Quantitative Remote Sensing Study on Regional Soil Erosion——Bin County of Heilongjiang as an Example

Based on Chinese soil loss equation （CSLE） model, this paper utilized technical advantages of RS and geographic information system （GIS） on data access and erosion factors database building to study prediction methods of regional soil erosion. The spatial analysis module of ARCGIS platform was applied to study the spatial distribution of erosion and the inter-relations of the factors influencing regional soil erosion in the research area. As a result, the mean soil erosion modulus of Bin County is 3 555.42 t/（km^2.a）, which suggests moderate degree erosion. The mean soil erosion modulus of clayey meadow soil is higher than those of dark brown soil and black soil. Vegetation factor values are between 0.1-0.2. The mean slope gradient and slope length values are respectively 1.335 and 6.061 which shows slope length is a dominant factor. And soil type, vegetation coverage and topographic factors have remarkable relevance to each other. Therefore, RS, GIS and CSLE are applicable in regional scale to disclose spatial distribution characteristics of soil erosion and to analyze the characteristics of dominant soil erosion factor quantitatively.

Relationship Between Watershed Landscape Pattern Change and Runoff-Sediment in Wind-Water Erosion Crisscross Region

This paper selected the typical wind-water erosion crisscross region Xiliugou watershed for research to reveal the impact of the landscape pattern change of the underlying surface in wind-water erosion crisscross region where soil erosion is most serious on rainfall and runoff as well as erosion and sediment.Based on the Landsat TM image data and measured data of runoff-sediment in that watershed,the paper analyzed the characteristics of watershed landscape pattern change and runoff-sediment and explored the relationship between landscape index and runoff-sediment yield by means of GIS and Fragstats.The results were included as follows.(1)Grassland was the dominant landscape.In terms of the number of patches and area change rate,from 1985 to 2010,cultivated land,forest land and construction land were most stable,followed by unused land.Unused land,grassland and cultivated land experienced the most dramatic conversion and maximally affected by human activities.(2)The inter-annual difference between annual runoff and annual sediment load was significant.Compared with the annual sediment load,the trend of decreasing runoff was more obvious.The correlation coefficient of runoff-sediment was 0.67,representing a significant correlation.(3)There was a significant correlation between the landscape index and runoff-sediment.The runoff was negatively correlated with the largest patch index,patch cohesion index,aggregation index and contagion index,but positively correlated with landscape morphology index and landscape division index.And the sediment was negatively correlated with the contagion index,aggregation index and plaque cohesion index,but positively correlated with other landscape indexes.The results indicate that with the increase of the largest patch index,patch cohesion index and aggregation index,the rainfall infiltration capacity increase obviously and the soil erosion reduce significantly.Therefore,increasing the largest patch index,patch cohesion and aggregation index of the watershed landscape can enhance the function of water storage and soil conservation as well as ecological optimization in the windwater erosion crisscross region.The results can provide theoretical support for the ecological environment construction and comprehensive utilization of water and soil resources.

Comparison and quantitative assessment of two regional soil erosion survey approaches

Regional soil erosion surveys are the first step of soil conservation planning.Grid and sampling ap-proaches are commonly used for soil erosion surveys at the regional scale.With the grid approach,the region is divided into grids(e.g.,1 km × 1 km),and the soil erosion rate of each grid was calculated.With the sampling approach,a small portion of the area(typically 4%or less)was taken and then the soil erosion rate was calculated.Based on the above calculation,both approaches evaluated the soil erosion area(which is the area where the soil erosion rate is greater than the soil loss tolerance(t))and its distribution in the whole region.The purpose of this paper is to compare the assessment results of the two approaches and analyse their practicality using Yunyang County,Chongqing,China(area is 3636 km^(2)).The soil erosion rate,percentage of soil erosion area(PSEA,which is the ratio of the area where the soil erosion rate is greater than the soil loss tolerance(t)to the area of the total study region)and its spatial distribution were compared between the two approaches.The results showed that the grid approach overestimated the average soil erosion rate and PSEA overall for all 33 sample units and the whole region in comparison to the sampling approach.The sampling approach can yield a reasonable spatial distribution of the soil erosion rate in the whole region.In addition,the soil erosion regions were more clustered than those using the grid approach,which can be more suitable for soil conservation planning.Therefore,the sampling approach is an efficient and practical approach in regional soil erosion surveys.The results can provide insights into regional soil erosion surveys.

侵蚀地形对马尾松林下土壤特性的影响

土壤是植被生长的重要物质基础,其分布和发育受土壤侵蚀的影响。红壤丘陵区马尾松林下土壤侵蚀严重,生态环境脆弱,探清该区马尾松林下土壤侵蚀对土壤分布及其特性的影响,对该地区的植被重建和生态恢复具有重要意义。基于调查取样和分析测试获取的数据,采用统计和灰色关联度分析法分析侵蚀地形对红壤丘陵区马尾松林下土壤特性的影响。结果表明:不同侵蚀地形的土壤特性差异显著,相对于山脊坡和鞍部坡,切沟土壤理化性质的大部分指标含量最高,微生物数量最多,土壤酶活性最大;不同侵蚀地形的土壤特性指标间的相关性差异较大,与山脊坡和鞍部坡相比,切沟的土壤理化性质指标与土壤酶及微生物指标的显著正相关明显增多,土壤特性与切沟的关联度也最高;切沟形成的微环境提升了土壤特性,为植被恢复提供了有利的条件。因此,加大侵蚀沟的环境研究可为快速恢复该地区的土壤与植被提供科学依据。

决定区域成矿特点的因素浅析

决定大区域成矿类型的究竟是什么，是否是岩浆岩的时代和成分、含矿岩基侵蚀断面的深度、沉积岩的成分和分散在其中的金属受到岩浆的同化作用？根据近年来最新研究资料，对这些问题作了否定回答，并提出了决定区域成矿特性的一系列因素。

京、津、唐地区沙漠化灾害及发展趋势

京、津、唐地区的沙漠化问题作为一种鲜为人知的地质灾害正在区内某些地段发展和蔓延.沙漠化土地主要分布在永定河和滦河冲积扇区,潮白河故道区亦有零星分布.沙漠化在本区是近期出现的现象,是人为过度经济活动造成生态环境质量退化的结果.

黄土高原沟蚀区地表蚕食度空间分布特征和影响因素研究

In China’s Loess Plateau severe gully erosion(LPGE)region,the shoulder-line is the most intuitive and unique manifestation of the loess landform,which divides a landform into positive and negative terrains(PNTs).The spatial combination model of PNTs is of great significance for revealing the evolution of the loess landform.This study modeled and proposed the Surface Nibble Degree(SND),which is a new index that reflects the comparison of the areas of PNTs.Based on 5 m DEMs and matched high-resolution remote sensing images,the PNTs of 164 complete watersheds in the LPGE were extracted accurately,and the SND index was calculated.The spatial distribution trend of SND was discussed,and the relationship between SND and the factors that affect the evolution mechanism of regional landform was explored further.Results show that:(1)The SND can be calculated formally.It can quantify the development of the loess landform well.(2)The SND of the LPGE has evident spatial differentiation that increases from southwest to northeast.High values appear in Shenmu of Shaanxi,Shilou of Shanxi,and northern Yanhe River,whereas the low values are mainly distributed in the southern loess tableland and the inclined elongated ridge area of Pingliang in Gansu and Guyuan in Ningxia.(3)In the Wuding River and Yanhe River,the SND decreases with the increase in flow length(FL).In the North-Luohe River and Jinghe River,the SND increases with FL.(4)SND is significantly correlated with gully density and sediment modulus and moderately correlated with hypsometric integral.As for the mechanism factors analysis,the relationship between loess thickness and SND is not obvious,but SND increased first and then decreased with the increase of precipitation and vegetation in each geographical division,and we found that the land use type of low coverage grassland has greater erosion potential.