Temporal shift of hydroclimatic regime and its influence on migration of a high latitude meandering river

: Blåfield Linnea, Marttila Hannu, Kasvi Elina, Alho Petteri

Publisher: Elsevier

: 2024

: Journal of Hydrology

: 130935

: 633

: 0022-1694

: 1879-2707

DOI: https://doi.org/10.1016/j.jhydrol.2024.130935

: https://doi.org/10.1016/j.jhydrol.2024.130935

: https://research.utu.fi/converis/portal/detail/Publication/387108422

Climate change alters high latitude hydrological cycle from snow-dominated to rain-dominated by diminishing the magnitude of spring flood and shifting the hydroclimatic regime. These changes in temperature, precipitation patterns, and discharge strongly influence geomorphological processes in fluvial environments, leading to alterations in sediment transport, erosion, accumulation, and landscape changes. We conducted comprehensive analysis of hydrological, and meteorological trends and shifts of a boreal Oulanka River system, spanning over the past five decades. A strong signal of warming temperatures (+0.61 Celsius/decade), reduced winter conditions and warmer summers (+0.41 Celsius/decade) was detected. The spring flood magnitude diminished 7 %, but high discharge peaks (>annual p90m3/s) during other seasons increased 10 % together with the annual minimum discharge which increased 28 %. Simultaneously, precipitation intensity increased during summer. The meander migration rate (mean 0.89 or 2.55 m/year) and bank erosion volume were interconnected to ground frost, high snow sum, high discharge, and high-water level during spring flood, but no significant long-term trends were observed. Our findings underscore that climate is the first-order control on fluvial geomorphology and emphasizes the complex interplay between various hydrological and climatic factors that shape the dynamics of river systems. Based on the results, we expect to see changes in the spatial–temporal distribution of high latitude rivers sediment yield in future. In addition, more attention should be addressed to the thaw seasons controlling the sediment, as majority of the observed shifts took place in these months.

1-s2.0-S0022169424003299-main.pdf