RESUMO
Under the background of climate change, extreme wind events occur frequently in Northeast China, and the soil erosion caused by these extreme wind events has attracted progressively more attention from scholars. We used the methods of linear analysis, Sen+Mann-Kendal trend analysis, and Kriging interpolation to analyze the spatial and temporal characteristics of extreme wind in Northeast China from 2005 to 2020, and used the RWEQ wind erosion estimation model to calculate the annual soil wind erosion of typical wind erosion sites and wind erosion under extreme wind conditions. The results showed that the extreme wind frequency in Northeast China presented a significant upward trend from 2005 to 2020, with an increase of 2.9 times·a-1. The annual average extreme wind frequency in Northeast China ranged from 1 to 49 times·a-1, and the high frequency areas were distributed in the northwest of Xilin Gol, the west of the Hulunbuir Plateau, and the northeast of Changbai Mountain. The average contribution rate of extreme wind to soil wind erosion in four typical sites (Xilinhot, New Barhu Right Banner, Nenjiang, and Tongyu) was 31%.
Assuntos
Conservação dos Recursos Naturais , Vento , Conservação dos Recursos Naturais/métodos , Solo , China , Mudança ClimáticaRESUMO
Understanding the spatial distribution characteristics of soil erosion and sediment connectivity is important for formulating integrated watershed management measures. Based on the InVEST sediment delivery ratio model, we used the connectivity index and soil loss model to measure the spatial distribution characteristics of sediment connectivity and soil erosion in Erdaoling watershed of brown soil hilly region of low mountains in western Liaoning. By exploring slope, aspect and land use characteristics under different sediment connectivity levels and soil erosion levels, we analyzed the relationships among topography, land use, sediment connectivity, and soil erosion. The results showed that the average sediment connectivity in the watershed was -3.79, and that the average soil erosion was 614 t·km2·a-1. High connectivity was mainly found in sloping farmland, while low connectivity was mainly found in forest and grassland. The soil erosion intensity of 93.3% of the watershed area was below moderate, with only 1.1% of the area being above extremely strong. The higher the sediment connectivity level, the higher the proportion of the area <5° slope, while the area proportion of the rest slope was relatively stable. The proportion of cultivated land area increased, while the proportion of forest and grassland land area decreased. The area proportion on negative slope decreased, while that on positive slope increased. With increasing soil erosion intensity, the area proportion of slope <8° increased and the area proportion of the rest slope was relatively stable. The proportion of forest and grassland area decreased, while the proportion of other land use area increased. The proportion of slope area on positive slope increased, while that on negative slope decreased. Land use was a key factor influencing the spatial response relationship between soil erosion and sediment connectivity in this watershed.
Assuntos
Erosão do Solo , Solo , Florestas , China , Conservação dos Recursos Naturais/métodosRESUMO
The stability of 3-5 mm aggregates of black soil collected from Heilongjiang Province were analyzed by Le Bissonnais method under different freeze-thaw cycle treatments (0, 1, 3, 5 and 9). The aggregate porosity were measured by wax-coated method. The results showed that the contents of different size aggregates fluctuated with the freeze-thaw cycles, and the variation coefficient of aggregate content turned stable gradually. There were significant differences of the content of above 0.25 mm aggregate among the treatments of fast wetting, slow wetting, and wet stirring. Aggregate porosity increased with increasing freeze-thaw cycles, ranging from 32.4% to 41.4%. Low variation of aggregate contents occurred in different breakdown patterns with increasing freeze-thaw cycles. There was negative correlation between porosity and mean weight diameter, suggesting the aggregate porosity was important in the aggregate stability under freeze-thaw condition.
Assuntos
Solo , CongelamentoRESUMO
Shelterbelt system is one of the main components of cultivated slope land in rolling hill black soil region of Northeast China, which plays an important role in the control of gully erosion. Based on the Quickbird high-resolution remote sensing image and the digital elevation model (DEM), and combining with field survey data, this paper analyzed the effects of shelterbelt system in a small watershed of rolling hill black soil region in Heshan Farm of Heilongjiang Province on the control of gully erosion in the cultivated slope land, and put forward an optimized scheme for gully erosion control based on the features of gully erosion in the cultivated slope land and their relations with the distribution of the shelterbelt system. In the study area, the current distribution of the shelterbelt system promoted the occurrence and development of shallow gully and gully directly and indirectly. The proposed scheme for optimizing the distribution of the present shelterbelts included the adjustment of the direction of the shelterbelt perpendicular to the aspect of slope, the enhancement of the maintenance and regeneration of the shelterbelts to reduce the gaps of the shelterbelts, the increase of the shelterbelt number, and the decrease of the distances between shelterbelts. A method for calculating the shelterbelt number and the distances between the shelterbelts was also given. This study could provide scientific basis for the gully erosion control and the shelterbelts programming in the cultivated slope land of rolling hill black soil region.