Abstract:The effects of leaf water potential(LWP) and the variations of soil-plant-atmosphere continuum(SPAC) water potential gradient are analyzed by studying the dynamic changes of the LWP in Qinghai alpine semi-arid area.Results show that the pre-dawn and evening LWP is high,while the minimum peak value is observed at about 13 o'clock.The daily average LWP in June is the lowest during the whole growing season.The study also shows that the LWP has significant correlations to air temperature,photosynthetic active radiation,and humidity under the condition of full irrigation,while there is a remarkable positive correlation between the LWP and the soil water content(SWC) when soil water is restricted.With the ascendant order of soil,leaf,and atmospheric water potentials in SPAC system,a water potential gradient is created.Meanwhile,the correlation between the pre-dawn LWP and the SWC is higher than that between the LWP and atmospheric water potential in the whole growing season of Caryopteris mongolica Bunge.

Abstract:Efficient utilization of check-dam-induced land is one of the important ways to keep the sustainable development of the conversion of arable land into grassland or forestland on the Loess Plateau.An investigation was launched to check soil moisture,organic matter,total nitrogen,and total phosphorous,as well as soil available nutrients in the soil profiles of the check-dam-induced land in Zhifang watershed,the first tributary of Jinghe River.Results showed that land types,in terms of the level of soil available nutrients in different types of lands,followed the descendant order of long-term check-dam-induced land,short-term check-dame-induced land,terrace,and sloping wasteland.The discrepancy of soil organic matter,total nitrogen,total phosphorous and available nutrients among soil layers in the profiles of check-dam-induced lands was insignificant.The supply ability of soil available nutrients demonstrates the sustainability and the sediment in the check-dam-induced lands readily enriches available nutrients,suggesting that there is the great potential for the growth of crop yields.

Abstract:Based on remote sensing and geographic information system technologies,the effects of altitude and slope factors on the process of land use/cover changes in Sanjiang Plain during 1954-2005 were studied.Results showed that during the past five decades,landuse in Sanjiang Plain changed substantially and cropland increased by 2.25 times.In contrast,wetland,woodland,and grassland decreased considerably.Changes of land use types have different features in altitude classes.Cropland increased mainly at the locations below 200 m,especially at locations below 100 m.Wetland decreased mainly in the same way as cropland in terms of altitude.Woodland and grassland showed a fluctuant changing trend in all altitude classes during different periods.Built-up land changed in all altitude classes,but mainly happened below 200 m.For slope degree,cropland increased at all slope classes and increased mainly at locations below 1°.The area of cropland had a relatively small increase at locations above 10°.Changes of woodland,grassland,and wetland mainly happened on 1° slope degree class.Water body and built-up land also changed mainly at sites with small slope gradients.

Abstract:A typical slope land with black soil in Guangrong small watershed of Northeast China was taken as the study area.Soil water content and bulk density were measured from soil samples.Spatial analysis,classic statistics,and geostatisitcs were used to explore the effects of topographic factors on soil water and bulk density.Results show that slope has the first significant influence on soil water and bulk density and the correlations are significantly negative.Elevation and slope position have significant effects on soil water and slope aspect has no significant influence on soil water and bulk density.Result from geostatistics analysis demonstrates that soil water and bulk density have a median spatial heterogeneity and a strong spatial heterogeneity,respectively.Slope has the more important effect on soil water and bulk density than others and plays an important role in the control of soil and water loss in the study area.

Abstract:As the response characteristics to rainfall infiltration into weathered materials of rocks,hydrological properties have important influences on the initiation of debris flow.In this paper,Xiaojiang basin was taken as the study area to investigate the difference of hydrological properties of weathered materials from different kinds of rocks.19 samples of weathered materials from 9 kinds of rocks with different elevations and 5 samples of debris flow deposition were collected in 5 debris flow valleys in the upper,middle,and lower reaches of Xiaojiang basin.Liquid and plastic limits and permeation experiments were taken to obtain the hydrological characteristics of each sample.Based on the construction of the index system with three indicators of hydrological characteristics,the variation of hydrological characteristics for each indicator were systematically analyzed.Results indicate that for each indicator,there are significant differences in weathered materials.The variation of its hydrological characteristics is significant for different indicators.In addition,for each indicator,there is the good consistency in hydrological characteristics of debris flow deposits in the 5 typical debris flow valleys of Xiaojiang basin.The index system,can reflect the hydrological properties of weathered materials,systematically,objectively,and reasonably.It may be helpful for the susceptibility analysis of debris flow to rocks based on hydrological characteristics of their weathering products.

Abstract:By using the ArcViewGIS Citygreen 5.0 model,six different land cover categories in the second ring road of Xi'an City were digitized,data of precipitation and soil hydrologic characters were analyzed,and benefits from storm-runoff reduction by urban forest were quantified.It was found that the total benefit from storm-runoff reduction was 150 682.06 m3 for the typical 24 h storm events of 3.2 cm in summer.Landuse categories,in terms of the net discharge reduction,were in the descendant order of residential area,road,park,culture area,industrial area,and commercial area.The storm-runoff reduction benefit per hectare was mainly related to impervious surface and forest coverage,and landuse categories were in the descendant order of park,road,culture area,industrial area,residential area,and commercial area.

Abstract:Artificial vegetation was set up on the slope in the Zhuozi County section of Hohhot-Jining expressway in 2003 and 2004.By contrast to bare slope,soil properties have changed remarkably and have increased with plantation time.A comprehensive evaluation index system for soil quality based on soil physical,chemical,and biological properties is established.Based on the system method and multivariate statistics,the changes of soil quality during soil formation on expressway slope are evaluated.The work is expected to reveal the changes of soil quality and the coupling relationship between vegetation and soil.Using SPSS analysis software,the membership function value,component capacity,and weights of soil quality factors by PCA are calculated and then the SQI(soil quality index) values for all plots are calculated.Results show that soil quality has increased since artificial vegetation was set up.The SQI values indicate that soil quality does not change with the time of artificial vegetation extending.Because management measures are different annually and artificial vegetation does not form a steady community,the SQI value for 2-year plantation plot is higher than that for 3-year plot.Among all plots,the highest SQI value is 0.649,which is distinctly higher than other plots.

Abstract:The effects of different kinds of ecological restoration(alfalfa fallowing,natural vegetation restoration,and cropping) and fertilization management(chemical fertilizer + organic manure,chemical fertilizer + straw,chemical fertilizer application,and no fertilizer application) on the physical properties of degraded black soil were investigated.Results showed that fertilization management decreased soil bulk density,but increased porosity,capillary capacity,max moisture capacity,field water capacity,and the content of water-sable aggregates as compared with natural vegetation restoration.Chemical fertilizer,together with organic manure,significantly improved them as compared with other fertilizer treatments.However,significant difference was only observed between alfalfa fallow and natural vegetation restoration in terms of bulk density and porosity due to short time of ecological restoration.Bulk density,porosity and capillary capacity,max moisture capacity,and field water capacity changed greatly in 0-10 cm soil layer as compared with them in 10-20 cm soil layer.Both the content of water-stable aggregates(0.25 mm) and the mean weight diameter increased in the ascendant order of natural restoration,alfalfa fallow,and fertilization management.

Abstract:Soil moisture content in the karst cluster-peach mountains is a key factor to control hydrology and environment of the area.The wide distribution of rock has the profound impacts on soil moisture movement and its distribution.Study of soil moisture distribution plays an important role in hydrologic dynamic and eco-hydrology.In this study,soil moisture contents in the typical karst cluster-peach mountains in Puding County,Guizhou Province were measured by TDR.The influences of rock are then revealed based on the observed data.Results show that soil moisture content is lower in underlying strata and higher in soil layers above strata due to thicker soil layers,and however,it is lower if soil layer becomes thin.Soil moisture content is found to be higher near the dissolved stone because of the recharge from precipitation.Soil moisture content in the soil layers with gravel is higher because gravel within soil may increase water infiltration into soil.However,the influence is reduced with increasing depth.

Abstract:Research on soil anti-erodibility was conducted for the two types of herbages planted on the triploid Populus tomentosa woodland which was converted from cropland to forest.Results showed that the differences in the content of water stable aggregates in high,middle,and low layers were little in comparison with those on ploughed land.However,the contents of coarse water-stable aggregates in high and middle layers on woodland were far more than those on farmland.The content of organic matter for artificial herbage was greater than that for natural herbage,but the difference was not distinct.The content of organic matter is greater than that on woodland due to farmyard manure.The anti-erodibility index based on micro-aggregates is not prominent in comparison with the content of water-stable aggregates,although it shows that the anti-erodibility of woodland is better than that of farmland to some degree.

Abstract:Based on the experimental plot research in Ansai Integrated Experimental Station on Water and Soil Conservation,the effects of landuse pattern change on runoff in slope scale were discussed.Four kinds of landuse patterns were designed in the loess area,including millet only(pattern a),two-thirds millet and one-third panicum virgatum(pattern ab),two-thirds millet and one-third abandoned land(pattern ac),and two-thirds millet and one-third alfalfa(pattern ad).Research results indicated that runoff had close relationships with high rainfall amount and changed with seasonal rainfall.Compared with pattern a,the other three landuse patterns(ab,ac,and ad) had positive effects of runoff reduction in the same degree.With the slope degree varying from 10° to 25°,runoff from the plots of patterns a,ab,and ad increased all along,but runoff from the plot of pattern ac decreased after increased.Because of the compound effects of vegetation cover,rainfall,and disturbance,monthly runoff was not consistent with annual runoff.

Abstract:An assessment model for sandy desertification in regional scale is established based on CBERS images in 2000 and 2006.Tendency of land cover change in Mu Us Desert is analyzed and desertification assessment in county scale is made.The conclusions are as follows:(1) Desertification in the study area tends to be steady.(2) The three types of semi-fixed desertification,semi-flow desertification,and non desertification change severely.(3) Result from desertification assessment in county scale shows that the number of extremely severe desertification counties decreases significantly and the counties turn to severe and moderate sandy desertification.Mu Us Desert is in a good status in general.

Abstract:Oriented to examine the impacts of scales of topographic parameters in regional soil erosion assessment,filtering method was applied to generalize fine resolution DEM(cellsize = 5 m) in ERDAS and ArcGIS systems.The effects of generalization have been assessed by comparing the general topographic characters,statistical analyzing of derived slopes and curvatures,as well as resultant contours and streams.The results show that fine resolution DEMs can be generalized,and the generalized DEMs,with a scaling factor of 5 or 10,and a 3*3 filtering window,are comparable to 10 m resolution DEMs and 1∶50 000 topographic maps in representing ground reliefs.

Abstract:以陕西省土壤分类信息系统中的土类数据制图为例,分析了基于Google Earth(GE)的专题地图的制图原理与技术,提出了一套基于GE的一般地理专题图的制图技术流程,并讨论了其关键技术。指出了GE制图工具目前存在的两个缺陷,提出了相应的解决方法,并介绍了陕西省土壤分类信息系统中GE制图结果和应用方案。

Abstract:Water is the primary limiting factor for plant growth and crop production in the loess hilly-gully area of the Loess Plateau.Because the annual precipitation is relatively low and its seasonal distribution is variable in the area,it is extremely important to study the soil water balance such as storage water and adjusting plant water requirement.Lysimeter is an excellent and classical instrument for measuring each component of field water balance equation such as evapo-transpiration and drainage.It is wildly used in field evapo-transpiration,rainfall infiltration experiment,and experimental hydrology.In 2005,the weighting sensor system and power source were improved and host computer and data colleting software of Lysimeter were updated,which were installed in the Ansai Research Station of CAS for studying filed water evaporation and transpiration transformation.After improvement,the instrument can work under Windows interface and the data collecting is more convenient.The modified Lysimeter shows some of the new characteristics,which are:the weight of the contained soil column is 19~26 t,the weighting precision is 152 g(0.05 mm) and can measure evapo-transpiration and groundwater replenishment and leakage;the measured area and soil depth are 3 m²(1.5 m×2 m) and 3.0 m,respectively,which may fully display water transformation in the crop rooting system such as root system development,water consumption,soil water and groundwater transformation,and groundwater level dynamic;the supply and drainage system can simulate the change of groundwater level,which can reflect the actual conditions and allow researches on soil water dynamic during crop growth.

Abstract:To study the impacts of pipeline construction on eco-environment in the middle-low mountainous area,the quantitative prediction is made for the changes of landuse,agricultural production,the area and biomass of vegetation,soil erosion,and ecological system integrity in the Daba Mountains by the Sichuan-Shaanxi natural gas pipeline construction.An analysis of possible influences made to the eco-environment of the middle-low mountainous area by the pipeline construction is then presented.Results show that the construction can change the structure of regional landuse,which can in turn influence local agricultural production,reduce the area and biomass of vegetation,and increase soil erosion.Nevertheless,the influences are temporary and can be alleviated,as they mainly concentrated in the construction period.The environmental effects of the project will not essentially alter the original eco-integrity of the middle-low mountainous area.Therefore,the ecological system remains its complete structure and consistent operating process.

Abstract:In recent ten years,the concept of slope ecological protection has emerged and the relevant practices are booming.It is urgent to develop a new method for analyzing the stability of slope covered with vegetation because the influences of vegetation on the stability of slope have to be considered.Based on the summary of the existed researches,this paper puts forward a new method for stability analysis of sandy soil slope covered with vegetation.As the distribution principle of root in soil and the improvement of soil shearing strength caused by roots are considered in the method,the method could be put into practice in the near future.

Abstract:The prediction of soil moisture is significant to the research on agricultural production and water cycles.Artificial neural network is used to approximate the phase space reconstruction of chaotic soil moisture time series and the future soil moisture was then predicted.Results show that this method is easier to be used in practice because it only needs one parameter-soil moisture time series.The comparison between the predicted value and the measured value indicates that the prediction method has a little relative error and better prediction accuracy.The study also demonstrates the utility and efficiency of the method for predicting soil moisture.

Abstract:The sedimentation impacts of incoming water and sediment from the six observation stations in the middle reaches of the Yellow River on Sanmenxia reservoir and its downstream area are studied by using the sediment discharge balance method. The downstream sedimentation index induced by incoming sediment from the middle reaches of the Yellow River, the area rich in sediment and coarse sand, and the source area dominated by coarse sand are analyzed by using profile method. Results show that incoming sediment from Longmen station has the greatest contribution to sedimentation in the lower reaches; incoming sediment from Huaxian County, Hejin, and Zhuangtou stations has smaller contribution; and incoming water and sediment from H eishiguan and Wuzhi stations are favor of downstream scour. Analysis by profile method indicates that the amounts of sedimentation in Sanmenxia reservoir and its downstream area are 0. 25, 0. 257, and 0. 329 hundred million tons for one hundred million tons of sediment from the middle reaches of the Yellow River, the area rich in sediment and coarse sand, and the source area dominated by coarse sand, respectively. The coarser sediment, the greater contribution to downstream sedimentation is.

Abstract:Soil loss tolerance(T-value) is an important value to judge gradation of soil erosion and efficiency of its control countermeasures.In this study,soil formation rates(SR) of the purple soils(a Regosols) in the hilly area of Sichuan,China were determined by Barth equation(SR-estimated) and field measurements(SR-measured) with the three treatments of soil types(J1s,J3s,and J3p soils),vegetations(wheat-maize,loquat tree,and ryegrass),and soil depths(10,20,40,and 60 cm).SR-estimated values are generally smaller than SR-measured values.SR-measured values vary significantly among the treatments.Based on the SR-measured values,the T-value was determined as 800 t/(km²·a) for J3s purple soil,and 1 200 t/(km²·a) for J1s and J2s soils in the studied region.

Abstract:This article attempts to get the information on rocky desertification under different background conditions in the karst area using spectral features and mathematical method,so as to improve the accuracy and timeliness of desertification intelligent classification.The Yachi demonstration area is taken as a study area and different platforms and different bands of remote sensing data are used.Based on the 3S technologies,the spatial distribution and characteristics of the karst area are summarized through processing,analysis,and classification.A quantitative research is carried out to understand the spectral characteristics in different conditions and diversities.Results from the study provide some references for other areas to develop the interpretation of remote sensing intelligent desertification.

Abstract:Experiments on apparent resistivity,moisture content,density,compressibility,strength,collapsibility of unsaturated loess were performed in laboratory.Testing data were analyzed using correlation analysis model.The relations of apparent resistivity to moisture content,density,compressibility,strength,and collapsibility of unsaturated loess were analyzed using the factor analysis method.Results showed that the contribution of the apparent resistivity was greater than those of moisture content,density,compressibility,an collapsibility of unsaturated loess.

Abstract:The "5·12" Wenchuan earthquake has induced many secondary geological disasters and directly threatens the life of the victims.So,it is very important to adequately understand secondary geological disaster and take effective emergency measures.This study is based on the field investigation of Tianjiaba landslide in Qingchuan County.The landslide is found to be an over burden landslide and is in latent instability,which is still in the instability during rainstorm and strong aftershock.The area influenced by the landslide is determined in view of landslide kinematics.The emergency measures of relocation,crack filling,and simple monitoring are taken.All the works are of important significance to the secondary geological disaster prevention after earthquake.

Abstract:Temporal and spatial distribution of soil moisture in the loess area of West Shanxi Province is studied by using the geological statistics method.Results show that the variation function model can well describe the spatial features of soil moisture.Soil moisture on different slopes has strong and moderate spatial autocorrelation,which indicates that it has the significant spatial autocorrelation on slope scale.The result can be validated by the fractal dimension.The distribution of soil moisture is analyzed by using geological statistics and a new methodology for temporal and spatial distribution of soil moisture is presented.

Abstract:Seven typical compound types of fruit tree and crops in the loess region were selected and soil moisture was tested by the traditional weighing method to find out the relations of soil moisture affected by the compound types in horizontal and vertical directions.Results indicated that soil moisture for the compound types was related to the orientation and distance from the shelterbelt in horizontal direction.The competition between fruit tree and crops was not significant.Soil moisture was mostly influenced by the intensity of shading light.The main competition layer of roots for soil moisture was within 60 cm of soil surface in vertical direction.The comparison with soil moisture for the single crop indicated that compound types of apple tree and other crops helped to maintain soil moisture.The compound types of walnut,peach,and other crops had different effects on soil moisture.More assistance to corn was observed rather than competition and more competition to peanut was found rather than assistance.

Abstract:The effects of water and low temperature stress on germination of Onobrychis viciifolia seeds were investigated.Onobrychis viciifolia seeds were cultivated in a plant growth chamber with different PEG concentrations(10%,15%,20%,25%,and 30%) and the 5 ℃ cold pretreatment.Results indicated that different concentrations of PEG and the 5 ℃ cold pretreatment shortened the average germination time and increased the germination percentage of Onobrychis viciifolia seeds.30% PEG and low temperature stress for 4 days significantly improved germination of Onobrychis viciifolia seeds.

Abstract:The loess gully area is characterized by the climate of 9 drought years out of 10.In order to realize the maximum utilization of rainwater resources,the catchment used for afforestation experiment was treated with several kinds of common and new materials with the function of seepage prevention and suitable treatment methods were selected.They include spraying methyl sodium silicate,spraying RG-100C1 macromole emulsion,spraying 3F gram waterproofing agent,mixing 3F gram waterproofing agent,spreading cement,and spraying water.Through the analyses of various research methods,spraying methyl sodium silicate is found to be the best in collecting water and thus,has a greater value in extension.

Abstract:Sediment samples collected in blowouts were analyzed.Results indicate that particle size and sorting parameters vary systematically with blowout position.Sediment in a trough blowout is mainly composed of medium and fine sand,with less coarse sand and silt.No gravel is observed in the trough blowout.Because of relatively uniform composition of sediment particles,frequency curve varying with different depths of the trough blowout show the single peak symmetry.In response to wind erosion and accumulation,the contents of coarse sand and fine sand,the plural size for frequency curve,and the average particle size change significantly.The results testify the flow models of blowout.

Abstract:Yanchuan County of North Shaanxi Province,Niuchang of Southwest Guizhou Province,and Jingjing County of Hebei Province are selected as the typical areas of the loess landscape,karst landform,and hilly landform,respectively.DEM is taken as the research object in the three landform areas with spatial resolution of 5 m according to the map scale of 1∶10 000.Six slope algorithms to extract slope are used and comparison analysis is made to identify suitable algorithms for different landforms.Results show that the reasonable algorithms are three-order inverse distance square weight difference and three-order inverse distance weight difference.The accuracy of the algorithm using eight adjacent units is higher than the algorithm using two or four adjacent units.

Abstract:Based on the landuse status and the natural and socio-economic conditions of 40 districts and counties in Chongqing City from 1999 to 2006,the spatial-temporal variation of landuse economic efficiency of the districts and counties are analyzed by selecting evaluation indexes and using the factor analysis of multivariate statistics.Results show that the landuse economic efficiency in different districts and counties differs greatly.The districts and counties with better landuse economic efficiency are mostly in good economic development and they are the main urban area and districts within its economic radiation zone.The districts and counties with poor landuse economic efficiency are backward and they are mostly located in the relatively remote mountain area.Moreover,the difference is displaying a growing trend.The landuse economic efficiency in various districts and counties displays an improved trend.Number of districts and counties with high efficiency increased steadily.In the light of the results from analysis,the authors propose some suggestions and measures to enhance landuse economic efficiency.

Abstract:Building hillslope into terraced land is an important engineering measure for soil and water conservation in Ruhe watershed of Guyuan City.On the 15°～25° slope of the hilly area,Guyuan station of soil and water conservation chooses bench terrace as the main form of building hillslope into terraced land.The conservation bench terrace in the watershed has obtained remarkable benefits of foundation,economy,society,and ecology by elaborate planning and design after four year construction.The design factors for conservation bench terraces are expounded and their benefits are analyzed and calculated.

Abstract:In order to reveal the degradation of planted forest communities under human-induced disturbance,the influences of grazing disturbance on soil physical properties under planted Pinus tabulaeformis forest on the Loess Plateau were analyzed by spatial contrast method.Results showed that compared with the soil in the undisturbed area,with the increase of grazing disturbance intensity,sand content increased,and clay content decreased.Consequently,soil texture became coarse.Soil bulk density increased 0.09~0.39 g/cm3.The total porosity,capillary space,and non-capillary space decreased greatly with the increase of grazing disturbance intensity.Soil water content,water-holding capacity,and infiltration rate decreased due to grazing disturbance.Compared with undisturbed soil,soil water content and water-holding capacity on heavily disturbed land and moderately disturbed land decreased significantly.Compared with the undisturbed soil,with the increase of grazing disturbance intensity,the initial infiltration rate and the stable infiltration rate decreased,and the saturated infiltration rate decreasedtoo.

Abstract:Based on the results observed in plots and from statistical analysis,vegetation coverage,species diversity,richness,number of species,index of grassland quality,and biomass percentage of palatable herbage are selected as the evaluation indices to study grassland degradation and protection countermeasures on the subalpine meadow.Using the typical ecological area on the grassland of subalpine meadow,the relationships between the evaluation indices and existing circumstances are analyzed.Results show that the quantificational indices reflecting the ecology of vegetation are considered in the method.The indices are closely related each other and are correlative.They are easy to be derived and applied,in accord with the local conditions of the ecological quality,and can be used to scientifically and objectively appraise the regional ecological quality on the grassland of subalpine meadow.Excessive grazing,excessive and disordered mining,human destruction,and biological chain unbalance are artificial factors of grassland ecology degeneration.Therefore,to control excessive grazing,stop excessive and disordered mining,and build some natural preservation areas are the protection countermeasures of ecology and environment.

Abstract:Yulin area is situated in the transitional zone between the typical wind-sand-grassland area and the knoll-gully area,where both water erosion and wind erosion are extremely serious.The regional ecological environment is more and more brittle and changeable.For the judgment to the Yulin ecological environmental quality and the change,research was conducted to establish ecological environmental appraisal index systems of the transitional zone.The research was based on RS and GIS software and three issues of Landsat TM4,3,2 wave bands synthesized satellite data.Information source of Yulin area in 1980,1995,and 2000 were used and information extraction was carried on under the man-machine interactive work way.Combined with various influence factors of ecological environment quality,the ecological environment quality appraisal model for the area was established.By the study of 20 year land utilization and land cover change,as well as the appraisal analysis of various types of ecological environment quality,it is found that the Yulin ecological environment has been improved remarkably.However,on the whole,its ecological environment quality level is not high and the deteriorated tendency has not been under control.

Abstract:Based on the meteorological data from meteorological station in Baota District,Yan'an City from 1980 to 2007,climate change at the beginning is analyzed and the change of climatic productivity is calculated by using Thornthwaite Memorial model.Results show that rainfall amount decreases by 2.73 mm/a and temperature increases by 0.05 ℃/a.Wind speed and relative humidity are decreasing and sunshine hour is increasing.Climatic productivity in Yan'an area is increasing but not significant.Rainfall is an important limiting factor for climatic productivity and the "warm-wet" climate is the most beneficial for crop climatic productivity.

Abstract:Agricultural structure of Yan'an City has been regulated since the Grain for Green project was implemented according to the changes of rural landuse structure.This paper adopts qualitative and quantitative methods to evaluate landuse structure and the effects of agricultural structure adjustment in combination with agricultural development after the implementation of the project in the city.Evaluation results show that agricultural structure adjustment has promoted the rural economic development and ecological environment construction of the city.Lastly,some suggestions are given on agricultural structure adjustment targeted at the requirements of ecological environment construction and market of the city to promote agricultural development stably with regional agricultural resource advantages.

Abstract:The water source area of the middle route project for south-to-north water transfer in Shaanxi Province is a severe soil erosion area that may affect the diverted water quality.To ensure the diverted water quality in the project,the present situation of soil and water loss and the influence factors are analyzed based on the historical data and the remote sensing interpretation data.By analyzing soil erosion degree and various factors influencing soil and water loss,some specific and effective measures for controlling soil and water loss were put forward.

Abstract:With the rapid development of economics in Shenzhen City,there is a severe shortage of water supply.Basic situation and utilization efficiency of water resources in Shenzhen City are introduced.Current problems of exploitation and utilization of water resources in Shenzhen City are analyzed according to the demands for national eco-city and sustainable development.To promote sustainable utilization of water resources,some measures are put forward,such as establishing water-saving industry system,strengthening waste water treatment,optimizing water resource scheme,and perfecting water resource management system.

Abstract:The main eco-environmental problems in Southern Shaanxi Province were revealed,which include soil and water loss,frequent geological hazards,and the low level of environmental pollution prevention.The annual potential economic loss in regional development caused by soil fertility loss,river channel and reservoir dredging,economic compensation for converting farmland to forest and grassland,and engineering water shortage was estimated by using the methods of market value substitution,shadow engineering,recovery cost,and value compensation.Their possible influences on water quality in the Middle Route of South to North Water Transfer Project were analyzed.Based on the analyses,some countermeasures of solving the eco-environmental problems were proposed,such as enhancing soil and water conservation and headwater area protection for the accelerated eco-environmental development,implementing the resident removal avoidance and ecological migration,and taking the comprehensive treatment of environmental pollution.

Abstract:A large area of water-level-fluctuating zone will be emerged after the completion of the reservoir engineering of dry-hot valleys in the Jinsha River.This paper presents that using vetiver and integrated engineering technology may prevent some problems from probably appearing in the water-level-fluctuating zone,such as soil and water loss,water pollution,and damages to the ecological system.The likelihood of existed ecological environment problems and the characteristics of vetiver and its functions are briefly introduced.In addition,the program of ecological restoration for the water-level-fluctuating zone is proposed.It is expected that a sustainable ecological system may be established.

Abstract:Basic information and remarkable achievements of Yangtze River Management project of Hubei Province in the recent 20 years were summarized.By taking the seventh stage of Yangtze River Management project of Hubei Province as an example,problems in drawing up feasibility report on the Yangtze River Management were presented in the aspects of project area selection,minor watershed division,characteristic minor watershed selection,management measure,and so on.Through the analysis of these problems,suitable countermeasures and suggestions were proposed,including principles when choosing watershed,requests and contents of watershed regionalization and soil and water investigation,details in sloping land management,slope water system,and diminutive irrigation and soil conservation design.

Abstract:Over the last half century,tremendous theoretical results have been achieved in the study of soil reinforcement by root system in various aspects.This paper focuses on the brief description of the relevant theoretical models of soil reinforcement by root system,including Mohr-Coulomb Strength Theory,Reinforced Theory,and Anchorage Theory,as well as major mathematical models covering Side Roots Theoretical Model(W-Model),Vertical Root-soil Interacting Mechanics Model,and Lateral Root-soil Interacting Mechanics Model.In addition,key study fields are analyzed and recommended pertaining to root distribution,friction of root-soil,and root mechanics.