The 2010–2015 megadrought in central Chile: impacts on regional hydroclimate and vegetation

Abstract. Since 2010 an uninterrupted sequence of dry years, with annual rainfall deficits ranging from 25 to 45 %, has prevailed in central Chile (western South America, 30–38° S). Although intense 1- or 2-year droughts are recurrent in this Mediterranean-like region, the ongoing event stands out because of its longevity and large extent. The extraordinary character of the so-called central Chile megadrought (MD) was established against century long historical records and a millennial tree-ring reconstruction of regional precipitation. The largest MD-averaged rainfall relative anomalies occurred in the northern, semi-arid sector of central Chile, but the event was unprecedented to the south of 35° S. ENSO-neutral conditions have prevailed since 2011 (except for the strong El Niño in 2015), contrasting with La Niña conditions that often accompanied past droughts. The precipitation deficit diminished the Andean snowpack and resulted in amplified declines (up to 90 %) of river flow, reservoir volumes and groundwater levels along central Chile and westernmost Argentina. In some semi-arid basins we found a decrease in the runoff-to-rainfall coefficient. A substantial decrease in vegetation productivity occurred in the shrubland-dominated, northern sector, but a mix of greening and browning patches occurred farther south, where irrigated croplands and exotic forest plantations dominate. The ongoing warming in central Chile, making the MD one of the warmest 6-year periods on record, may have also contributed to such complex vegetation changes by increasing potential evapotranspiration. We also report some of the measures taken by the central government to relieve the MD effects and the public perception of this event. The understanding of the nature and biophysical impacts of the MD helps as a foundation for preparedness efforts to confront a dry, warm future regional climate scenario.

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The 2010–2015 mega drought in Central Chile: Impacts on regional hydroclimate and vegetation

10.5194/hess-2017-191 ◽

2017 ◽

Cited By ~ 20

Author(s):

René Garreaud ◽

Camila Alvarez-Garreton ◽

Jonathan Barichivich ◽

Juan Pablo Boisier ◽

Duncan Christie ◽

...

Keyword(s):

River Flow ◽

Potential Evapotranspiration ◽

Regional Climate ◽

Climate Scenario ◽

Annual Rainfall ◽

Central Chile ◽

Groundwater Levels ◽

Tree Ring Reconstruction ◽

Neutral Conditions ◽

Northern Sector

Abstract. Since 2010 an uninterrupted sequence of dry years, with annual rainfall deficits ranging from 25 to 45 %, has prevailed in Central Chile (western South America, 30–38° S). Although intense 1- or 2-year droughts are recurrent in this Mediterranean-like region, the ongoing event stands out because of its longevity and large spatial extent. The extraordinary character of the so-called Central Chile Mega Drought (MD) was established against century long historical records and a millennial tree-ring reconstruction of regional precipitation. The largest MD-averaged rainfall relative anomalies occurred in the northern, semi-arid sector of central Chile but the event was unprecedented to the south of 35° S. ENSO neutral conditions have prevailed since 2011 (but for the strong El Niño 2015) contrasting with La Niña conditions that often accompanied past droughts. The precipitation deficit diminished the Andean snowpack and resulted in amplified declines (up to 90 %) of river flow, reservoir volumes and groundwater levels along central Chile and westernmost Argentina. In some semiarid basins we also found a conspicuous decrease in the runoff-to-rainfall coefficient. A substantial decrease in vegetation productivity occurred in the shrubland-dominated, northern sector, but a mix of greening and browning patches occurred farther south where irrigated croplands and exotic forest plantations dominate. The ongoing warming in central Chile, making the MD one of the warmest 6-year period on record, may have also contributed to such complex vegetation changes by increasing potential evapotranspiration. The understanding of the nature and biophysical impacts of the MD contributes to preparedness efforts to face a dry, warm future regional climate scenario.

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Linkages between Solar Activity and Climatic Responses

Energy & Environment ◽

10.1260/0958305053749462 ◽

2005 ◽

Vol 16 (2) ◽

pp. 239-253 ◽

Cited By ~ 9

Author(s):

William J. R. Alexander ◽

William J. R. Emeritus

Keyword(s):

Solar Activity ◽

River Flow ◽

Southern Oscillation ◽

Sunspot Cycle ◽

Annual Rainfall ◽

Sunspot Activity ◽

Periodic Sequences ◽

Groundwater Levels ◽

Flood Peak ◽

Climatic Responses

Statistically significant 21-year periodicity is present concurrently in South African annual rainfall, river flow, flood peak maxima, groundwater levels, lake levels and the Southern Oscillation Index. This is directly related to the double sunspot cycle. The first years of the periodic sequences are characterised by sudden, regular and therefore predictable, reversals from sequences of well below average rainfall and river flow (droughts) that are suddenly broken by sequences of well above average events (floods). These reversals are directly related to corresponding six-fold increases in sunspot activity at this time. The two sunspot cycles that comprise the double sunspot cycle also have fundamentally different effects on the hydrometeorological responses. These observations are solidly based and will require a re-assessment of the nature of the solar activity that gives rise to them.

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Modelling the Impacts of Climate Change on Shallow Groundwater Conditions in Hungary

Water ◽

10.3390/w13050668 ◽

2021 ◽

Vol 13 (5) ◽

pp. 668

Author(s):

Attila Kovács ◽

András Jakab

Keyword(s):

Climate Change ◽

Climate Models ◽

Climate Model ◽

Groundwater Resources ◽

Regional Climate ◽

Shallow Groundwater ◽

Predictive Modelling ◽

Climate Impacts ◽

Annual Rainfall ◽

Groundwater Levels

The purpose of the present study was to develop a methodology for the evaluation of direct climate impacts on shallow groundwater resources and its country-scale application in Hungary. A modular methodology was applied. It comprised the definition of climate zones and recharge zones, recharge calculation by hydrological models, and the numerical modelling of the groundwater table. Projections of regional climate models for three different time intervals were applied for the simulation of predictive scenarios. The investigated regional climate model projections predict rising annual average temperature and generally dropping annual rainfall rates throughout the following decades. Based on predictive modelling, recharge rates and groundwater levels are expected to drop in elevated geographic areas such as the Alpokalja, the Eastern parts of the Transdanubian Mountains, the Mecsek, and Northern Mountain Ranges. Less significant groundwater level drops are predicted in foothill areas, and across the Western part of the Tiszántúl, the Duna-Tisza Interfluve, and the Szigetköz areas. Slightly increasing recharge and groundwater levels are predicted in the Transdanubian Hills and the Western part of the Transdanubian Mountains. Simulation results represent groundwater conditions at the country scale. However, the applied methodology is suitable for simulating climate change impacts at various scales.

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Zustand und Entwicklung der Trockenheit in Schweizer Wäldern

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2015.0352 ◽

2015 ◽

Vol 166 (6) ◽

pp. 352-360 ◽

Cited By ~ 3

Author(s):

Jan Remund ◽

Sabine Augustin

Keyword(s):

Regional Differences ◽

Climate Models ◽

Potential Evapotranspiration ◽

Regional Climate ◽

Regional Scale ◽

Climate Scenario ◽

Regional Climate Models ◽

Weather Extremes ◽

Climatic Regions ◽

Site Water

State and development of drought in Swiss forests Climate scenarios for the 21st century for Switzerland show increasing temperatures and more frequent weather extremes and the risk of drought will become more important. The objective of the study was the calculation of indicators which allow the estimation and evaluation of drought risks on a regional scale. The site water balance and the ratio between actual and potential evapotranspiration (ETa/ETp) were used as indicators. They are closely related to vitality parameters of trees. For projections in the future were used the A1B climate scenario, which assumes a warming of 2.7 to 4.1°C in Switzerland, and three regional climate models (CLM, RCA, REGCM3), which predict different developments regarding precipitation and temperature. Historical time series between 1951 and 2012 and scenarios up to 2100 for different climatic regions were calculated. The indicators reproduce well the measured trends and the regional differences. In all regions there was in the past a trend to increased drought. The Geneva/ Vaud region as well as the western midlands and north Switzerland show the most pronounced changes. Projections with the CLM model (which reproduced best the historic trend 1981–2010 for Switzerland) show increasing drought and, in general, an increasing variability of the climate for the mid-century.

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Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-10053-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 10053-10093

Author(s):

W. A. Timms ◽

R. R. Young ◽

N. Huth

Keyword(s):

Potential Evapotranspiration ◽

Shallow Groundwater ◽

Flood Plain ◽

Critical Issue ◽

Continuous Cropping ◽

Deep Drainage ◽

Groundwater Levels ◽

Salt Leaching ◽

Perennial Vegetation ◽

Semi Arid

Abstract. The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr−1 rainfall), such as parts of Australia's Murray-Darling Basin (MDB). In this unique study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8–1.2 m depth under perennial vegetation and at 2.0–2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91–229 t ha−1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥10 m depth that is not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m−1 at 21 to 37 m depth (N = 5), whereas deeper groundwater was less saline (290 mS m−1) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3–9.5 mm yr−1 (0.7–2.1% rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditionsafter changes in land use and a thick clay dominated vadose zone. This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5% of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed.

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High-Resolution, Integrated Hydrological Modeling of Climate Change Impacts on a Semi-Arid Urban Watershed in Niamey, Niger

Water ◽

10.3390/w12020364 ◽

2020 ◽

Vol 12 (2) ◽

pp. 364 ◽

Cited By ~ 1

Author(s):

Boubacar Abdou Boko ◽

Moussa Konaté ◽

Nicaise Yalo ◽

Steven J. Berg ◽

Andre R. Erler ◽

...

Keyword(s):

Climate Change ◽

Bias Correction ◽

Regional Climate ◽

Correction Method ◽

Groundwater Table ◽

Annual Rainfall ◽

Urban Watershed ◽

Bias Correction Method ◽

The Impact ◽

Semi Arid

This study evaluates the impact of climate change on water resources in a large, semi-arid urban watershed located in the Niamey Republic of Niger, West Africa. The watershed was modeled using the fully integrated surface–subsurface HydroGeoSphere model at a high spatial resolution. Historical (1980–2005) and projected (2020–2050) climate scenarios, derived from the outputs of three regional climate models (RCMs) under the regional climate projection (RCP) 4.5 scenario, were statistically downscaled using the multiscale quantile mapping bias correction method. Results show that the bias correction method is optimum at daily and monthly scales, and increased RCM resolution does not improve the performance of the model. The three RCMs predicted increases of up to 1.6% in annual rainfall and of 1.58 °C for mean annual temperatures between the historical and projected periods. The durations of the minimum environmental flow (MEF) conditions, required to supply drinking and agricultural water, were found to be sensitive to changes in runoff resulting from climate change. MEF occurrences and durations are likely to be greater from 2020–2030, and then they will be reduced for the 2030–2050 statistical periods. All three RCMs consistently project a rise in groundwater table of more than 10 m in topographically high zones, where the groundwater table is deep, and an increase of 2 m in the shallow groundwater table.

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Implications of deep drainage through saline clay for groundwater recharge and sustainable cropping in a semi-arid catchment, Australia

Hydrology and Earth System Sciences ◽

10.5194/hess-16-1203-2012 ◽

2012 ◽

Vol 16 (4) ◽

pp. 1203-1219 ◽

Cited By ~ 13

Author(s):

W. A. Timms ◽

R. R. Young ◽

N. Huth

Keyword(s):

Potential Evapotranspiration ◽

Shallow Groundwater ◽

Flood Plain ◽

Critical Issue ◽

Continuous Cropping ◽

Deep Drainage ◽

Groundwater Levels ◽

Salt Leaching ◽

Perennial Vegetation ◽

Semi Arid

Abstract. The magnitude and timing of deep drainage and salt leaching through clay soils is a critical issue for dryland agriculture in semi-arid regions (<500 mm yr−1 rainfall, potential evapotranspiration >2000 mm yr−1) such as parts of Australia's Murray-Darling Basin (MDB). In this rare study, hydrogeological measurements and estimations of the historic water balance of crops grown on overlying Grey Vertosols were combined to estimate the contribution of deep drainage below crop roots to recharge and salinization of shallow groundwater. Soil sampling at two sites on the alluvial flood plain of the Lower Namoi catchment revealed significant peaks in chloride concentrations at 0.8–1.2 m depth under perennial vegetation and at 2.0–2.5 m depth under continuous cropping indicating deep drainage and salt leaching since conversion to cropping. Total salt loads of 91–229 t ha−1 NaCl equivalent were measured for perennial vegetation and cropping, with salinity to ≥ 10 m depth that was not detected by shallow soil surveys. Groundwater salinity varied spatially from 910 to 2430 mS m−1 at 21 to 37 m depth (N = 5), whereas deeper groundwater was less saline (290 mS m−1) with use restricted to livestock and rural domestic supplies in this area. The Agricultural Production Systems Simulator (APSIM) software package predicted deep drainage of 3.3–9.5 mm yr−1 (0.7–2.1% rainfall) based on site records of grain yields, rainfall, salt leaching and soil properties. Predicted deep drainage was highly episodic, dependent on rainfall and antecedent soil water content, and over a 39 yr period was restricted mainly to the record wet winter of 1998. During the study period, groundwater levels were unresponsive to major rainfall events (70 and 190 mm total), and most piezometers at about 18 m depth remained dry. In this area, at this time, recharge appears to be negligible due to low rainfall and large potential evapotranspiration, transient hydrological conditions after changes in land use and a thick clay dominated vadose zone. This is in contrast to regional groundwater modelling that assumes annual recharge of 0.5% of rainfall. Importantly, it was found that leaching from episodic deep drainage could not cause discharge of saline groundwater in the area, since the water table was several meters below the incised river bed.

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Future Flows Climate: an ensemble of 1-km climate change projections for hydrological application in Great Britain

Earth System Science Data ◽

10.5194/essd-4-143-2012 ◽

2012 ◽

Vol 4 (1) ◽

pp. 143-148 ◽

Cited By ~ 20

Author(s):

C. Prudhomme ◽

S. Dadson ◽

D. Morris ◽

J. Williamson ◽

G. Goodsell ◽

...

Keyword(s):

Climate Change ◽

Time Series ◽

Great Britain ◽

River Flow ◽

Potential Evapotranspiration ◽

Time Step ◽

Climate Change Projections ◽

Groundwater Levels ◽

Temperature And Precipitation ◽

Climate Change Uncertainty

Abstract. The dataset Future Flows Climate was developed as part of the project ''Future Flows and Groundwater Levels'' to provide a consistent set of climate change projections for the whole of Great Britain at both space and time resolutions appropriate for hydrological applications, and to enable climate change uncertainty and climate variability to be accounted for in the assessment of their possible impacts on the environment. Future Flows Climate is derived from the Hadley Centre's ensemble projection HadRM3-PPE that is part of the basis of UKCP09 and includes projections in available precipitation (water available to hydrological processes after snow and ice storages have been accounted for) and potential evapotranspiration. It corresponds to an 11-member ensemble of transient projections from January 1950 to December 2098, each a single realisation from a different variant of HadRM3. Data are provided on a 1-km grid over the HadRM3 land areas at a daily (available precipitation) and monthly (PE) time step as netCDF files. Because systematic biases in temperature and precipitation were found between HadRM3-PPE and gridded temperature and precipitation observations for the 1962–1991 period, a monthly bias correction procedure was undertaken, based on a linear correction for temperature and a quantile-mapping correction (using the gamma distribution) for precipitation followed by a spatial downscaling. Available precipitation was derived from the bias-corrected precipitation and temperature time series using a simple elevation-dependant snow-melt model. Potential evapotranspiration time series were calculated for each month using the FAO-56 Penman-Monteith equations and bias-corrected temperature, cloud cover, relative humidity and wind speed from HadRM3-PPE along with latitude of the grid and the day of the year. Future Flows Climate is freely available for non-commercial use under certain licensing conditions. It is the dataset used to generate Future Flows Hydrology, an ensemble of transient projections of daily river flow and monthly groundwater time series for representative river basins and boreholes in Great Britain. doi:10.5285/bad1514f-119e-44a4-8e1e-442735bb9797.

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Future Flows Climate: an ensemble of 1-km climate change projections for hydrological application in Great Britain

Earth System Science Data Discussions ◽

10.5194/essdd-5-475-2012 ◽

2012 ◽

Vol 5 (1) ◽

pp. 475-490 ◽

Cited By ~ 6

Author(s):

C. Prudhomme ◽

S. Dadson ◽

D. Morris ◽

J. Williamson ◽

G. Goodsell ◽

...

Keyword(s):

Climate Change ◽

Time Series ◽

Great Britain ◽

River Flow ◽

Potential Evapotranspiration ◽

Time Step ◽

Climate Change Projections ◽

Groundwater Levels ◽

Temperature And Precipitation ◽

Climate Change Uncertainty

Abstract. 1. The dataset Future Flows Climate was developed as part of the project "Future Flows and Groundwater Levels" to provide a consistent set of climate change projections for the whole of Great Britain at both space and time resolutions appropriate for hydrological applications, and to enable for climate change uncertainty and climate variability to be accounted for in the assessment of their possible impacts on the environment. 2. Future Flows Climate is derived from the Hadley Centre's ensemble Projection HadRM3-PPE that is part of the basis of UKCP09 and includes projections in available precipitation (water available to hydrological processes after snow and ice storages have been accounted for) and potential evapotranspiration. It corresponds to an 11-member ensemble of transient projections from January 1950 to December 2098, each a single realisation from a different variant of HadRM3. Data are provided on a 1-km grid over the HadRM3 land areas at a daily (available precipitation) and monthly (PE) time step as NetCDF files. 3. Because systematic biases in temperature and precipitation were found between HadRM3-PPE and gridded temperature and precipitation observations for the 1962–1991 period, a monthly bias correction procedure was undertaken, based on a linear correction for temperature and a quantile-mapping correction (using the gamma distribution) for precipitation followed by a spatial downscaling. Available precipitation was derived from the bias-corrected precipitation and temperature time series using a simple elevation-dependant snow-melt model. Potential evapotranspiration time series were calculated for each month using the FAO-56 Penman Montieth equations and bias-corrected temperature, cloud cover, relative humidity and wind speed from HadRM3-PPE along with latitude of the grid and the day of the year. 4. Future Flows Climate is freely available for non commercial use under certain licensing conditions. It is the dataset used to generate Future Flows Hydrology, an ensemble of transient projections of daily river flow and monthly groundwater time series for representative river basins and boreholes in Great Britain. 5. doi:10.5285/bad1514f-119e-44a4-8e1e-442735bb9797

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