Abstract:The severe drought disaster began in Autumn 2009 has strong impacts on agriculture and life in the southwest region of China. Based on the analysis of natural causes,the human activities focusing on change of eco-environmrnt,such as land use change,soil and water conservation,mining,and water resource engineering,are discussed to show the possible impacts and their approaches. The basic natural cause of the terrible drought disaster is the poor weather condition with very little precipitation in 7 months from September 2009 to March 2010. Adjusting capacity loss of soil water supply induced by deforestation,cash crop planting with higher water consumption,water system destroy induced by large-scale mining,and capacity loss of water resource engineering are the main causes that make the disaster happen and become worse. Only when considering the special local conditions and the process of eco-hydrological system in the region and practicing integrated water system management,we can prevent and reduce the negative impacts of climate change for the regional sustainable development.

Abstract:Based on the method combining statistical analysis with the compilation of historical archives,this article makes an investigation of the temporal and scale properties of flood disasters that occurred in the Guanzhong reach of Weihe River during the last 400 years. According to the related historical archives,99 flood events were recorded during the period,with an approximate frequency of 4 years. 52 of these floods are classified into small-scale flood,35 into medium-scale flood,8 into large flood,and 4 into catastrophic flood. Three main flood sub-periods are also distinguished. The period from 1600 to 1669 and the period from 1670 to 1859 were characterized by low-frequency floods,with a rising and a relatively level tendency,respectively,while the period from 1860 to 1995,by high frequency floods. Periodical analysis indicates that quasi 3-year is a most prominent cycle and 7.14-year,a secondary cycle,which are supposed to correspond to the 2～7 year cycle of ENSO.

Abstract:According to the analysis of elements,compounds,and grain size of 128 samples,we study the flood variation indicated by sediment in floodplain in the Jingyang reach of Jinghe River during deposit of floodplain. Results show that the contents of Mn,Ni,Cu,Zn,Ga,Pb,Ba,Rb,V,Al₂O₃,Fe₂O₃,and K₂O change obviously in the profile. Each component changes obviously in the entire profile,which can clearly reflect the variations of flood and precipitation with high resolving power. The profile may be divided into 18 sediment layers,indicating 18 flood events at different scales and 18 years with much precipitation. The finer grain size is,the higher contents of Mn,Ni,Cu,Zn,Ga,Pb,Rb,V,Al₂O₃,Fe₂O₃,and K₂O are and the lower content of Ba is,which indicates small flood intensity,low flood level,and less precipitation in deposition. In contrast,the coarser grain size is,the lower contents of Mn,Ni,Cu,Zn,Ga,Pb,Rb,V,Al2O3,Fe₂O₃,and K₂O are and the higher content of Ba is,which indicates high flood intensity,high flood level,and more precipitation at deposition. The small changes of two or more elements,compounds,and grain size in the thin layer formed in the same sediment layer in the 18 floods indicate two or more flood peaks frequently appeared in the period of most floods. Sediment in the 14th,12th,13th,8th,5th,and 1st layers in floodplain in the Jingyang reach of Jinghe River reflects that annual precipitation increases in the whole basin and annual rainfall is greater than 800 mm.

Abstract:The evolution history of karst rocky desertification (KRD) in Guizhou Province is analyzed from the perspectives of man-land relationship and its contradiction,geological backgrounds,etc. It is concluded that the evolution of the KRD undergoes the long process from quantitative to qualitative changes. The KRD is caused by the increase of population which exceeds the carrying capacity of land resources at a specific period and leads to the imbalance and aggravation of man-land relationship. It is also closely related with the historical changes of production mode and productivity. Meanwhile,those central administrations' strategic orientation for the province also has some impacts on its eco-environment. Therefore,the fundamental ways for rehabilitation of the KRD are to control population size and raise their quality,improve agricultural productivity,and adjust industrial layouts and policies. Moreover,an ecological compensation system may benefit the province greatly.

Abstract:Land cover of He'nan Province had been monitored from 1980s to 2005. Based on remote sensing and GIS technique,the analysis on the spatiotemporal characteristics of land cover change and driving factors was made. Results show (1) Change area:The areas of urban and build up type of land cover were increased observably and the area of water body also had an obvious increase. The areas of rural settlement and deciduous broadleaf was appreciably increased and the area of evergreen broadleaf had a slight increase. On the other side,the areas of shrub grassland,irrigated cropland,unirrigated cropland,and bottom land had an obvious decrease. (2) Change speed:Urban and build up type had a very sharp increase slope and water body had second fast increase speed. The sort order of decrease speed from maximum to minimum is:sand land,bared land,marsh,meadow grassland,bottom land,shrub grassland,unirrigated cropland,and irrigated cropland. (3) Spatial conversion:The spatial conversion mostly occurred between cultivated land and settlement. Additionally,the increase of urban and build up type included the rural settlements assimilated by urban. The part of water body increase was mainly converted from bottom land and shrub grassland was mainly converted to unirrigated cropland. The natural environmental factors were stable and less important to the change of land cover. However,population,economy,adjustment of agricultural structure,policies,and transportation play the fundamenta1 roles in land cover change. The concurrent correlation analysis indicates that the most important driving factors of land cover change in He'nan Province are rapid economic development and accelerated urbanization process.

Abstract:The concept of ecosystem health is introduced in highway roadside ecosystem by taking Dabao Highway (from Dali City to Baoshan City) and Sixiao Highway (from Simao City to Xiaomengyang Town) in the longitudinal range-gorge region as examples. Distance index,coordination index,and health index are adopted and ecosystem health state on highway roadside is assessed. Then the effect caused by highway construction on the roadside ecosystem health is analyzed. Results indicate that highway construction has dramatic effects on highway roadside ecosystem health,with affected scope mostly within 200 m. The nearer to the road,the harder the effect is. The affecting degrees on highway roadside ecosystem health under different landforms caused by the two selected highways are obviously different. The degree of Dabao Highway is higher than that of Sixiao highway,except the ecosystem within 0—50 m to road on mountainside section. The compared result between different landforms shows the order of mountaintopmountainside.

Abstract:Aimed at reducing rural road erosion in the loess hilly region,some engineering measures and biological measures were initially proposed. The engineering control measure design was outlined here,which includes arching center road,blocking and cutting road flow by pond,water storage cellar,and cut-off ditch along road side. Some grasses suitable to road surface planting were also selected. To evaluate the effect of the road erosion controlling designs,several road sections were taken to monitor road erosion for several years. Results showed that intercepted sediment volume from the section with integrated engineering measures was a decrease of 40%～82% compared with no protective measure section. In grass-covered section,erosion modulus was decreased by 58%～70% and runoff,by 50%～69% compared with the bare road. Practice has proved that the integrated conservation measure of water storage tank,cellar,cut ditches,and planting can effectively prevent road erosion.

Abstract:In the management of sloping farmland in Tielugou small watershed in the Three Gorges Reservoir Region,measures such as terracing and forest were taken. In order to find out the measures with the best ecological benefits,19 runoff plots adopting 7 kinds of measures were established in the area by taking longitudinal farming (corn) as the contrast measure. Experimental results showed that terracing (peach + perennial ryegrass) gave the best ecological benefits. Other investigations also revealed that terracing (peach + perennial ryegrass) gave the best economic benefits,about 13 950 yuan/hm². Therefore,terracing (peach + perennial ryegrass) was completely worthy of promotion in sloping land management in the Three Gorges Reservoir Resion.

Abstract:By means of fuzzy probability assessment model,an assessment indicator system was built to assess the suitability for ecological restoration of Andamu River. The suitability for ecological restoration was divided into four grades:not suitable,low suitability,suitable,and very suitable. Results showed that the total suitability for ecological restoration of Andamu River was between the low suitability and the suitable grade. The proportion of four grades that various types of riparian take up was 10.0%,30.6%,26.7%,and 11.7%,respectively. On the base of subsection assessment sketch of riparian zone ecological restoration suitability,ecological restoration suggestions for each grade of riparian zone were brought forward.

Abstract:This study is based on the investigation and analysis of natural and economic conditions and the extent of environmental damages and land use in Lu'an mining area. According to the actual conditions of Lu'an mining area and taking the restoration of original capacity of destroyed land as the starting point,six ecological restoration models suitable to Lu'an mining area are put forward in order to restore and improve the ecological environment. The models are the ecological restoration model of stable subsidence area,the ecological restoration model of dynamic subsidence area,the ecological restoration model of coal gangue field,the ecological restoration model of disused land,the ecological restoration model of environmental pollution region,and the ecological restoration model of homestead service. Each ecological restoration model contains several sub-models. Results from survey indicate that the system of ecological models is scientific and reasonable. Moreover,the high economic and ecological benefits have been obtained in recent years.

Abstract:This study is based on the concept of water environment carrying capacity and is combined with the current water environmental situation. Through the establishment of evaluation index system and the application of vector norm method,the evaluation of water environmental carrying capacity in Southern Shaanxi Provine from 2000 to 2007 are made. Results show that the change of water environmental carrying capacity has a fluctuated tendency,but becomes more and more gently. According to the specific circumstances of it,some countermeasures are proposed:strengthening regional water conservation and protecting water sources,revising industrial distribution,speeding up the construction of sewage treatment facilities,increasing small-scale water conservancy project construction,and establishing water resource compensation mechanism.

Abstract:Carbon fixation benefit is an important part of the soil and water conservation benefits on degraded land and has a great significance in comprehensive evaluation of ecological rehabilitation. Taking bare land as a contrast,different types of human induced vegetation are studied. According to the studies on carbon pool and carbon fixation value of them,there was an obvious increase in vegetation carbon pool and soil pool after human induced rehabilitation. Vegetation carbon pools in strong interfered Pinus massoniana,bamboo-burl-groove Pinus massoniana,glassed-bamboo-burl-groove Pinus massoniana,and bamboo-burl-groove Pinus elliotti were 6.12,6.83,8.20,and 32.69 t/hm²; soil carbon pools of them were 1.16,1.37,1.60,and 2.71 times those on bare land; and the total values of carbon fixation were 0.36,0.60,0.87,and 2.78 times those on bare land,respectively.

Abstract:Mankind activity and climate variety are the diplex factor of shallow groundwater decline in the valley area of Hutuo River. The questions are worth discussing that how the shallow groundwater changes from crude state to false state and what change the shallow groundwater in space and time has. After all,the discussion will provide the gist for mankind controlling their activities,self-restraining groundwater,and ensuring the harmonious relation between mankind and groundwater. This article chooses integrated index means,filters the disturbing index,and establishes the quantitative analysis system. On the base of the above,the disturbing degree of mankind activities to shallow groundwater is quantitatively analyzed. Results show that spatially,the disturbing degree decreases gradually from the west to the east in different ages; in view of the whole area,the disturbing degree increases from thewest to the east; and the disturbing degree increases from 0～0.4 to 0.2～1.0. Temporarily,the disturbing degree in the whole area increases along with time,but it is different in different areas. The disturbance of mankind activities to shallow groundwater goes through different stages.

Abstract:Based on the data of the second national soil survey and the field investigations,the change of soil granularity and soil organic matter in Nenjiang basin during recent twenty years was analyzed by the mathematical statistical method and with the aid of GIS technology. Result showed that soil texture had changed. The percentage of silt was nearly 50% and it had hardly any change during this period. However,the content of sand and clay were different from the survey result. Soil sand particle decreased by 22.95%,while clay particle increased by 50.09%. The soil texture was mainly clay loam and clay,with the area percentage being 32.52% and 66.51%,respectively. In Nenjiang basin,loam decreased by 17.45%,while clay loam and clay increased by 9.34% and 8.20%,respectively. Compared with the second national soil survey,soil organic matter showed a decreasing trend,in the range from 0.55% to 12.26%. The downward trend of soil organic matter in the lower Nenjiang basin was obviously reduced by 33.11%,but in the upper,soil organic matter increased by 27.14%. On the whole,the undeveloped soils in Nenjiang basin do not show serious desertification trend,but soil desertification in the lower region is more serious than in upper region. Soil organic matter has different results in different regions in Nenjiang basin.

Abstract:Field plot experiments were employed to investigate soil water and soil temperature effects of ridge furrow of peanut under film mulching,liquid film mulching,and straw mulching. Remarkably reduced evaporation was found under the three mulching techniques. Compared to 0—30 cm soil layer,the soil moisture contents after irrigation under the three kinds of plant cover and bare ground were increased by 67.35%,35.44%,and 5.1%,respectively. Film mulching significantly increased soil temperature of peanut root zone. Straw mulch cover material hindered the sun's direct radiation on the surface. Compared to bare land,soil temperature in 0—25 cm root zone was reduced by 1.3 ℃～5.5 ℃. Mulching increased product as high as 167.07%.

Abstract:Arable land resource is the cornerstone of ensuring food security and social stability. The article analyzes the changes of cultivated area and grain production and the variant characteristics of minimum per-capita cultivated land area and pressure index in Hubei Province from 1978 to 2008. It also forecasts arable land area,population,food output,minimum per-capita cultivated land area,and land pressure index in the next 10 years by using GM (1,1) method. Results show that (1) Since 1978,the per-capita arable land area and per-capita food production have declined,yet minimum per capita arable land area has generally decreased and cultivated land pressure index is on growth fluctuation. (2) In the next 10 years,minimum per-capita arable land area will gradually decrease and pressure index will increase year by year. Furthermore,the declination speed of per-capita arable land will be faster than that of minimum per-capita arable land.

Abstract:Ecological restoration and settlement construction connect and interpenetrate with each other. Development of rural settlement must be based on the ecological environment protection and restoration,gradually reduce the pressure on regional ecological environment,and reverse the vicious circle of "ecological degradation—poverty" in rural settlement. Through field research,literature study,and theoretical analysis methods,the paper puts forward a rural settlement development pattern benefit to ecological restoration in loess hilly and gully region of North Shaanxi Province based on the knowledge of ecological environment,its repair pathways,and its restrictive factors. It is concluded that the rural settlement should adjust its landuse structure to favor soil and water conservation in the production tillage management,adjust the scattered settlement living space structure,shift population to resolve the question of overloaded population,and further improve the works on village relocation and combination in rural settlement.

Abstract:Severe soil erosion has threatened land resources in Northeastern China,however,a few researches were conducted on sediment yield in the region. To study the characteristics of the evolution of sediment yield in the Songhua River basin,the characteristics of temporal variation of precipitation were analyzed by using daily precipitation records from 116 stations and the characteristics of temporal variation of runoff and sediment load were analyzed based on daily runoff and sediment yield data from 14 typical hydrological stations. Results showed that from 1961 to 1990,there was no obvious increasing trend of precipitation or runoff in the studied watersheds,but the increasing trend of sediment load was obvious,with an average trend of 34.7% in each 10 years,and the trend was more obvious in hilly region than mountainous region. Sediment yield has increased sharply since 1979 and human activities,rather than precipitation,may play an important role in the increase of sediment yield.

Abstract:Discovering soil erosion characteristics in karst area is significant for studying the processes of rocky desertification. By combing field investigation with experiment and through sample analysis,direct shear test,and simulation scouring test,soil erosion characteristics for different land types in the typical karst area are studied. Results are as follow:Soil thickness on shrub land is greater than forest land and cultivated slope land. Soil compactness degree on cultivated slope land is less than shrub land and on shrub land,less than forest land. By soil slaking rate and scoring modulus,the order of the land types is cultivated slope landshrub landforest land. On the whole,soil erosion characteristic on cultivated slope land has a significant difference and there is no significant difference in soil erosion characteristic between shrub land and forest land. Therefore,protecting and recovering vegetation in karst area and reducing cultivation activities are the main approaches to protect soil and control rocky desertification.

Abstract:Based on field experiment in the hinterland of Taklimakan Desert,the vertical distribution of soil moisture and growth characteristics of Calligonum mongolicum under different treatments were contrasted and analyzed. Results showed that (1) the vertical distribution of soil moisture was affected obviously by different soil moisture conserving treatments. Differences among treatments were not big in the early irrigation interval,but a reverse phenomenon was observed in the later irrigation interval. Soil moisture content increased at depths of 0—20 cm,30—60 cm,and 20—40 cm under treatments of mulching film,mulching sand,and spurting inhibitor,respectably. (2) Both predawn and postmeridian water potential were affected obviously by different treatments. By predawn water potential,the order was mulching filmmulching sandspurting inhibitorCK,but postmeridian water potential of mulching film was less than spurting inhibitor. (3) Comparing with CK,it was clear that hydrological environment of plant was improved with soil moisture conserving treatments. The growth condition of Calligonum mongolicum under mulching film and mulching sand was better than spurting inhibitor.

Abstract:This study is based on the investigated data of landuse sifts and variations and the statistical information on society and economy in the urban area of Kaifeng City in 1988 and 2002. Landuse change extent and dynamic degree,transfer matrix,and information entropy model are referred. Driving factors of landuse change are discussed by the analysis of landuse change characteristics in the city. The research on regional landuse change and driving forces can afford theoretical attestation for optimizing configuration,layout,and management of regional landuse.

Abstract:In order to understand the growth and distribution conditions of the herbage in different foresttypes of Ziwuling Mountains, we conducted an investigation on the species composition , structural characteristics, and differences under three forest types of Quercus liaotungensis , Pinus tabulaeformis , and Pinusshenkanensis and compared those items with those on south-faced slope . Our results show that the total number of species presenting under the three forest types and on south-faced slope ranges from 21 to 34. The species diversity of herbaceous plants under P . tabulaef ormis forest is close to that on south-faced slope . The height , degree of coverage , and herbaceous biodiversity of herbaceous plants in the three forest types are significantly different to those on south-faced slope , but no difference is found among the three forest types.The order of species , by the correlation of herbaceous under the three forest types and on south-faced slope ,is Q . liaotungensis >species on south-faced slope >P . tabulaef ormis >P . shenkanensis. Generally speaking , closing environmental closure leads to lower density and less biodiversity of herbaceous in forest . However , density and species biodiversity of herbaceous under well conserved Q. liaotungensis and artificial P.

Abstract:By using a self-designed lysimeter to measure surface runoff on a slope in Taihang Mountains,we analyze the impacts of the factors influencing runoff in the Granitic Gneiss Region (GGR) of the mountainous area. The analysis shows that (1) rainfall intensity is a key factor for initiating runoff. Surface runoff occurs when rainfall intensity is above a critical value. The gentler the slope,the higher is the critical value of rainfall intensity needed to initiate runoff. When rainfall intensity reaches a critical value,runoff becomes positively correlated with rainfall significantly. However,the correlation between runoff and rainfall intensity is insignificant. (2) Runoff does not increase with the increase in the catchment area. A strong slope infiltration capacity enhances convergent runoff infiltration into soil. Surface slope is also a key factor influencing the process of runoff in the GGR area. With increased slope,surface runoff increases significantly. Since different slope aspects have different soil textures,runoff on sun-ward slope is higher than that on shade-ward slope. The averaged runoff coefficient for sun-ward slope is higher than that for shade-ward slope as well. Generally,however,runoff coefficient is low in the study area. For instance,it has the maximum of 7.3% for a 2 meter-length slope. An important finding from the study is that there exists a very strong infiltration capacity on the GGR slope in the study area. This has a significant implication for understanding the mechanisms of surface runoff,infiltration,and groundwater recharge in the region.

Abstract:In order to analyze the influences of land surface slope on runoff and concentration and solute transport,the total infiltration amount,the average of overland flow velocity,surface runoff and the changes of Br-,NH4+,and NO3-concentrations in surface runoff were studied in indoor soil tank experiment under artificial rainfall simulation. Three slopes (5°,10°,and 15°) and three rainfall intensities (30,60 and 120 mm/h ) are tested. Results show that with slope increasing,the average of overland flow velocity and the total amount of surface runoff are increased and the beginning time and termination time of surface runoff are advanced. The total infiltration amount is decreased with slope increasing. No obvious change in Br-concentration is observed and the course lines of Br^-concentration in surface runoff are almost coincident. The NH⁺₄ concentration appears a reducing trend and this trend becomes obvious with rainfall intensity increasing. Change of NO^-₃ concentration is not evident. The relationship between the averaged overland flow velocity and surface slope expressed by simple power function.

Abstract:Based on 24 year rotation and fertilizer experiments, the effects of rotation and fertilization on the growth , yield and water consumption of spring maize were studied . Results showed that at the same fertilization level , leaf area , yield, and biomass of continuous cropping maize were higher than rotation treatment .Under the same rotation conditions, RT —NPM had the highest leaf area, yield, and biomass, RT —NPM was the second , and RT —NP was the lowest . Yield and biomass of the three treatments were significantly different . The averaged soil water content in 0—300 cm layer decreased firstly and then increased in different development stages and eventually fell to the lowest level in the silking stage . The order of treatments, by water consumption of spring maize, was CT —NPM >RT —NPM >RT —NPK >RT —P . The rotation maize had the highest water use efficiency , continuous cropping maize was in the second level , and RT —NP and RT —NPK were in the lowest level.

Abstract:Through contrast experiments,soil evaporation and water use efficiency of winter wheat after applying soil amendment fertilizer were studied using the method of farmland water balance and micro-lysimeter. Results indicated that after applying soil amendment fertilizer,the mean water consumption of winter wheat during the growth period decreased by 491.67 m³/hm² averagely,compared with the contrast. Soil evaporation of winter wheat and the ratio of soil evaporation to water consumption during the stage from seeding to jointing also decreased. The water use efficiency was 2.62 kg/m³ under the treatment of 2 250 m³/hm² irrigation water and the yield increased by 32.68% under the treatment of 1 950 m³/hm² irrigation water.

Abstract:To accurately estimate carbon pool and features of artificial Pinus tabulaeformis in Ziwuling forest area,we use wet-burn method to account carbon storage and density on the spatial scale and analyze distribution characteristics at different levels. Results show that the mean carbon rate is 0.446 2,but it is quite different on spatial scale and has great significance between them. The total carbon storage is 7.649 8 Tg and its density is 164.55 t/hm². However,layers of carbon storage have the order of soil layertree layerlitter layerherb layershrub layer,showing the uneven distribution of the characteristics on spatial scale. In addition,artificial Pinus tabulaeformis in Ziwuling forest area has grown for only about 20 years and still grows well. If efficient management measures are taken for artificial Pinus tabulaeformis,its communities will have a greater potential for carbon sequestration.

Abstract:In order to understand the dynamics of soil water-stable aggregates and the relationship with soil nutrients on the land from the converting cropland into forest land project in the karst hilly area of Guizhou Province,4 kinds of the land with 5 to 8 years conversion age in the Zhongshan area of Liupanshui City were selected for a systematical study through the approach of substituting the temporal serial for spatial serial. In addition,the land of moderate rocky desertification and natural restoration pine samples were selected as controls. Results showed that the content of soil water-stable aggregates increased promptly in the forest stage years,and The water-stable aggregates were mainly in the range from 5 to 2 mm and there was an obvious tendency that water stable aggregates were in the transformation to a greater particle size. 0.25 mm aggregates were significantly correlated with soil organic carbon,total K,and quick acting K,but not with alkaline hydrolysis nitrogen and total P. It was necessary to keep soil organic carbon in a good balance in order to improve soil structure on the arable land in converting cropland into forest land project.

Abstract:Soil erodibility is the intrinsic factor which has effect on water erosion on slope and is related to soil texture,soil organic matter,and other soil properties. Sediment particle is analyzed by using plot data from rainfall simulation experiments. Results show that (1) during rainfall,particle composition of sediment changes with time. Sand content increases,silt content keeps constant,and clay content decreases. (2) Rainfall intensity is the important factor to the particle composition of sediment. With rain intensity increasing,sand content increases and slit and clay contents are reduced. (3) The effect of slope gradient on sediment is complicated. When slope becomes steeper,sand content increases first and then decreases,whereas silt and clay contents decrease first and then increase. When slope gradient is 20°,sand content reaches the maximum and slit and clay contents,the minimum.

Abstract:The contents of soil organic carbon (SOC),dissolved organic carbon (DOC),and microbial biomass carbon (MBC),as well as profile distribution and its relationships in the four main soil types (Lime concretion black soils (LS),Fluve-aquic soils (FS),Paddy soils (PS),and Red soils (RS)) in Anhui Province are studied. Results showed that the contents of SOC,DOC,and MBC were significantly different in the four soils,but the trend of their profile distributions was basically the same. The contents in topsoil were higher and decreased with soil depth increasing. The orders of SOC,DOC,and MBC in topsoil were PSLSFSRS,LSFSPSRS,and FSLSRSPS,respectively. DOC and MBC were only a small part of SOC. The percentages of DOC and MBC over SOC were in the range from 4.92% to 18.97% and from 1.86% to 5.68%,respectively. There was a close relation among SOC,DOC,and MBC. The relationships between SOC and DOC,between SOC and DOC,and between DOC and MBC were all significant or very significant at 10%,5% or 1% level,respectively.

Abstract:The study bosed on historical date of typical Lou soil profile in different years. In order to know the historical evolution and characteristics of nutrient on soil profile , the change of fertility and profile distribution of typical Lou soil in recent 30 years was studied by sampling . Results showed that the soil nutrient contents increased significantly in different soil layers ( except for total potassium) since the 1980s. Organic matter increased by 104. 6%; total nitrogen , by 61. 7%; total phosphorus, by 21. 6%; available nitrogen ,by 67 . 3 %; and available phosphorus, by 255 percent .Total potassium in the whole profile decreased to some extent , but in the top-soil , it declined only by 9. 6 %. In top-soil , the ration of soil nutrient content were greater in 2008 than those in 1982 . Long-term fertilization is helpful to enhance soil fertility and the fertility of Lou soil is propitious to growth and absorption for plants .

Abstract:Soil has the fractal characteristic. Soil fractal dimension (SFD) can be used as an important index of soil. In this study,30 soil samples from 7 soil types and 4 landuses were collected. Soil particle-size distribution,soil bulk density,saturated water content,saturated hydraulic conductivity,and soil organic matter were measured. The SFD was then calculated according to soil particle-size distribution. Results showed that the fractal dimension in Beijing region had a low variation coefficient. Significantly positive correlative relationships between the SFD and clay content and between the SFD and saturated hydraulic conductivity were found. The fractal dimension was negatively correlated with the ratio of (sand content + silt content)/clay content. The SFD can be a potential parameter to reflect soil texture,but is not a rational indicator to reflect soil physical properties under complex geographical environment.

Abstract:Soil erodibility is the intrinsic factor which has effect on water erosion on slope and is related to soil texture , soil organic matter , and other soil properties. Sediment particle is analyzed by using plot data from rainfall simulation experiments.Results show that ( 1)during rainfall, particle composition of sediment changes with time . Sand content increases, silt content keeps constant , and clay content decreases. ( 2) Rainfall intensity is the important factor to the particle composition of sediment . With rain intensity increasing , sand content increases and slit and clay contents are reduced. ( 3)The effect of slope gradient on sedi- ment is complicated . When slope becomes steeper , sand content increases first and then decreases, whereas silt and clay contents decrease first and then increase . When slope gradient is 20 ° , sand content reaches the maximum and slit and clay contents, the minimum.

Abstract:Based on the experiment of one-dimensional vertical infiltration in laboratory,the effects of sodium polyacrylate (SA) on infiltration capacity into sand,loam,and clay soils and the fitting effect of different infiltration models are studied. Four concentrations of the SA (0 ,0.08 % ,0.2 % ,and 0.5%) were added to these three soils. Results showed that the initiation infiltration capacity of the three soils was the highest. The curve of cumulative infiltration volume went up quickly and then the upward trend went down with the process of infiltration. For the three types of soil without SA,the order of soils was loess soilsand soilLou soil,by the cumulative infiltration capacity. The concentration of SA was controlled in the range from 0.08 % to 0.5 % by weight. The infiltration capacity of these soils significantly decreased with the increasing of SA. The infiltration capacity of sand soil was affected most obviously by the concentration of SA. Based on the study,water infiltration into soil can be simulated well by Horton infiltration model and the fitting effect of Horton model is better than that of Kostiakov and Philip models.

Abstract:By the methodology of ? The T emporal for The Spatial?, the changes of soil physical and chemical properties on the southeastern edge of Mu Us sandy land were studied. Results showed that soil physical and chemical properties changed regularly in the process of desertification. With the increased degree of desertif- ication, the contents of soil clay, soil water, organic matter, organic carbon, and total nitrogen decreased,while the content of soil sand, soil bulk density, and C/ N increased. With the increased depth, the content of soil water and soil bulk density increased and the contents of organic matter, organic carbon, and total n- i trogen decreased, while C/ N increased firstly and decreased later. Results of correlation analysis showed that the correlations of soil bulk density or C/ N ratio with other indicators were negative, while the correlations of other indicators were positive. T he negative correlations of soil bulk density with the content of organic matter and total nitrogen were significant at the level of P< 0.01 and so was the positive correlation between the content of organic matter and total nitrogen. T he correlations of the content of soil clay with soil water, soil bulk density, the content of organic matter, and total nitrogen were significant at the level of P< 0. 05 and so were the correlations of soil water with soil bulk density, the content of organic matter, and total n- itrogen. Soil quality was reduced and there were close correlations in soil physical and chemical properties in the process of desertification.

Abstract:Keeping minor principle stress and medium principle stress fixed and loading in the direction of maximum principle stress are the potential stress path in practical projects,under which several groups with different water contents of true triaxial tests about remolding loess are studied. Results show that the values of initial elastic modulus and principal deviator stress decrease with water content increasing. In certain defined principal deviator stress,lateral deformation increases with water content increasing. The Poisson's ratio can be greater than 0.5 in the direction of minor principle stress and the expansion in the direction of minor principle stress is greater than that in the direction of medium principle stress.

Abstract:Based on several traditional field investigations in Gonghe basin,Qinghai Province,laser 3D scanner and sub-meter differential GPS were used to monitor the boundary of branch gully erosion in the south of Weiliantan gully head. After the data were collected,point-cloud data processing software-Real Works Survey,AutoCAD,and GIS software were used to compare and analyze the raw data. Results showed that high precision and non-contact measurement of laser 3D scanner could accurately simulate landform surface in soil erosion monitoring. High precision GPS data can be used as part of supplement data in the area where laser 3D scanner can not reach. Moreover,the limitations and improvements of laser 3D scan technology applied in soil erosion research were discussed. Our study is expected to provide a feasible method in the research on soil erosion monitoring.

Abstract:In recent years,rapid popularity of automatic weather stations has greatly promoted the development of meteorological observations in soil and water conservation. Previous observations by artificial means on duty can not meet the needs of the development of modern soil and water conservation. Remote control and wireless data transmission of meteorological observation system are the future development trend. By combining the DAVIS Vantage Pro2 automatic weather station produced by a United States company with China Unicom CDMA1X technology,wireless remote control and remote access to automatic weather station are achieved to obtain meteorological data. Results show that the system of wireless transmission automatic weather station has many advantages,such as easy installation and use,real-time online,high-speed transmission,landing quick,affordable,and safe and reliable monitoring. Particularly in the transmission of intermittent,sudden or frequent,small amounts of meteorological data,it shows a good performance. Real-time data transmission in Fangshan County,Shanxi Province erected by CDMA1X technology-based automatic weather station with remote control terminal of Beijing Forestry University has proved that the system of wireless transmission automatic weather station can be applied to soil and water conservation and other meteorological observation fields.

Abstract:The Loess Plateau of Gansu Province is located in semi-arid and semi-humid transition zone. The accurate estimation of potential evapotranspiration is one of the main works in assessment of water resources. Based on the meteorological data at Xifeng National Base Climate Station in 1961—2006,5 kinds of model for calculating potential evapotranspiration widely used in semi-arid area are chosen for the evaluation with reference of evaporation. The FAO Penman—Monteith (1998) model has a significant relevance,small standard deviation with evaporation,and the high stability and is the most suitable model for calculating the potential evapotranspiration. The next suitable model is the FAO PPP—17 model. The Hargreaves model has the advantages of fewer climatic factors,convenient use,and higher accuracy over other models in estimating potential evapotranspiration. It is demonstrated that the Priestley—Taylor model has some reference values in calculating evapotranspiration,but the model shows a low relevance level with evaporation. Therefore,the model should be modified before it is put into use. The association between calculated value of the 24Radiation model and evaporation dose not reach the level of assumption checking in summer and thus its use is limited. The model should not be used in research work in the Loess Plateau of Gansu province.

Abstract:In order to improve the quality and speed of soil bulk sampling,a new soil bulk sampler was manufactured and the parallel test with traditional soil bulk sampler was carried out. The test result shows that (1) the test result is credible. The T-test result indicates that there is no notable difference between the new sampler and the traditional sampler. (2) The new sampler can save labor. (3) Little soil area is disturbed when using the new sampler

Abstract:Based on the monthly averaged maximum and minimum temperatures in Hexi corridor oasis from 1960 to 2005,the characteristics of spatiotemporal variation and the abrupt change are analyzed by the methods of climate tendency rate,5-year running means,and Mann—Kendall abrupt change test. Results are reported as follows:Firstly,the maximum and minimum temperatures increased obviously,the warming amplitude of minimum temperature is remarkably higher than maximum temperature,and the anti-symmetrical warming trends presented. Secondly,the warming amplitudes of maximum and minimum temperatures are obviously different in different regions. By the maximum temperature,the order is central partwestern parteastern part and by the minimum temperature,eastern partcentral partwestern part. Thirdly,the maximum and minimum temperatures increased during each season,but they are higher in winter than other seasons. Fourthly,the abrupt changes of maximum and minimum temperatures are apparent and they are different in different regions and seasons.

Abstract:Using observed microclimatic data,we analyzed the microclimatic characteristics over irrigated shelter forest land and the external influence factors in Tarim Desert in autumn and make the comparison with shifting sand land. Results showed that the irrigated shelter forest land had particular climate functions,such as modifying surface temperature differences,reducing soil temperature,and improving humidity. Surface temperature between shelter forest land and shifting sand land had significant difference. Surface soil temperature in shelter forest land was lower than that in shifting sand land in the daytime,whereas it was contrary in the nighttime. The daily difference of surface soil temperature in shifting sand land was 18.26 ℃ higher than that in shelter forest land. From 09:00 to 15:00,the average air temperature in shelter forest land was 1.44 ℃ higher than that in shifting sand land,whereas in other time,it was 3.22 ℃ lower averagely. The difference between shelter forest land and shifting sand land in the daylight was greater than that in the night. The daily difference of air temperature in shelter forest land was 4.41 ℃ higher than that in shifting sand. Air absolute humidity and relative humidity in shelter forest land was higher than those in shifting sand. Microclimate among different shrubs species exhibited the different characteristics but no significant difference. Soil surface temperature,air temperature,and humidity between different forest covers showed the different characteristics. The observed results are of significance to further exploring material and energy exchange near surface layer under irrigation condition in the extremely arid conditions.

Abstract:Working out a small watershed planning on the Loess Plateau needs many kinds of geographical data. By taking the Majiagou watershed in Ansai County,Shannxi Province as a typical experimental area,taking the DEM of the watershed as the basic data set,and using ArcGIS and various space analysis technologies,data mining experiments on slope graduation,landform classification,and aspect graduation are conducted and a series of data mining parameters and the indexes for drawing up the planning are obtained. Based on the multi-dimensional geography spatial data sets,a new method of data superimposition and fusion that takes the value code as the core are proposed. The research result has a certain reference value in the planning instruction for other small watersheds on the Loess Plateau.

Abstract:A removable laboratory system of soil and water loss (RLSSWL) is proposed and developed. RLSSWL can substitute removable experimentation laboratory (vehicular) for the field and immovable soil on runoff plot. By adopting artificial rainfall simulation to runoff plot of different gradients,RLSSWL may be used to analyze soil physicochemical properties and soil erosion processes on hillslope and thus greatly improves the efficiency of soil loss observation. The erosion soil-bin has a hydraulic automatic rising device,as key part of RLSSWL,and soil-bin gradient can be adjusted from 0° to 30° according to different experiment requirements. Using RLSSWL may accelerate data collection,shorten experiment period,and make data collection more convenient. Based on the soil erosion characteristics in Yangtze River,an interflow collection device is added in RLSSWL. By improving the soil-bin,it becomes more practicable and rational to soil erosion experiment on hillslope. Meanwhile,rainfall intensity of artificial rainfall simulation has a wider range,which can be adjusted between 20 and 170 mm/h.

Abstract:The variation characteristics of global solar radiation and sunshine hours in Shaanxi Province are analyzed. Total solar radiation and sunshine hours in Shaanxi Province show a consistently decreasing trend from north to south. The Weibei Plateau area is the second high-value area of global solar radiation and sunshine hours. April to August in North Shaanxi Province and May to August in Guanzhong and South Shaanxi Province are the best period for the use of solar energy resources. Result from the study is useful in understanding regional climate change,guiding agricultural production,and using solar energy resources.

Abstract:¹³⁷Cs and ²¹⁰Pb techniques are used to date a sediment core (MG4-2) retrieved from Maigang Reservoir in Ziyun County,Southwest Guizhou and infer its sedimentation rates. Three distinctive ¹³⁷Cs peaks are identified in this core,which are ascribed to the abundant fallouts occurring in 1964,1975,and1986. The ²¹⁰Pb ages calculated with CRS model are generally coincident to the ages inferred with ¹³⁷Cs activities. However,there are also some discrepancies in the dates derived from the two methods. In particular,the age calculated with ²¹⁰Pb for the depth with an age of 1964 inferred with ¹³⁷Cs activities is remarkably different from the ¹³⁷Cs age. Although the sedimentation rates derived with the two methods are different,both of them indicate a quite similar trend of changes in accumulation in the reservoir during the last decades. Sedimentation was rather slow in the earlier stage,then was fast in the middle stage,and finally slowed down again in the later stage. Such variations in sedimentation rate in MG4-2 may be due to the human being activities in the catchment of Maigang Reservoir. Simultaneous uses of ¹³⁷Cs and ²¹⁰Pb methods may allow cross-checks of the results derived with the two methods and thus lead more reliable and accurate chronology and sedimentation rate.

Abstract:The appropriate experiment method for researches on seed loss and displacement is probed through several rainfall simulation experiments on loess incline. Based on the conventional method of simulated rainfall experiment,the following aspects need to be stressed:(1) Seeds for experiment should represent the main species and different shapes in the study area. (2) Seeds should be placed on soil surface as seed loss mainly occurs on the soil surface. (3) Seeds need to be dyed to distinguish the original seeds in soil. (4) Seeds of each species should be placed in a definite location and misplaced among species in order to accurately measure the distance of seed movement. (5) The amount of seeds placed in experiment should not be too much because this way influences soil surface roughness. (6) It is better for the big seeds to be placed in the bottom of seed placement area to avoid its effect on runoff path.

Abstract:Based on the DEM (digital elevation model) of Jiangjiagou watershed,Yunnan Province,the watershed is compartmentalized into some sub-units according to landform by using Geographical Information System software. With the information data of land use,soil classification,hydrology,and meteorology,the fitting CN values for sub-watersheds are presented and the CN distribution map is drawn by the GIS software. The hydrograph of calculated runoff process by the SCS model and isochrones method is fitted well with observed runoff data. It shows that SCS model can be successfully used in Jiangjiagou watershed and simulated result can supplement observed data. This paper provides a method to study the distributed hydrological model in Jiangjiagou watershed.

Abstract:It is essential for regional soil erosion survey and monitoring to calculate LS factor at the watershed and regional scales. Based on the theories of slope hydrology and soil erosion and the technologies of digital terrain analysis,the principles for slope and length factor are summarized and the methods and flowchart are suggested. By taking Xiannangou as an example,the LS themes are extracted and the characters are analyzed statistically and cartographically. The issues that should be studied urgently are discussed at last.

Abstract:The disused sandy soil districts of the Yellow River suffer comparatively serious soil and water loss. The result of soil erosion in different underlying surfaces and slope surfaces is obtained through the 2006's observation from the experimental station of soil and water loss. According to the statistical data of 2006's observation from the three runoff plots in upstream,middle-stream,and low-stream of the disused districts of the Yellow River,the soil erosion module from ordinary farmland is found to be 1 191~2 714 t/km² per year; from forestland,550~1 157 t/km² per year; and from gully-slope land,7 779~8 658 t/km² per year (for slope degree between 17° and 22°). The soil erosion module from artificial disturbed farmland is 2 to 4 times that from undisturbed farmland.

Abstract:Taking China as the test area,the three kinds of methods for detecting the cloud and snow on Spot Vegetation S10 images are compared. According to the comparison,BISE is the best for detecting cloud among the three; the cloud extracted by the status map (SM) is too little; cloud and the ice and snow extracted by the detector V2.0 overlap each other. The averaging of timely neighboring (before and after the cloud pixels) cloudy (or ice and snow)-free pixels is adopted to remove cloud,ice,and snow. The result is valuable for noise reduction and application accuracy improvement of Spot Vegetation S10.

Abstract:Based on the analysis of structural characteristics and species status in the Castanopsis orthacantha community,a primary vegetation type in the phosphorus mineral region of Fuxian Lake watershed,the paper analyzes and develops the reasonable species disposition pattern of Castanopsis orthacantha community in the abandoned phosphate mining. Results show that Castanopsis orthacantha has the prominent role in the maintenance of species composition and community structure,so it is the best species in the restoration of phosphorus mineral region. The reasonable species disposition may make the restored Castanopsis orthacantha community to be the reasonable structure,abundant species,and biosystem stability and restore the ecological service functions of the mining as soon as possible.