chapter 14
Drought in the Oasis of Central Western Argentina
Elma Montaña and José Armando Boninsegna
Introduction
This chapter discusses droughts and episodes of water scarcity in the context of the Mendoza River basin, an area in central-western Argentina where a dynamic agriculture emerges in an arid complex Mediterranean climate. The Mendoza River basin is similar to many dryland territorial configurations on both sides of the central Andes or to the Palliser Triangle in the Canadian Prairies, where “green oases” emerge as a result of human-built irrigation systems. As in many semi-arid and arid regions of the Americas, the sensitivity of the regional economy and population to climate variability and the new threats of global warming lead to questions of how to reduce vulnerability of agricultural producers, integrate climate change into their activities, and foster the best possible adaptive strategies for facing inevitable climate change consequences.
The chapter assumes that climate and water-related issues should be understood in terms of coupled natural and social systems. In these terms, the presence and the impacts of droughts should be discussed from a perspective that integrates both the natural and social scientific views. The first section of this chapter deals with the natural scientific perspective; it discusses the climatological conditions that characterize the basin and their impact on regional water scarcities. Following the conceptual approach discussed in Chapter 1, the second section of this chapter deals with the social dimension, focusing on the vulnerabilities of the basin and paying special attention to the social and economic structures of the basin in setting up variable conditions of vulnerability for different producers. The third section focuses on the adaptive capacity of these rural producers, linking this capacity to the social and economic structures. Finally, policy implications for managing future droughts are discussed.
Several natural and social studies, which are the main inputs to this chapter, have been carried out in the region. The natural studies have focused on hydrological cycles, their relationship to agriculture, and the vulnerability of the region to water scarcities, which are the main constraints to economic growth and expansion. Rainfall, runoff variability, and their relationship with large-scale circulation anomalies and different climate conditions have been discussed in both past (Prieto et al. 2000; Compagnucci and Vargas 1998; Rutllant and Fuenzalida 1991; Cobos and Boninsegna 1983) and more recent studies (Gonzalez and Vera 2010; Viale and Norte 2009; Vargas and Naumann 2008; Masiokas et al. 2006; Boninsegna and Delgado 2002). Past droughts have been analyzed by Villalba et al. (2012), and Christie et al. (2011), and Le Quesne et al. (2009) used tree ring series to reconstruct the Palmer Drought Severity Index back to year 1346, providing an insight into the central Andes drought recurrence. Climate change impacts on the Cordillera have been addressed by Bradley et al. (2006), Nuñez (2006), Urrutia and Vuille (2009), Nuñez and Solman (2006), and Vera et al. (2006). Glacier evolution has been the subject of several studies (Le Quesne et al. 2009; Bottero 2002; Luckman and Villalba 2001; Leiva 1999). An estimation of the future streamflow of the San Juan and Mendoza Rivers was made by Boninsegna and Villalba (2006a, 2006b).
In the region, risk and vulnerability studies have focused mainly on water and water scarcity–related issues, as well as on the potential impacts of climate change. The historical perspective of the relationship between water and society can be found in Marre (2011), Montaña (2011, 2008a, 2007) and Montaña et al. (2005) while studies concerning the possible role of global change in altering risk patterns appear in Scott et al. (2012) and Salas et al. (2012). Vulnerability has been addressed by Masiokas et al. (2013), Montaña (2012a, 2012b) and Diaz et al. (2011). New ways of thinking about conservancy ethics, society, and adaptation applied to the central Andes region are found in Montaña (2012a), Montaña and Diaz (2012) and Diaz et al. (2011). As indicated earlier, the chapter integrates this diversity of studies.
Climate Variability and Droughts in Mendoza
The central western Andes region of Argentina, where the province of Mendoza and the Mendoza River are found, is complex in terms of its orography, climate, and socio-economic development. The topography is characterized by the steep north-south barrier of the Andes, which strongly modulates the climate between the western (Chilean) and eastern (Argentinian) sides of the mountains. In the eastern slope of the Andes, located in central-western Argentina, Mendoza is part of what is called the “dry pampas,” where most of the scarce yearly precipitation occurs during the hot summer months. During the cold winters, snow accumulates in the higher mountains and occasionally in the valley, where frost episodes are common. As in the case of the Canadian Prairie provinces, the winter snow melts during the spring due to the rise of temperature, increasing river runoff, which peaks in the summer months of December and January. This runoff provides water for human consumption, agricultural activities, and hydroelectric production. This hydrological cycle, which is conditioned by climate, is crucial to sustain human activities in the region. In this context, the Andes have been defined as a “natural water tower” capable of collecting, storing, and distributing water from rain and melting snow (Viviroli et al. 2007, Vitale 1941).
Most of the irrigated agriculture in the Mendoza region is both intensive and diversified. Famed worldwide for its viticulture, Argentina produces approximately 1.5 billion litres of wine per year. Other agriculture-based industries—such as olive oil, and canned and preserved food production—are also highly developed. Tourism, while a relatively new industry, is becoming an important source of revenue for the region. A more marginal agriculture, which has limited access to irrigation and is highly dependent on summer precipitation, extends throughout the eastern and northern part of the province. Only 3.6% of the provincial territory is irrigated, an area identified as “the oasis,” which provides the conditions for agriculture and urban development. This concentration of activity clearly highlights the region’s potential for producing goods but also its increasing vulnerability to climate variability.
In recent years, there has been increasing concern about the implications of climate change for the region. Recent projections indicate a probable decrease in snow in the mountains and a rise in temperature during the present century, two factors that could seriously increase the water deficit and compromise the survival of the oasis. Reducing (as much as possible) the uncertainties in the long-term forecast of hydrological supply is essential to designing adaptive measures whose implementation will require long-term efforts.
The amount of snowfall and its accumulation, the variation of temperature, and the influence of some climate forcing systems, such as the El Niño–Southern Oscillation (ENSO), regulate the quantity of water available in the mountains. The water regime is highly dependent on the amount of snow that falls during winter and accumulates in the high basins. Temperature regulates the occurrence and rate of the snowmelt and runoff volumes to the extent that the seasonal temperature cycle produces variations in the height of the 0°C isotherm. The position of this line allows for estimating the surface on which the accumulation and/or melting of the snow will occur. The melting of the accumulated snow produces runoff, with the largest volumes produced during the spring and summer months (Figure 1).
Figure 1. Annual snow accumulation measured at Toscas station (3,100m asl). Note the existence of an accumulation period, from early May until late September when snow starts melting. The snowmelt is quite fast at the measuring station and is completed by mid-November. Snow persists at higher elevations until the end of summer. Also note the large variability in the timing and quantity of the snowfall. (Source: DGI (General Department of Irrigation). 2012)
The largest inter-annual climate variability driver in the tropical and subtropical regions of South America is the ENSO. Montecinos and Aceituno (2003) noted that during El Niño there is a tendency for the occurrence of above-average rainfall between 30° and 35° S in winter and from 35° to 38° S in late spring. Precipitation anomalies are opposite during La Niña episodes. Increased blockages in the southeastern Pacific during El Niño events produce westerly winds at lower latitudes—a key element that explains winter humidity conditions in central Chile.
At larger scales, the Pacific Decadal Oscillation (PDO) and long-term trends in the Antarctic Oscillation have influenced the climate in the Andes. Wetter conditions are present during the positive phase of the PDO in the subtropical belt of South America. Consistent with these observations, Masiokas et al. (2010) have reported an association between periods of low and high runoff in Andean rivers (between 30° and 35° S) and in the negative and positive phases of the PDO, respectively, during the twentieth century.
Figure 2 shows periods of snow and runoff shortages between 1910 and 2010. Assessing these periods as drought onsets is not easy, because of the high variability in snowfall and streamflows.
Long-term climate change assessed by different regional circulation models indicates that there will be an increase in temperature (+2.5°C to +3.0°C A2 scenario), less snowfall and runoff (-10% to -15%), and an increase in summer precipitation in the oasis (+30%) between 2090 and 2100. The model of CONAMA (2006), for example, shows a decrease in precipitation on the upper mountain, which could experience up to a 15%–20% snow deficit, but a steady increase in precipitation (rain) concentrated from October to March in the productive oasis (Figure 3) of the valleys. This summer input of water in the oasis hydrology differentiates Mendoza’s oasis from the central Chile situation, where the summers are normally very dry.
Figure 2. Mendoza River snowfall and streamflow, showing the regional average of snowfall measurements and regional average of streamflow measurements for the period November to February, expressed as percentage of water equivalent, base period 1966–2000. Note the variability in the annual record of snowfall and runoff. Years in blue are El Niño–Southern Oscillation years. The correlation coefficient between the series is r = 0.945, p <0.001 (highly significant). Filled bars are mean snow measurements (mean of 10 stations), green line indicates streamflow measurements (mean of 8 stations), and dashed line represents the Pacific Decadal Oscillation (PDO) low-frequency index.
(Modified from Masiokas et al. 2010).
It is extremely important to account for all interactions among the variables. For instance, if mountain temperatures rise steadily, snow cover will melt early in the year, provoking a rise in runoff during the early spring months and a drop during the summer, just when agriculture most needs irrigation (Figure 4). The increase in summer precipitation could make the situation even worse, since summer precipitation has been found to be detrimental to vineyard yields due to the increase in hailstorms and fungal diseases (Agosta et al. 2012).
Figure 3. Shown are (a) Mendoza annual precipitation 1961–90, (b) Mendoza annual precipitation 2071–2100 according to PRECIS (Providing Regional Climates for Impacts Studies) circulation model, and (c) difference between future and present estimates. The figure shows a steady increase in precipitation to the east of mountain foothills but a decrease in the higher Cordillera.
Figure 4. Hydrograph of Rio Vacas (Mendoza River basin) and modelled hydrograph of Rio Vacas (Mendoza River basin) with similar snow cover, but temperature +1.5°C higher than present values
In a viticulture-based agriculture (with the grapes rapidly growing from January to the harvest period in March), this change in the hydrogram produces an agricultural drought situation even with above-average snowfall in the mountains, a situation that calls for adaptive measures such as increasing reservoir capacity.
Drought is a regional natural hazard and should be considered a normal part of climate rather than a departure from normal (Glantz 2003). In these terms, it is difficult to assess whether a drought exists and/or its degree of severity. In the Argentinian and Chilean central Andes, instrumental and paleoclimate records could provide a method to analyze periods of water scarcity, at least from a meteorological point of view. However, it is difficult to define each of those periods as “drought,” with all its negative connotations. Periods of drought are not by themselves a disaster; qualifying them as a disaster depends on anthropogenic and environmental impacts. The magnitude of the impacts in turn depends on the timing, duration, and intensity of the phenomenon.
All types of drought originate from a deficit in precipitation (Wilhite and Glantz 1985). If the precipitation scarcity lasts for an extended period, a meteorological drought could occur. But there are also hydrological droughts that are defined as the departure of surface water and groundwater supplies from average conditions. This situation can occur even with average or above-average precipitation.1 It is when these conditions affect agriculture that an agricultural drought is declared. The start and end of drought are difficult to determine, particularly in regions where climate variability is high. When meteorological water scarcity is coupled with hydrological scarcity, and in turn agricultural and social systems are impacted, a severe drought could occur.
Historical records and narratives are valuable tools for analyzing such events (Prieto et al. 2000). Indeed, severe droughts have occurred in the region lasting long enough to jeopardize the survival of fruit trees and grapevines. During the years 1966–70, the quantity of snow in the Andes was extremely low. Moreover, during those years, there was very little rain during the summers in the valleys. Desperate measures were used to try to cope with the situation, such as draining Cordillera lakes using explosives. This recent historical episode reveals how vulnerable the region is to lasting hazards (Prieto et al. 2010).
However, it is not always easy to measure the cause of a climatic disaster. Several factors, including economic conditions, agricultural mismanagement, hailstorms, frost, plant diseases, and drought affect wine production; untangling the roll of each factor and isolating the effect of drought is particularly difficult. Frederick (2011), for example, pointed out that “the drought occurring between 1967 and 1970 brought agricultural expansion to a temporary halt.” On the other hand, after analyzing the contribution of wine production to the provincial gross domestic product (GDP) of Mendoza during the twentieth century, Coria (2014) concludes that the main stressor seems to be several economic crises due to government mismanagement. But coincidentally, the analysis shows a 50% reduction in the added value of wine in the industry in 1969. However, there is no mention of water shortages.
Vulnerability to Drought in Mendoza
Mendoza looks like an idyllic oasis fed by waters from Andean snows. It has a territorial configuration characterized by two opposing landscapes. On the one hand, there are green oases with neat rows of grapevines, tree-bordered roads and streets, and irrigation channels and drains. On the other, there are non-irrigated lands (the “desert”) occupied by a scattered population of goat breeders in a “no-man’s land,” defined as a subordinate space that is empty and void of interest.
This territorial configuration follows a very similar pattern from north to south along the central Andes, both in Chile and Argentina. In these drylands, agriculture is only possible through systematic irrigation, and the oases develop as intensively exploited territories. In the province of Mendoza, for example, oases account for only 3.6% of the total area, but they are home to 98.5% of the province’s population and are the centre of most economic activities, among which grape growing and winemaking stand out. Most of the population resides in the city of Mendoza, with a population of about one million people. The second largest city has close to 100,000 inhabitants, followed by a number of small towns in the margins of the oases.
Agriculture is less diversified than in the central Chilean valleys or the Canadian Prairies, as grape growing accounts for about half of the cultivated area of the Mendoza River basin, followed by horticulture (23%) (CNA 2002). Agriculture in the basin is highly integrated with the industrial sector, because 99% of grape production is destined for winemaking. Approximately 23,000 irrigators in the basin account for 89% of surface water use (DGI 2007). In the basin, however, only 45% of farmers irrigate with surface water; 27% irrigate with groundwater only (CNA 2002), and 28% use both surface water and groundwater. Marked differences occur among grape-growing and horticultural productive systems and among wine growers in particular. Among wine growers, there are small producers with traditional vineyards at one end of the spectrum and representatives of the “new viticulture,” which is part of a modern global agribusiness, at the other end of the spectrum. In the case of horticulture, small- and medium-scale producers, in some cases of Bolivian origin, produce vegetables for regional consumption, relying on social and family networks to organize their production to successfully develop their agricultural activities.
The agricultural, industrial, and urban sectors are highly dependent on the water resources provided by the Mendoza River, but this dependence affects the region’s social and political life, going well beyond a functional dependence on water resources. As Worster (1985) argues, the situation here constitutes a modern “hydraulic society,” in which the social tissue is strongly associated with a comprehensive and intensive manipulation of water resources within an order imposed by a hostile environment. The conflicts of the hydraulic society (Montaña 2008a) become palpable precisely when the hostility of these drylands is exacerbated by water scarcities and drought.
Under these conditions, the agricultural communities of the Mendoza River basin are inherently vulnerable to drought. Studies carried out by Montaña (2012a, 2012b) in Mendoza show that drought is the climate exposure most mentioned by agricultural producers in the Mendoza River basin as affecting their operations, followed by hail and frost. References to water scarcity are not only limited to the flow of the river or the water received through irrigations ditches but also involve groundwater, particularly in summer. Structural water scarcities and growing demands add up to recurrent drought crises. When asked about the causes of water scarcity or drought, not all of the explanations provided by farmers are associated with climate, climate change, or hydrological factors. Explanations also include human factors, such as upstream expansion of agriculture and urban sprawl, rightly perceiving the converging natural and human processes that are involved in defining a situation of vulnerability and which give rise to water conflicts that could turn a “natural” phenomenon into a disaster. Farmers are used to dealing with water scarcity and drought, and they consider them a structural problem that will be increasingly problematic in the future. However, they do not seem to be aware of the severity of the droughts that could arise in the context of significant modification of climate conditions, as discussed in the previous section of this chapter.
Drought, as a climate hazard, could overlap with other stressors, such as economic and social crises, generating double exposures (Leichenko and O’Brien 2008). When agricultural producers of Mendoza are asked about the most important problems affecting their productive activity, they identify exposures to economic and social stressors to be just as relevant as climate and water factors. These stressors include economic exposures (national macroeconomics trends, the labour market), social exposures (migration of young rural dwellers and aging of the remaining rural population), and socio-cultural exposures (the Bolivian origin of the horticultural producers and the Aboriginal origin of goat breeders from the desert lands). Even in situations where water scarcity is not the main stressor, it certainly becomes the coup de grace that puts small-scale producers, already impacted by the new rules of the globalized agriculture, on the edge of the agricultural system or just expulsed to the urban sector.
Indeed, drought does not impact everyone in the same way. Sensitivity to drought in the oasis of the Mendoza River varies depending on the actors being considered. Consumers of potable water are less sensitive because legislation gives them priority over other uses. It is different for those in the agricultural sector, where every producer would like to be prepared for a drought situation but where only the wealthiest succeed. It is a circular process: the better adapted, the less sensitive (and vice versa). Differences also emerge in relation to the type of water rights and sources accessed by producers, where having access to a well, being in an upstream/downstream location in the basin, and having access to infrastructure, as well as other factors, make a difference. No less relevant is the nature of the productive system; for example, viticulture is less sensitive to drought because grapes tolerate water stress relatively well, whereas horticulture is more sensitive to drought because it requires a reliable water supply.
In the context of these exposures, sensitivity and adaptation are defined by access to factors such as natural, human, social, and institutional capital, as well as economic resources, technology, and infrastructure. As a result of the sensitivity/adaptive capacity equation that involves these factors, vulnerabilities are also unequally distributed in space and in relation to different social groups or actors. Producers who irrigate with only surface water are more vulnerable to reduced river flows than are those with alternative water sources, such as wells, who are better adapted to face droughts. But it is not a question of simply having a well; it is also necessary to have the economic resources required to maintain it, to keep the pump in good condition, and to bear the energy costs associated with using it. Many small-scale producers in the Mendoza River basin, who were better off in the past, had managed to establish wells on their farms. But due to decreasing agricultural profits in the context of the agribusiness model, these farmers are now unable to bear pumping costs. This is an example of exposure to water-related factors aggravated by economic exposures, reinforcing circular patterns of vulnerability and poverty.
During periods of water crisis, irrigators located at the tail end of the systems may receive less water than they are entitled to, so farmers seek to settle at the head of the distribution systems or canals to ensure that they will receive their due. Farmers with better access to water are more likely to succeed in their agricultural activities and, in turn, to have access to better (and more expensive) locations. Oppositely, farmers in the lowest part of the irrigation system are impoverished by poor agricultural performances. Lacking resources, they are unable to move to better locations. Higher temperatures and evapotranspiration reinforce these patterns, concentrating wealthier producers in the upper and cooler areas with higher thermal amplitude and relegating poor producers, who try hard to keep their farms afloat, to the lower and warmer zones. Extreme hydroclimatic events, such as extended droughts, will only consolidate or accelerate the existing tendency toward a spatial and socio-economic segregation of agricultural producers in the oases of central-western Argentina, widening the gap between the dominant players of the local agribusiness and those who are barely able to survive as subsistence producers. In many cases, these small-scale producers have no other alternative than to neglect their farms and seek jobs to generate the necessary income, or even worse, to exit agriculture and migrate to cities, where they join the growing population of urban poor. Thus, scenarios of increasing water deficits suggest an intensification of the current process of socio-spatial segregation: wealthy producers get wealthier uphill, while the smaller producers do increasingly poorly downstream (Montaña 2012a).
Drought Adaptation and Preparedness
Differences in vulnerability among the different players in this hydraulic society may change considerably based on specific adaptive practices. The flows of Río Mendoza are regulated by the Potrerillos Dam, which was built in the upstream section of the basin to both reduce seasonal and inter-annual variability in the river discharge and to compensate for spring and autumn water deficits in crops. However, given the spatial distribution of agricultural lands and the less favourable, scattered location of goat breeders in the drylands downstream from the main users of the Río Mendoza waters, more intense and regulated use of water upstream by the groups with highest social power (i.e., those in the oasis) clearly reduces the possibilities of water “escaping” to the downstream part of the basin where desert communities (and goat breeders) are located. This evident inequity constitutes an interesting case in which a particular set of adaptive practices benefit some sectors and increase the vulnerability of other groups, exposing the complexity of this coupled natural and social system. Although their subordinate social position largely determines the sensitivity of these poor rural communities to various economic and environmental factors, extended droughts will ultimately be the trigger for increased conflicts in this hydraulic society (Masiokas et al. 2013; Montaña 2012b, 2008).
At the farm level, a broad classification of adaptive strategies can differentiate between traditional and “innovative” technologies. There is a clear distinction between the capitalized farmers who apply the latter and the small-scale producers and peasants who are restricted to the former. Every agricultural producer tries to have access to groundwater and make more efficient use of the resource, but not all of them can afford access to the aquifers. Just a small proportion of producers (less than 10%) can pay for permanent irrigation, which differs from many producers in the central Chilean valleys, where modern irrigation is more widespread as a result of a more capitalistic approach to viticulture. Smaller producers and peasants have to settle for more passive forms of adaptation, such as irrigating only the more profitable crops, or simply abandoning their water quantity and quality expectations and their productivity prospects and looking for alternative livelihoods. This is one of the reasons for the increasing impoverishment of small farmers, who become increasingly dependent on off-farm sources of income or sell their lands and migrate. For them, drought is devastating. Among the more highly capitalized farmers, innovative strategies in response to water scarcity involve, among other things, automatic irrigation systems (drip irrigation and others). The capitalized agricultural producers cannot sustain their activity without access to groundwater, as it is inherent to their technology and management style, allowing them to become less dependent on the surface irrigation scheme. This technology enables them to adopt another innovative adaptive strategy: diversifying locations and relocating properties in the foothills upstream to minimize hydro-climatological risks, an action that impacts negatively on aquifer conservation and on the agro-ecological conditions of downstream lands of the basin (Montaña 2012a).
An obvious adaptive measure is to more efficiently use the resource. In terms of developing agriculture with a reduced water demand, there is ample room for improvements through the modernization of irrigation systems. In the case of the Mendoza River basin, where grapes are the main crop, this modernization would have a very positive impact, both for individual producers and for the basin as a whole. But, as has been said, only the medium or large and well-capitalized farmers fully engaged in the “new viticulture” are able to make these investments. Even at low interest rates, loans to reconvert irrigation systems are not suitable for small growers, as their profitability is not sufficient to sustain this level of debt. As already experienced by under-capitalized producers in Chilean agriculture and many small farmers in the Canadian Palliser Triangle, small producers would probably not survive water efficiency measures, given that their adoption would entail economic, social, and political costs difficult to cope with. There is also potential to conserve more of the water currently used by households and industry in the region. A flat rate tariff for drinking water, low efficiency in residential facilities, and obsolete pipelines in the distribution system, together with little control over its use for garden irrigation and recreation, are all factors that explain the high rate of consumption per capita of a growing population and which certainly could be improved.
Local actors claim that more investment in infrastructure is required to deal with water shortages, but the Mendoza River basin has already benefited more from infrastructure works to improve the supply of the resource (dam, reservoir, waterproofing of irrigation channels, irrigation water distribution systems) than from measures aimed at controlling the demand, both rural and urban. And it is the rising water consumption of a growing population and increased economic activities that make the hydroclimatic scenarios where droughts are a central feature more complex.
From the perspective of increasing regional resilience, it is also necessary to understand the different types of drought and their patterns to decide which adaptive strategy to adopt and which type of investment to make. For instance, the region has limited adaptive potential in the long term to respond to hydrological droughts (characterized by decreasing streamflow in the river and dams). A potential adaptive strategy would be to capture and store summer rainwater that is not currently contributing to the river flow, making better use of groundwater and fostering the combined use of surface/groundwater. This strategy needs to occur not just on an individual basis as it is today in the basin, but as a planned collective strategy for managing the hydraulic system as a whole.
It should be noted, however, that the pursuit of efficiency in water use, although a worthy objective in terms of adaptation, is not a new issue. Mendoza, like other basins in Chile and the Canadian Prairies, is a region where rural people have had to historically coexist with water scarcities. Making more efficient use of water is an old goal, inherent to water management in drylands. Moreover, it constitutes a permanent adaptive measure to pursue, with or without climate change. This long adaptive history, however, has not resulted in rural people developing a healthy adaptive capacity to droughts. Rather, it seems that adaptation to increasing drought risk and climate variability will only be taken seriously when an extreme drought is declared. If historical memory is not enough to remind us of the impacts of intense and prolonged droughts in the regions of central-western Argentina, the scientific studies presented above should alert us to the need to take action before it is too late.
In coping with drought, there is always the idea that water limitations can be overcome and the oasis can be expanded. In fact, the “new viticulture” and its modern irrigation based on intensive use of groundwater have pushed the agricultural frontier over the foothills, degrading the agronomic and ecological conditions downstream2 of the basin. From a social perspective, this degradation affects the small producers in downstream areas, who, already harassed by economic difficulties and a reduced income, become increasingly vulnerable. It is a desertification process that takes place within the oasis itself. Recovering land from the desert in the upstream (or losing it, according to one’s point of view) means a desertification of the downstream by moving the oasis upstream (Montaña 2008a). Any surplus of water that might be used to expand the oasis must first be used to recover the old oasis areas that are becoming degraded.
Lessons Learned and Pending Tasks
In the context of intense droughts, climate predictions at local and regional spatial scales are valuable not only for societal benefits but also for planning and managing socio-economic sectors sensitive to climate variations. Several international scientific research centres currently provide global-scale climate predictions. Their ability to make climate predictions at regional and local scales, however, is very limited, not only because of the restricted levels of predictability but also because of the limited ability of current climate models to represent fundamental regional and local physical processes. Climate predictions for the Andes region are particularly challenging in terms of the current models. However, the fact that ENSO and other contributing forces of climate variability can be accurately predicted by the current climate models provides a basis from which to further explore predictability and develop climate prediction tools for the region with a minimum degree of certainty.
Physical indicators and climate indices, such as snowfall, snowfall distribution, mountain temperature, runoff (if possible from all the tributaries), reservoir and lake levels, temperature and precipitation at the oasis, groundwater levels, different uses of water (human consumption, irrigation, hydropower, industry, agriculture, natural ecosystems, cultural uses), and surface cultivation with annual and perennial crops, among other factors, are the main input variables for such models. These physical indicators and climate indices must then be combined with socio-economic variables to predict impacts on communities, assess vulnerabilities, and adopt the most appropriate adaptive strategies.
Based on this case study of Mendoza, it is apparent that preparedness for future drought cannot rely on the short historical memory of local communities. Preparedness planning should also integrate insights from long-term studies. In addition, preparedness plans must incorporate a dynamic model of the oasis that considers both natural and social systems, making sure that the adaptive actions of some groups do not create new vulnerabilities for others, at least not without proper remediation. Moreover, it has become clear that the scope of this undertaking should not be limited to the oasis—the more visible part of the territory—but should also encompass the Cordillera as the main source of water and look downstream to the “invisible spaces” of the desert (Montaña 2005), protecting the cultural diversity associated to the indigenous groups which live there and conserving the ecosystem services that support their style of development.
Advances in better planning and mitigation tools have been made, and these tools are now available worldwide. The main challenge, however, is to transform the social, economic, and political structures that have created an unequal distribution of vulnerability in the basin; without such transformation, drought (a rather normal climate event) becomes a hazard and a disaster for many. It is also fundamental to support governments and decision makers and to empower local people and other social actors to overcome the “short-termism” of the market drivers and narrow economic interests. Once this is achieved, more effective drought preparedness and mitigation plans can be prepared. In the agricultural sector, new and more efficient irrigation systems are needed, reclaimed waters could be better exploited, and training and social organization could contribute to developing more efficient traditional irrigation systems. In the urban sector, new water-conserving technologies need to be explored to more efficiently use water, and urban residents need increased awareness of water limitations. As a case study, Mendoza illustrates that drought takes a number of different forms and that adaptive strategies must be tailored to cope with the particularities of each one within the natural and social context.
Notes
1 It is the Cordillera’s precipitation (especially snow) that feeds the irrigation system. The region can benefit from rain in the foothills and in the plains, but the irrigation system is not designed to capture these resources.
2 This process has been particularly studied for the River Tunuyán basin, south to the Mendoza River basin. See Chambuleyron (2002).
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