Valley complexes as ecosystem assets of heat island of urban agglomerations (on the example of the right-bank part of Kyiv)
The analysis of the influence of the valley network of the right-bank part of Kiev on the formation of summer surface temperatures based on the use of materials of space remote sensing is carried out. The results of processing Landsat satellite images from 1987 to 2018, presented as isotherms, were used. Comparison of temperature data, hypsometry, geomorphologic features, types of earth cover was carried out according to profiles crossing the valleys in the most representative areas. The main factors influencing the formation of the temperature field within the valleys are vegetation, insolation exposure and anthropogenic stress. The studies revealed the lowest temperatures in the valleys at the foot of the slopes of the northern exposure, covered with woody vegetation. It was established that the temperatures in the valleys with wood cover are 5–6С and lower than the temperatures on the built-up water divide and 2–30С lower than in the park zones on the water divide. As a result of the peculiarities of the internal atmospheric circulation, stagnation in the valleys, with significant anthropogenic pressure (buildings, highways, railways), positive thermal anomalies and even geochemical ones are formed. Unfavorable ecological conditions (high level air pollution, flooding of foundations) are formed on the river Lybid and Kiyanka stream. Due to climatic changes and constantly growing anthropogenic pressure (increase in the area of impermeable surfaces, density and number of storey of residential buildings), temperatures within the city's “thermal island” for the study period increased by an average of 2–30С. Preservation of the valley network in its natural state provides a kind of oases within the city with favourable microclimatic and recreational conditions.