Basic Physical Processes and Regularities of Winter and Spring River Runoff Formation under Climate Warming Conditions
I. L. Kalyuzhnyi and S. A. Lavrov
A mechanism of climate change influence on the Medvenka River runoff in the winter- and springtime is revealed based on the generalized long-term observations carried out at the Podmoskovnaya water-balance station. It is demonstrated that average increase in the monthly mean temperature in January and February 1981–2008 of 2.8C resulted in 1.9-time increase in the runoff over these months and its 15% decrease in April compared to the period of 1958–1980. The analysis of the observation materials and mathematical modeling of processes of migration and moisture infiltration in freezing and thawing soils allows establishing the fact that a decrease in the depth of soil freezing and, correspondingly, in moisture migration in the wintertime towards the freezing front and its accumulation in the frozen layer (a 56% increase in the runoff), available thaws (38%), and the fall increase in the soil moistening (6%) are major factors influencing the winter runoff increase.