Györgyi Gelybó

Impact of expected climate change on soil water regime under different vegetation conditions

A mathematical model was applied for the Bükk Mountains (Hungary) to evaluate the effects of climate change on soil water balance elements and soil water regime. Model runs using SWAP model were performed for combinations of four distinctive soil types and three land use systems of arable land, grassland, and forest. The temporal variation of soil water regime under changing climatic conditions was examined considering no land cover change occurring in the future. The climate data consisted of the predictions of two regional climate models, the Swiss CLM and the Swedish RCA. The RCA results showed 45% to 50% and the CLM showed 5% to 14% higher future precipitation outlook compared to present conditions. Considering different land use types, the projected number of days with soil moisture deficit was the highest in forest ecosystems for both the upper 50 cm soil layer and the whole soil profile, which could be as high as 61% of days below optimal soil water content range. Our results showed increased water fluxes, especially in deep percolation in far future period and a strong influence of soil properties on the changes in the climate model results, indicating significant long-term effects of climate change on soil water regime.

Effects of Land Use and Management on Soil Hydraulic Properties

Abstract Soil hydraulic properties are among the most important parameters that determine soil quality and its capability to serve the ecosystem. Land use can significantly influence soil properties, including its hydraulic conditions; however, additional factors, such as changes in climate (temperature and precipitation), can further influence the land use effects on soil hydraulic properties. In order to develop possible adaptation measures and mitigate any negative effects of land use and climatic changes, it is important to study the impact of land use and changes in land use on soil hydraulic properties. In this paper, we summarize recent studies examining the effect of land use/land cover and the associated changes in soil hydraulic properties, mainly focusing on agricultural scenarios of cultivated croplands and different tillage systems.

A comparison of the observed trends and simulated changes in extreme climate indices in the Carpathian Basin by the end of this century

Global warming results in shifts of mean temperature and precipitation, and also, in frequency and intensity changes of climate extremes. In this paper, temperature and precipitation extreme indices are analysed and compared for the Carpathian Basin (located in Central/Eastern Europe). For past trends, daily meteorological observations from the 20th century are used. In the case of future changes (2071-2100 relative to 1961-1990, A2 and B2 scenarios), the simulated daily outputs are obtained from regional climate model experiments. The results suggest that the regional climate of the Carpathian Basin got warmer during the second half of the 20th century, especially in the last quarter. Regional warming is expected to continue in the 21st century, cold temperature extremes are projected to decrease in frequency, while warm extremes will tend to increase significantly. Regarding precipitation, the regional intensity and frequency of extreme precipitation have increased in the past decades, while the total precipitation decreased in the region and the mean climate became drier. The projected changes in different seasons are opposite to each other; the extreme precipitation events are expected to become more intense and frequent in winter, while a general decrease of the extreme precipitation indices is expected in summer.

Soil CO2 Emissions in a Long-Term Tillage Treatment Experiment

Abstract The aim of our study was to investigate the effect of plowing (P) and no-tillage (NT) management on soil CO2 emissions from an arable field (i.e., winter wheat) in a 13-year-old experiment. In 2015, CO2 measurements were taken weekly in P and NT during the growing season and biweekly during the dormant season using the static chamber technique. Measurements were more frequent in a 7-day campaign scheduled right before and immediately after a soil disturbance caused by plowing to detect the short-term effects of soil management on CO2 emissions. We investigated the relationship among soil CO2 emissions, soil temperature, and soil water content. Soil CO2 emissions increased during the vegetation period and were higher in NT than P, although they were only significant from jointing to maturity stages. In contrast, CO2 emissions were higher in P compared to NT at a relatively short but well-monitored measurement interval just after plowing. Long-term systematic plowing resulted in lower CO2 emissions than that in NT during vegetation season, but a sudden pulse in CO2 emissions were detected in P directly after soil disturbance caused by plowing. These observations indicate that plowing can temporarily have a major effect on soil CO2 emissions.

Evaluation of ozone deposition models over a subalpine forest in Niwot Ridge, Colorado

In this study, we evaluated three conceptually similar ozone gas deposition models. These dry deposition models are frequently used with chemical transport models for calculations over large spatial domains. However, large scale applications of surface-atmosphere exchange of reactive gases require modeling results as accurate as possible to avoid nonlinear accumulation of errors in the spatially representative results. In this paper, model evaluation and comparison against measured data over a coniferous forest at Niwot Ridge AmeriFlux site (Colorado, USA) is carried out. At this site, no previous model calibration took place for any of the models, therefore, we can test and compare their performances under similar conditions as they would perform in a spatial application. Our results show systematic model errors in all the three cases, model performance varies with time of the day, and the errors show a pronounced seasonal pattern as well. The introduction of soil moisture content stress in the model improved model performance regarding the magnitude of fluxes, but the correlation between measured and modeled ozone deposition values remains low. Our results suggest that ozone dry deposition model results should be interpreted carefully in large scale applications, where the accuracy can vary with land cover sometimes are biased.

Evaluation of three semi-distributed hydrological models in simulating discharge from a small forest and arable dominated catchment

Abstract Catchment scale hydrological models are promising tools for simulating the effect of catchment-specific processes and management on soil and water resources. Here, we present a model intercomparison study of runoff simulations using three different semi-distributed rainfall-runoff catchment models. The objective of this study was to demonstrate the applicability of the Hydrologiska Byrans Vattenavdelning (HBV-Light); Precipitation, Evapotranspiration and Runoff Simulator for Solute Transport (PERSiST); and INtegrated CAtchment (INCA) models on Somogybabod Catchment, near Lake Balaton, Hungary. The models were calibrated and validated against observed discharge data at the outlet of the catchment for the period of January 1, 2006 –July 12, 2015. Model performance was evaluated using graphical representations, e.g. daily and monthly hydrographs and Flow Duration Curves (FDC) and model evaluation statistic; Nash–Sutcliffe efficiency (NSE) and coefficient of determination (R2). The simulation results showed that the models provided good estimates of monthly average discharge (0.60–0.90 NSE; 0.60–0.91 R2) and satisfactory results for daily discharge (0.46–0.62 NSE; 0.50–0.67 R2). We found that the application of hydrological models serves as a powerful basis for ensemble modelling of average runoff and could enhance our understanding of the eco-hydrological and transport processes within catchments. On the other hand, it can highlight the uncertainty of model forecasts and the importance of goal specific evaluation.