Risk of gully erosion: methods and examples of estimates

Risk of damage of buildings and infrastructure by gully erosion can be estimated on the net of flowlines or by evaluation of depths of gullies with erosion model, or by calculation of some simplified measures of erosion rate, which are correlated with such calculated gullies depths and/or with the measurements of gully erosion. The most exact approach is based on calculation of the transformation of longitudinal profiles of linear erosion features along all flowlines on DEM with GULTEM model. The model includes calculation of gully erosion and thermoerosion, gully bank widening and collapsing. This requires detailed meteorological, hydrological, morphological and lithological information and includes model calibration on the measurement data. The simplified methods are based on the calculation of critical runoff depth at which linear erosion of the soil begins for each point on the catchment. The total sediment yield at each point by all flows above critical or difference between the maximum runoff depth and its critical value is calculated within such approach. This requires much less hydrological, morphological and lithological information, but takes into account only initial conditions on the catchment. Calculations of the risk of gully erosion were performed on the net of flowlines for the gas fields on the Yamal Peninsula with existing and designed structures and buildings. Comparison of the results of evaluating the gully erosion potential by the simplified methods with the data of calculations of gully erosion using the detailed dynamic model and field measurements showed their satisfactory agreement. This confirms the possibility of using express-methods for a quick assessment of the scope of using territories for development with the following detailed calculations with the use of GULTEM on certain areas of construction for evaluation of the risks of landscape and infrastructure disturbance.

Funding: This research was funded by RFBR grant 18-05-60147 "Extreme hydrometeorological phenomena in the Kara Sea and the Arctic coast".