Process-Based Modeling of the High Flow of a Semi-Mountain River under Current and Future Climatic Conditions: A Case Study of the Iya River (Eastern Siberia)

Abstract

The purpose of the study was to analyze the formation conditions of catastrophic floods in the Iya River basin over the observation period, as well as a long-term forecast of the impacts of future climate change on the characteristics of the high flow in the 21st century. The semi-distributed process-based Ecological Model for Applied Geophysics (ECOMAG) was applied to the Iya River basin. Successful model testing results were obtained for daily discharge, annual peak discharge, and discharges exceeding the critical water level threshold over the multiyear period of 1970–2019. Modeling of the high flow of the Iya River was carried out according to a Kling–Gupta efficiency (KGE) of 0.91, a percent bias (PBIAS) of −1%, and a ratio of the root mean square error to the standard deviation of measured data (RSR) of 0.41. The preflood coefficient of water-saturated soil and the runoff coefficient of flood-forming precipitation in the Iya River basin were calculated in 1980, 1984, 2006, and 2019. Possible changes in the characteristics of high flow over summers in the 21st century were calculated using the atmosphere–ocean general circulation model (AOGCM) and the Hadley Centre Global Environment Model version 2-Earth System (HadGEM2-ES) as the boundary conditions in the runoff generation model. Anomalies in values were estimated for the middle and end of the current century relative to the observed runoff over the period 1990–2019. According to various Representative Concentration Pathways (RCP-scenarios) of the future climate in the Iya River basin, there will be less change in the annual peak discharge or precipitation and more change in the hazardous flow and its duration, exceeding the critical water level threshold, at which residential buildings are flooded.

Comparison of Ratioing and RCNA Methods in the Detection of Flooded Areas Using Sentinel 2 Imagery (Case Study: Tulun, Russia)

“…The R255-Siberia Federal Highway runs through a floodplain area, and the Trans-Siberian Railway follows along the Azey River (Figure 12). According to Kalugin [41] both these infrastructures contribute to an increase in flooding in the urban area and a decrease in the longitudinal slope of the water surface, resulting in a lower streamflow velocity. The road crosses the flooded area and acts as a barrier on the southern zone, while the railway line acts as a barrier on the north, limiting the flooded area from west to east.…”

Climate Change Effects on River Flow in Eastern Europe: Arctic Rivers vs. Southern Rivers

“…The ECOMAG-based [18] models of flow formation in the basins of the Northern Dvina, Pechora, Don, and Kuban rivers were used to study changes in the water regime, which had previously been used for large rivers in Europe, Asia and Northern America [19][20][21][22][23], as well as in mountain rivers [24][25][26]. This model makes it possible to calculate the spatial distribution of the processes of snow cover and snowmelt formation; soil freezing and thawing; vertical heat and moisture transport in frozen and unfrozen soil; evapotranspiration; surface, subsurface and groundwater flow; and streamflow transformation in the channel system.…”

Leveraging Soil Moisture Assimilation in Permafrost Affected Regions

“…In 1984In , and 2001, floods wreaked havoc in the southern section of the Iya watershed, with the July 2001 flood being the most catastrophic [60]. Extreme rainfall-floods devastated the city of Tulun and other villages on the river floodplain in the summer of 2019, on the rivers of the Iya catchment, becoming the most devastating floods in the area [61,62]. The Iya-Tulun stream gauge registered the largest rise in water level during June 2019 (from 474 to 1387 cm over three days), which was the first flood of the year.…”