Browsing by Autor "Ronny Berndtsson"

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Drought impact in the Bolivian Altiplano agriculture associated with the El Niño–Southern Oscillation using satellite imagery data
(Copernicus Publications, 2021) Claudia Canedo Rosso; Stefan Hochrainer‐Stigler; Georg Ch. Pflug; Bruno Condori; Ronny Berndtsson
Abstract. Drought is a major natural hazard in the Bolivian Altiplano that causes large agricultural losses. However, the drought effect on agriculture varies largely on a local scale due to diverse factors such as climatological and hydrological conditions, sensitivity of crop yield to water stress, and crop phenological stage among others. To improve the knowledge of drought impact on agriculture, this study aims to classify drought severity using vegetation and land surface temperature data, analyse the relationship between drought and climate anomalies, and examine the spatio-temporal variability of drought using vegetation and climate data. Empirical data for drought assessment purposes in this area are scarce and spatially unevenly distributed. Due to these limitations we used vegetation, land surface temperature (LST), precipitation derived from satellite imagery, and gridded air temperature data products. Initially, we tested the performance of satellite precipitation and gridded air temperature data on a local level. Then, the normalized difference vegetation index (NDVI) and LST were used to classify drought events associated with past El Niño–Southern Oscillation (ENSO) phases. It was found that the most severe drought events generally occur during a positive ENSO phase (El Niño years). In addition, we found that a decrease in vegetation is mainly driven by low precipitation and high temperature, and we identified areas where agricultural losses will be most pronounced under such conditions. The results show that droughts can be monitored using satellite imagery data when ground data are scarce or of poor data quality. The results can be especially beneficial for emergency response operations and for enabling a proactive approach to disaster risk management against droughts.
Drought risk in the Bolivian Altiplano associated with El NiñoSouthern Oscillation using satellite imagery data
(2019) Claudia Canedo Rosso; Stefan Hochrainer‐Stigler; Georg Ch. Pflug; Bruno Condori; Ronny Berndtsson
Abstract. Drought is a major natural hazard in the Bolivian Altiplano that causes large losses to farmers, especially during positive ENSO phases. However, empirical data for drought risk estimation purposes are scarce and spatially uneven distributed. Due to these limitations, similar to many other regions in the world, we tested the performance of satellite imagery data for providing precipitation and temperature data. The results show that droughts can be better predicted using a combination of satellite imagery and ground-based available data. Consequently, the satellite climate data were associated with the Normalized Difference Vegetation Index (NDVI) in order to evaluate the crop production variability. Moreover, NDVI was used to target specific drought hotspot regions. Furthermore, during positive ENSO phase (El Niño years), a significant decrease in crop yields can be expected and we indicate areas where losses will be most pronounced. The results can be used for emergency response operations and enable a pro-active approach to disaster risk management against droughts. This includes economic-related and risk reduction strategies such as insurance and irrigation.
Early warning and drought risk assessment for the Bolivian Altiplano agriculture using high resolution satellite imagery data
(2018) Claudia Canedo Rosso; Stefan Hochrainer‐Stigler; Georg Ch. Pflug; Bruno Condori; Ronny Berndtsson
Abstract. Implementation of agriculturally related early warning systems is fundamental for the management of droughts. Additionally, risk-based approaches are superior in tackling future drought hazards. Due to data-scarcity in many regions, high resolution satellite imagery data are becoming widely used. Focusing on ENSO warm and cold phases, we employ a risk-based approach for drought assessment in the Bolivian Altiplano using satellite imagery data and application of an early warning system. We use a newly established high resolution satellite dataset and test its accuracy as well as performance to similar (but with less resolution) datasets available for the Bolivian Altiplano. It is shown that during the El Niño years (warm ENSO phase), the result is great difference in risk and crop yield. Furthermore, the Normalized Difference Vegetation Index (NDVI) can be used to target specific hot spots on a very local scale. As a consequence, ENSO early warning forecasts as well as possible magnitudes of crop deficits could be established by the government, including an identification of possible hotspots during the growing season. Our approach therefore should not only help in determining the magnitude of assistance needed for farmers on the local scale but also enable a pro-active approach to disaster risk management against droughts that can include economic-related instruments such as insurance as well as risk reduction instruments such as irrigation.
HEAVY METALS IN AQUATIC PLANTS AND THEIR RELATIONSHIP TO CONCENTRATIONS IN SURFACE WATER, GROUNDWATER AND SEDIMENTS - A CASE STUDY OF POOPÓ BASIN, BOLIVIA
(Lund University, 2005) M.E. García; Jochen Bundschuh; Oswaldo Eduardo Ramos Ramos; J. Quinatanilla; Kenneth M. Persson; Lars Bengtsson; Ronny Berndtsson
"The uptake of the heavy metals Cd, Zn, Pb, As, and Fe by aquatic plants — thereby entering the human food chain — was studied in the Poopó basin, located in the semiarid, central Andean highland of Bolivia. At twenty sites around Poopó and Uru-Uru lakes, samples of aquatic plants, sediments, surface water and groundwater were taken. The spatial distribution of heavy metals indicate that most of the Cd and Pb influx into the semiarid Poopó basin results from mining activities and subordinate from geothermal activities, which are both located in the NE of Poopó basin. Also, arsenic concentrations are of similar magnitudes, released from mining activities and natural weathering of As-bearing rocks and predominantly observed in the W, SE, and S of Poopó basin. In the aquatic plants, concentrations of Cd, Zn, Pb and As were found in the ranges 0.0–45.0, 0–197, 0–858, and 83–943 mg/kg, respectively. The heavy metal concentrations found in aqueous plants are correlated to varying extents to the corresponding heavy metal concentrations in sediments, surface water and groundwater. High Cd and Pb concentration in aquatic plants sampled within Poopó Lake (15–23 and 858–936 mg/kg, respectively) correlate strongly with high Cd and Pb concentrations of its alkaline water (1.37–1.51 and 0.36–0.38 mg/L, respectively) as well as with high Cd and Pb concentrations in the lake sediments (20–25 and 210–260 mg/kg, respectively). However, at other sampling sites of the basin this correlation of Cd does not always exist. For As and Zn, no correlation could be found between the respective concentrations in aquatic plants, sediments, surface water and groundwater. There is no correlation between Cd, Zn, and Pb concentrations in surface water and groundwater. This shows that these heavy metals are predominantly fixed in the sediments and taken up by plants and/or transported as sediment load to Poopó Lake (Cd, Zn, and Pb cations are only stable in larger amounts under acidic conditions, e.g. in the acidic rivers influenced by mining activities, and nearby groundwater bodies, which are found in the NE of Poopó basin). In contrast the anions of arsenic are more soluble in surface water and groundwater with a neutral or slightly alkaline pH."
Modeling Lake Titicaca Daily and Monthly Evaporation
(2018) Ramiro Pillco Zolá; Lars Bengtsson; Ronny Berndtsson; Belén Martí-Cardona; Frédéric Satgé; F. Timouk; Marie‐Paule Bonnet; Luis Mollericon; Cesar Gamarra; José Pasapera
Abstract. Lake Titicaca is an important water ecosystem of South America. Due to uncertainties in estimating the evaporation losses from the lake, surface water storage calculations are uncertain. In this paper, we try to improve evaporation loss estimations by comparing different methods to calculate daily and monthly evaporation from Lake Titicaca. These were: water balance, heat balance, mass transfer method, and the Penman equation. The evaporation was computed at daily time step and compared with estimated evaporation using mean monthly meteorological observations. We found that the most reliable method of determining the annual lake evaporation is using the heat balance approach. To estimate the monthly lake evaporation using heat balance, the heat storage changes must be known in advance. Since convection from the surface layer is intense during nights resulting in a well-mixed top layer every morning, it is possible to determine the change of heat storage from the measured morning surface temperature. The mean annual lake evaporation was found to be 1700 mm. Monthly evaporation computed using daily data and monthly means resulted in minor differences.
Modelling Lake Titicaca's daily and monthly evaporation
(Copernicus Publications, 2019) Ramiro Pillco Zolá; Lars Bengtsson; Ronny Berndtsson; Belén Martí-Cardona; Frédéric Satgé; F. Timouk; Marie‐Paule Bonnet; Luis Mollericon; Cesar Gamarra; José Pasapera
Abstract. Lake Titicaca is a crucial water resource in the central part of the Andean mountain range, and it is one of the lakes most affected by climate warming. Since surface evaporation explains most of the lake's water losses, reliable estimates are paramount to the prediction of global warming impacts on Lake Titicaca and to the region's water resource planning and adaptation to climate change. Evaporation estimates were done in the past at monthly time steps and using the four methods as follows: water balance, heat balance, and the mass transfer and Penman's equations. The obtained annual evaporation values showed significant dispersion. This study used new, daily frequency hydro-meteorological measurements. Evaporation losses were calculated following the mentioned methods using both daily records and their monthly averages to assess the impact of higher temporal resolution data in the evaporation estimates. Changes in the lake heat storage needed for the heat balance method were estimated based on the morning water surface temperature, because convection during nights results in a well-mixed top layer every morning over a constant temperature depth. We found that the most reliable method for determining the annual lake evaporation was the heat balance approach, although the Penman equation allows for an easier implementation based on generally available meteorological parameters. The mean annual lake evaporation was found to be 1700 mm year−1. This value is considered an upper limit of the annual evaporation, since the main study period was abnormally warm. The obtained upper limit lowers by 200 mm year−1, the highest evaporation estimation obtained previously, thus reducing the uncertainty in the actual value. Regarding the evaporation estimates using daily and monthly averages, these resulted in minor differences for all methodologies.
Multi-criteria Decision Analysis (MCDA) for Integrated Water Resources Management (IWRM) in the Lake Poopo Basin, Bolivia
(Springer Science+Business Media, 2010) Andrés Calizaya; Oliver Meixner; Lars Bengtsson; Ronny Berndtsson
Precipitation variability and its relation to climate anomalies in the Bolivian Altiplano
(Wiley, 2018) Claudia Canedo Rosso; Cíntia Bertacchi Uvo; Ronny Berndtsson
Precipitation variability over the Bolivian Altiplano is strongly affected by local climate and temporal variation of large‐scale atmospheric flow. Precipitation is the main water source for drinking water and agricultural production. For this reason, a better understanding of precipitation variability and its relation with climate phenomena can provide important information for forecasting of droughts and floods, disaster risk reduction, and improvement of water management. We present results of an analysis of the austral summer precipitation variability at six locations in the Bolivian Altiplano and connections to climate variability. For this purpose, the variability of the summer precipitation was related to El Niño–Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO), North Atlantic Oscillation (NAO), Antarctic Meridional Mode (AMM), and Atlantic Multidecadal Oscillation (AMO). A statistically significant correlation between climate indices and precipitation was found in various spectral frequencies and power. The variability of the summer precipitation was associated with the climate indices using a band‐pass filter, representing the signal at a particular period of time. For the ENSO, band‐pass filtering was applied for Niño3.4 and Niño3 at band ~2–7 years, for NAO band ~5–8 years, and for AMM band ~10–13 years. The variability of summer precipitation was related to all studied climate modes by negative relationships. The physical explanation for this is first the dry air transported from the Pacific Ocean to the Altiplano during El Niño events. Second, NAO and ENSO are dynamically linked through teleconnections. Third, the intertropical convergence zone (ITCZ) shifts are northwards during the warm phases of AMM. These physical mechanisms lead to a reduced austral summer precipitation associated with positive phases of the ENSO, NAO, and AMM. The results can be used to better forecast precipitation in the Bolivian Altiplano and provide support for the development of policies to improve climate resilience and risk management of water supply.
Role of Hydrological Studies for the Development of the TDPS System
(Multidisciplinary Digital Publishing Institute, 2016) Claudia Canedo Rosso; Ramiro Pillco Zolá; Ronny Berndtsson
The South American Altiplano in the Andes is, aside from Tibet, the most extensive high plateau on Earth. This semiarid area represents important water resources storages, including the Lakes Titicaca and Poopó located in the northern and central Altiplano, respectively. The two lake basins and the southern saltpans constitute a large watershed, called the Lake Titicaca, Desaguadero River, Lake Poopó, and Coipasa Salt Flat System (TDPS hydrologic system). The Altiplano climate, topography, and location determine the TDPS hydrologic functioning. Scarce data and high spatial variability represent challenges to correctly simulate the TDPS water budget. Consequently, there is an important need to improve the understanding of the water resources in current and future climate over the area. The paper provides a comprehensive state-of-the-art regarding current knowledge of the TDPS hydro-socioeconomic system and summarizes the data needs to improve the current hydrological understanding.