Архив метки: drought

EXTREME DROUGHT ON THE EAST EUROPEAN PLAIN DURING THE HEAT WAVE IN THE MIDDLE OF THE 20th CENTURY: CLIMATIC CHARACTERISTICS AND ANALOGUES IN THE MODERN CLIMATE CONDITIONS

Arid Ecosystems

UDC 551.5; 58.032.3

Popova V.V., Bokuchava D.D., Matveeva T.A. EXTREME DROUGHT ON THE EAST EUROPEAN PLAIN DURING THE HEAT WAVE IN THE MIDDLE OF THE 20th CENTURY: CLIMATIC CHARACTERISTICS AND ANALOGUES IN THE MODERN CLIMATE CONDITIONS // Arid Ecosystems. 2023. Vol. 29. № 2 (95). P. 3-11. | PDF

The unprecedented annual flow anomalies of the Volga and the Northern Dvina rivers in 1920-1940 are considered in the context of global Early 20th Century Warming (ETCW) and climate extremes of recent decades. The study of hydrological and climatic characteristics reveals that the ETCW period manifested itself on the East European Plain in the long-term drought in 1936-1940, that, according to Palmer drought severity index, has no analogues it terms of intensity and duration in this region. The results of the cross-spectral analysis of the variability of river flow and the North Atlantic Oscillation index, as well as the analysis of empirical orthogonal functions of the surface level atmospheric pressure anomalies indicate the relationship of the hydroclimatic extremes of the period considered with anomalies of the North Atlantic atmospheric circulation and the positive phase of the Atlantic multidecadal Oscillation (AMO).

In terms of intensity, duration and impact on river flow, the dry period from the late 1960s to the mid-1970s, with a maximum of 1972, can be considered as the most similar analogue to the drought of the 1930s. In the spectrum of the annual Volga River runoff, the anomaly of the 1972 manifests itself as the second rate maximum of the runoff variance after the absolute maximum of the 1930s. From the point of view of the atmospheric circulation conditions and links with the positive phase of the AMO, the extreme heat and drought of 2010 can be recognized as an analogue of droughts in the period of the ETSW. At the same time, it is different by the absence of significant consequences for river runoff due to the increase in precipitation of the cold period during the period of modern climate warming.

Keywords: warming of the mid-twentieth century, East European Plain, river runoff, extremes, drought, Palmer index, circulation conditions.

Funding. The study was carried out for the Russian Scientific Foundation project No. 22-27-00495 “Climatic and Circulation Factors of Anomalies of Humidification of Large River Basins of European Russia in the Era of Warming of the Mid-twentieth Century”.

DOI: 10.24412/1993-3916-2023-2-3-11

EDN: CAILXD

INFLUENCE OF CLIMATE CHANGE ON SOIL DEGRADATION IN ARID ZONES OF THE VOLGA REGION

Arid Ecosystems

UDC 631.434.52:504.123(470.4)

Gubarev D.I., Levitskaya N.G., Derevyagin S.S. INFLUENCE OF CLIMATE CHANGE ON SOIL DEGRADATION IN ARID ZONES OF THE VOLGA REGION // Arid ecosystems. 2022. V.28. № 1 (90). P. 20-27. | PDF

The aim of the research was to establish the impact of climate change on the processes of soil degradation and desertification in the arid zones of the Volga region. The material for the research was the observational data for 1971-2020 on 20 meteorological stations, as well as the results of soil-ecological and hydrogeological monitoring at research stations of the Federal State Budgetary Scientific Organization «Federal Center of Agriculture Research of the South- East Region» in the prevailing soil and climatic zones on the territory of the Saratov region (forest-steppe, steppe, dry steppe and semi-desert). Identified signs accompanying aridization, desertification and land degradation differentiated by natural zones. In particular, the average annual air temperature increased, compared with the climatic norm, by 1.0-1.2°С, the greatest increase was observed in August (by 2.0-2.2°С). The average temperature of the soil surface during the warm period increased by 1.1-1.5°C. The risks of severe atmospheric droughts during the entire growing season increased throughout the entire territory, most noticeably in the semi-desert zone (from 55 to 82%). The amount of precipitation in the spring increased by 10-25%, and in the summer – decreased by 23-30%. The boundaries of the semi-desert zone have shifted to the north and northwest. The tendency of changes in the hydrological regime of zonal soils from non-leaching to periodically leaching in 20-40% of years is outlined. The values of the aridity indices of the territory, calculated for the period from 2001 to 2020, increased in comparison with the climatic norm for 1971-2000 by 3-6%. This is an indicator of an increase in climate aridity during its current warming. As a result, high rates of dehumification (decrease in the relative humus content by 21-35%) and changes in the structural state of the arable layer and grain size distribution (decrease in water-resistant aggregates >0.25 mm from 39 to 31.8% and the absolute content of physical clay by 7.5%). At the same time, there is an increase in the mineralization of groundwater from 2500 to 7000 mg/l, as well as an increase in the content of toxic salts in the soil solution. Thus, the content of Cl—, SO42— ions in the places of replenishment with groundwater increased from 0.27 to 0.56 mg/eq. and from 0.27 to 13.27 mg/eq. respectively. The cation values also increased: Ca2+ – from 0.30 to 4.41 mg/eq., Mg2+ – from 0.12 to 5.59 mg/eq., The sum of K+ and Na+ – from 0.09 to 0.28 mg/eq. In the lowered elements of the relief, the development of processes of local salinization and waterlogging is noted.

Keywords.Climate change, aridization, drought, degradation, salinization.

Financing. The article was made within the state assignment No. 0751-2019-0008 “To develop theoretical foundations for structuring agricultural landscapes, adapting them to climatic and geomorphometric features of the territory in order to preserve and optimize the use of land resources to obtain an economically reasonable level of quality agricultural products”.

DOI: 10.24412/1993-3916-2022-1-20-27