Showing papers in "Research of Soil and Water Conservation in 2012"

Analysis on Land Use Dynamic Change and Its Impact on the Water Environment in Dianchi Lake Drainage Area

Abstract: The study area was divided into 5 big categories according to Class One Classification: arable land,woodland,construction land,water body and other land typeThe Edras remote sensing image processing software and the ArcGIS geographic information system software were used to calibrate,match and enhance the Landsat-5(TM) remote sensing satellite images of four periods of 1974,1988,1998 and 2008The resolution of Landsat-5(TM) original data is 30 mThrough the GPS field investigation,the visual interpretation of remote sensing image was obtained and the images of each period were interpreted with human computer interactive interpretation technology to generate the distribution situation of land use at four time pointsThe ArcMAP module in the ArcGIS was used to conduct a map overlapping analysis,the transition matrix of land use spatial dynamic change was established according to Markov model and 2 indices of land use area variation rate and land use dynamic state were used to quantitatively analyze the land use structural change in the study area,in which the unit root test and cointegration test were adopted to analyze the simulation of land use and water environment change in the drainage areaOn the basis before that,Markov forecast model was used and both the land use results in the later period and the effect on the water environment were forecast with the Matlab softwareThe results showed that: ① the land use situation in the Dianchi Lake basin in the past 30 years had significantly changed,in which the changes of the arable land,construction land and other similar changes were extremely great,while the changes of the water body and forestland were not so obvious;② the results of Markov model forecast showed that the land for construction in the study area further increases through 2015 to 2030,while the woodland,water body and other types of land further decreases,but the rate of decrease is gradually becoming smaller and the cultivated land area continues to decrease as well;③the correlativity existing between TP and BOD under 5% significant level and COD under 20% significant level can be obtained;④the indices of water pollution have a tendency of continuous deterioration over the years

Review and Prospect of Freeze-thaw-induced Erosion Research

Abstract: Main advances at home and abroad in the field of freeze-thaw-induced erosion are reviewed.The notion of freeze-thaw-indued erosion is firstly discussed and clarified.Then some research results such as the cause,type,intensity classification,erosion rate,main influence factors,erosion prediction and prevention and control of freeze-thaw erosion are presented and analyzed.The problems and shortcomings of current freeze-thaw-induced erosion research are pointed out.Research directions and key issues of freeze-thaw-induced erosion in a certain period of the future are finally put forward in terms of the real research situations of freeze-thaw-induced erosion in China.

Study on Soil and Water Loss in Karst Forest in Mulun

Abstract: Forest soil erosion is an important indicator for evaluating ecological benefits of forest hydrology.The comparison of soil and water losses between the karst forest and shrub—grass vegetation was carried out in Mulun National Nature Reserve from 2006 to 2010 through the slope surface runoff plots.The results showed that:(1) the average surface runoff in Karst forest was 1.77 mm/a(0.78~2.85 mm/a),which occupied 0.10% of the local average annual rainfall and reduced 69.8% compared with the shrub—grass slope(5.87 mm);(2) the average soil erosion in Karst forest was 17.7 kg/(hm2·a),9.9~28.5 kg/(hm2·a),decreasing 69.8% compared with shrub—grass soil erosion(58.7 kg/hm2·a);(3) the average total nutrient loss(N,P,K) in Karst forest was 0.019 kg/(hm2·a),reducing 70.3% compared with the shrub—grass(0.064 kg/hm2·a);(4) soil and water loss and nutrient loss mostly concentrated from May to August,accounting for 76.3%,92.7% of the total annual loss,which matched the rainfall pattern in the same area.

Land Use Change and Its Driving Force Analysis in the Central Area of Chongqing City from 1986 to 2007

Abstract: Using the case study of central area in Chongqing City,based on the Landsat TM images 1986,2000 and 2007 for central area in Chongqing City,as well as actual land use maps and socioeconomic and demographic data,we analyzed the dynamic changes of urban land use/land cover as well as driving factors in the central area of Chongqing from 1986 to 2007.The present land use situation,the dynamic degree of land use and a land use conversion matrix were introduced to describe the temporal and spatial variation of urban land use.The results show that there were major changes in the land use structure in the study area from 1986 to 2007.The areas of shrub land and construction land had a net increase,while the cropland use types presented a net decrease,and the forestland decreased first and then increased.The major patterns of 1and use change were the conversions of the cropland to construction land and forestland,and in particular to urban construction areas.The land use comprehensive indices were 279.3 in 1986,281.4 in 2000 and 282.3 in 2007,respectively,and the dynamic degrees of all land uses,especially,the shrub land and construction land changed a lot during the 21 years.The reasons for change and mechanism of land use include development of economy and population,landscape,industrialization policy of politics and economy.The development of economy is the main driving force,the state macroscopic policies play an important role in the structural changes of land use in this region,too.

SWAT Model of Runoff Study under Different Land Use Land Cover Scenarios in Source Region of the Yangtze River

Abstract: Land use and land cover change play an important role in catchment hydrology cycle.In order to analyze the hydrology effect caused by land use and land cover change,runoff and depth of runoff in the source region of the Yangtze River basin was estimated based on land use and land cover scenarios and SWAT model.The result showed: runoff decreased 16.7% with 304.12 m3/s and depth of runoff decreased 14.02 mm under the situation of forest and grass land covering whole area of the basin;runoff increased 16.1% with 424.32 m3/s and depth of runoff increased 13.49 mm when the forest and grass land area changed into sand and bare land;runoff and depth of runoff increased most when there were no forest and grass land,the runoff reached to 469.67 m3/s,increased 28.4%,depth of runoff increased 23.88 mm;there was a little increase of forest and grass land growing perfectly,runoff and depth of runoff increased 5.6% and 4.72 mm.It is obvious that increase of forestland and grassland made the runoff decrease and the increase of sand and bare land led to rise of runoff.

Trend Analysis of Precipitation and Its Erosivity over Last 53 Years Based on the Daily Rainfall in Changwu County

Abstract: The daily observation data from 1957 to 2009 were used to systematically analyze the trend of precipitation,erosive precipitation and the precipitation erosivity in Changwu County.The results showed that:(1) the mean annual precipitation was 577.8 mm and the erosive precipitation was 340.7 mm,and for precipitation erosivity 1 691.2(MJ·mm)/(hm·h).Their coefficients of variations were 22.5%,34.4%,43.2% respectively.And the proportion of 76.1%,83.4% and 85.8% concentrated in summer and autumn,53.2%,65.5% and 70.1% focused on the period from July to September;(2) over the last 53 years,precipitation and erosive precipitation were detected with an insignificant negative trend and for precipitation erosivity,it was slightly positive trend,the seasonal change patterns among the three elements were similar,for all three elements,there were slightly positive trend both in summer and winter and slightly negative trend both in autumn and spring,for April it was significant negative trend and positive trend for June;(3) the trends of precipitation,erosive precipitation and precipitation erosivity were equally influenced greatly by the change of summer and autumn especially in summer,in monthly scale,by the changes from July to September especially in August.The impact,whatever from two seasons or three months,was intensified gradually among three elements.The results indicated that the changes of three elements differentiated but showed great same phase over the last 53 years.

Land Eco-sensitivity Assessment Based on LUCC in Ecological City

Abstract: Land eco-sensitivity assessment is an important method in analyzing regional Eco-environmental safety.This article is based on the studies of land use and coverage change with the interpretation result from Landsat images.It analyzes the land use degree of Shangluo City and gave the land eco-sensitivity classification,which included soil and water conservation,disaster prevention and ecological protection.Then an improved classification model was taken through the gray model and the variation coefficient.By contrasting sensitivity in each level of land use degree change,the ecological recovery mode in study area was analyzed.The results showed: the land use degree in Shangluo City has been declined from 1990 to 2009,large area converted form cropland to forest which gave a better environment;the sensitivities of partition based on the index level showed the middle sensitive area was the largest.According to the variation coefficient gave the more reasonable proportion,the partition was improved based on uncertainties.Because of the least amount of land use degradation area was taken in high sensitive region,it was considered that the ecological construction model in study area was still worth discussing.

Study on Winter Wheat Canopy Interception Process of Rainfall and Simulation

Abstract: The effective utilization of rainfall by winter wheat was directly influenced by canopy interception.Influences of rainfall and rainfall intensity on characteristics of canopy interception of winter wheat were studied by simulative rainfall experiment and statistical analysis,and a canopy interception model suitable for winter wheat was established.The results showed that throughfall was significantly positively related with rainfall(P0.01),while relationships between canopy interception and rainfall significantly showed a power function(P0.01).A negative exponential correlation between rainfall intensity and percentage of throughfall(P0.01) and a negative power correlation between rainfall intensity and percentage of interception(P0.01) were found.The trend of canopy interception of winter wheat was consistent under different rainfall intensities,while the duration to reach the canopy interception capacity was longer with lower rainfall intensity.Rainfall intensity had no significant influence on canopy interception capacity of winter wheat.Interception decreased with the increase of rainfall intensity,indicating a negative relation with rainfall intensity at the constant rainfall conditions.Canopy interception capacity of winter wheat showed a positive correlation with LAI(P0.01).A mechanism model for rainfall interception process of the winter wheat was developed,and the model parameters were fitted based on the measured data both from the natural rainfall experiment and simulated rainfall experiments.A parameter,α,indicating evaporative capacity of rainfall intercepted by winter wheat canopy,was set to 0.008.Simulated values were consistent with measured ones,indicating that the improved model can be used for estimating rainfall interception of winter wheat canopy.

Effects of Drought and Re-watering on Photosynthetic Characteristics of Maize Leaf

Abstract: In this study,Maize(Zea mays L) cross seeds(cvHudan4) were grown in potsAnd three water treatments: normal water supply(CK),moderate water stress(MS) and severe water stress(SS) were designed to investigate the effects of water stress and re-watering on photosynthesis and chlorophyll fluorescence of maize leaf at elongation stage and booting stage,in order to provide theoretical basis for the explanation of compensation mechanism of maizeThe results showed:(1) leaf water potential(ψleaf) reduced under drought stress,and leaf water potential of severe stress at elongation stage could recover rapidly and exceeded the control after re-watering,but the booting stage was slow;(2) severe stress at elongation stage and booting stage reduced the leaf net photosynthetic rate(Pn),stomatal conductance(Gs),the intercellular CO2 concentration(Ci),maximal efficiency of PSⅡ(Fv/Fm) and photochemical quenching coefficient(qP),but after five days of re-watering,these parameters can be recovered to control;the Ci was lowest,compared with control,stomatal limation value(Ls) increased by 685%,952%,Fv/Fm reduced 172% and 061%,which indicated stomatal limitation was the major factor to the reduction of Pn;(3) under the severe stress at elongation stage,the water use efficiency of leaf(WUE)was higher than the control,which showed the compensation effect;under drought stress at booting stage,the WUE showed that MS CKSSAfter the first day of re-watering,the WUE were at peaks,then tended to declineThese results suggested that there would be different responses of photosynthetic characteristic between elongation stage and booting stage

M-DEM-based Stream Fractal Dimension of Artificial Backhoe Cultivated Loess Slope

Abstract: This paper aims to explore a way to illustrate the stream network forming process with its fractal geometry characteristic of micro-topography in the micro scale,and provide the scientific basis for further research about slope surface water erosion process and prevention.In this paper,4 M-DEMs for artificial backhoe cultivated loess slope with the slope gradient of 15° and the rainfall intensity of 90 mm/h were built during the evolution of soil erosion from before rainfall(BR)→splash erosion(SpE)→ sheet erosion(ShE)→ rill erosion(RE) based on laboratory experiment.Then stream networks for different catchments thresholds were extracted with the support of ArcGIS 9.3 soft package.Correspondingly,fractal dimensions were calculated based on the grid method.The results showed that:(1) fractal theory could be safely adopted to the study of river network with its forming process of micro-topography;(2) the optimal catchments thresholds of each rainfall stage were 15,20,25,30 cm2,and the optimal fractal dimensions were 1.067,1.088,1.068 and 1.079,respectively;(3) Artificial backhoe slope erosion was still in the primary stage.In general,a methodology on a micro-topographic stream with its fractal dimension is illustrated,and it should be safe to be adopted for further research for surface micro-topographic.

Research Progress of River Ecological Restoration

Abstract: The ecological restoration of river ecosystem has become a research hotspot because the river ecosystems were generally severely damaged.On the basis of broad access to the information of the domestic and international ecological restoration,the influence factors of river ecological system have been analyzed,which were hydrological conditions,watershed climate,river geomorphology,hydraulic characteristics of rivers and water quality.The stress of the river ecosystem which was forced by human activities in the traditional water conservancy project,pollutant emissions,excessive diversion of water project and fishing activities aslo was analyzed.On the basis of a clear river ecosystem repair concepts and tasks,several theoretical studies on river restoration have been analyzed and summarized,which were river health,river ecological water demand,scale and river restoration mechanism,and the model of river restoration.In addition,the principles of river restoration and several important technical issues of ecological restoration have been analyzed and evaluated in this paper.Finally,several issues were proposes which should be particular concerned in the research and construction of China′s ecological restoration and development proposals.

Effects of Land Uses on Soil Physical and Chemical Properties in Hilly Areas of Wuling Mountain

Abstract: To study effects of land uses on soil physical and chemical properties,soil samples collected from different land uses(cropland,orchard,woodland,unused land,intercropping land) of the hilly areas of Wuling Mountain were analyzed,which provided a scientific basis of land using and the conservation of soil and water.The result showed that the soil physical and chemical properties were significantly affected by land uses,the contents of organic carbon,total nitrogen,available nitrogen and available potassium of woodland were the highest,but the soil moisture in this land was the lowest;the contents of organic carbon,total nitrogen,available nitrogen of intercropping land were the lowest;the contents of soil moisture and bulk density of unused land were the highest,but the contents of available phosphorus and available potassium were the lowest,and other nutrients were on the low level.The soil nutrients of the five land uses decreased with the increase of depth of soil layer.The reduction of soil organic carbon of all the five land uses was similar,but the reduction of the other nutrients was different among the land uses.Based on the classification standard of soil nutrients in the second soil investigation of China,the contents of soil available phosphorus and available potassium kept mid-high level,the contents of soil total nitrogen and organic carbon kept deficient status,and the soil nutrients of woodland were abundant.

Spatiotemporal Distribution of Drought and Flood Disasters over the Last 50 Years of Liaoning Province

Abstract: Based on the daily precipitation data from 1960 to 2009 of 49 stations in Liaoning Province,temporal trend and spatial distribution of annual and seasonal drought and flood disasters were discussed according to the drought and flood region index which is defined by the grade division of Z-index of single station.The results show that annual drought,summer drought and autumn drought index have increasing trend,and temporal trend of spring drought index is not obvious over the last 50 years.There are both decreasing trend of annual and summer flood index.The spatial distribution of either annual drought or seasonal drought shows that the highest frequency regions are in the west and northwest Liaoning Province.Annual drought,spring drought and summer drought have lower frequency in northeast Liaoning Province,and the lowest frequency regions of autumn drought are in the east and the southeast.The spatial distribution of annual flood and summer flood disaster is similar,the highest frequency regions are in the east and the southeast,and the lowest is in the west of Liaoning Province.There is some correlation between severity of drought and flood disasters and the concentration degree of precipitation.

Distribution Characteristics of Soil Particulate Organic Carbon and Mineral-associated Organic Carbon of Different Land Use in Karst Mountain

Abstract: The content and distribution characteristics of both soil particulate organic carbon(POC) and mineral-associated organic carbon(MOC) in the soil(0—40 cm) under different land use types were studied in Zhongliang knoll,Chongqing.The results revealed that:(1) the average content of the soil organic carbon(SOC) under different land use were woodlandvegetable landgrasslandgardenabandoned farmland;(2) the contents of soil fine particulate organic carbon(FPOC) were more than soil coarse particulate organic carbon(CPOC) in all land use except garden;(3) the contents of POC were different in the soil layer under different land use.Between 0—20 cm,the average contents of CPOC were gardengrasslandvegetablewoodlandabandoned farmland,and the contents were obviously different in each land with different use.The average contents of FPOC were woodlandgrasslandvegetable landgardenabandoned farmland.Between 20—40 cm,the highest content of CPOC and FPOC appeared in vegetable land,while the lowest occured in abandoned farmland,the distributions of the contends of MOC under different land use types were the same as SOC;(4) the component of soil organic carbon ratio was approximately expressed as: MOC/SOCCPOC/SOCFPOC/SOC except garden;(5) the correlation analysis shows that,under different land use types the SOC and POC were positively correlated,and correlation was not consistent,woodland and grassland correlated significantly(P0.01),abandoned farmland correlated significantly(P0.05),and vegetable and orchard land did not remarkably correlate.So,human interference and tillage would affect contribution POC′s in SOC pool.

Effect of Shelterbelts Distribution on Ephemeral Gully Erosion in the Rolling-hilly Black Soil Region of Northeast China

Abstract: The ephemeral gully erosion in cultivated slope lands in rolling-hilly black soil region of northeast China is very serious.As one of the most important parts of cultivated slope lands,the shelterbelt system would inevitably affect the process of ephemeral gully erosion.Based on the Quickbird high-precision remote sensing and digital elevation model,and combination with field survey results,the rules of shelterbelts distribution and ephemeral gully erosion in a small watershed of rolling-hilly black soil region in Heshan Farm of Heilongjiang Province were analyzed.The results showed that the critical slope length and catchment area for the ephemeral gully development in the region were positive linearly correlated with the number of shelterbelts in the catchment of the ephemeral gully,which means increase of the number of shelterbelts and decrease of the distance between the shelterbelts could increase the critical slope length and catchment area,then decrease the possibility of ephemeral gully erosion occurrence.The distance between the shelterbelts in the study area was too large to prevent the slope from ephemeral gully erosion,and the breaks of shelterbelts benefited the development of ephemeral gully.In addition,ridge culture was adopted in the region,the direction of furrows were affected by the shelterbelts,some of the furrows straight through low-lying water line,and some furrows along slope were formed,which induced the ephemeral gully erosion.Thus increase of the number of shelterbelts in the slope lands,decrease of the distance between shelterbelts,enhancing the management and update of shelterbelts,and adjusting unreasonable distribution of shelterbelts could be the way to prevent ephemeral gully erosion.

Forms and Pollution Assessment of Nitrogen in Surface Sediments of Changshou Lake

Abstract: In order to illuminate nutrient occurrence characteristics in surface sediments of Changshou Lake,sediments samples at 15 sampling sites were collected in April of 2009.Forms and pollution degree of nitrogen in the surface sediments of Changshou Lake were analyzed by chemical extraction in this paper.Results were as followed.(1) Content of total nitrogen(TN) ranged from 1 240.00 mg/kg to 5 110.00 mg/kg.The main form of total nitrogen(TN) was organic nitrogen(ON).Ammonium nitrogen(NH+4—N) was the dominant part of inorganic nitrogen(IN).(2) Coefficient of variation of every nitrogen forms ranged between 0.1 and 1.0,which belonged to moderate intensity of variation.(3) Current of water played an important role in the distribution and migration of nitrogen,the impact of aquaculture was not obvious.But the water degree had some influences on distribution of nitrogen.(4) The correlation analysis among different nitrogen forms suggested that the concentrations and distribution of total nitrogen(TN) were mainly controlled by organic nitrogen(ON),and inorganic nitrogen(IN) was affected by ammonium nitrogen(NH+4—N) almost.(5) The surface sediments showed moderate degree pollution,so local government should strengthen the monitoring and management of Changshou Lake urgently.

Study on Soil Environmental Quality Based on Fuzzy Comprehensive Evaluation——A Case Study of Liwu Copper Area in Jiulong County

Abstract: Copper mining in the Liwu has 30 years of history,which has a significant impact on the surrounding soil environment.Taking the soil of Liwu Copper as the study object,collecting and analyzing data,using the fuzzy comprehensive evaluation method to evaluate the soil environment quality,and carring out a study on the heavy metal content and spatial distribution in the soil of Liwu copper,based on soil quality standard and soil environment quality standard(1995) GB15618,we found that copper mining had an important impact on the soil environment quality.The whole soil environment quality is better,but it is worse in some palaces.The soil environment quality followed by the poor to good level is heap leaching soilheap leach soilsoil closed to copper outfallnative soilsoil of copper downstream near the river.The soil remediation and protection in the poor soil environment quality area are the key work in the future.

Research and Analysis on Large-scale Loess Landslides in Loess Tableland Area of Weibei

Abstract: On the basis of detailed investigation and geological survey on large landslide at the edge of loess tableland lying on the north of Weihe River in Baoji City,some conclusions could be drawn by discussing several factors including topography,lithology,geological structure,groundwater and human activities,etc.First of all,neotectonic movements create 100 m to 200 m high,25°to 45° steep and gibbous slopes on the edge of loess tableland which is an advantage topographic environment for landslide occurrence.Secondly,controlling factors of landslide in the area are special kinds of lithologic association,loess—terrain—red clay of Sanmen group and loess—Hipparion laterite—bedrock respectively involving soft intercalations which are Sanmen group red clay and Hipparion laterite,and anisotropy due to small-scale faults and joints in slopes.Thirdly,underground water and human activities are the main triggers to large loess landslides at present.Based on the obtained results,identification elements including topographic characteristics,failure modes and dynamic effect are determined.

Ecological Health Assessment of Shijiazhang Urban Ecosystem in Fasting Urbanizing City

Abstract: Urban ecosystem health assessment is the basis of making city planning,construction and management policy.According to the actual status of Shijiazhuang City,five indices were selected to build up an evaluation system,including dynamics,organizational structure,resilience,ecosystem service function and population health.Fuzzy mathematical models were employed to analyze and evaluate the healthy state of Shijiazhuang urban ecosystem from 2005 to 2009 based on the method of mean-squared deviation to determine index weight.Results showed that the healthy state of Shijiazhuang ecosystem was changed from sub-healthy level on 2005—2007 to healthy level on 2008—2009.The favorable factors affecting urban ecosystem healthy state of Shijiazhuang included organizational structure,resilience and ecosystem service function,while unfavorable factors included dynamics and population health.Main stress factors to healthy development were per capita water consumption,foreign capital actually utilized,10 thousands Yuan GDP energy consumptions,proportion of RD funding,proportion of environmental protection investment in GDP,per capita income and proportion of high-education people.Finally,some suggestions were proposed to improve urban ecosystem healthy level.

Comparison Study on Purification of Integrated Constructed Wetland in Living-water Garden between Spring and Summer

Abstract: Water samples were regularly taken at six locations of the Living-Water Garden in Chengdu from January to June 2011 in order to study seasonal efficiency of constructed wetland in wastewater treatment.Water samples were analyzed for total nitrogen(TN),ammonia nitrogen(NH3—N),total phosphorus(TP) and dissolved phosphorus(DP).Removal rates of TN,NH3—N,TP and DP were 45.5%,65.7%,77% and 72.6% in spring,and 56.9%,87.1%,76.9% and 73.7% in summer,respectively,nitrogen and phosphorus removal efficiency were 4% and 6% higher in the left zone than in the right zone of the parallel wetland plant pond-bed area,indicating a seasonal difference in removal efficiency of nitrogen and no difference in removal efficiency of phosphorus.

Runoff and Sediment Characteristics of Slope Land in Karst Areas of Guizhou Province

Abstract: Soil erosion and rocky desertification strongly affect local sustainable development in karst area.In order to prevent and control efficiently soil erosion in karst area of Guizhou Province,runoff and sediment characteristics of different types of slope land were studied by means of runoff plots observation.Five types of runoff plots were set including commercial forest(pear trees),water conservation forest(Cinnamomum camphora),water conservation forest(cypress),slope farmland(crops) and bare slope land.The results showed that when the slope gradient was 13°,the slope land covered with crops and pear trees were good in protecting soil erosion,which could reduce runoff by 47.5% and 25.8%,respectively,and sediment yield by 78.5% and 58.9%,respectively.The slope land covered with Cinnamomum camphora and cypress were not significant in runoff reduction,while they could reduce sediment yield by 44.7% and 79.3%,respectively.When the slope gradient was 18°,the slope land covered with pear trees,Cinnamomum camphora,cypress and crops could reduce runoff by 45.8%,4.9%,3.8% and 16.6%,respectively,and sediment yield by 91.3%,81.1%,77.4% and 61.6%,respectively.When the slope gradients was 25°,sediment yield of the slope farmland was almost eight times more than that of the bare slope farmland.Runoff and sediment yield had power function relationship with rainfall(P),maximum rainfall intensity of 30 min(I30) and slope gradients(s).The sediment yield of slope land met linear function with the runoff of slope land.

Estimation of Nitrogen and Phosphorus Loading of Agricultural Non-point Sources along Nansi Lake Based on GIS

Abstract: In this paper,the counties and towns in Ji′ning City along the Nansi Lake shore were selected as the main study area.The factors of Universal Soil Loss Equation(USLE) were determined by runoff and soil erosion,remote sensing(RS) and geographic information systems(GIS).The loss of nitrogen and phosphorus was calculated by USLE.The objective of this study was to provide a scientific basis for decreasing and controlling loss of nitrogen and phosphorus from agricultural sources.The results indicated that the most loss of nitrogen and phosphorus from the Yutun Town,Wanglu Town and Tangkou Town locating in west coast of Nansi Lake.The maximum value of loss of nitrogen and phosphorus was from Yutun Town and was 439.9 t/a and 271 t/a,respectively.The most loss of nitrogen and phosphorus from the Shiqiao Town,Mapo Town,Huancheng Town and Hanzhuang Town locating in east coast of Nansi Lake.The maximum value of loss of nitrogen and phosphorus was from Shiqiao Town and 174 t/a and 120.6 t/a,respectively.The losses of nitrogen and phosphorus by field survey and USLE were more consistent and both showed a significant linear correlation(p0.01).The loss of nitrogen calculated by USLE was lower than it by field survey while the loss of phosphorus by estimated by USLE was higher.The reason was that loss of nitrogen was mainly from farm soil erosion along Nanshi Lake,while the loss of phosphorus was mainly from livestock and poultry breeding and secondly from farm soil erosion.

Study on Canopy Density Retrieval Method from SPOT5

Abstract: In order to determine the value of regional factors of biological-control in forest,Yunyang County in Chongqing was selected as the study areaOn the basis of investigated canopy density data from 58 forest blocks,we calculated the average and standard deviation of digital number(DN) for each band of corresponded SPOT5,then analyzed the stability of SPOT5 in various forest canopy densityRegression and correlation analysis were taken between 38 different random selected canopy density data and corresponding average DN values of each band for SPOT5,and we established the method of retrieving canopy density by combining different bandsThe other 20 investigated canopy density data were applied for accuracy testOur results showed,the average DN values in infrared red,red and green bands of SPOT5 manifested stable over various canopy density forest blocks,their maximum deviation are 138%,1565%,2452%,and their average deviation are 1011%,1094%,1778%;red and green bands are the optimal combination for retrieving canopy density,their determination coefficient of fitting equation is 066The accuracy test results showed,the maximum positive and negative deviation between retrieving results and investigation data is +1692%,-1606%,with an average deviation of-208%According to 10% graduation statistics,the deviation of all the results were less than 15%,the general accuracy is relatively highWhile the error of retrieving result was 20%,the maximum error of corresponding factors of biological-control was less than 10%,which can be used as the reference of calculating factors of biological-control in monitoring regional soil erosion

Study on Urban Expansion and Its Ecological Effect in Beijing City

Abstract: With the fast development of urban economy and urban expansion,a large number of people concentrated in the central city and changes in a large-scale land use and land cover had taken place in Beijing in the past several years.In order to study characteristics of urban expansion and its ecological environment effect in Beijing,an integrated approach of remote sensing(RS) data(1990,2000 and 2007),GIS spatial analysis and ecosystem service value assessment method was developed to examine the tempo-spatial patterns and the rationality of urban expansion and to explore their ecological effect in recent 17 years.The findings indicated that there was a remarkable expansion in urban land cover since 1990s.The most evident spatial characteristic is to sprawl from central city to the outer along main traffic lines and several hot spots.Due to urban expansion,cropland area of 1 719.25 km2 was reduced,forest area of 220.25 km2 was reduced,and ecosystem service value of 2.18 billion Yuan was lost.Because of urban land expansion,a large area of cropland and natural land around the cities were occupied by buildings,roads and other impervious surfaces.As a result,the green shelter function and ecological effect of the city became weaker and weaker day by day.

Effect of Soil Properties and Soil Enzyme Activity in Different Improvement Measures of Saline-alkali Soil in Yinchuan Plain

Abstract: The soil properties and soil enzyme activities in saline-alkali land of the Yinchuan Plain were studied after the soil was improved with straw,organic fertilizer,flue gas desulfurization waste and saline-alkali soil conditioner.The results showed that four measures reduced soil pH,total salt content and soil bulk density to some extent,flue gas desulfurization waste and saline-alkali soil conditioner significantly reduced soil pH and total salt content,saline-alkali soil conditioner and organic fertilizer reduced soil bulk density and increased soil porosity remarkably.The improvement measures significantly increased soil invertase activity,urease and alkaline phosphatase activity after improvement,the increase rates were 0.02%-85.0%,2.7%-53.3%,17.9%-49.7%,respectively.The effect of the improvement measures on change of catalase activity was not significant.There was a positive correlation relationship(p0.05) among soil pH,total salt content and soil bulk density,and soil porosity had a negative correlation relationship with soil pH,total salt content(p0.05).There was a negative correlation relationship(p0.05) among soil bulk density and soil porosity,hydrogen peroxide enzyme,urease activity.There was a positive correlation relationship(p0.05) among soil alkaline phosphatase,invertase,catalase and urease activity.

Study on the Driving Force of Land Use Change at Differernt Scales——A Case Study of the Xinbei District of Changzhou City

Abstract: To analyze the driving force mechanism of the land use change at different scales during the rapid urbanization,the canonical correlation analysis and the spatial logistic regression analysis were used to study at the general scale and the local spatial scale.The result indicated that the variable quantity of GDP,the volume of investment in fixed assets,gross industrial output value,gross agricultural output value,average net rural per capita income,per capita GDP,total population,urbanization rate,were the main reasons for the land use change of the Xinbei District of Changzhou City at the general scale;the nearest distance of water system,towns,the provincial highway,the main road of urban and rural areas were the significant reasons for the land use change of the Xinbei District of Changzhou City at the local spatial scale.The fast development of economy and the rapid growth of population were the two main social and economic driving forces of land-use change in Xinbei District of Changzhou City;the transportation accessibility and the distance to the downtown were the two impact factors producing the spatial difference in land use change.In conclusion,the land use change was deeply affected by the population and economic growth,traffic systems and policies during the rapid urbanization in China.

Relationship between Climate Change and Glacier Retreat over the Last 40 Years in Lenglongling Range of Eastern Qilian Mountains

Abstract: The glacier outlines of the year 1973 were delineated manually from a Landsat MSS scene.The glacier outlines of the year 1999 and 2010 were delineated in a semi-automated way using band TM3/TM5 ratio images of Landsat ETM or TM scenes.The decrease in glacier extent was 56.21% between 1973 and 2010 because of rise of temperature,and a rapid and accelerating shrinkage in the last decade was detected,which was consistent with the temperature increase from 1997.Overall,south facing glaciers shrank most,which indicated that glaciers on this aspect were more sensitive to climate changes in this region.Given the temperature increase in the future,based on IPCC,the glaciers in this region will continue to retreat.With glaciers retreat and mass loss,their contribution to runoff will decrease,thereby serious sustainability concerns will be raised.

Dynamic Changes of Soil Moisture in Different Dunes of Ketu Sand Land in Qinghai Lake Basin

Abstract: In this paper,we selected three kinds of dunes in Ketu sand land on the east of Qinghai Lake,analyzed the soil moisture,as well as correlations between soil moisture and rainfall.The results show that: soil moisture in fixed dune has less variation along the profile,whereas the largest variation of soil moisture along the profile was observed in active dune with artificial measures(artificial vegetation and straw checkers).During the observation periods,soil moisture of the fixed dune was the highest in 0—80 cm depth,followed by active dune,and active dune with artificial measures.The three kinds of dunes have similar temporal variation trends,which can be divided into three stages such as freezing stagnation period(from December to next March),compensation period(from April to July) and dehydration period(from August to November).Soil moisture is the highest in summer and autumn.The impact of precipitation on the upper soil is more significant,which mainly influences 60 cm depth in the active dune with artificial measures,20 cm depth in the fixed dune.In addition,our research suggests that the artificial vegetation and straw checkers can inhibit surface soil moisture evaporation,improve surface soil moisture and reduce wind erosion,which is quite important for the initial growth of vegetation before the dune is fixed.

Effects of Different Sizes of Biochar and Their Additiont Rates on Soil Shrinkage Characteristics

Abstract: Soil shrinkage characteristics play a key role in the quantitative evaluation on soil structure and hydraulic properties.Because of the highly developed porous structure and huge specific surface area,biochar addition into soil can not only change the soil biochemical properties,but also affect the soil shrinkage characteristics.In this paper,the effects of application of 3 biochar sizes(2～1 mm,1～0.25 mm,0.25 mm) and 5 application rates(0,10,50,100,150 g/kg) on soil shrinkage characteristics were examined by using centrifugal method.The relationships between the soil specific volume with the pressure and the water content were fitted by using power function and the three straight lines model,respectively.The results showed the power function and the three straight lines model could well simulate the changes of the soil specific volume with the pressure and the water content.The biochar addition significantly changed the soil shrinkage properties,and the soil specific volume increased with the rise of the biochar addition rates under the same pressure condition.The soil shrinkage characteristics values decreased with the increasing proportion of biochar application at the false saturated stage and structure stage,but it increased at the super normal stage.The effects of different particle sizes of biochar on the soil shrinkage characteristics were not statistically significant.The results indicated that addition of the biochar into soil could reduce the soil shrinkage during the soil desiccation and improve the soil structure and water retention capability.

Analysis on Dynamics of Landscape Types in Qitaihe City

Abstract: The research on driving mechanism of land use change has been a hot spot,and the change of landscape types is obvious in coal mining areaThis paper studied the dynamics of landscape types and regulation of the principleBased on the remote sensing image of Qitaihe mining area from 2000 to 2010,the study area was classified by ERDASThe changes were quantified by variation and converting matrix of the landscape types and characteristicsWith the statistic data of society and economy in Qitaihe,this paper analyzed the driving forceThe results showed that the area of forest-grass land and barren land were decreasing,the farmland and coal mining area were increasing,the variation of the landscape types was at a high levelDynamics of landscape types was the main characteristicPopulation and primary industry product were the main influencing factors for distribution of the change of farmland,and the forest-glass land and coal mining area were related with primary industry product and final consumption expenditureBecause of environment-protection policy and measures of land reclamation,remediation and restoration,the speed of coal mining land development increased slowly