Abstract:From the samples collected in field, in Xizhaogou wa tershed in Inner Mongolia, China in 2005.Soil organic matter content is measured in laboratory.The result indicated that the soil organic matter content in the gully with seabuckthorn flexible dam is much higher than that without the flexible dam.The flexible dam has the notable ecological effects of improving soil organic matter content and soil fertility in gully.At the same time, the result shows that soil organic matter content has a certain vertical variation, but the maximal value occurs in the surface soil layer in most cases.Soil organic matter content increases gradually from upstream to downstream in the gully with seabuckthorn flexible dams and in the dam body.This change is similar to the longitudinal change of sediment thickness in the gully with dams.

Abstract:A study of conservation tillage was conducted in the semi-arid area of the west Loess Plateau, Gan- su Province, to determine the eff ects of diff erent tillage measures on soil water infiltration.Results show that no-tillage with straw cover(NTS) can improve soil structure property, soil organic carbon content, and soil water infiltra tion.Path coeff icient analysis indicates an improvement of soil water infiltration due to the increase in soil macro-porosity and total organic carbon content.The contribution of total organic carbon to soil water infilt ration is also essential to soil macro-porosity.

Abstract:Soil erosion processes on hillslopes of purple soil under three near-surface hydrological conditions of free drainage, saturation and seepage were studied by stimulated rainfall experiments.Results showed that near-surface hydrological conditions greatly affecting soil erosion processes on hillslopes of purple soil.At slope gradients from 5° to 15°, erosion rate from hillslopes shif ted from 1.31 2.02 g/(min?m²) under free drainage to 1.83 5.50 g/(min?m²) under saturation condition; under seepage condition, erosion rate reached to 4.40 16.41g/(min?m²).Erosion rate under saturation condit ion was 1.40 2.73 times greater than that under free drainage; erosion rate under seepage condition was 3.36 812 times greater than that under free drainage and was 2.40 2.98 times higher than that under saturation condition.Meanwhile, slope gradient had a great impact on purple soil erosion processes.

Abstract:Through the analysis of the erosion characteristics of Mt.Mang loess and the coal ash on 25 slope, little runoff was found at the beginning of rainfall under the conditions of different materials and diferent rainfall intensities.As rainfall continued, runoff and sediment increased gradually and then reached sharply high values.After the process continued for a few minutes, they dropped to a steady state.The sharp value and steady time were very different under different materials and different rainfall intensities and occurred early when rainfall intensit y increased.Generally, the sharp value and steady time for sediment occurred 13 min less than runoff.In addition,the erosion characteristics of light coal ash are the same as those of loess under high rainfall intensity.

Abstract:Four tillage treatments were carried out for five years by simulated rainfall in the middle area of the Loess Plateau: traditional tillage(T), traditional tillage with straw incorporated(TS), no-tillage(NT), and no tillage with straw cover(NTS).Runoff starting time, amount of runoff, and amount of soil erosion were measured af ter harvest of pea.Under rainfall intensity of 85 mm/h, ru noff process was alleviated and the amou nt of ru noff was red uced using NTS.Compared to NT, TS, and T, the amounts of runoff under NTS were red uced by 2.4%, 12.1%, and 34.7%, respectively; infiltration rates were increased by 2.7%,13.6%, and 38.6%; runoff starting times were slowed down 1.17, 0.83, and 3.83 min; the amounts of soil erosion were red uced by 0.3%, 17.7%, and 62.4%.Therefore, the effects of soil and water conservation under NTS are most obvious and soil erosion is easily to take place u nder traditional tillage.

Abstract:Heavy rain event has a significant influence on soil water content in arid area.Through field investigatioq on soil water content under Nitraria tangutorun nebkhas in different sucession periods before and after a heavy rain event(47.6 mm) at Minqin County, its effects on soil water content and reservation of nebkhas were analyzed.Results indicate that(1) soil water content and reservation of nebkhas in different succession periods have a consistent variation trend in 1 m thick soil layer.The range of vertical variation for soil water content is biggest in rudimental period and it has a most unstabilized variation.Stabilized period has anot her extreme.(2) Soil water content replenishment depths of nebkhas in diff erent succession periods are different from each other.Ma ximum soil water content replenishment depth of nebkhas in developing and degrading period is 50 cm and in rudimental and stabilizing period, 30 cm.(3) The total amounts of soil water content replenishment in different succession periods are diff erent from each other.The total amount of soil water content replenishment in developing period is the biggest, about 74.66% 90.06% of the total preci pitation and in stabilizing period, the smallest, about 12.27% 12.86% of the total precipitation.

Abstract:Soil water is a critical factor of eco-environmental construction and land exploitation.Based on the fixed observation in the immigrant demonstration area of Nort hwest Guangxi Province from April to September in 2006, the dynamic change of soil water on hillslope with various landuse types was analyzed.Results showed that the dynamic change of soil water storage had the similar trend with the change of rainfall.In temporal scale, soil water storage in 0-1 m layer had the significant differences among various land use types.Landuse types rankes in the decreasing order of slope farmland, orchard land, wasteland, natural shrub land, and arbor woodland.In spatial scale, soil water storage on hillslope was in moderate variation and had some differences among various landuse types.Soil water storage of grassland and shrub land was higher in 0-20 cm layer, but it was higher on slope farmland and orchard land in 60-100 cm layer.Soil wa- ter had the increasing trend from the top down to the bottom along the hillslope with the different land use struct u res.However, the range of variation for soil moist ure along the hillslope with contour terrace was smaller than that of natural slope.

Abstract:Reforestation plays an important role in soil conservation and soil carbon sequestration.Five types of artificial vegetation were selected in the Wangdonggou watershed located in the hill and gully area of the Loess Plateau to understand the influences of artificial vegetation on soil properties.Soil moisture, soil or- ganic C(SOC), and total soil nit rogen were investigated under different types of vegetation.During dry sea- son, there was the intense water consumption characteristic in locust tree forest land and soil water content below the 200 cm depth ranged from 5.8% to 7.1%, showing a decrease wit h depth.Compared to grass- land, Chinese pine forest land had a soil water content of 15% in the same layer.Soil moist ure used for ori- ental arbor-vitae, sea-buckthorn, and apple was mainly distributed between 20 and 200 cm from soil surface.Although natural rainfall had a supplement to the forest land, soil water within 50 cm of soil surface was recharged in rainy season.Compared with grassland, SOC content was increased by 9.3% for Chinese pine and decreased by 40.1% for orchard.SOC contents of sea-buckthorn, oriental arbor-vitae, and locust tree were lower than those on grassland, although not significantly.

Abstract:This paper aims to explore the way to find the species combination for the vegetation restoration on the abandoned filed in the loess hill and gully area.From the classification of 33 abandoned field samples by the TWINSPAN classification method, it follows that there were 5 comm unities in the past 40 years, include ding the communities of Artemisia aria, Leymus secalinus, Lesped eza davurica Stipa bungeana, Artemisia gmelinii, and Bothriochloa ischaemum.The main species niche characteristics were analyzed based on the resources and environment integration of each community.Finally, some suitable species combi- nations were found.This result can offer people the direction to nat ural vegetation restoration.

Abstract:Abstract: Soil water characteristic model, holding water parameter, and specific water capacit y on three farming-withdrawn lands(6, 11, and 16 years) and four enclosed grasslands(Thymus mongolicus, Artemisia gmelini, Stipa gra is and Sti bungeana communities) are studied by cont rasting wit h slope plantation in a typical grassland on the Loess Plateau.Results show that soil holding and supplying water capabilities in enclosed grassla nds are better than farming-wit hdrawn lands and the cultivated sloping land, but grazing on the 11 year grassland has a significant eff ect on the capacities.The t rea tments, in terms of soil holding water capabili t y, rank in the descendant order of Stiρa bungeana, Stipa grand is, Thymus mongolicus, Artemisia gmeli 巾,16 yea r withdrawing, 6 year withdrawing, cultivated sloping land, and 11 year withd rawing(grazing for 8 years) and in terms of supplying water capa bility, Stiρa bungeana, Thymus mongolicus, Artemisia gmel in, Stipa grand is, 16 year withdrawing, 6 year withdrawing, and 11 yea r withdrawing(grazing for 8 years), and cultivated sloping land.Farming-wit hdrawn land and enclosed grassland can improve soil holding and supplying water capability by promoting soil water physical properties.

Abstract:We investigated soil moist ure deficit, interannual and inner-ann ual changes, dry layer features, and restored capability of nat ural precipitation in slope Caragana land and wasteland in the hilly and gullied area of Nort hern Shaanxi Province by positioned measurements and comparative analyses.Results showed that water storage in 0 -10 m soil profile was only 26.2% 41.2% of its water-holding capacity in slope Ca- ragana land, while it was 39.8% 41.2% in slope wasteland.Slope segments, in terms of spatial dist ribu- tion of soil water storage, were in the ascendant order of south faced slope, semi-sout h faced slope, andnorth faced slope, as well as upper slope and lower slope.Inter-annual variation of soil moist ure lowered wit h increased soil depth and the changes of soil water storage mainly took place in O-2 m soil profile.Soil water storage was characterized by obvious seasonal changes but lagged behind rainfall.Within growing season, averaged soil water storages were of significant diff erence between slope Caragana land and wasteland and the variation of soil moisture content was alleviated with increased soil depth.There existed a dry soil layer in soil profile to different extent in bot h Caragana land and wasteland.Comparatively, in deep soil, the dried degree of the soil layer was greater in Caragana land than wasteland.In a bumper year of precipitation, the restored depth of soil moist ure was down to 1.0 m of the soil profile in Caragana land and to 1.2 min wasteland.In Caragana land, the restored depth of soil moisture was 60 cm greater in a bumper year of precipitation than a lean year and soil water storage increased by 3 times in 0-5 m soil.

Abstract:Soil nutrients, enzyme activities, and t heir correlations during land use change in the semiarid area of the Loess Plateau are studied.Results show that catalase activit y may indicate the right transformation condition of available P and available K in alfalfa land and organic matter, total N, and alkaline N in waste- land, as well as the negative transformation condition of available P in Sea-buckthorn land, but it may not indicate the fertilizer condition in field soil.Polyphenol oxidase activity may indicate the right transformation degree of organic mat ter and total N in field soil and the negative transformation degree of organic matter and total N in vegetable garden and orchard, but it may not indicate the hum us transformation degree in soil.Invertase activity may indicate the right transformation degree of alkaline N in field soil, vegetable garden and orcha rd, alfalfaland, and wasteland and the negative transformation degree of alkaline N in sea-buckthorn land.At the same time, it may fully indicate the negative transformation degree of available P in wasteland and the right transformation degree of other nut rients.Urease activit y may indicate the fertilizer level of total N, alkaline N, and organic matter in vegetable garden and orchard.Phosphatase activity may indicate the right t ransformation condition of available P in vegetable garden and orchard, field soil, and wasteland, but it may not indicate the phosphorus transformation condition of other land uses.

Abstract:Many researches on soil erosion and soil and water conservation under various conditions can be conducted using artificial rainfall simulation.The research period can be greatly shortened with the aid of the technique.Rainfall simulation has already become an important technique for laboratory and filed experiments and an efficient approach to collecting data of soil erosion, soil and water conservation benefits, and soil erosion modeling.Based on the discussion of basic requirements and types of artificial rainfall simulator, the structure, principles, advantages, and disadvantages of trough rainfall simulator are analyzed in detail.The objective is to stimulate the processes of research and manufact ure on rainfall simulator and to promote the progress of related researches in our country.

Abstract:Soil water-holding agent is a kind of material for water saving developed in recent years.The agents of LT 200, LT-100(made in San-yan Ind ust rial Company, Japan), Huang-guan and Bo-ya were tested in field experiments to study the effects of different soil water-holding agents on spring wheat plant, tree transplant, and tree seeding raising.Results showed that in the experiment of spring whea t plant, LT- 200, LT-100, H uangguan and Boya increased yields by 13.60%, 11.43%, 4.13%and 3.52%, respectively, with the average of 8.17%.They increased water use eff iciency by 1.00, 0.84, 0.31 and 0.26 kg/ mm ? hm², respectively, compared with controls(field without adding soil water-holding agents).Especially, the increases by adding LT-200 and LT 100 agents were significant. At same time, LT-200, LT- 100, Huangguan and Boya enhanced soil water storage in 120 cm depth by 27.64, 26.92, 14.04 and 13.82 mm, respectively, compared with cont rols in spring wheat planting experiment.Soil water-holding agents couldincrease the dry root weight of spring wheat, but the increases were insignificant.Effects of different soil water-holding agents on tree transplant and tree seeding raising in one year growth were limited.Applied methods and the amount of soil water-holding agents added to soil need further studies.

Abstract:The decennial evolvement of abnormal rainfall in flood season over the Loess Plateau of China were studied using the rainfall data of the recent 40 years.Results showed that the range of abnormal rainfall decreased in flood season.The rainfall belt significantly shif ted to the south with 1.8 lat.degrees from 1960s to 1990s and 0.6 lat.degrees from 1960s to 1980s.Each of the first 3 models of rainfall had different change points and periods, but multiple periods and weak surges corresponded wit h rainy time, being contrary to the time of rain shortage.The region sensitive to abnormal rainfall flowed from nort heast to southwest.The west part of the Loess Plateau tended to be arid.

Abstract:This article put forward a sequential mathematical model for warping dam construction in small watershed.The productive benefit and sediment holding capacity of the dam were considered as the main elements.The best const ruction sequence was based on the analysis of maximizing economic benefit.Comparing with other models, the model took three practical factors of discount rate, harvest insuring rate and constructive investment into account.Finally, the model was applied to Hushan small watershed to prove its rationality.

Abstract:Soil fertilities of three you ng broadleaf mixed plantations were compared with those of a Cunninghamia lanceolata plantation.The soils of the broadleaf mixed plantations were rather strong in acidity.Among four plantations, the contents of soil organic mat ter, total N and available P were the highest in the first evergreen broadleaf mixed plantation, and its other nutrient contents were higher than the C.lanceolata plantation or similar to the latter; Total P, total K, alkalized N and available K were the highest in the sec- ond evergreen broadleaf mixed plantation, and its soil organic matter, total N and available P contents were greater than C.lanceolata plantation; Soil organic matter, total N and alkalized N of the third evergreen broadleaf mixed forest were greater than those of the C.lanceolata plantation, whereas its other nutrient contents were lower than the latter.The amounts of soil bacterium, fungi and actinomyces of the first and second evergreen broadleaf mixed plantations were greater than those of C.lanceolata plantation, and their urease,phosphoric acid enzyme and catalase activities were high, indicating that the two plantations significandy improved soil fertility.

Abstract:Based on vegetation communities inside and outside fish-scale pits on the different slopes of small watershed, the relationships between vegetation comm u nities inside and outside fish-scale pits and latitude as well as slope aspect are discussed.The results d rawn from this case study are as follows:(1) The coverage of t he vegetation community inside fish-scale pits on northern slope is higher than that on southern slope, reaching a very significant level.(2) Slope aspect is not the dominant factor in determining the diversity of the vegetation communities.(3) The relationships between altitude and the vegetation community richness outside fish-scale pits with different land uses, Shannon-Wiener indexes, and indexes for the vegetation communities inside and outside fish-scale pits with the same land use pattern can be described by parabolic functions, reaching a remarkably significant level.However, the relationship between altitude and diversity indexes of vegetation communities inside fish-scale pits does not reach a significant level.The results imply that community diversity can be increased by methods of changing niche, such as fish-scale pit preparation.

Abstract:Photosynthetic rate(P.), transpiration rate(T.), stoma conductance(G.), and light response curve of Potentilla d iscolor Bunge were measured in the field using an open gas exchange system, Li-6400 Porta ble Photosynthesis System in the hilly area of the Loess Pla tea u.Results showed that the diurnal va ria- tion of net photosynthetic rate presented a single-bottom curve.The maximal P.was 14.91 μmol/(m²?s) at 8:00 a.m and the minimum P0.13 μmol /(m²?s) at 14:00 p.m.Potentilla d iscolor Bunge got into the state of photosynthetic noon break. The light compensation point, the light saturation point, and apparent quant um efficiency of Potentilla discolor Bunge were 51.4, 527, and 0.0566 μmol/(m²? s),respectively.This indicated that Potentilla d iscolor Bunge was a typical sun plant.During the course of light response, with RPA increasing, T, rose and its diurnal variation was in agreement with G,.There was an exponent rela tionship between T, and G, The water use efficiency(WUE) of Potentilla d iscolor Bunge abided wit h a parabola model as RPA increased.At the beginning, WUE increased greatly and the maxim um appeared at 4.68 mmol/mol when RPA was 800 μmol/(m² ? s).Then WUE decreased with a less variation.

Abstract:Soil conservation can greatly influence runoff by reducing sediment into river.Runoff cost for sediment control, shown as RRS(ratio of runoff retained to sediment retained) of different soil and water conser- vation measures is an important integrated indicator to evaluate the impact on runoff and sediment synchro- nously.Based on the reported research results on the effects of soil and water conservation on runoff and sed- iment in North China, runoff cost for sediment control with different measures and integrated measures at different basin scales is analyzed.The regional differences of runoff cost for sediment control by integrated and individual measu res are distinct.If soil and water conservation measures with a smaller RRS are adopted, more runoff can be saved in red ucing the same amount of sediment and water resource conditions can be improved in the arid and semi-arid areas.

Abstract:Based on the theory of unsat urated soil water dynamics, a three-dimensional axisymmet ric model is set up to simulate soil water movement under gravity subsu rface drip irrigation(SDI).Soil water movement is simulated with the aid of Galerkin finite element method and the model is testified wit h experiments.The result shows that this model can be used to simulate soil water infilt ration process wit h higher accuracy u nder SDI.Wetting pattern and infiltration process are simulated concerning different irrigation technique factors.Under the same irrigation quantity, pressure head and emitter diameters have a minute eff ect on the wetting distribution pattern and so they can be ignored in the process of SDI pipe design, while they have a significant impact on the emitter effluent.During t he SDI pipe design, the emitter diameter and water pressure head can be determined according to the field lengt h and t he water loss of infiltration pipe.Moreover, the lower pressure can be adopted.The pipe depth has conspicuous influence on wetting distribu tion pattern and so its de- sign can be based on the field practical situation.All t he conclusions can provide a theoretical basis for rea- sonable gravity SDI design and operation.

Abstract:This study is based on the characteristics of nat ure, society, and economy of Wuqi County, Shaanxi Province.Through frequency analysis and expert consultation, the evaluation index system of ecoenvironment quality for Wuqi County is stablished and the weight of each index is calculated by using the met hod of analytic hierarchy process(A HP).Af ter eliminating the dimension influence, the eccγenvironment qualit y index for Wuqi Count y from 1995 to 2004 is calculated.In view of the nat ural eco-environment, social eco-environment, and economic eco-environment, the va riation of eco-environmental quality of Wuqi county in the past ten years is qualitatively evaluated and quantitatively analyzed.The research work provides a reference for sustaina ble development of Wuqi County and the Loess Plateau.

Abstract:Since the beginning of converting farmland to forest or grassland, fewer researches have been done to evaluate the comprehensive efficiency of converting farmland to forest or grassland in a region.Starting wit h an explanation for the necessity of indicator and using a theoretical approach, the authors try to find a set of scientific indicators for converting farmland to forest or grassland in a region.The indicators can be easily mani pulated by technical staff, and hopefully, the results can be used pragmatically and completed gradually.

Abstract:The purpose of the study was to compute design flood frequency by the optimized algorithm.According to the regulations of design flood frequency computation for water resources and hydropower projects, a curve fitting method of design flood frequency was presented by using the particle swarm optimization and applying the WLS, ABS, and WLS.The method was then applied to the practical computation of design flood frequency.Results indicate that the method presented in the study is better than the empirical fitting met hod.Comparing with other conventional optimization met hods, it requires a lower target function and need not compute the differential coefficient.The method is a new way of inferring statistical parameters of design flood frequency curve.

Abstract:Soil samples under plastic shed vegetables in Longdong and its surrounding areas on the Loess Plat- eau were analyzed.Results showed that both soil salt accumulation and acidulation in topsoil were evident and the amounts of main soil n ut rients are increased.The reasons for the change are the over applied fertiliz- er, poorly added organic manure, continuous cultivation, irrational irrigation, etc.We should increase or- ganic man u re, limit mineral fertilizer application, improve fertiliiing practice, perform irrigation and drainage scientifically, and u ndertake rational rotation in the future.

Abstract:Based on complexit y and nonlinearit y of soil erosion and sediment in small watershed under single rainfall event, the support vector regression(SVR) and method of the principal component analysis(PCA) were used to determine key factors affecting soil erosion and sediment from Wangjiagou watershed under sin- gle rainfall event.Results showed tha t mud runoff depth, peak flood discharge, maximum 30 min rainfall in- tensity, and rainfall amount were key factors affecting soil erosion and sediment in Wangjiagou watershed.An erosion prediction model by SVR was developed based on observed data for 60 rainfall events in Wangjia-gou watershed.The model validation indicated that the model predicted precision reached as much as 86% for60 rainfall events.The research illustrates that SVR provides a new approach to study complexity and non- linearity of soil erosion and sediment in small watershed under a single rainfall event.

Abstract:The bryophytes play a very important role in soil and water conservation and water source holding in a slope ecosystem.This paper studies the species, spatial variabilit y, and the environmental factors of the bryophytes on four slopes including railway slope and natural slope along the Cheng-Kun railway and the ChengYu railway.The result shows that the species of the bryophytes are significant!Y.different between the Jiajiang site and the Jintang site.There are about 7 species in Jiajiang site, whereas only 2 species site in Jin- tang site In Jiajiang site, the species of bryophytes on railway slope are more than the species on natural slope, but the species of bryophytes in Jintang site are the same on railway slope and nat ural slope.Largest water holding of bryophytes in Jiajiang is distinctly higher than that in Jintang site.The biomass of bryo- phytes is negatively related to the weight of withered litters.However, the biomass of bryophytes is positively related to soil rigidit y, while there is a negative relation between the biomass of bryophytes and the coverage of herbage.

Abstract:According to the basic principles of fractal theory and spatial scale effect, Cesium- 137 isotope tracer technique was used to measure annually averaged soil erosion modulus of small watershed in the hilly area wit h pu rple soil in Cent ral Sichuan Province.Moreover, annually averaged deposition modulus of differ- ent small watersheds was investigated.The relation of sediment delivery ratio to rainwater collection area of small watershed was discussed.The statistical model of the relation between sediment delivery ratio and spa- tial scale effect !If small watershed was constructed.The model can be used to estimate sediment delivery ra- tio and sediment yield of small data-lacked watershed in the hilly area with pu rple soil.

Abstract:By analyzing the data of sediment observed in 11 hydrological stations in Ganjiang River, severe soil and water loss is found in Taojiang, Ganshui, Zhangshui, Pingjiang, Wujiang and Suichuanjiang, etc.The average volume of sediment in the upper reaches of Ganjiang River is larger than that in the lower reaches.Transported sediment mod ule is 144/km2 in Wan’ an statjon, 136/km ² in Ji’an station, 131/km² in Xiajiang station, 112/km² in Zhangshu station, and 114/ km ² i n Wuzhou station.The average diameter of sediment particles is 0.04 0.066 mm, and the change in sediment content is consistent with the changes of bot h the seasons of a year and rainfall or runoff.Lastly, suspended load and soil and water loss are studied, and the countermeasures are presented so as to be the basis for the further technical application in the future.

Abstract:According to the data from the investigation of vegetation with soil and water conservation supervise measures, this paper discusses the roles of self-recovering vegetation in development and construction projects and probes into the effects of self-recovering vegetation on the evaluation indexes of soil and water conservation.The results obtained indicate that if surface soil is well preserved, surface vegetation self-recovering accounting for nearly one-fourths afforestation area can be gained in the abundant rainfall area.De- pending on self-recovering vegetation on disturbed ground in the abu ndant rainfall area, primary vegetation coverage degree can reach more than 50% within 2 years.Owing to serious vegetation damage, shrubbery vegetation can not be completely recovered wit hin 2 years and self-recovering vegetation on disturbed ground is generally the herbage communities.

Abstract:Meixian County of Guangdong Province was approved as one of the demonstration counties for soil and water conservation eco-rehabilitation in 2002.Many control measures have been developed, eco-rehabilitation benefit monitoring has been implemented, and notable effects have been obtained.Based on the prac呻 tices in the county, a suitable assessment system for eco-rehabilitation benefits is provided.Meanwhile, the system is applied to analyze and appraise monitoring results.It has been proved that the benefits from the eco-rehabilitation of soil and water conservation in the county are improved to a great extent.

Abstract:The historical change of desertification in Shiyang River basin was introd uced and the desertification monitoring results in 1999 and 2004 were analyzed.The total area of desertif ication was found to increase by 6.47%, about 164271.6 hm2 from 1999 to 2004, with an average annual i ncrt·ase by 1.29%.From the view desertification changes in type and degree, it is concluded that the desertif ica t i on l'vol u tion t rend of Shiyang River basin is characterized by the whole improvement but local deterioration.

Abstract:Soil erosion is t he first and most important problem to a highway construction project.Usually,highway construction units do riot carry out soil and water conversion supervision, so implementing the supervision is very essential to highway engineering.Meanwhile it is proved to be feasible from theory or prac- tice.The program of implementing soil and water conversion supervision in highway engineering should in- elude establishing standards and regulations, deciding operation model, drawing up operation program, mak- ing management ways and working systems, and determining the major contents of supervision.

Abstract:With the method of BP neural network, simulation and prediction of runoff generation and sediment yield in four different runoff plots(farmland, wood land, artificial grassland, and abandoned land) are studied.Relative errors of runoff generation in four different plots are 0.2%- 5.7%, 0.1%- 2.5%, 0.7%-2.9%, and 0.1%-3%, respectively; relative errors of sediment yield, 0.1%-3.2%, 0.2% -3.1%,0.6%-4.2%, and 0.2%-2.7%; maximum relative errors of runoff generation, -11%, 14%,-14.6%, and 18%; the maximum relative errors of sediment yield, 10.9%, 27.3%, 15.0%, and 26.3%.The results show that the effect of simulation and prediction of runoff generation and sediment yield using the met hod of BP neural network is good and that application of this method to the analyses of impound and intercepting sediment from runoff plot is feasible.

Abstract:Soil and water conservation at county level is characterized by the extensive project management, tremendous construction projects, dispersed locations, and various document types.In the meantime, the 3S technologies have applied to soil and water conservation, gradually and widely.Accordingly, the GIS based management information system on soil and water conservation at count y level is analyzed and designed.Sys- tem needs and target, fundamental techniques and functions, and initial operation are outlined.The management system function struct ure is discussed, including assistant plan design, dynamic data management, wa- tershed management, document management, and thematic map management, as well as such functions as inquiry, statistics, and report form.It will not only provide a scientific means for project management of ecological construction, but also bring forward a new pattern for the construction of management information system on soil and water conservation at county level.

Abstract:Water resou rces are a kind of strategic resources and have the vital significance to the regional ecological environment security and sustainable development.This paper utilizes the GIS secondary development technologies to set u p an information system for regional water resource management, which includes data management subsystem, model base subsystem, and water resource management subsystem.Evaluation model of regional water resource stress based on the artificial neural network belongs to the model base sub- system and it quantitatively reflectst he coordinated degree between regional water resource conditions and regional population, economy, and environment by the water resource stress index.The model is then vali- dated by the case studies for the whole Shaanxi Province and cities in the province.The result proves that it has theoretical f easibilit y and realistic significance.Its application and the development foreground are discussed finally.

Abstract:Water resources are the main limited factor in Inner Mongolia, and so a development plan should consider the balance of water demands and supplies firstly.Based on water resource carrying capacity, this paper attempts to analyze and assess the rationality and feasibility of the eleventh five-year plan of Inner Mongolia A utonomous Region.The methods of scenario analysis and pressu re assessment are applied.Resuits show that the amount of water demands is some 2.52 ×1010 m3 under Scenario 1(water saving situa tion as past five years) and 2.06 ×1010 m³ under Scenario 2(water saving situation as planning for future five years).The water supplies would reach 2.29 ×1010 m³ up to 2010 and t hus, the wa ter supplies should meet the demand under Scenario 2 in general.But there is a: remarkable regional gap of water resource distribu tion in Inner Monglia.Only 24% of availa ble water resources are distributed in the middle and western area and the water shortage occurs in this area even if under Scenario 2.So the area of irrigation land should be decreased in fragile desert and semi-desert region along inland rivers and the Yellow River, such as in the Alashan area.The indust rial planning also should be regulated in accordance with water carrying capacity.

Abstract:This study takes the dynamic characteristics of soil moist ure of a whole year on Zanthoxylum Forest land in Huajiang karst valley, Guizhou Province as the overall objective.The relationships between soil water content and soil structure, vegetation hararteristics, and the dynamics of soil moist ure in different soil layers are analyzed and the change zones of soil water content in vertical direction are divided.Results indi- cate that water holding capacity of topsoil is higher than that of subsoil.The actual water content on forest land is higher than fallow land, and in deeper soil, higher than surface soil.Soil water content wit hin topsoil changes fastest due to the effects of evaporation and precipitation and it follows by intermediate layer and deepest layer due to the effects of transpiration and soil struct ure, respectively.Vertical change zone of soil moisture can be divided as follow: 0-20 cm is the rapidly changing layer, 20-50 cm is the transitional layer, and >50 cm is the stable layer.

Abstract:Karst collapse in intermontane basin is not completely different from that in Tangshan City.The karst collapse occurred mostly in the period between lower water and high water and it happened in loose cover of different thicknesses.In the region, water table in loose cover is the same as that in bedrock.On the basis of the characteristics, the main causes of karst collapse are analyzed in terms of the formation mecha- nism of soil cavit y.It is found that over pumped groundwater induces karst collapse in thick cover while rain- water seepage induces karst collapse in thin cover.The measures for preventing collapse are proposed accord- ing to the distribution of the disaster.

Abstract:As a result of population growth and economic development, t he intensity of landuse has been in- creased greatly, which has had and continues to have a negative impact on environment, especially in the mou ntainous areas with fragile ecological environment.Unreasonable landuse in the mountainous areas has a negative impact on ecological environment and sustainable economic development.Taking Yongding dist rict of Zhangjiajie City Hu’nan Province for an example, this paper reveals land use changes and their effects on ecological environment in the mountainous area of Western Hu 'nan Province.Results indicate that, with the growt h of urban area, the construction area, containing residing area, mining area, and transportation area have been increasing continually, while the area and qualit y of cultivated land have been decreasing gradual- ly.A large amount of natural forest has been cut down, which weakens the ecological functions.Land use changes have enormously influenced the ecological environment, such as intensive soil erosion, worsening of t he water quality, and biodiversity loss.

Abstract:Taking Zhifanggou watershed for an example, t his paper aims to design an evaluation index system for agricult ural ecology securit y in the loess hill and gully region.The developing course of eco-economic sys- tem is divided into 4 stages according to the conditions of agricult ural ecology securit y in nearly 70 years.Then the authors discuss the main factors which affect agricult ural ecology securit y and obtain a series of e- valuation indexes by analyzing the 4 stages.The evaluation indexes are selected, classified, and confirmed based on the index selecting principles of scientific foundation, developing condition, practicalit y, and so on,and by ref erring to the model of “ pressure state response”(PSR) and the suggestions from several experts.The evaluation index system of agricult ural ecology security suitable for the region is established, in- eluding ecological environment, social-economy, and integrative function, as well as 20 specific indexes.

Abstract:A review on the current situation of researches on soil water resource is presented.Based on t he concept of characteristics, a new definition of soil water resource is suggested.It has been pointed out that the soil water resource are defined as the renewable amount of soil water resources, which can be directly uti- lized for plants including crops and soil microbes at the depth where plant roots can absorb soil water.The article also expounds the characteristics of soil water resource, such as dependence on recipitation, easy consumption, beyond exploitation, validity or unavailable usability on site, and possibilit y to be controlled.The index system established for assessment includes four indexes: maximal stock of soil water resource, available quantit y of soil water resource, unavailable quantity of soil water resource, and the amount of actual storage.According to the assessment indexes, preliminary calculation for a typical area in the loess hilly area is performed.

Abstract:Rainfall can be intercepted and assimilated by soil and water conservation forest.Based on the ana- lyses of hydrological effects of canopy, litter fall, and soil for different stands such as Masson pine, Pinus elliotii, Chinese chestnut, and Masson pine &.Chinese chestnut mixed forest, the study showed that in terms of the interception amount of forest canopies, stands ranked in the descendant order of Pinus elliotii, Masson pine, needle-board leaf mixed forest, and Chinese chestnut.Stands, in terms of the effective inter- ception amount and water holding of soil for litter, ranked in the descendant order of Chinese chestnut, nee- dle-board leaf mixed forest, Masson pine, and Pi nus elliotii.When planting and managing soil and water conservation forest, the three layer hydrologic function should be optimized simultaneously and a prior con- sideration should be given to the needle-board leaf mixed forest.The forest had a complicated vegetation structure and was propitious to exert interception eff ect of needle leaf forest and headwater conservation function of litter and soil of board leaf forest.

Abstract:The landuse change and landscape heterogeneity in the Dongda coal mine are studied in comparison with no coal-mining subsidence.The changes of patch number and its avreage in various landuses, as well as fragmentation index, diversity index, evenness index,dominance index, and so on are analyzed.Results in- dicate that the development tencJency of ecological environment is unreasonable in the Dongda coal-mining subsidence area because coal-mining subsidence causes distortion of land surface, such as cracks, subsidence hole, and landslide.Consequently, it breaks the cultivated land into small pieces, brings an increase in patch number and a decrease in patch average area, and severely destroys vegetation in the region.

Abstract:The analyses of rainfall and evaporation of years in Northwest Liaoning Province showed t hat the significant difference between rainfall and evaporation is one of the important reasons for drought taking place in spring.The drought degree can be scaled by means of humidit y coefficient(0.33).Based on the coefficient.t he empiric frequency of 0.33 is calculated for every season in 20 years.The result showed that the distributing frequency of 0.33 is highest in summer and 85.71% in aut umn.Such a state can provide a good chance for taking the cover measure to control soil moisture in successive seasons.The control measures of deeply loosening soil in summer and plastic film used in aut umn can improve rainfall infiltration into soil and provide sufficient moist ure for seeding in next spring.

Abstract:The area of rocky desertification is about 704.98 km2 in the Qianjiang karst region of Chongqing City, occupying 29.39% of the total land area.Rocky desertification is seriously threatening living, production, and livelihood of local people and it becomes a serious problem in Chongqing City and South China.This paper dwells on the current situation of rocky desertification in Qianjiang karst region and its hazards and explores the causes of rocky desertif ication.Results indicate that the geological environmental factors, such as vegetation and soil, are basic to rocky desertification formation.Human irrational act ivities are the primary factor of rocky desertification formation and development.Some constructive prevention strategies and advices are proposed.

Abstract:Based on the harmonious development degree composed of assessment functions of economic and environmental benefits, the types of harmonious development between economy and environment and t heir dynamic evolution of Wuhu City are studied.Results show that harmonious development between economy and environment in the city has experienced the stages of elementary harmonious development and delayed econom behind environment(in 1995 and 1996), elementary harmonious development and environment and economy synchronization(in 1997), medium harmonious development and delayed economy behind environ- ment(in 1998 and 2000), medium harmonious development and environment and economy synchronization(in 1999 and 2001), medium harmonious development and delayed environment behind economy(in 2002 and 2003), and better harmonious development and delayed environment behind economy(in 2004).Unstable development of environment is the domina nt factor restricting the best harmonious development and synchronous development bet ween economy and environment in the city.

Abstract:This study is cond ucted for the purpose of improving the economic development of the coast zone of J iangsu Province.Based on the natu ral characteristics of the study region, the article discusses the characteristics of eco-environmental frangibility, the shortage of the resources such as capital, technology, and man- power, and the issues of polluted eco-environment with the economic development.For the contradictions be- tween economic povert y and eco-environmental frangibilit y, the cycling economic development pattern for the coast zone is expounded.At last, for the coast zone to develop cycling economy, it is suggested that the clean prod uction and eco-agricult ure should be developed in view of the protection of local eco-environment.

Abstract:The study was conducted for different grazing systems in the ecotone of grassland and farmland in Ningxia sandy lands.Results indicated that soil moist ure was higher in the 6th rotational grazing area and lower under the conditions of continuous grazing and enclosing.The varieties of it with seasons and rainfall amount under different grazing systems had the same trends.Soil bulk densities under enclosing and u nder 6, 4, and 2 areas rotational grazing were 6%, 7.77%, 1.96%, and 1.43% lower than that of continuous graz- ing, respectively, and soil porosities, 7.38%, 4.67%, 3.79%, and 4.72%, respectively.The contents of soil organic matter, total nit rogen, total phosphorus, and total potassium presented their maximums under free grazing, but the differences among the grazing systems tested were not notable.It was also showed t hat soil rapidly available potassium u nder the 6 areas rotational grazing was higher, and under continuous grazing was lower than the others.

Abstract:Terraced land may create a better environment for crop production by moisture conservation.In addition, terraced land is more resistant to soil erosion during intense storm and sediment from terraced land is lower than that from slope land.In yan’an, drought and poor soil fertility are the main rest rictive factors for the prod uction of dryland crops.From the practical perspective, research on t he techniques of water loss and use is essential.Great attention has been paid to the management, demands, and more efficient use of the limited water resource on terraced land.In this paper, the approaches of effective conservation and eff icient use of water on terraced land in Yan’an are reviewed, including conservation tillage, mulch cultivation, limit- ed irrigation, and introduction of water-saving varieties.Soil fertilit y improvement should be suitable to the local agricult u ral conditions in Yan’an.