Sebastian Vicuna

Using a Gridded Global Dataset to Characterize Regional Hydroclimate in Central Chile

AbstractCentral Chile is facing dramatic projections of climate change, with a consensus for declining precipitation, negatively affecting hydropower generation and irrigated agriculture. Rising from sea level to 6000 m within a distance of 200 km, precipitation characterization is difficult because of a lack of long-term observations, especially at higher elevations. For understanding current mean and extreme conditions and recent hydroclimatological change, as well as to provide a baseline for downscaling climate model projections, a temporally and spatially complete dataset of daily meteorology is essential. The authors use a gridded global daily meteorological dataset at 0.25° resolution for the period 1948–2008, adjusted by monthly precipitation observations interpolated to the same grid using a cokriging method with elevation as a covariate. For validation, daily statistics of the adjusted gridded precipitation are compared to station observations. For further validation, a hydrology model is driven...

Irrigation infrastructure development in the Limarí Basin in Central Chile: implications for adaptation to climate variability and climate change

One option to deal with climate variability in agriculture is to build irrigation infrastructure, although this may lead to the overdevelopment of water resources, leading to ‘basin closure’. The Limarí Basin, in central north Chile, has relied on irrigation infrastructure over the last 30 years to increase water supply reliability and extend irrigated acreage, especially for permanent crops. This situation has reduced adaptation opportunities in the basin, which is currently experiencing a severe drought that, according to climate change projections, is expected to persist in the future, with important consequences for the sustainability of agriculture production.

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

Abstract 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. Kundzewicz Citation 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.

Water–food–energy nexus in Chile: the challenges due to global change in different regional contexts

This paper modifies the traditional representation of the water–food–energy (WFE) nexus by emphasizing the flows or influences between components. This allows a better representation of the dynamic nature of the WFE nexus in response to global change drivers. It applies a conceptual figure to synthesize the status and future challenges of the nexus in four regions of Chile that are currently under pressure due to climate variability, relative water scarcity and strong competition for water from different sectors.

Water option contracts for climate change adaptation in Santiago, Chile

ABSTRACT Climate change–induced extreme events pose an important challenge for urban water managers. In Santiago (Chile), the total cost of such events can be reduced by an option contract that sets ex ante water prices and water volumes to be traded when certain triggering conditions are met. This article discusses two types of option contracts: water leasing to trade water from agriculture to urban uses during droughts; and a savings option contract to reduce urban water consumption during short-term turbidity events. We find that water option contracts are flexible instruments that improve the distribution of hydrological risks.

VULNERABILITY AND ADAPTATION TO CLIMATE CHANGE IN AN IRRIGATED AGRICULTURAL BASIN IN SEMI ARID CHILE

In many agronomic settings, irrigation is the only plausible system to sustain a dependable and economically viable agriculture. That is the case of semi-arid and Mediterranean basins such as the Limari basin in Chile. In this basin a complex reservoir and irrigation system helps sustain more than 40,000 has of cultivated land with less than 150 mm of average annual precipitation. The very existence of this infrastructure, combined with favorable solar radiation fluxes throughout the year, causes water demand for irrigated agriculture to grow steadily. Upstream from the reservoir system there are 9,000 has of irrigated land that benefits indirectly from the built infrastructure (by using all available water during hydrologically average years). However, the lack of storage capacity makes these higher lands very sensitive to the significant climate variability, characteristic of the region. On the other hand climate change scenarios for this basin project a strong decline in available streamflow and a change in seasonality towards a higher relative proportion of water in winter months relative to summer months (when water is most needed). In this work we present a method to estimate climate impacts and a vulnerability assessment for a semi-arid snowmelt dominated basin and a method to test the value of irrigation policies as an adaptation strategy. Examples of these policies are related to new infrastructure that helps reduce the impacts of climate variability and seasonality changes as well as policies designed towards expanding the amount of land under irrigation.

The Conjunctive Use of Reservoirs and Aquifers: Tradeoffs in Electricity Generation and Water Supply

Although the literature on conjunctive use of surface and groundwater is extensive few papers have analyzed the benefits of coordinating reservoir and aquifer operations. In this work we evaluate reservoir and aquifer operations under three different management schemes. We constructed a monthly non-linear programming model embedded into an annual stochastic dynamic programming model (SDP/NLP model). This model was applied to a case study of the operations of the Merced River Basin, located in the eastern San Joaquin Valley. In a first phase of this application we calibrate the model parameters to match historic operations and the historic level of reservoir-aquifer coordination. We then use the model to estimate the benefits of managing water storage under different institutional and economic scenarios. The scenarios include an electric power scenario (where the reservoir is operated to maximize hydropower benefits), a conjunctive use scenario (where reservoir and aquifer releases are jointed managed to maximize hydropower and agricultural benefits), and a non conjunctive use scenario (where the reservoir is operated independently of groundwater controls).

Using a Statistical Preanalysis Approach as an Ensemble Technique for the Unbiased Mapping of GCM Changes to Local Stations

AbstractAccounting for climate change, GCM-based projections and their uncertainty are relevant to study potential impacts on hydrological regimes as well as to analyze, operate, and design water i...

PROCESOS DE TOMA DE DECISIONES Y ADAPTACIÓN AL CAMBIO CLIMÁTICO

Climate change imposes certain challenges not only to ecosystems but to societies as well. The change in environmental conditions makes necessary to review the decision-making process related to adaptation to climate change. This review should consider future risks or current conditions of vulnerability through existing mechanisms in organizations or societies. From this analysis onwards, processes must be developed allowing, either to prepare the way to face expected future impacts or to decrease the current vulnerability regarding climate by creating more resilient systems. In this context, the role of the academy, as a knowledge source, results fundamentally. Nevertheless, this highlight the need to review and improve the communication processes from academy towards different interests groups by means of the co-production and strengthening of links among different society components.

An Analysis of Droughts in the California Central Valley Surface-Groundwater-Conveyance System

A series of drought simulations were performed using the California Department of Water Resources codes and historical datasets representing a range of droughts from mild to severe for time periods lasting up to 60 years. Land use, agricultural cropping patterns, and water demand were held fixed at the 1973-2003 mean and water supply decreased by effective amounts ranging between 25 and 50 percent for the California Central Valley, representing light to severe drought types. An examination of the impacts includes four sub-basins, the Sacramento Basin, the San Joaquin Basin, the Tulare Basin, and the Eastside Drainage. Model output results suggest the greatest impacts are in the San Joaquin and Tulare Basins, regions that are heavily irrigated. Surface diversions decrease by as much as 42 percent in these regions. Stream-to-aquifer flows reversed and aquifer storage dropped. Most significant was the decline in groundwater head for the severe drought cases, where results suggest the water table is unlikely to recover within the simulation time period. However, the overall response to such droughts is not as severe as anticipated and the northern Central Valley may act as groundwater insurance to sustain California during extended dry periods.