Anthropogenic and Climate Change Contributions to Uncertainties in Hydrological Modeling of Small Rivers Watershed Runoff

Roman M. Corobov, Gennadii N. Syrodoev, Ilya D. Trombitsky

Abstract: The movement and storage of water on watershed scales is a complex system affected by climatic, geologic, soil, land use, anthropogenic and other factors. The nature of processes inherent in surface and subsurface hydrology is best investigated by hydrologic models simulating these processes over different spatio-temporal scales and physiographical conditions. In 2014-2015 the SWAT (Soil and Water Assessment Tool) model was used as a basis for the follow-up investigations of Moldova small rivers’ potential streamflow in current and likely future climate. Actuality of this research was caused by the observed and expected deficit of water resources, necessary for the sustainable functioning of the country’s economy. The study showed that SWAT, being useful for design purposes, is less powerful in modeling the flow of small anthropogenically altered streams when the simulated runoff, which eventually enter to the river stream, does not reflect water losses resulted from human activities in their watersheds. In particular, the observed three-year streamflow of a pilot river was only between 10 and 20 percents of the corresponding modeled runoff. The likely alterations of rivers streamflow in the conditions of climate change were estimated according to the latest high resolution climate change projections based on new approaches to accounting for the greenhouse gas concentrations – the so-called Representative Concentration Pathways, which assume different radiative forcings in the current century. The SWAT modeling of the future runoff from three small rivers’ watersheds, as a function of the projected values of local air temperature and precipitation, has demonstrated a possible reduction in the water yields that could reach in Moldova, depending on a time horizon and radiative forcing, from about 2% to 21%, causing additional uncertainties in water supply planning.

Keywords: climate change, hydrological modeling, Moldova, SWAT, uncertainties.

Pages: 14 – 34 | Full PDF Paper