollution prevents the use of groundwater in a region where demand is strong.<\/p>\n

In collaboration with researchers at the University of Guelph in Canada, the Bertolo group is mapping these pollutants to understand how the chlorinated solvent compound behaves and propose strategies to eliminate it from the aquifer. To do this, the next step is to use a system developed by the Canadian researchers to take rock samples and install special monitoring wells. \u201cThe equipment allows us to collect water from more than 20 different fractures in the same drilling,\u201d he says. \u201cWe\u2019re going to do a mathematical model to reproduce what happens and make some forecasts.\u201d<\/p>\n

Bertolo says it is important to better map the groundwater and analyze its quality, because it is a resource that can supplement city water supplies. \u201cGroundwater is a little-known resource.\u201d Monica Porto, an engineer at the USP Polytechnic School (Poli\/USP), does not believe it is possible to greatly expand the use of these waters in the S\u00e3o Paulo Metropolitan Region. In her opinion, to go beyond a flow rate of about 10 cubic meters per second (m3<\/sup>\/s) extracted from thousands of existing wells would take thousands of new drillings. \u201cBut we can not do without these 10 m3<\/sup>\/s; we need to take care of them.\u201d<\/p>\n

Porto, who was a past president and is still a member of the advisory board of the Brazilian Association of Water Resources, is thinking of ways to ensure a secure water supply for the population. Lack of water is, in fact, among the most serious things that can happen to a city. \u201cWe are forced to work with a very low probability of failure.\u201d According to Porto, in 2009 the S\u00e3o Paulo state government commissioned a consulting firm to do a study on what would need to be done to guarantee the water supply. The study was completed in October 2013, when the state was already in the midst of the most severe water crisis in its history. Porto says it is impossible to consider Greater S\u00e3o Paulo in isolation, because there is nowhere else to draw water from without a dispute with neighbors. Therefore, the study covers the mega-metropolis, which includes more than 130 municipalities and a population of 30 million people.<\/p>\n

The public works needed to improve water security have started, with a system to collect water from the Juqui\u00e1 River in the Ribeira Valley, which should be completed by 2018. Construction of the Pedreira and Duas Pontes dams, which should supply the Campinas region, is in the environmental licensing phase. \u201cManaus and Campinas are the only cities in Brazil with more than one million people and no water reservoir,\u201d says Porto. Manaus does not need it, situated on the banks of the Amazon river, but Campinas, which relies on the Cantareira system, does. Porto, who at home \u201cmakes a great effort\u201d to save water, says the current crisis is important for raising public awareness about the need to reduce consumption. \u00a0It also highlights the importance of the set of measures that need to be reviewed on an emergency basis. \u201cWe have to learn from the pain,\u201d she says, and jokingly adds that it better not rain too much to make this \u201cteachable moment\u201d of the crisis go away. \u201cBut if it does not rain very soon, I will stop joking: we need rain.\u201d<\/p>\n

Projects<\/strong>
\n1.<\/strong> Understanding the causes of the biases that determine the onset of the rainy season in Amazonia in climate models using GoAmazon-CHUVA [rain project] measurements (13\/50538-7<\/a>); Principal investigator<\/strong>\u00a0Jos\u00e9 Antonio Marengo Orsini (CEMADEN); Grant mechanism<\/strong>\u00a0Regular Line of Research Project Award – GoAmazon; Investment<\/strong>\u00a0R$57,960.00 (FAPESP).
\n2.<\/strong> Establishment of the hydrogeological conceptual model and fate and transport of chlorinated organic compounds in the fractured aquifer of Jurubatuba region, S\u00e3o Paulo (13\/10311-3<\/a>); Principal investigator<\/strong>\u00a0Reginaldo Antonio Bertolo (IGc-USP); Grant Mechanism<\/strong>\u00a0Regular Line of Research Project Award; Investment <\/strong>R$502,715.27 (FAPESP).<\/p>\n

Scientific articles
\nMAKARIEVA, A. M. et al<\/em>. Why does air passage over forest yield more rain? Examining the coupling between rainfall, pressure and atmospheric moisture content<\/a>. Journal of Hydrometeorology<\/strong>. v. 15, n. 1, p. 411-26. Feb. 2014.
\nMAKARIEVA, A. M. et al<\/em>. Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics<\/a>. Atmospheric Chemistry and Physics<\/strong>. v. 13, p. 1039-56. 25.\u00a0Jan. 2013.
\nESPINOZA, J. et al<\/em>. The extreme 2014 flood in South-western Amazon basin: The role of tropical-subtropical South Atlantic SST gradient<\/a>. Environmental Research Letters<\/strong>.\u00a0v. 9, n. 12. Dec. 2014.
\nWENDLAND, E. et al<\/em>. Recharge contribution to the Guarani Aquifer System estimated from the water balance method in a representative watershed<\/a>. Anais da Academia Brasileira de Ci\u00eancias<\/strong>. In press.
\nOLIVEIRA, P. T. S. et al<\/em>. Trends in water balance components across the Brazilian Cerrado<\/a>. Water Resources Research<\/strong>. v. 50, n. 9, p. 7100-14. Sep. 2014.<\/p>\n","protected":false},"excerpt":{"rendered":"The water shortage in Brazil is closely related to its forests ","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"categories":[156],"tags":[217,200,240],"coauthors":[95],"class_list":["post-162352","post","type-post","status-publish","format-standard","hentry","category-cover","tag-climate","tag-environment","tag-geology"],"acf":[],"_links":{"self":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/162352","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/comments?post=162352"}],"version-history":[{"count":0,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/posts\/162352\/revisions"}],"wp:attachment":[{"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/media?parent=162352"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/categories?post=162352"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/tags?post=162352"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/revistapesquisa.fapesp.br\/en\/wp-json\/wp\/v2\/coauthors?post=162352"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}