• Energy Research

Study Region: : The Thaya river basin provides multiple water uses in the transboundary region of Lower Austria and Southern Moravia. Due to the low precipitation (P) to reference evapotranspiration (ETo) ratio, the Thaya river basin is among the most sensitive to climate change in the region. Study Focus: : The main objective is to understand the changes in the water balance variables including actual evapotranspiration (ET), P and runoff (RO) and their drivers for the period 1981–2020, and 2001–2020 in the case of using remote sensing data. New Hydrological Insights for the Region: : The analyses confirm previously reported increasing trends in air temperature, ETo, and no trends in P. ET consistently increased during spring and decreased during summer, although insignificantly. This change was associated with a significant increase of spring vegetation development followed by summer stagnation. The spring RO shows significantly decreasing trends, especially in the upland water source areas. The correlation analysis reveals a different behavior along the altitude gradient, with ET in the uplands generally limited by available energy whilst in the lowlands by available water in spring. In summer, however, the entire basin is often water-limited, with a more pronounced limitation in the lowlands. Complex adaption measures reflecting the different hydroclimate relations across the altitudinal gradient are needed to sustain the water dependent sectors operating in the region facing increasing aridity.

This archive contains figures from the paper "Global hotspots in soil moisture-based drought trends", published in Environmental Research Letters.

Abstract Decreasing soil moisture and increasing frequency and intensity of soil drought episodes are among the frequently discussed consequences of ongoing global climate change. To address this topic, a water balance model SoilClim forced by climate reanalysis ERA5-Land was applied on a global scale to analyze the spatiotemporal variability of changes in soil moisture anomalies. The results revealed that the soil relative available water (AWR) significantly decreased on 31.1% of global non-glaciated land and significantly increased on 5.3% of such global non-glaciated land in 1981–2021. Decreasing AWR trends were detected over all continents and were particularly pronounced in South America, which experienced significant drying on more than half of the continent. The main drought ‘hotspots’ were identified in equatorial Africa, a large part of South America, the Midwest United States, and in a belt extending from eastern Europe to eastern Asia. A seasonal analysis of region-specific patterns further suggested drying in Europe in summer but an absence of a drying trend in winter. These results were supported by an analysis of the area affected by percentile-based drought on individual continents, revealing statistically significant increasing trends of 5th- and 10th-percentile droughts on all continents except Australia at an annual scale. Nevertheless, summer and autumn drought frequency increases were also detected in Australia. The seasonal trends were the most rapid in South America and Europe (except in winter). The distributions of AWR values, evaluated by Z scores, shifted remarkably toward drier conditions during the 2001–2021 period, particularly in South America and Asia. These results underscore the alarming increase in soil drought on a global scale, highlighting the need for effective drought management strategies.