SUMMARY
Modeling of geodynamic risk is a highly relevant scientific issue; its solution requires solving particular problems in creating a model of the geological environment, selecting the risk factors, creating a model of process, acknowledging the scenarios and prognoses. Geodynamic risk in the areas of development of subsident soils can be defined as the possibility of massif deformations during changes in the soil condition (degradation). The limit state is the state of full water saturation, when the possibility of subsidence is low. Application of the three-term gradation to the scale of conditions sets the boundary values of soil moisture – the indicators of mild, average and critical changes. The predicted condition of the massif is set by a system of features – independent variables, input parameters correlated with values of moisture and values of degradation of subsidence properties. The predicted value of subsidence degradation under additional loading and in natural conditions is found using the group method of data handling. Widespread presence of subaerial loess-like formation in the composition of the geological environment in stratigraphic-genetic complexes of different composition and properties, and in water-bearing horizons, leads to intense development of exogenous geological processes and vulnerability of the environment.Typification of the geological structure of the massif was performed using the results of analysis of numerous engineering-geological studies (Dnipro, 1960-2007). The total number of wells is 785, the depth varies from 15 to 56 m. The mapping of surfaces of particular horizons, terrain, thickness of aeration zone was developed using a "Surfer" demo-version. Interpolation was made using the Kriege method. Development of models of surfaces of the top of and thickness of horizons and took the erosional washout into consideration. The analysis of cartographic material shows that loess and paleosol horizons have different consistencies. The following processes were modeled: the change in the condition in relation to moisture of the subsident soil massif within the zone of low-intensive aeration, the value of additional pressure equals 0.3 MPa; the change in the condition in relation to moisture of the subsident soil massif within the zone of averagely intensive aeration, the value of additional pressure equals 0.3 MPa (Fig. 5 b). The results of the prognosis indicate the importance of predicting the subsidence degradation as a factor of geodynamic risk, maximum values reach 0.24 m. Comparing this value to the value of acceptable settling of constructions may suggest the practicability of introducing the method of predicting subsidence to the practice of engineering-geological studies and planning.