Basins In Chile Research Articles

Adaptive Governance, Uncertainty, and Risk: Policy Framing and Responses to Climate Change, Drought, and Flood.

As climate change impacts result in more extreme events (such as droughts and floods), the need to understand which policies facilitate effective climate change adaptation becomes crucial. Hence, this article answers the question: How do governments and policymakers frame policy in relation to climate change, droughts, and floods and what governance structures facilitate adaptation? This research interrogates and analyzes through content analysis, supplemented by semi-structured qualitative interviews, the policy response to climate change, drought, and flood in relation to agricultural producers in four case studies in river basins in Chile, Argentina, and Canada. First, an epistemological explanation of risk and uncertainty underscores a brief literature review of adaptive governance, followed by policy framing in relation to risk and uncertainty, and an analytical model is developed. Pertinent findings of the four cases are recounted, followed by a comparative analysis. In conclusion, recommendations are made to improve policies and expand adaptive governance to better account for uncertainty and risk. This article is innovative in that it proposes an expanded model of adaptive governance in relation to "risk" that can help bridge the barrier of uncertainty in science and policy.

Signatures of Directional and Balancing Selection in the Silverside Basilichthys microlepidotus (Teleostei: Atherinopsidae) Inhabiting a Polluted River

Currently environmental pollution is one of the most important factors affecting natural populations and acting as a strong selective pressure. Therefore, identifying genes and their alleles implied in population survival within contaminated areas is a relevant issue. In this context, freshwater systems are likely among those that have been most impacted by pollution. The Maipo River is one of the most polluted basins in Chile, surrounded by 40 % of the human population of the country. There are five populations of the endemic silverside Basilichthys microlepidotus inhabiting this river, two in polluted areas and three in non-polluted areas. The goal of this study was to identify candidate loci or loci potentially under directional and balancing selection related to pollution in B. microlepidotus. To this end, a genome scan (AFLP markers) was performed, comparing between fish located in polluted and non-polluted areas and between fish inhabiting polluted sites. Eight loci (5.37 % of the total loci) were identified as loci potentially under selection; of these, six (4.0 %) showed signatures of directional selection and two (1.34 %) showed signatures of balancing selection. This study contributes to demonstrating that pollution could be implicated in selection even within a basin. As far as we know, this is the first study to date that has detected loci potentially under balancing selection associated with pollution, indicating that pollution influences the maintenance of polymorphisms in these loci.

A simple logistic model to understand the occurrence of flood events into the Biobío River Basin in central Chile

AbstractWe predict flood events by fitting two simple logistic regression models between mesoscale rainfall and El Niño‐Southern Oscillation (ENSO) index with local scale flooding into the Biobío River Basin in Chile from 1948 to 2002. Two different and complementary logistic models were studied: Logit and Probit. The models perform alike suggesting that the methodology is robust. The best model is most accurate during the autumn over 80% hit rate and in winter 66% hit rate, which are the seasons with high risk of floods. This work represents a first step in the development of a complete hydrological framework for the Biobío River Basin. The Logit distribution shows better results; thus, we suggest to use this distribution to relate flood events with mesoscale precipitation and ENSO index in the Biobío River Basin. Finally, these results explain the flood events and its relation with risk management. In forthcoming studies we will extend the methodology over this region and Chile taking advantage of the availability of higher resolution (temporal and spatial) weather products along with investigating climatic patterns and Intergovernmental Panel on Climate Change (IPCC) climate change scenarios.

PMP and PMF estimations in sparsely-gauged Andean basins and climate change projections

Mixed-regime Andean basins present a complex scenario for flood analysis. In this study, we propose a methodology for incorporating orographic effects influenced by mountainous barriers in the Probable Maximum Precipitation (PMP) estimation method in sparsely-gauged basins. The proposed methodology is applied to the Puclaro Reservoir basin in Chile, which is affected by the Andes. The PMP estimations were calculated by applying statistical and hydrometeorological approaches to the baseline (1960–1999) and climate change scenarios (2045–2065) determined from projections of the ECHAM5 general circulation model. Temperature projections for the 2040–2065 period show that there would be a rise in the catchment contributing area that would lead to an increase in the average liquid precipitation over the basin. Temperature projections would also affect the maximization factors in the calculation of the PMP, as precipitable water content, raising it to 126.6% and 62.5% under scenarios A2 and B1, respectively; the probable maximum flood (PMF) would increase to +175.5% under the A2 scenario. These projections would affect the safety of dam design and would be generalizable to zones with similar mixed hydrology and climate change projections. We propose that the methodology presented could be also applied to basins with similar characteristics.Editor Z.W. Kundzewicz; Associate editor A. Porporato

Identifiability analysis: towards constrained equifinality and reduced uncertainty in a conceptual model

Different sets of parameters and conceptualizations of a basin can give equally good results in terms of predefined objective functions. Therefore, a need exists to tackle equifinality and quantify the uncertainty bands of a model. In this paper we use the concepts of equifinality, identifiability and uncertainty to propose a simple method aimed at constraining the equifinal parameters and reducing the uncertainty bands of model outputs, and obtaining physically possible and reasonable models. Additionally, the uncertainty of equifinal solutions is quantified to estimate the amount by which output uncertainty can be reduced by knowing how to discard most of the equifinal solutions of a model. As a study case, a conceptual model of the Chillán basin in Chile is carried out. From the study it is concluded that using identifiability analysis makes it possible to constrain equifinal solutions with reduced uncertainty and realistic models, resulting in a framework that can be recommended to practitioners, especially due to the simplicity of the method.

Water management problems in the Copiapó Basin, Chile: markets, severe scarcity and the regulator

This research focuses on the determination of the factors that led to the failure of water management in the Copiapó Basin in Chile. Interestingly, the existence of full private ownership and free tradability of water rights has not prevented the overexploitation of groundwater resources. In the paper, firstly, water regulation and the role of the regulator in Chile are briefly discussed. Secondly, the evolution of water resources in the Copiapó region is characterized and analyzed, and the granting of water use rights in the basin in the last 30 years is concisely described. Thirdly, we examine and analyze prices and quantities traded in the water market of the Copiapó region. We will argue that this crisis is a consequence first of failure in regulatory implementation and second of an extremely rigid regulatory framework that leaves limited room for adjustment to changing conditions, especially regarding the emergence of new information concerning water availability. We believe this investigation is not only relevant for this case in particular, but also for other regions and countries where water markets are in place.

Adaptive capacity in a Chilean context: A questionable model for Latin America

• We assess the governance related adaptive capacity of a river basin in Chile. • We examine governance indicators and adaptive responses to past drought events. • Present coping mechanisms may undermine long term resilience. • Governance barriers block transformative approaches to climate change. Climate change impacts are already being keenly observed in the Andes, with significant implications for water use due to alterations in both volumes and seasonality from changes in snow and ice. Concurrently, the style of water governance in Chile has long been held up by international institutions such as the World Bank as a potential model for other Latin American countries seeking to reform their own water governance frameworks. In light of both these issues, a closer inspection of the Chilean water governance context in relation to its adaptive capacity to climate change is warranted. To this end, a governance-related adaptive capacity assessment was applied to a Chilean river basin, the Aconcagua in Region V that focussed on both short and long term resilience, as well as proactive and reactive capacity. Results show that for the Aconcagua Region, the Chilean water governance regime demonstrates significant challenges in adapting to increasingly recurrent and intense periods of drought. Reactive coping techniques for climate variability can be quickly mobilised through the networks that exist. However, longer term preparations and transformative approaches for meeting the mounting challenges of climate change are blocked by lack of trust and cooperation, lack of agency at regional operational levels and lack of accessible and appropriate information on water resources.

Exploring possible connections between hydrological extreme events and climate change in central south Chile

Motivated by recent extreme flow events in the Mataquito River located in the Mediterranean region of Chile, we performed a detailed trend analysis of critical hydroclimatic variables based on observed daily flow, precipitation and temperature within the basin. For the period 1976–2008, positive trends in temperature were observed, especially during spring and summer months. At the same time, we found negative trends in the frequency and intensity of precipitation, especially during spring months. We observed an increasing difference between average streamflow in the rainy season as compared to the snowmelt season. Part of this trend is caused by larger flows during autumn months, although no positive precipitation trends are observed for these months. Finally, significant reductions in minimum flow during spring/summer and a disproportionate concentration of high-flow events occurring in the last 10 years were also identified. These high-flow events tend to happen during autumn months, and are associated with high precipitation and high minimum temperatures. Based on a simple assessment of changes in irrigated agriculture and land use, we concluded that other non-climatic factors seem not to be as relevant to the detected flow trends. All these results are in accord with future climate change scenarios that show an increase in temperature, a reduction in average precipitation and a reduction in snow accumulation. Such future scenarios could seriously hamper the development of economic activities in this basin, exemplifying also a fate that may be shared by other similar basins in Chile and in other regions of the world.Editor Z.W. KundzewiczCitation Vicuña, S., Gironás, J., Meza, F.J., Cruzat, M.L., Jelinek, M., Bustos, E., Poblete, D., and Bambach, N., 2013. Exploring possible connections between hydrological extreme events and climate change in central south Chile. Hydrological Sciences Journal, 58 (8), 1598–1619.

La demanda, evaluación y asignación del agua en el contexto de escasez: un análisis del ciclo hidrosocial del valle del río La Ligua, Chile

This paper examines the development of export-oriented agriculture and the allocation of water resources for irrigation in La Ligua river basin in Chile's Norte Chico. The paper uses a theoretical framework within the political ecology tradition in order to approach questions of demand, evaluation and allocation of water resources, and related issues, and to show how they are shaped by social power relations. The paper highlights in particular how a hydrological assessment was used to respond to rapid and uncontrolled groundwater exploitation, which ultimately produced unequal outcomes among different farmers. The paper concludes that, to better understand issues around the allocation of water resources, the concept of the hydrosocial cycle is more useful than that of the hydrological cycle

DETERMINATION OF MINING ACTIVITY OF RIVER SEDIMENTS OF THREE CHILEAN BASINS BY PARTICLE INDUCED X-RAY EMISSION (PIXE)

Mining is one of the most important industrial activities in Chile and there is growing concern on pollution by some mining and metallurgical processes. We have studied the contents of heavy metals in sediments from three river basins in Chile. Samples were collected based on hydrologic criteria in six sites along the rivers in their path from the Andes to the Pacific Ocean. Particle induced X-ray emission (PIXE), was used to determine elemental concentrations, and enrichment factors were used to evaluate the significance of anthropogenic sources. The results indicate the presence of Si, Al and Fe as major components. Cu, Cr, Mn, Pb and Zn are the main trace elements. In the Aconcagua river basin, which has less mining activity, the elemental concentrations are within the range of normal crust. Instead, samples from Choapa and Cachapoal river basins present high enrichment factors, mainly in copper. This is consistent with the fact that copper mines operate in the area. A correlation of the values obtained to copper using ICP and PIXE technique was statistically acceptable. Therefore, determination of Cu in river sediment by PIXE allows identification of areas affected by mining activities in river basins of northern Chile.

Modelling basin effects on earthquake ground motion in the Santiago de Chile basin by a spectral element code

SUMMARY Simulations of strong ground motion within the Santiago de Chile Metropolitan area were carried out by means of 3-D deterministic wave propagation tool based on the spectral element method. The simulated events take into account the pronounced interface between the low-velocity sedimentary basin and the bedrock as well as topography of the area. To verify our model we simulated a regional earthquake recorded by a dense network installed in the city of Santiago for recording aftershock activity after the 2010 February 27 Maule main shock. The results proof the alluvial basin amplification effects and show a strong dependence of spectral amplification in the basin on the local site conditions. Moreover, we studied the seismic response due to a hypothetical Mw= 6.0 event occurring along the active San Ramon Fault, which is crossing the eastern edge of the city. The scenario earthquakes exhibit that an unfavourable interaction between fault rupture, radiation mechanism and complex geological and topographic conditions in the near-field region may give rise to large values of peak ground velocity in the basin. Finally, 3-D numerical predictions of ground motion are compared with the one computed according to ground motion prediction equations selected among the next generation attenuation relationships, in terms of ground motion peak values and spectral acceleration. The comparison underlines that the 3-D scenario simulations predict a significantly higher level of ground motion in the Santiago basin, especially over deep alluvial deposits. Moreover, also the location of the rupture nucleation largely influences the observed shaking pattern.

Changes in meridional fluxes and water properties in the Southern Hemisphere subtropical oceans between 1992/1995 and 2003/2004

As part of the WOCE (World Ocean Circulation Experiment) Hydrographic Programme (WHP), nominally zonal lines across the subtropical gyres in the Southern Hemisphere oceans were occupied from 1992 to 1995: line P06 (nominally along 32.5°S in the Pacific Ocean), A10 (along 30°S in the Atlantic Ocean), and I03 and I04 (along 20°S in the Indian Ocean). These lines were revisited from 2003 to 2004 to examine changes in circulation and water properties over the 8- to 12-year interval between visits. A simple comparison of the two hydrographic sections would be affected by variations with time scales shorter than the interval between visits even in the deep ocean, so two ocean global circulation models, OFES and SODA, were employed to study meridional flux changes. A time series of the heat flux across the latitude circle 32.5°S from 1980 to 2005 shows moderate negative correlations (with the correlation coefficient r = −0.5 to −0.6) with the Southern Oscillation Index. A composite study shows that during El Niño years, the westerly jet just south of 32.5°S in the Pacific shifts northward, resulting in a northward Ekman temperature transport anomaly, and thus weaker southward temperature transport. The transport variations also show moderate negative correlations ( r = −0.4 to −0.6) with the Southern Annular Mode Index. A similar composite study shows that during positive Southern Annular Mode Index years, the Ekman pumping anomaly around 32.5°S spins down the wind-driven gyre over the South Indian and South Pacific oceans, causing a southward transport anomaly. The Atlantic transport is not sensitive to either index. An Ekman transport anomaly in the South Indian Ocean also contributes to the southward transport anomaly. The salt transports are correlated negatively with the Southern Oscillation Index which is similarly explained by the Ekman transport, but the relationship between the salt transport and the Southern Annular Mode Index remains unknown. The substantial seasonal or higher-frequency variations are filtered out by comparing the water properties on neutral density surfaces. Along the South Pacific P06 line, Subantarctic Mode Water on γ = 26.8 (the neutral density surface of 1026.8 kg m −3) becomes cooler and fresher by up to 0.2 °C and 0.04 psu (practical salinity unit). The property changes are largest in the Chile Basin and smallest in the Tasman Sea. In the deep Southwest Pacific Basin, a small but statistically significant freshening of 0.002 psu was found in the Circumpolar Deep Water ( γ = 28.11). Along the South Atlantic A10 line, Subantarctic Mode Water and Antarctic Intermediate Water were found warmer and saltier to the east of the Mid-Atlantic Ridge (e.g. by 0.2 °C and 0.05 psu on γ = 26.8; 0.1 °C and 0.02 psu on γ = 27.4). North Atlantic Deep Water and Antarctic Bottom Water were found warmer and saltier particularly in the Argentine Basin (e.g. by 0.02 °C and 0.004 psu on γ = 28.0; 0.01 °C and 0.002 psu on γ = 28.2). Along the south Indian I03/I04 lines, Subantarctic Mode Water was found warmer and saltier to the west of 95°E (e.g. by 0.2 °C and 0.05 psu on γ = 26.8) and cooler and fresher to the east (e.g. a difference of −0.2 °C and −0.05 psu on γ = 26.8).

Shear wave velocity model of the Santiago de Chile basin derived from ambient noise measurements: a comparison of proxies for seismic site conditions and amplification

SUMMARY We determined a high-resolution 3-D S-wave velocity model for a 26 km × 12 km area in the northern part of the basin of Santiago de Chile. To reach this goal, we used microtremor recordings at 125 sites for deriving the horizontal-to-vertical (H/V) spectral ratios that we inverted to retrieve local S-wave velocity profiles. In the inversion procedure, we used additional geological and geophysical constraints and values of the thickness of the sedimentary cover already determined by gravimetric measurements, which were found to vary substantially over short distances in the investigated area. The resulting model was derived by interpolation with a kriging technique between the single S-wave velocity profiles and shows locally good agreement with the few existing velocity profile data, but allows the entire area, as well as deeper parts of the basin, to be represented in greater detail. The wealth of available data allowed us to check if any correlation between the S-wave velocity in the uppermost 30 m (v30S) and the slope of topography, a new technique recently proposed by Wald and Allen, exists on a local scale. We observed that while one lithology might provide a greater scatter in the velocity values for the investigated area, almost no correlation between topographic gradient and calculated v30S exists, whereas a better link is found between v30S and the local geology. Finally, we compared the v30S distribution with the MSK intensities for the 1985 Valparaiso event, pointing out that high intensities are found where the expected v30S values are low and over a thick sedimentary cover. Although this evidence cannot be generalized for all possible earthquakes, it indicates the influence of site effects modifying the ground motion when earthquakes occur well outside of the Santiago basin.

Contested H 2O: Science, policy and politics in water resources management in Chile

This paper critically explores the politics that mediate the use of environmental science assessments as the basis of resource management policy. Drawing on recent literature in the political ecology tradition that has emphasised the politicised nature of the production and use of scientific knowledge in environmental management, the paper analyses a hydrological assessment in a small river basin in Chile, undertaken in response to concerns over the possible overexploitation of groundwater resources. The case study illustrates the limitations of an approach based predominantly on hydrogeological modelling to ascertain the effects of increased groundwater abstraction. In particular, it identifies the subjective ways in which the assessment was interpreted and used by the state water resources agency to underpin water allocation decisions in accordance with its own interests, and the role that a desocialised assessment played in reproducing unequal patterns of resource use and configuring uneven waterscapes. Nevertheless, as Chile’s ‘neoliberal’ political-economic framework privileges the role of science and technocracy, producing other forms of environmental knowledge to complement environmental science is likely to be contentious. In conclusion, the paper considers the potential of mobilising the concept of the hydro social cycle to further critically engage with environmental science.

Substitution between water and other agricultural inputs: Implications for water conservation in a River Basin context

Substitution of irrigation water with other agricultural inputs could be an important means to conserve water in the face of growing pressures on water resources from both nonagricultural water demands and environmental water requirements. This paper discusses the potential of such substitution through an empirical analysis based on a multiple-input crop production function at the field and farm scales complemented with a numerical modeling exercise at the basin scale. Results from the crop production function analysis show that under both crop yield and net profit maximization, water is a substitute to other crop inputs for high-value crops, and is a complement to water for low-valued crops. At the basin scale, an integrated economic–hydrologic river basin model is used to analyze the role of other factors in crop input substitution, including the spatial connections among water sources and demands, hydro-agronomic conditions, and institutional settings for water allocation. Results show that in the case study area, the Maipo River basin in Chile, where water is very scarce, moving from the current, input-constrained, situation to full optimization of water resources leads to an increase in all crop inputs, including water. In that case, 301 million m 3 of additional water use results in additional net profits of USD 11 million. However, if the water fee is raised by a factor of eight while overall basin irrigation profits are maintained at the original, baseline level, a reduction of water withdrawals by 326 million m 3 is traded off with costs of USD 43.2 million for other inputs. Irrigation districts with a high share of low-value crops have a low potential for substituting water with other crop inputs. Therefore, investments for water substitution should also be kept low in these areas.

Water markets as a mechanism for intersectoral water transfers: the Elqui Basin in Chile

The Elqui River in north-central Chile provides water for a medium-sized urban area and a small but thriving irrigated agriculture sector. A number of factors combined to provide incentive for the municipal water company servicing the coastal urban area to purchase water-use rights from irrigators in the early 1990s. This transfer was a well-recorded example of Chilean water markets functioning as proponents had expected. And despite the elapsed time, and Chile’s favorable system of transferable water-use rights, these trades remain among the very few recorded cases of intersectoral trading in the country. By purchasing water rights this water supply company was able to reduce its cost of raw water provision. Economic analysis of this transfer showed relatively modest economic gains from trade. Although, the value of water in municipal water supply is high, the value of water to profitable farmers is also high. The construction of the Puclaro Dam on the Elqui River demonstrates that the intersectoral water transfer that occurred in the early 1990s will not be the ultimate solution to the urban water supply needs of this urban area.

Hydrography of the eastern South Pacific Ocean: results from the Sonne 102 cruise, May–June 1995

Abstract Full - depth conductivity–temperature–depth/hydrographic measurements were taken in May – June 1995 along 28°15′, 35°15′, and 43°15′S from the Chilean coast to 86–88°W from the R.V. Sonne . Sections of potential temperature, salinity, neutral density, and oxygen are presented to illustrate the water-column structure in this sparsely sampled region. A more comprehensive database on all available hydrographic data from the region was compiled. These data and available meteorological data are used to help in the interpretation of the Sonne results. A number of important features found in the sections are discussed, including a shallow salinity minimum (apparently ventilated from south of ∼37°S), salt fingering as a possible mechanism to transport high-salinity subtropical water into the shallow salinity minimum, Equatorial Subsurface Water, Subantarctic Mode Water, and Antarctic Intermediate Water. Geostrophic calculations of alongshore flow show the poleward Peru – Chile Undercurrent at each of the three sections with a poleward descending core and peak velocities of ∼10 cm s −1 . As in earlier works, a deep Pacific outflow is found near the Chilean coast, part of a clockwise deep circulation in the Chile Basin.

Circulation and variability in the Chile Basin

Current observations at several depths between 250 and 3750m are reported from a 30°S, deep sea site 150km off the Chile coast for the period July 1993–June 2001. These results are used with current observations from a nearby slope site, satellite altimeter data, and hydrographic and Acoustic Doppler Current Profiler data from the WOCE P6E section along 32.5°S to address mean and variable flow in the Chile Basin. Strong current variability in the upper ocean for periods more than 100 days is explained in terms of remotely forced Rossby waves, local baroclinic instabilities of coastal currents and variable wind forcing. Intraseasonal to seasonal current variability at the deep ocean site was greatest during La Niña events while intraseasonal variability at the slope site was greatest during the 1997–1998 El Niño event. Mean westward and poleward flow was observed at all depths at the deep sea site but upper ocean means were not significantly different from zero. There was a well-defined, mean poleward flow of 0.6±0.3cms−1 at 2450m depth there. Geostrophic current calculations are presented for the P6E section with levels of no motion based on our current observations and other constraints. These reference choices yield reasonable and consistent results for the steady-state heat balance of the deep Chile and Peru Basins. Results show a deep equatorward flow of 3–4Sv on the eastern flank of the East Pacific Rise and a deep poleward boundary flow of about 10Sv within 1500km of the Chile coast. Up to half of the total mid-depth outflow of the South Pacific may take place east of the Rise. Thus the deep poleward boundary current off Chile is a major component of the deep circulation of the global ocean but the dynamics of this current remain a puzzle.

Physical and economic efficiency of water use in the river basin: Implications for efficient water management

With growing water scarcity and increasing competition across water‐using sectors, the need for water savings and more efficient water use has increased in importance in water resources management. Improvement in the physical efficiency of water use is related to water conservation through increasing the fraction of water beneficially used over water applied, while enhancing economic efficiency is a broader concept, seeking the highest economic value of water use through both physical and managerial measures. Physical and economic efficiency measures are both useful indicators for water management at the irrigation system and river basin level. However, the relationship between physical efficiency and economic efficiency is not always clear, and the values of these measures may indicate different directions for water policy and investments in irrigation. Open research questions include, for example, the following: How does the change in responsiveness of water allocation and irrigation technology to economic incentives affect physical and economic irrigation efficiency? What is the impact of a change in irrigation system efficiency on basin physical and economic efficiency? How do changes in water withdrawals affect basin physical and economic efficiency under a given water requirement? To explore these issues, an integrated economic‐hydrologic river basin model is applied to the Maipo River Basin in Chile. A series of modeling scenarios is defined, and policy implications based on changes in physical and economic efficiencies for basin‐wide irrigation water management are analyzed.

Integrated economic‐hydrologic water modeling at the basin scale: the Maipo river basin

AbstractIncreasing competition for water across sectors increases the importance of the river basin as the appropriate unit of analysis to address the challenges facing water resources management; and modeling at this scale can provide essential information for policy makers in their resource allocation decisions. This paper introduces an integrated economic‐hydrologic modeling framework that accounts for the interactions between water allocation, farmer input choice, agricultural productivity, non‐agricultural water demand, and resource degradation in order to estimate the social and economic gains from improvement in the allocation and efficiency of water use. The model is applied to the Maipo river basin in Chile. Economic benefits to water use are evaluated for different demand management instruments, including markets in tradable water rights, based on production and benefit functions with respect to water for the agricultural and urban‐industrial sectors.