Identifying the spatiotemporal characteristics of individual red bed landslides: a case study in Western Yunnan, China

Strata in red bed areas have typical characteristics of soft-hard interbedding and high sensitivity to water. Under the comprehensive action of internal stratigraphic structure and external hydrological factors, red bed landslides have highly complex spatiotemporal characteristics, presenting significant challenges to the prevention and control of landslide disasters in red bed areas, especially for slope and tunnel engineering projects. In this study, we applied an interdisciplinary approach combining small baseline subset interferometric synthetic aperture radar(SBAS-InSAR), deep displacement monitoring, and engineering geological surveying to identify the deformation mechanisms and spatiotemporal characteristics of the Abi landslide, an individual landslide that occurred in the red bed area of Western Yunnan, China. Surface deformation time series indicated that a basic deformation range developed by March 2020. Based on In SAR results and engineering geological analysis, the landslide surface could be divided into three zones: an upper sliding zone(US), a lower uplifted zone(LU), and a toe zone(Toe). LU was affected by the structure of the sliding bed with variable inclination. Using deep displacement curves combined with the geological profile, a set of sliding surfaces were identified between different lithology. The groundwater level standardization index(GLSI) and deformation normalization index(DNI) showed different quadratic relationships between US and LU. Verification using the Pearson correlation analysis shows that the correlation coefficients between model calculated results and measured data are 0.7933 and 0.7577, respectively, indicating that the DNI-GLSI models are applicable. A fast and short-lived deformation sub stage(ID-Fast) in the initial deformation stage was observed, and ID-Fast was driven by concentrated rainfall.

Spectral Reflectance Characteristics of Different Snow and Snow-Covered Land Surface Objects and Mixed Spectrum Fitting

The field spectroradiometer was used to measure spectra of different snow and snow-covered land surface objects in Beijing area.The result showed that for a pure snow spectrum,the snow reflectance peaks appeared from visible to 800 nm band locations;there was an obvious absorption valley of snow spectrum near 1 030 nm wavelength.Compared with fresh snow,the reflection peaks of the old snow and melting snow showed different degrees of decline in the ranges of 300～1 300,1 700～1 800 and 2 200～2 300 nm,the lowest was from the compacted snow and frozen ice.For the vegetation and snow mixed spectral characteristics,it was indicated that the spectral reflectance increased for the snow-covered land types(including pine leaf with snow and pine leaf on snow background), due to the influence of snow background in the range of 350～1 300 nm.However, the spectrum reflectance of mixed pixel remained a vegetation spectral characteristic.In the end,based on the spectrum analysis of snow,vegetation,and mixed snow/vegetation pixels,the mixed spectral fitting equations were established,and the results showed that there was good correlation between spectral curves by simulation fitting and observed ones(correlation coefficient R2=0.950 9).

THE ENVIRONMENTAL CHARACTERISTICS OF FOREST LAND AND THE TECHNIQUES OF REFORESTATION IN FIRED LAND IN DAXING'AN MOUNTAINS

Analysis of nature environmental condition and evalwtion of selection and integration ofteclmiques have been carried out in Daxing’an mountains from 1987. The character of soil generaion in this area is influenced by the frigid, coniferous forest vegetation, weather, glacier and late soil formation process. Syntliesis teclmiques for high yield plantation include high seedling quality,suitable site preparation and eftbctive protectioll measures for yoimg trees.

Soil Moisture Characteristics in Karst Area with Different Land Use Types

Ecological efficiency changes of soil moisture were researched in karst areas with different land type uses, including farmland, abandoned farmland （1 y） and shrub land （1 y）, sparse wood land （15 y）, secondary forest （25 y） and the re- sults showed that physical property of soil was not a simple ＂improvement＂ process during land type evolution. Specifically, from farmland to secondary forest, the con- tent of topsoils changed from being washed away to accumulation and soil bulk density changed from increasing to decreasing. For example, soil bulk densities of abandoned farmland and shrub land increased by 6.6% and 11.57% compared with farmland, and of sparse wood land and forest land decreased by 5.0% and 10.0%. The change trend of soil bulk density was just in contrary to total porosity. Available water capacity was the lowest of shrub land, but increased in rest land types. The increase tended to be volatile in 5.1%-12.5% of different land types and water-sta- ble aggregate content （〉0.25 mm） reached the highest of sparse wood land. The destruction rate, however, was declining in the process of land type evolution and the increase was in the range of 34.0%-64.7% compared with farmland. The de- struction rate of aggregate was of negative correlation with organic matter. Water- holding capacity was the best of forest land and abandoned farmland and the poor- est of shrub land, close to sparse wood land. Water-supplying capacity from high to low was as follows： farmland〉sparse wood land〉secondary forest〉shrub land〉a- bandoned farmland. It is obvious that water-holding capacity and water-supplying capacity are not consistent, but both are closely related to the content of soil clays, porosity, and aggregate stability.

Studies of Soil Physical Properties and Community Characteristics of Different Abandoned Lands in the Minqin Oasis,Downstream of the Shiyang River

[Objective] The aim was to explore physical properties and community characteristics of abandoned lands in different years in Minqin Oasis, downstream of the Shiyang River, [Method] The evolution of environment and plant community characteristics in different abandoned lands were analyzed after abandonment for 1, 2, 3, 4, 5, 8, 15, 24 and 31 years, and the plant community characteristics, water content, bulk density, porosity and mechanical composition of soil in the different a- bandoned lands were also researched in the Minqin Oasis, downstream of the Shiyang River. [Result] Plant of 32 species spread over 14 family live through fifty years appeared in abandoned lands in the study area. Shrubs was 6 species, herbs was 26 species among them, which were 18.75%, 81.25% respectively. The goose- foot family （6 species）, the composite family（4 species）,the grass family（4 species）, caltrop family（3 species） were 53.13% among them. Within the range of 0-40 cm of different abandoned Land, the soil moisture content showed a trend of first increase and then decrease with the increase of soil depth changes in soil bulk density and porosity of less obvious. In the range of 0-40 cm soil depth, the largest proportion of fine sand, followed by silt and clay and the smallest proportion of coarse sand in every plot, but the proportion of the each silt size varies little with the years aban- doned. [Conclusion] The research provides references for vegetation reconstruction and eco-environment construction in abandoned lands in downstream of Shiyang River.

Analyzing land use characteristics of rural settlements on the urban fringe of Liangjiang New Area, Chongqing, China

The objective of this paper is to analyze land use characteristics of rural settlements in urban fringe so as to provide references for optimizing the regional distribution of rural settlements, consolidating rural settlements, and coordinating urban-rural integrated development. The methods of spatial statistical analysis, buffer analysis, Ripley's K function, kernel density analysis based on GIS(Geographic Information System) were used to analyze the characteristics of scale, spatial differentiation and spatial patterns of the rural settlements in Liangjiang New Area in Chongqing Municipality of China. The fractal dimension formula was also developed to reflect fractal feature of the rural settlements. The results show that, the scale of rural settlements in Liangjang New Area takes on distinct characteristics of spatial differentiation along with changes in elevation, gradient, location, geohazards distribution, and the like. The fractal characteristic of rural settlements has obvious regional variations subject to the 6 factors of location in the Liangjiang New Area. Overall, the worse the terrain conditions are, the larger the fractal dimension values become. The better the locationconditions, the larger the fractal dimension values are. The spatial pattern in the township scale presents three kinds of distribution as being aggregated, uniform and random. In contract, the spatial pattern in the plaque scale displays a banding distribution from a general view with several aggregation zones centering on each town center. From the results, we can see that the characteristics of rural settlements in urban fringe are more complicated. For such kind of rural settlements in special regions, in the rural land consolidation more attention should be paid to improve the rural living environments and public services, as well as to promote the harmonious relationship between the urban and rural areas.

Characteristics and Process of Land Use Changes in the Yangtze River Delta, China

As one of the developing countries China has an arable land per capita far below the world’s average level. With a high-density population and the quick development of economy and urbanization, the Yangtze River Delta shows the typical characteristics of land use in developed regions of China, which are: high land reclamation rate and low arable land per capita; intensive land use and high output value; and rapid increasing of construction land area and fast diminishing of arable lands. The analysis indicates that the process of the arable land changes in the Yangtze River Delta could be divided into four different change stages over the past 50 years.

Do Land Characteristics Affect Farmers' Soil Fertility Management?

Soil fertility management （SFM） has important implications for sustaining agricultural development and food self-sufifciency. Better understanding the determinants of farmers’ SFM can be a great help to the adoption of effective SFM practices. Based on a dataset of 315 plots collected from a typical rice growing area of South China, this study applied statistical method and econometric models to examine the impacts of land characteristics on farmers’ SFM practices at plot scale. Main results showed that in general land characteristics affected SFM behaviors. Securer land tenure arrangements facilitated effective practices of SFM through more diversiifed and more soil-friendly cropping pattern choices. Plot size signiifcantly reduced the intensities of phosphorus and potassium fertilizer application. Given other factors, 1 ha increase in plot size might reduce 3.0 kg ha-1 P2O5 and 1.8 kg ha-1 K2O. Plots far from the homestead were paid less attention in terms of both chemical fertilizers and manure applications. Besides, plots with better quality were put more efforts on management by applying more nitrogen and manure, and by planting green manure crops. Signiifcant differences existed in SFM practices between the surveyed villages with different socio-economic conditions. The ifndings are expected to provide important references to the policy-making incentive for improving soil quality and crop productivity.

Characteristics of deep drainage and soil water in the mobile sandy lands of Inner Mongolia, northern China

Quantification of deep drainage and the response of soil water content to rainfall patterns are critical for an effective management strategy of soil water conservation and groundwater utilization. However, there has been little information on how rainfall characteristics influence soil water dynamics and deep drainage in mobile sandy lands. We used an underground chamber to examine the responses of deep drainage and soil water content in mobile sandy lands to rainfall characteristics in Inner Mongolia during the growing seasons of 2010, 2011 and 2012. Results showed that rainfall in this area was dominated by small events （〈5 mm）, which increased soil water con- tent in the surface soil layers （0-40 cm）, but did not increase soil water content in the deeper soil layers （greater than 40 cm）. Soil water content at the 0-100 cm depth increased significantly when the total amount of rain was 〉20 mm. Rainfall amount, intensity and the duration of dry intervals were significantly related to the soil water content in different soil layers. Deep drainage was significantly correlated with rainfall amount and intensity, but not with the duration of dry intervals. The coefficients of deep drainage in the mobile sandy lands ranged from 61.30% to 67.94% during the growing seasons. Our results suggested that rainfall infiltration in the mobile sandy lands had considerable potential to increase soil water storage while recharging the groundwater in this region.

ANALYSIS OF THE CLIMATIC CHARACTERISTICS OF LANDING TROPICAL CYCLONES IN EAST CHINA

The intensity, landing time, track trend and intensity variation of tropical cyclones (TCs) afterlandfall are analyzed using the TCs data (of best track from the China Meteorological Administration)between 1949 and 2006 for the western North Pacific and South China Sea. The trend differences of trackand intensity between the TCs that directly land in East China and those making the second landfall in EastChina after landing in Taiwan Island are categorically discussed. The results show that the first kind oflanding TCs are more likely to go northward or turn while the second kind of TCs have a larger tendency tokeep going northwest. The intensity of the first kind of TCs is more persistent than the second one. There isa higher percentage for the intensity to be weakened significantly if the TCs keep going west to northwest orsouthwest after landing.

Material Composition and Engineering Characteristics of Red Clay in Guigang, Guangxi

There is fine and uniform clay with aluminous and ferrous cementation in the red clay found in Guigang, Guangxi. It has the characteristics of shrinkage outwardly, rigid upper but soft lower and well grown fissure. In addition there are engineering characteristics such as high water content, low compactness and low compressibility, high strength and high contractility but slight expansibility. This paper discusses the red clay's engineering characteristics and its change regulation with depth by analyzing changes in the red clay's grain size composition, mineralogical constitution, and chemical composition.

Soil-water characteristics and shear strength in constant water content triaxial tests on Yunnan red clay

The shear strength parameters for geotechnical designs are obtained mainly from consolidated drained （CD） or consolidated undrained （CU） triaxial tests. However, during construction, the excess pore-air pressure generally dissipates instantaneously while the excess pore-water pressure dissipates with time. This condition needs to be simulated in a constant water content （CW） triaxial test. The study on Yunnan red clay is carried out to investigate the soil-water characteristics and the shear strength characteristics under the constant water content condition. Osmotic technique is used to obtain the soil-water characteristic curve. A series of CW triaxial tests are conducted on statically compacted specimens. The experimental results show that the soil-water characteristic curve has a low air entry value of 7 kPa due to large pores in non-uniform pore size distribution, and a high residual value exceeding 10 MPa. In addition, the initial degree of saturation and net confining stress play an important role in affecting the shear characteristics under the constant water content condition. Finally, a new semi-empirical shear strength model in terms of degree of saturation is proposed and then applied to Yuunan red clay. Simulation result shows that the model is capable of capturing some key features of soils. The model can be used in whole engineering practice range, covering both unsaturmed and saturated soils.

Simulation analysis on characteristics of land surface over western Qinghai-Xizang Plateau during freez-ing-thawing period

Using the Global Energy and Water Cycle Experiment-Asian Monsoon-Tibet Plateau Experiment (GAME-Tibet) observa-tional data-from October 2002 through September 2003-of Gaize in the western Qinghai-Xizang Plateau (QXP),the land-surface characteristics of the Qinghai-Xizang Plateau are simulated by the improved land-surface model Common Land Model (CoLM).The results show that CoLM can reproduce the land-surface characteristics of plateau areas well.In the sur-face-energy balance of the western QXP in the winter half year,the sensible heat (SH) flux constituted the dominant energy,and the latent heat (LH,here and after) flux is very small.Although the LH flux nearly equals zero in freezing season,it cannot be ig-nored during the period of freezing-thawing in QXP.In the transition season from midto late-May,the frequent phase change of soil water that is caused by the freezing-thawing process leads to the increase of LH flux and decrease of the Bowen ratio.The simulation results also indicate that the changes of surface effective heat fluxes (SH and LH flux) are associated with precipitation and the frequent change between freezing and thawing processes in soil surface.

Multifractal characteristics and spatial variability of soil particle-size distribution in different land use patterns in a small catchment of the Three Gorges Reservoir Region,China

Characterizing soil particle-size distribution is a key measure towards soil property.The purpose of this study was to evaluate the multifractal characteristics of soil particle-size distribution among different land-use from a purple soil catchment and to generalize the spatial variation trend of multifractal parameters across the catchment.A total of 84 soil samples were collected from four kinds of land use patterns(dry land,orchard,paddy,and forest)in an agricultural catchment in the Three Gorges Reservoir Region,China.The multifractal analysis method was applied to quantitatively characterize the soil particle size distribution.Six soil particle size distribution(PSD)multifractal parameters(D(0),D(1),D(2),(35)a(q),(35)f[a(q)],α(0))were computed.Additionally,a geostatistical analysis was employed to reveal the spatial differentiation and map the spatial distribution of these parameters.Evident multifractal characteristics were found.The trend of generalized dimension spectrum of four land use patterns was basically consistent with the range of 0.8 to 2.0.However,orchard showed the largest monotonic decline,while the forest demonstrated the smallest decrease.D(0)of the four land use patterns were ranked as:dry land<orchard<forest<paddy,the order of D(1)was:dry land<paddy<orchard<forest,D(2)presented a rand-size relationship as dry land<forest<paddy<orchard.Furthermore,all land-use patterns presented asΔf[α(q)]<0.The rand-size relationship ofα(0)was same as D(0).The best-fitting model for D(0),D(1),D(2)andΔf[α(q)]was spherical model,forΔα(q)was gaussian model,and forα(0)was exponential model with structure variance ratio was 1.03%,49.83%,0.84%,1.48%,22.20%and 10.60%,respectively.The results showed that soil particles of each land use pattern were distributed unevenly.The multifractal parameters under different land use have significant differences,except forΔα(q).Differences in the composition of soil particles lead to differences in the multifractal properties even though they belong to the same soil texture.Farming behavior may refine particles and enhance the heterogeneity of soil particle distribution.Our results provide an effective reference for quantifying the impact of human activities on soil system in the Three Gorges Reservoir region.

DYNAMIC CHARACTERISTICS OF PRESENT PRODUCTIVITY FOR CULTIVATED LAND IN THE FARNMING-PASTORAL ZONE OF INNER MONGOLIA

In this article, the distribution of cultivated land, the changes ofcultivated land productivity, and regional differentiation of the Change forpresent productivity in the Farming-Pastoral Zone, Inner Mongolia arediscussed. Then, the close relationship between dynamic characterlsticsdivision and atmospheric circulation systems is revealed. Finally, based ondynamic characteristics, four regions are divided, including thenortheastem area, the eastern area, the western area, and the middle area.

Particle Size Characteristics of Soil in Karst Area with Different Land Use Pattern—A Case Study of Shuifang Spring,Jinfo Mt.,Chongqing

This paper tried to analyze the particle size characteristics of the soil samples in Shuifang Spring catchment area,Jinfo Mt.,Chongqing with different land use patterns that are horse race grassland, rhododendron bush,bamboos,and the grassland near the Shuifang spring.The different land usepattern in karst area is of great affection to the particle size characteristics of soil.The median diameter of the karst surface layer soil becomes gradually smaller and smaller in following sequence:horse race grassland,grassland near the Shuifang Spring,

Analysis of the Sedimentary Characteristics and Origin of the “Old Red Sands ”in the Coastal Areas of Southeast Fujian

The "Old Red Sands" are widely distributed and typically developed over the coastal areas of Southeast Fujian, but there are different views on their origin. Based on the overall field investigations and a series of lab studies, the paper suggests that the "Old Red Sands" are mainly formed by the beach wind-drift sands and ,locally, by slope wash and alluviation.

Different Characteristics of Peasant Issues from the Connections between Peasants and Land

The paper analyzes the different characteristics of peasant issues formed by connections between peasants and land at different historical stages,and offers a reference for us to look squarely at peasant issues in the reality.The characteristics of peasant issues with land as the inherent feature are:the degree of connection decides the classification and policies of peasants;the private ownership of land decides the political status and influences of peasants;the inherence of private connections with land determines the future of peasants.The characteristics of peasant issues with land as the core value are:the peasant issues with land as the core is the key to victory of new-democratic revolution;the peasant issues with land as the core is the basis of establishment of socialist system;the characteristics of peasant issues with land as the guarantee are:carriers of peasants interests change from unicity to diversity;peasants change from identity certification to vocational certification;the economic influence of peasants changes and penetrates from part to entirety.

Temporal-spatial Characteristics of the Urbanization of Rural Land in Xinjiang

Relying on remote sensor technology, GIS and Land--sat TM digital images,the authors use spatial and statistical analysis to examine the temporal-spatial characteristics of the change caused by urban construction in Xinjiang’s rural areas from the end of the 1980s to the end of the 1990s. The primary findings show the following: 1) The urban construction in rural areas has increased drastically. The expansion speed of urban land use has accelerated over the past decade. The sub-land use changes caused by the urbanization of rural are characterized by salient regional differentiation among the three main regions and among the 85 counties of Xinjiang. 2) The shift of land use is mostly characterized by cultivated land and grassland being used for urban and industrial projects. Moreover, this change of land use is characteristic of regional differences. 3) Factors of rural-urban construction land use changes in Xinjiang, are undoubtedly affected by natural environment, social, economic conditions, and to a larger degree by population growth, GDP development and industrial development..

The Epidemic Characteristics and Control Strategies of Sugarcane Red Rot

Sugarcane red rot caused by Colletotrichum falcatum Went. is an important epidemical fungal disease. The outbreak of large-scale epidemics would cause huge losses to sugarcane production. At present,the pesticide control effect is not ideal. Moreover,due to long-term continuous cropping and changeable climate in recent years,favorable conditions for the occurrence of red rot have been created. The disease was often prevalent in various sugarcane areas,caused serious damage and seriously affected the sugarcane production. With the rapid spread of the disease worldwide,the control of sugarcane red rot has become the hot spot in the field of sugarcane production and research. In this paper,the epidemic characteristics of sugarcane red rot were analyzed in combination with the field investigation. To provide theoretical basis for prevention and control of red rot in China and effective control the widespread occurrence of the disease,combined with the latest research results at home and abroad,we proposed to select resistant varieties mainly,use biological control agents such as Trichoderma spp.,Pseudomonas spp.and Bacillus spp. to treat the seed cane and soil,timely apply chemical pesticide in critical periods and strengthen scientific and effective comprehensive coordinated prevention and control measures such as field management against red rot.