Attributing the drivers of runoff decline in the Thaya River basin

Authors: FISCHER, M. - Czech Globe - Global Change Research Institute; PAVIK, P. - Collaborator; VIZINA, A - Collaborator; BERNSTEINOVA, J. - Czech Globe - Global Change Research Institute; PARAJKA, J. - Vienna University Of Technology; Anderson, Martha; REHOR, J. - Czech Globe - Global Change Research Institute; IVANCICOVA, J. - Czech Hydrometeorological Institute; STEPANEK, P. - Czech Globe - Global Change Research Institute; BALEK, J. - Czech Globe - Global Change Research Institute; HAIN, C - Nasa Marshall Space Flight Center; TACHECI, P. - Collaborator; HANEL, M. - Czech University Of Life Sciences Prague; LUKES, P. - Czech Globe - Global Change Research Institute; BLAHOVA, M. - Mendel University; ZAHRADNICEK, P. - Czech Globe - Global Change Research Institute; MACA, P. - Czech University Of Life Sciences Prague; RAPANTOVA, N. - Collaborator; FENG, S. - University Of Arkansas; JANAL, P. - Collaborator; ZEMAN, E. - Czech Globe - Global Change Research Institute; ZALUD, Z. - Mendel University; TRNKA, M. - Mendel University

Submitted to: Journal of Hydrology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/30/2023
Publication Date: 6/18/2023
Citation: Fischer, M., Pavik, P., Vizina, A., Bernsteinova, J., Parajka, J., Anderson, M.C., Rehor, J., Ivancicova, J., Stepanek, P., Balek, J., Hain, C., Tacheci, P., Hanel, M., Lukes, P., Blahova, M., Zahradnicek, P., Maca, P., Rapantova, N., Feng, S., Janal, P., Zeman, E., Zalud, Z., Trnka, M. 2023. Attributing the drivers of runoff decline in the Thaya River basin. Journal of Hydrology. 48. Article e101436. https://doi.org/10.1016/j.ejrh.2023.101436.
DOI: https://doi.org/10.1016/j.ejrh.2023.101436

Interpretive Summary: The Thaya river basin supports a wide range of water resource needs in the Czech Republic, from agriculture, to forest health, to municipal consumption. However, due to the close balance between annual precipitation and evapotranspiration in this region, the basin is vulnerable to changes in the prevailing climate. Climate change adaptation and mitigation efforts are under consideration, but effective response requires a good understanding of the regional hydroclimate. This study investigates a wide range of in situ and remotely sensed observations regarding precipitation, snow cover, evapotranspiration, and vegetation dynamics within the basin to provide a holistic assessment of regional land-water-climate dynamics and trends. The analysis suggests trends in increasing air temperature and evaporative demand and decreasing runoff. In addition, positive trends in remotely sensed vegetation indices indicate increasing water requirements. The results of this study indicate that complex adaptions to climate change will be needed to sustain the water-dependent sectors operating in the Thaya river basin characterized by an increasing aridity. These measures must reflect the different hydro-climate relationships that exist across elevation gradients, as well as shifting water and energy limits on evaporative fluxes.

Technical Abstract: Study Region: The water from Thaya river basin provides an essential source for the regional water balance and multiple water uses in the transboundary region of Lower Austria and Southern Moravia. It belongs to one of the most vulnerable river basins in the region, sensitive to climate change due to its small precipitation ('' ) to reference evapotranspiration ('''''') ratio. Study Focus: The main objective is to analyse the changes in water balance parameters, i.e. actual evapotranspiration ('''' ), '' and runoff (''''), and their drivers for the period 1981–2020 and 2001–2020 in case of more recent remote sensing datasets. New Hydrological Insights for the Region: The analyses confirmed previously reported increasing trends in air temperature (''''), '''''',and no trends in '' . Although not significantly, '''' consistently increased during spring and decreased during summer. This was associated with a significant increase of spring vegetation development followed by summer stagnation. The spring '''' showed significantly decreasing trends, especially in the uplands water source areas. The correlation analysis revealed a different behaviour along the altitude gradient with uplands generally limited by available energy whilst lowlands by available water in spring. In summer, however, the entire basin is often limited by water, with more pronounced limitation in lowlands. Complex adaptions measures reflecting the different hydro-climate relations across the altitudinal gradient will be needed to sustain the water dependent sectors operating in the Thaya river basin facing increasing aridity.