Preliminary Study On Prevention And Controlling Of Snowmelt Erosion On Slopes In Northeast China

The north-eastern region is an important commercial grain production base in China,and there are serious soil erosion problems on sloping arable land.Existing soil and water conservation measures are mostly designed for rainfall erosion control,and there is a lack of targeted research on the role of spring snowmelt erosion control,especially in terms of water and sand dynamics during snowmelt erosion.This paper uses the results of slope snowmelt erosion monitoring to analyse the characteristics and laws of the dynamic changes of water and sand at the scale of runoff plots and slope catchments under the influence of typical soil and water conservation measures,and by comparing the control role of measures in snowmelt erosion with that of rainfall erosion,the role and characteristics of typical measures in snowmelt erosion control are explained.The main conclusions are as follows.The main conclusions are as follows.(1)The characteristics and patterns of water-sand dynamics at the runoff plots and slope catchment scale.The indicators at both scales were closely related to the peak runoff volume,which was the best variable to describe the snowmelt process,and there was a strong correlation between the total runoff volume and the total sand production.There was a runoff-sediment lag relationship in the snowmelt erosion process.The time lag in the counterclockwise direction was dominant in the cross-monopoly,horizontal pit,shrub ridge and ridge plant belt plots with better water conservation benefits;the time lag in the clockwise direction was shown in the bare ground and smooth monopoly plots,indicating that different measures have different effects on the water-sediment process.The most important indicator of water-sand dynamics in the shrub ridge and ridge plant belt plots was the total runoff,and in the horizontal pit,cross-monopoly and smooth-monopoly plots was the total sandiment yeild,which was related to the mechanism and process of erosion control by different measures.The most important indicator of water-sand dynamics in the catchment and cross-monopoly plots was the total sandiment yeild,and the benefits of cross-monopoly were better than those of runoff plots at the catchment scale,indicating that there was a clear scale effect in snowmelt erosion control.(2)Typical water conservation measures under snowmelt and rainfall conditions to prevent erosion effect difference comparison.From the flow-producing conditions the ridge plant zone had a better erosion control effect,the smooth monopoly had a poorer erosion control effect,and the cross monopoly had a greater difference,which was related to the nature of precipitation and the impact of the measures on the production and sink flow.The difference in surface runoff intensity between the two types of erosion conditions was not significant,while the intensity of runoff under snowmelt conditions was less than that of rainfall in the cross-monopoly,and the intensity of snowmelt runoff was greater than that of rainfall in the ridge vegetation zone.The relationship between water and sand showed that the cross-monopoly was more effective in snowmelt erosion and the ridge vegetation zone was more effective in rainfall erosion,while the smooth-monopoly was less effective in both conditions.The effect of snowmelt erosion on soil retention was relatively better in the paratopia,about three times more effective than in rainfall erosion,which was related to the effect of the measure on runoff,microtopography and differences in soil thawing.(3)Typical measures of snowmelt erosion control benefits and optimization suggestions.Horizontal pits were the most effective measure,followed by horizontal monopolies,with little difference between shrub ridges and ridge plant belts,and poorer for smooth monopolies.Horizontal pits could be optimised in terms of fruit tree species selection and planting density.Ridge planting strips could be selected to form a combination of tillage measures + ridge planting strips.The arrangement of shrub ridges could be changed to facilitate the infiltration of snowmelt water.The cross-row could be combined with slope drainage measures such as grassed waterways to reduce the risk of erosion of slope channels due to runoff collection.This paper provided a theoretical basis for solving the problem that existing water conservation measures in the northeast were designed only for rainfall erosion by mastering the water and sand characteristics of snowmelt runoff at two scales: runoff cells and slope catchments.