Место издания:Nova Science Publishers Hauppauge NY
Первая страница:139
Последняя страница:192
Аннотация:High sandy and loamy terraces in the Arctic and Subarctic European Russia and West Siberia are deeply eroded by the natural gullies. Gully network density is more than 1.2-1.5 km/km2. There are several main processes, which trigger off natural gully erosion: 1) river channel migration and erosion of high banks; 2) ground ice melting resulting in cryoplanation; 3) migration of the thermokarst lakes; 4) active layer thaw slumps (skin-flow). In zones of production and transportation facilities the human impact increases gully erosion risk due to: 1) damage of vegetation cover; 2) snow water storage increase at upper parts of gully basins due to snow accumulation near constructions; 3) runoff coefficient increase on impermeable surfaces of the roads and buildings; 4) formation of local anthropogenic sources of the warm water.
Combination of high natural gully erosion risk and additional anthropogenic influence causes extremely intensive gully growths 20-30 m/year and up to 100-300 m/year . Gully channels formation is very intensive during the period of gully initiation, when gully morphological characteristics (length, depth, width, area, volume) are far from stable. About 80 per cent of gully length, 60 per cent of its area and 35 per cent of volume form only at 5 per cent of gully lifetime.
The GULTEM model to predict rapid changes of gully morphology at the first period of gully development was proposed. The model is based on digital elevations model analysis; calculations of runoff due to snowmelt or rainfall; solution of the equations of gully bed deformation for different types of soil (including frozen soil). The model of straight slope stability was used for prediction of inclination of gully’s side walls.
This model was used for gully network growths prediction in the Bovanenkovskoye gas productive field in the conditions of human interference. Calculations show, that under anthropogenic impact the whole drainage net will be transformed by erosion. Some of human-induced gullies can cross pipelines and roads, damage buildings and bore-well grounds.
Complicated processes of thermoerosion and thermokarst, which take place under permafrost conditions, prevent the use of hydrotechnical methods for soil conservation. The main measures to prevent erosion in the permafrost regions are 1) to avoid unstable geomorphic units for construction; and 2) to improve the quality of vegetation cover in the areas of gas exploitation activities. These recommendations can be used in optimisation-decision system for the choice of the measures to prevent gully erosion, buildings and constructions destruction