Abstract:Because the natural and geological environment along the south section of Sichuan-Tibet highway( in Tibet) is unique and fragile, debris flow in the area has repeatedly blocked off the mainstream, forming huge dams, and the outburst floods have caused catast rophic damages to the downstream in the recent decades.13 groups of indoor dam-br eak flood model tests were constructed to study the induced flood routing.It is found that the most important factor affecting the discharge of the outburst flood is the developing form of the breach, of which the gravitational initiation causes the largest discharge, followed by hydraulic initiation, and the least one is g radual erosion. The flood discharge and the upstream discharge show the linear relationship approximately . The flood peak occurs when 30% ~ 50% of the reservoir capacity is effused and the time of flood peak in the timeline concent rates on about 1/ 3 of the entire flood duration, no matter what the breach type is. The study can provide a reference to the prediction of debris flow dam-break flood and is beneficial to the comprehensive disaster mitigation in the downstream areas.

Abstract:In this paper, we studied the spatial distribution of soil nutrient components in dif ferent grass sloping lands in the Yunwu Mountains. Results showed that in the horizontal direction, southern slopes and bare lands had a similar distribution of soil organic C and total soil N in surface soils( 0-15 cm), whereas nor thern slopes had an opposite distribution pattern. Additionally, total P varied greatly along sloping lands regardless of slope direction. In soil profiles, soil organic C, to tal N, mineral N, Olsen P, and CEC were all decreased with soil depth and followed the order of nor thern slope > southern slope > bare land, yet pH values presented contrary distribution pattern. The distribution of available K varied with slope type, while total P changed slightly with soil depth. Both soil proper ties followed the order of bare land > norther n slope > southern slope. Our results suggest that soil nutrient conditions can be improved by natural re-vegetation and the improvement of soil nutrients are more obvious in northern slope than southern slope.

Abstract:Combined with the traditional and geostatistical methods, the distribution pattern of three forms of total, organic, and ammonium nitrogen in the sediment of Dianchi Lake was studied. Results showed that the spatial variation of various nitrogen forms in the sediment was great . The structural factor exerted a great impact on the total N dist ribution in the layer of 0 —50 cm, while the stochastic factor and structural factor showed a similar impact on the other N forms. Generally, the content of all N forms in the sediment decreased from the north to the south. Dark spot color was present in the center of the lake, indicating various N deposited preferentially in the lake center . Meantime, the spot color became light with the increasing depth, which suggested that the lake was polluted severely with the time.

Abstract:The impact of human activities on runoff and sediment change is one of the key topics worldwide.Runoff and sediment change is interactively affected by climate change and human activit ies. The impact of human activities on runoff and sediment change is analyzed based on the similar precipitation condition ( SPC)because precipitation is the source of runoff and the power of soil erosion and sediment delivery in the Yanhe River. In the paired??periods with SPC, the depth and process of precipitation are similar. A 50??year data series( 1952 - 2001) of annual precipitation in the basin and r unoff and sediment at Ganguyi Hydrology Station of the Yanhe River are analyzed. Results show that there are clear stages of runoff and sediment change influenced by human activities in the SPC. Compared with the period from 1954 to 1963, runoff in annual and flo od seasons from 1969 to 1977 is reduced by 18. 03% and 32. 52%, and sediment, by 47. 08% and 47. 52%,respectively; from 1981 to 1984, runoff is reduced by 29. 77% and 46. 29%, respectively, and sediment in bo th cases, by 73. 46% ; and from 1988 to 1996, runoff in annual and flood seasons is reduced by 71. 72% and 97. 79% and sediment, by 162. 07% and 161. 88%, respectively .

Abstract:It is difficult to plant grass on rocky slope during road bio-technique const ruction, because the key techniques are related to the features o f rocky slope, plant selection, and the optimization compound ratio of planting material .By taking the Loudi section of Louzhan Railway Line as an example, the environmental characteristics of the slope are analyzed and parameters correlated to slope vegetation protection for weathered rocky slope are studied .The grass composition based on laboratory seeding test is optimized by root growth and germination rate of grasses for slope protection .The influence o f main component parts of planting material on its strength is analyzed according to laboratory normal experiment .The schemes for optimum compound ratio of planting material are achieved, which make its strength maximum in different periods of rainfall after construction .Technology of the spraying, the coverage, and the later period management are practiced to ensure the implementation of mixly spray for rocky slope greening under the hot and rainy weather successfully .

Abstract:To reveal the mechanisms of soil erosion by sheet flow is important for the understanding of erosion processes on loess slope. With artificially simulated rainfall tests, sheet flow erosion processes on loess hill slope are studied and the follow ing results are obtained: ( 1) Under different rainfall intensities, sheet flow erosion varied similarly with rainfall process and can be described with power functions. Sheet flow erosion increased with rainfall duration increasing. ( 2) Under different slope gradients, sheet flow erosion increased with rainfall intensity increasing and can be described by linear equations. ( 3) Under different rainfall intensities, sheet flow erosion modulus increased firstly and then decreased with soil gradient increasing. Their relationship can be described by log-linear equations. ( 4) Under different rainfall intensities, the relationship can be descried by power equations. ( 5) Under different rainfall intensities, slope gradients, and slope lengths, sheet flow erosion can be described by ternary linear equations. Rainfall intensity affected erosion modulus most greatly, followed by slope gradient, and slope length behaved minimal impacts.

Abstract:Soil water content in 0 —160 cm layers in mobile dune, fixed dune, and sandy grassland was monitored regularly in sit u with neutron probe (CNC100, Beijing) from 2005 to 2008. The relationships between soil moisture and environmental factors were analyzed with multiple comparison and ANOVA. Results showed that three layers can be identified according to the vertical changes of soil water content in each site. They were drastic change layer (0 —40 cm), relative stable layer (41 —130 cm), and activity layer (131 —160cm) . Soil water content was increased with the increase of sample depth in layer of 0 —40 cm, but decreased in layer of 41 —130 cm in all sites. However, soil water content was decreased continuously with the increase of sample depth in layer of 131 —160 cm in mobile dune only, but increased in other sites. By the coefficient variation of soil water content, landscape units presented the order of mobile dune > fixed dune > sandy grassland. There was a significant difference in soil water content in all sites in each month and by soil water content, months have the order of J uly > August > J une > May > September . Variation of soil water content between years showed that there were a decreasing trend in fixed dune, a bit of difference in sandy grassland,and a complex pattern in mobile dune as affected directly by rainfall.

Abstract:On the Loess Plateau, dif ferent vegetation types in a forest water shed play an extremely important ecological role in soil and water conservation. By investigating and observing the 6 major forest types in Caij-i achuan watershed, analytical hierarchy is used to evaluate the vertical structure and water conservation capacity of forest types. Results show that the vertical structure of a good stand type is corresponding to strong water conservation. Accordingly, existing stands of Liujiaao water shed are adjusted and the ability of water conservation is greatly increased by 35. 99%. The most significant increase is the soil available water-holding capacity which is increased by 45. 94% .

Abstract:Daily changes of leaf water content, transpiration rate, leaf water potential, and root water potential of Robinia Pseu doacacia from different stand densities and soil water within 60 cm of soil surface in the proving ground were studied on typical clear days during the peak season. Results are listed as following : (1) Daily average leaf water content of different stand densities was lower in August than J uly and was in the sequence ofρ₂₂₀₀>ρ₂₀₀₀>ρ₁₄₀₀>ρ₁₆₀₀>ρ₁₈₀₀ in the two months. (2) Diurnal variation of t ranspiration rate was similar in both months, meaning that the curves changed f rom“double peak”style to“single peak”with increased stand density and all the peak values appeared between 13 :00 and 14 :00. Daily average transpiration rate wasρ₁₈₀₀>ρ₁₆₀₀>ρ₁₄₀₀>ρ₂₀₀₀>ρ₂₂₀₀ in July and August . (3) Daily average leaf water potential of different stand densities was in the following order in both months :ρ₁₈₀₀<ρ₁₆₀₀<ρ₁₄₀₀<ρ₂₀₀₀<ρ₂₂₀₀ and was apparently lower in August than in July, with more obvious daily variation in August than in July. (4) Root water potential was higher than leaf water potential, with daily variation obviously less than leaf water potential, and daily average root water potential of five stands with different densities was in the order ofρ₁₈₀₀>ρ₁₆₀₀>ρ₁₄₀₀>ρ₂₀₀₀>ρ₂₂₀₀ and was lower in August than in July, with more obvious daily variation in August than in July.(5) Difference between leaf and root water potential ( S —L ) was negatively related with transpiration rate ( Tr) and such a relationship can befitted by logarihmic curve. (6) Leaf water potential of R. Pseudoacacia increases with leaf water content, the relationship between them can be described by logarithmic curve. (7) With the increased soil depth, soil water variation was lower in July than in August and the average soil water in 0 —60 cm layer declined with increased stand density. From the respective of effective water utilization and the best growth vigor, 1800 st rains/ hm² is the reasonable stand density.

Abstract:The soil water characteristics in typical artificial forest lands ( Robinia pseudoacacia, Hippophae rhamnoides, and Caragana intermedia) with different ages and the slope grassland as contrast in the loess hilly region are studied. Results show that (1) soil water holding capacity in artificial forest lands is low and by soil water holding capacity, the artificial forest lands have the order of Robiniapseu doacacia > Hip pop hae rhamnoides > Caragana intermedia. Soil water holding capacity increases as the age increases. (2) Soil water conductivity increases significantly as the age increases and saturated hydraulic conductivity in Robinia pseudoacacia land is higher than that in Hip pop hae rhamnoides and Caragana intermedia lands at the matured stage. (3) The increase in the saturated soil water content is found with the increase in age. 4) Soil water holding capacity and conductivity in the artificial forest lands are not better than those in slope grassland repaired by itself .

Abstract:The effects of gravel mulch on soil microbial population, enzyme activity, and physicochemical properties were evaluated on the wasteland in Xiang shan area, Zhongwei City, Ningxia Hui Autonomous Region. Four typical sites were selected as a chronological sequence ( 3, 8, 15, and 25 years) and an adjacent no n-mulched gravel land was taken as the control. Results indicated that compared with the control, the number of microbes in the gravel mulched field was decreased. With the increased year of gravel mulched field, soil urinary enzyme activity presented a declined trend. The contents of soil organic carbon, total nitrogen, available nitrogen, and potassium declined for the sites of 3, 8, and 15 years. The soil water content in gravel mulched field was higher than the control, but the total salt content was much lower than the control.It is suggested that gravel mulch on wasteland can restore vegetation through preserving water, but soil fertility and microbial biomass are low .

Abstract:In order to investigate the effects of plastic mulch on soil temperature and water consumption of winter wheat on dryland, a field experiment was carried out . Results indicated that plastic mulch and manure increased soil temperature obviously at early growth stage and the effect only appeared on soil surface obviously at latter growth stage. Single plastic mulch had better effect in increasing soil temperature and was more previous compared with single manure at early growth stage, while single manure had higher temperature than single plastic mulch at latter growth stage. Plastic mulch and manure improved not only water consumption of wheat significantly through increasing water consumption from jointing to anthesis, but also yield and the WUE. Single plastic mulch had better effects in increasing soil temperat ure, saving water, and increasing yield and the WU E compared with single manure.Mixture of manure and plastic mulch reduced the effect in increasing soil temperat ure by plastic mulch at early growth stage and improved the effects at latter growth stage, reduced water consumption at seedling stage, and improved water consumption of mulch-covered wheat (3. 5 %) weakly, while yield and the WUE were increased sharply by 10. 6 % and 7. 6 %, respectively. By the influences of manure applied on soil temperature and water consumption of mulch-covered wheat, manure can regulate exuberant growth of mulch-covered wheat before winter, but promote mulch-covered wheat’s senescence during maturity stage.

Abstract:On the loess plateau, fluctuating land surface forms microrelief . Using the difference of soil moisture content on microrelief to improve the survival rate of vegetation has become an important method in ecological restoration and construction. Using probe-type TDR, we measure the soil water content on microrelief and the corresponding original slope in Hejia valley, Wuqi County, Shaanxi Province. Results show that microrelief has a significant impact on soil moisture content . In terms of soil water on sunny slope, landform units may be ranked in the descendant order of collap se, gully bottom, platform, shallow gully bottom, original slope, and scarp . The variation coefficient of soil water (0 —20 cm surface soil) at gully bottom is the biggest (0. 405) and on platform, the smallest (0. 226) . The variation coefficient of soil water on shady original slope is less than that on microrelief of sunny slope. Therefore, in the vegetation restoration of the Loess Plateau, we should configure vegetation types in the vegetation restoration units determined by the traditional principles according to the soil water characteristic on microrelief .

Abstract:The submerged soil may dissolve in water and influence water quality when a reservoir begins to run. the Laohutan Reservoir in Taihu Lake basin is taken as an example. In order to study the dynamic features of reservoir water about p H, DO, COD_Cr, BOD, nitrogen, phosphorus, and fluoride within 60 days,after taking samples from bamboo soil, paddy soil, and natural water on site, a simulation experiment is carried on. Results reveal that soaking bamboo land and paddy field soil lead to the reduction of the pH and DO in water and however, the contents of COD_Cr, BOD, nit rogen, phosphorus, and fluoride are increased. Compared to the paddy soil, bamboo soil impacts reservoir water quality more seriously. This is why we recommend taking corresponding treatment measures for bamboo soil .

Abstract:Removal effect of Cl adophora fracta (Dillw. ) Kuetz. on benzene, toluene, and xylene is studied using L9 (34 ) orthogonal design. Results show that the removal rates of benzene, toluene, and xylene are 46.6 %, 13. 6 %, and 7. 4 %, respectively. The effect of the different processing conditions of C. fracta on benzene removal rate is analyzed. Analysis indicates that the temperature is the primary factor of the removing effect and the exposure time and algal weight take the second and third places. For the removal of the toluene, the main factor is the exposure time and the next is the algal weight and temperature. But for xylene,the algae weight is the most important factor .

Abstract:The relat io n between diurnal variation of leaf net photo synthetic rate ( P_n ) and ecophy siological factors for three years old leaf of Hedera nepalensisvar. sinensis under drought stress was analyzed using CIRAS??2 portable photo synthesis system. T he diurnal variation of H . nep al ensisvar. sinensis photosy nthesis and its midday depression phenomenon was explained clearly and its predominant environmental factors under drought stress were ascertained. Results showed that diurnal variation of H . nep alensis var. sinensis photo synthesis and its micro-environmental factors were connected with soil moisture nearly at the same time. With the agg ravation of drought stress, the daily average and maximum P_n was decreased significantly . Compared with check treatment, the means of P_n in the drought stress of mild treatment, moderate treatment,and severe treatment were reduced by 15%, 47%, and 70%, respectively. With the aggravation of drought stress, the diurnal variation of photo synthesis changed from a single peak curve to a double peak curve and the predominant cause of midday depression turned into non-stomatal limitation. By the methods of stepwise multi??regression and principal component analysis, there was an obvious difference in the environmental factors of impact Pn under different drought stresses. Under the condition of mild soil moisture, the causes of diurnal variation of P_n can be classified into two categories: one was air temperature, relative humidity and CO₂ concent ration and another was photosynthetic active radiation. The effects of photosynthetic active radiation, CO₂ concentration, and relative humidity on P_n became more and more conspicuous with increase in drought stress and relative humidity was the dominant factor.??

Abstract:Four groups of agro-forestry intercropping trials were carried out in Anhui Province. Results showed that nitrogen and phosphorus loss in runoff was significantly reduced by contour cultivation of sweet potato and cotton as compared with longitudinal cultivation. The contents of nitrogen and phosphorus in runoff were 10. 481and 0. 122 mg/ L in contour cultivation of sweet potato, while they were 43. 112 and 0. 285 mg/ L in downslope cultivation, respectively.The contents of nitrogen and phosphorus in runoff were 3. 779 and 0. 109 mg/ L in contour cultivation of cotton, while they were 38. 980 and 0. 288 mg/ L in downslope cultivation, respectively. Ditches not only intercepted runoff and sediment, but also reduced the losses of nitrogen and phosphorus carried by water and sediment. In observation period, ditches intercepted the loss of nitrogen ( 575. 09, 631. 18, 199. 45, and 710. 05 mg in 1 to 4 plots) and the loss of phosphorus ( 54. 54, 21. 42, 23. 24, and 30. 13 mg in 1 to 4 plots) in runoff. Ditches also intercepted the loss of nitrogen ( 3. 00, 2. 95, 1. 07, and 3. 35g in 1 to 4 plot s) and the loss of phosphorus ( 0. 80, 0. 67, 0. 21,and 0. 69 g in 1 to 4 plots) in sediment . Sweet potato-poplar-cotton-poplar intercropping not only significantly reduced soil and water loss, but also reduced the amount of nitrogen and phosphorus loss. The losses of water and soil in sweet potato-poplar-cotton-poplar inter cropping were 2623 and 17. 31 g / m², while in single sweet potato-growing, they were 3138 and 19. 76 g/ m² and in single cotton-growing, 2658 and 17. 87 g/ m²,respectively. In sw eet potato and cot ton, the av erag ed losses of nit rog en and phosphorus in runoff were 17. 88 and 0. 25 mg / m², while in sediment, 21. 30 and 5. 24 mg/ m², respectively. In sweet potato-poplar-cotton-poplar inter cropping, losses of nit rog en and phosphorus in runof f w ere 14. 23 and 0. 22 mg / m², and in sediment, 20. 08 and 4. 85 mg/ m², respect ively. Agro-forestry production and eco-ditch measure have important roles in preserving water, soil, and nutrient and control ling agricultural non-point source pollution.

Abstract:The objects of soil and water conservation in the first national census for water resources include soil loss, erosion channel, and soil and water conserv ation measures. The census for soil loss adopts the methods of combing macro remote sensing survey with ground system sampling survey and utilizing soil erosion evaluation models to evaluate the distribution, size, and intensity of different erosion types. Erosion channel census uses the elementary data from remote sensing and DEM to gain the location of erosion channel and obtains the area, number, and distribution by field survey and spatial analysis additionally. Through analyzing various basic data comprehensively, soil and water conservation measures census acquires the types and quantity of engineering measures and plant measures.

Abstract:The risk degree assessment of regional landslide is a research topic important to the disaster prevention and landslide alleviation. According to the data of landslides, the future landslide frequency and it strend can be forecast and the forecast can dynamically evaluate the risk degree of regional landslides. Based on the landslide data in Wanzhou of the Three Gorges Reservoir area, the time records were analyzed and the Hurst index of the different regional ranks and time extensions was st udied. The experimental relationships of the Hurst indexes for the landslide areas of M > > 1 000 m², M > > 10 000 m², and M > 100 000 m² in 1980 —1990 and 1980 —1995 were acquired respectively. According to the Hurst indexes, this method forecasted the maximum fluctuation of landslides in the future 5 years. The function relationship between time correlation and the Hurst indexes was st udied by Fractional Brownian Motion. The relationship forecasted quantitatively the development trend of regional landslides. It is showed that the frequency forecast of regional landslides can dynamically evaluate the risk degree of regional landslides.

Abstract:Vegetation is one of the most important and most sensitive impacting factors of soil erosion. Vegetation information products that have high resolution in both time and space are needed to study dynamic changes of vegetation, for better understanding and monitoring of soil and water loss. A method is proposed to get high spatial and temporal resolution NDVI products, by matching the histogram of ETM NDVI( 30 m) to that of SPOT/ VEGET ATION NDVI product ( 1 km, one scene every month) . The estimated NDVI products( 30 m, one scene per month) are analyzed based on several indicators such as statistical characteristics of image, histogram similarity, and image fidelity. Results from the research can be applied to dynamic evaluation and monitoring o f regional soil and water loss.

Abstract:Soil and water conservation programs have been institutionalized and standardized since the end of 20th century, but lots of practitioners make some mistakes when they work on the soil and water conservation program between construction projects and production and construction projects. There are many dif ferences in the soil and water conservation program between construction projects and production and construction projects. Based on the years experience of making the program, we summarized the similarities and differences between construction projects and production and construction projects in view of service life, soil loss prediction, soil loss prevention target, and other aspects. This work may be helpful to avoid the mistakes in making soil and water conservation programs.

Abstract:Based on the data collected at the Sand Drift Observation Station of Chinese Academy of Sciences,the characteristics of friction velocity, aerody namicroughness length, and shear stress during a sand-storm passing the Tengger Desert region were analyzed. Results show that the elements vary with time during the passage of the sand storm. The variation of wind speed is highly correlated with the height and the coeff icient correlations are all bigger than 0. 9.

Abstract:Basef low is the main source of stream flow in the dry season of a year. Due to the difficulty in measurement, it is important to select an adaptive basef low separat ion method for further baseflow research. In order to test the applicability of automated base flow separation methods on the Loess Plateau, six watersheds located in the hilly and gully region were chosen to estimate several widely used techniques, which are PART, digital filter technique, and smoothed minima method. Comparison shows that the results of all three type methods have little difference. The discharge hydrograph demonst rates that the result of digital filter method is more consistent with the actual discharge condition. Since the true values of the baseflow index are unknown, it is difficult to find which method may give the best estimation. However, the digital filter method appears to be more plausible than other methods for this region and the results from the method are objective and authentic. For the study area, result from digital filter method shows that the basef low index is 37%~ 64%, which means that basef low accounts for a larg e proportion of the total runo ff . However, the baseflow volume has been gradually reduced in the recent 48 years.

Abstract:A grid-based distributed hydrological model (three different grid sizes : 1, 2, and 4 km) is used to study the impact of grid size on hydrological process modeling in a large catchment of Xinjiang River, China. Results from the study indicate that scaling of grid size absolutely affects the partition of water dist ribution between surface runoff and subsurface flow, with modeled base flow increasing obviously as grid size increases. Modeled annual stream flow shows a slight decrease as grid size increases. Scaling of grid size has no significant effect on actual evapot ranspiration of the catchment, but water infilt ration increases obviously when surface slope becomes flatter with a bigger grid size. After calibration, the three grid size models all have a well performance in modeling stream flow, but the 2 km grid size model performs better than the other two models. From this study, it can be concluded that fine resolution of grid size does not mean to improve the modeling accuracy in a distributed hydrological model and coarse resolution of grid sizes can be used for stream flow modeling, depending on watershed size and the level of accuracy required. For a specific resolution of soil data, there is an optimum grid size at which the model performs best .

Abstract:Transpiration water is the main mode of plant water consumption. This study takes Larix principis-rupprechtii Mayr in the north of Liupanshan Mountains as a study object. The water consumption characteristics of Larix principis-rupprechtii Mayr are studied using advanced SL??F technology and then the relationship between transpiration rate and environmental factors is analyzed. A regressive model is constructed through analyzing the meteoric factors. The fuzzy transpiration model based on Matlab is designed and simulated. Results indicate that air temperature and air relative humidity directly affect transpiration rate.Solar radiation intensity can affect the transpiration rate of Larix principis-rupprechtii Mayr by influencing air temperature and air relative humidity .

Abstract:The soil and water assessment tool (SWA T) is a physically-based continuous event hydrologic model. This paper mainly introduces the sensitivity analysis model of the AVSWA T2005 and its verification in Yunzhou Reservoir basin. Based on the sensitivity analysis, the main parameters affecting the simulated values in the watershed are determined. Results show that the CN2, SOL_AWC, and SOL_ K parameters have the most significant influence on the simulated values of runoff from Yunzhou water shed, the sensitivity being in a high level ; and the SLOPE and GWQMN have the more significant influence on runoff, the sensitivity being in a general level . The parameters are adjusted based on the above analyzed results and the model is verified using over 10 years data of monthly runoff . Satisfied simulation results are obtained with the relative error under 15 % and Nash-suttcliffes coefficient (Ens) more t han 0. 7. The simulation result of SWA T model for Yunzhou Reservoir basin is good. Therefore, the application of sensitivity analysis module of SWAT model in t he soil-gravel area of North China may improve the accuracy of simulation dramatically.

Abstract:The traditional methods of DEM matching without control points are based on least squares matching and their pull-in-range are poor. Aimed at this problem, a new method combining genetic algorithm with least squares matching was proposed by this paper . In order to avoid the scaling coefficient converge to the false extreme value 0 easily when using genetic matching method based on traditional matching model,this paper established a new matching model using distance grading. Accordingly, this paper designed the matching procedures of the method combining genetic algorithm with least squares matching. Results from experiments with simulated data and actual data show that the new method proposed by the paper keeps the least squares matching's merit of higher accuracy and the genetic algorithm's merit of larger pull-in-range and has better robustness and higher converging efficiency.

Abstract:The spatial distribution of species is one of the important research projects in ecology. In recent years,much progress has been made in predictive models of species with the development of applied ecology, but on the other hand, it makes more difficult to use the species distribution models because the number of available techniques or models is large and is increasing steadily, making it confused for users to select the most appropriate methodology for their needs. So evaluat ing and comparing the predictive accuracy of different distribution models has great significances for selecting and using these models. BIOMOD ( BIOdiversity MODelling ), a new computation framework based on R language, is presented. Yanhe River basin was selected as the study area. In order to select a suitable model for simulating and predict ing the typical species distributions in the study area, nine widely used modeling techniques in species predictions, such as artificial neural networks ( ANN), were compared to predict the representative species distribution. The comparison of their dif ferences in predict ion accuracy can not only provide evidence for select ing species dist ribution models, but also lay a foundation for projecting the species spatial distributions into different environmental conditions ( e. g. climate change scenarios) . Three available techniques of Roc, Kappa, and TSS were used to assess each model's performance. Results from the model comparison showed that the relative model performance and simulation accuracy of different models were quite different across species. The evaluation indicated that the nine models had the highest predictive accuracy for the Thymus mongolicus dist ribution, yet the predictive accuracy of the Artemisia gmelinii distribution was the lowest. Furthermore, the nine models can predict the distribution of the rest species very well. It is concluded that the RF model which has the highest predictive accuracy using the three methods is the best one among the nine models.

Abstract:Using the tools o f VS 2005, SQL 2005, Surfer 8. 0, etc., the regional services system o f drought monitoring and early warning and evaluating over Northwest China is built. The system is the first regional network system in Northw estern China. It is the B/ S structure and users can get much more information on meteorological drought, agricultural drought, and ecological droug ht by operating the system online. The system may supply over 50 indexes and model analysis, such as standardizatio n precipitation index, relative humid index, comprehensive drought index, Penman evapotranspiration, waterr esource evaluation, and drought disaster evaluation concerning to drought monitoring and early warning and evaluation, which all can be calculated automatically. The system is heavily integrated and automatic. Most operation processes can be finished automatically. Now the system has been used for drought monitoring and early warning and evaluation services over the northwest region for nearly two years and can supply drought services conveniently .

Abstract:Dam break can cause disastrous consequences to natural, economic, and social systems in the downstream area. A nalysis of vulner ability to dam-break disaster helps develop measures of mitigating disaster losses. This paper presents a quantitative method for evaluating vulnerability of dam-break disaster based on data envelopment analysis method with the downstream area of Huaxi dam as an example. Results show that Xiaohe District and Nanming District have high vulnerability, Huaxi District has middle vulnerability, and Yunyan District has low vulnerability in the study area. The study also provides some reference values for developing measures of mitigating disaster losses.

Abstract:The main purposes of the study are to understand the growth situation of Salix psammophila germplasm resources and the classification and distribution of traits in the Mu Us sandy land in China and manage and use the Salix psammophila germplasm resources, scientifically and effectively. In order to determine the main distribution area of Salix psammophila, line transect method combined with random sampling survey method is used. Mathematical statistics is applied to analyze the variation of Salix psammophila and its grow th status. Survey results are as follows: ( 1) The height and crown range of Salix psammophila are in line with normal distribution and the variation range of crown range is greater than height . ( 2) Salix psammophila in different origin areas has significant difference in height, but no significant difference in crown range. ( 3) Salix psammophila in different origin areas differs in survival rate of cutting.

Abstract:Based on investigating and collecting information on the present situation of agro-ecological environment in Jing huiqu irrigation district of Shaanxi Province, soil samples are collected and the contents of heavy metals are analyzed. Meanwhile, soil environmental quality for heavy metals is evaluated by single factor index. Results show the average contents of Pb, Cd, Hg, As, Cu, and Zn in soils ar e 46. 0%, 105. 7%,90. 6%, 47. 8%, 12. 6%, and 178. 6%, respectively, higher than soil backg round values of Shaanxi Province.Only the content of Cr is similar basically. The variation coefficient of Cd is the biggest ( 1. 547) and that of A s is the smallest ( 0. 105) . There are no significant correlations among Pb, Cd, Hg, As, Cu, Zn,and Cr. The correlation between heavy metals and soil fertility index is not significant . The pollution degree of Zn is the highest and the average single factor index is 1. 48, which means pollution degree is at a light level.T he average single factor index of As is 1. 11 and it is also at a light level. The average single factor index of Cd is at no pollution level. The content s of Cr, Pb, Cu, and Hg are lower than the initial values of soil pollution accumulation basically .

Abstract:Based on the TM images of the oasis irrigation area in Tailan River in 2000 and 2005 and using the RS, GIS, and landscape ecology method, this paper calculated the transformation matrix of the landscape mosaics and analyzed the relationship between the land use change and the dynamics of runoff and groundwater resources and their exploitation in the oasis irrigation area. Results showed that from 2000 to 2005, farmland area and water area increased and the annual average increased 3603. 8 and 151. 4 hm², respectively. The forest and grassland decreased constantly and were reduced by 2247. 07 and 14325. 9 hm² . In all, the greenbelt decreased 16 572. 97hm² . The grassland and forest turned into farmland from transformation matrix and the ratio was 13. 97 % and 5. 93 %, respectively. Although runoff decreased distantly, the quantity of exploited groundwater increased drastically from 5. 9 ×105 m³ in 1989 to 1. 39 ×107 m³ in 2003. As a result, the area of irrigated field and the quantity of wells increased quickly. Moreover, groundwater resources were exploited severely and the level of groundwater decreased instantly. The ratio of agricultural water to ecological water was irrational, agricultural water expanded quickly, and ecological water dwindled distinctly.

Abstract:Gravel land utilization in Ningxia Hui Autonomous Region has nearly a hundred year of history. In recent years, it is rapidly developed under the effective organization and guidance of the government . Such manner not only has significant economic benefits, but also has the ecological functions of water collection, moisture maintenance, warming, reducing dust, and controlling salt . Along with many years of farming, the traditional farming manner may cause land aging, even loss of the ecological functions of mulching land, which has a negative impact on local agro-ecosystem. The paper analyzes the land aging mechanisms based on the ecological function of the gravel land and gives some suggestions on strengt hening the management of gravel land ecosystem.

Abstract:Based on the remote sensing images of 1976, 1989, 2001, and 2007, the land use information of urban fringe in Harbin City was extracted with the method of human-computer interaction. This paper focused on the quantitative characteristic and space variation characteristic about the urban fringe of Harbin City. Results showed that during the 31 years from 1976 to 2007, the urban area of the city increased persistently, especially between 2001 and 2007. From the landscape pattern of construction land, the number of patches increased and the compactness index decreased from 1976 to 2001, while it was opposite after the year of 2001.The expansion of construction land had the obvious space differentiation characteristic and the expansion of urban construction land can be reflected in various directions at different times.

Abstract:Combining field monitoring and laboratory analysis, this paper analyzes COD_cr and TSS fluxes of a typical suburb discharge sewage in Dianchi Lake catchments. We use the pollution load of urban rainfall runoff to estimate the pollution load of suburb rainfall runoff and analyze the ratios of COD_cr and TSS caused by rainfall runoff to the total load. Results show that by suburb discharge sewage per capita load, COD_cr is 9. 58～10. 57 kg/ a and TSS is 2. 88～3. 14 kg/ a and by the suburb pollution load of rainfall runoff, COD_cr is 1. 166～1. 458 t/ (hm² ·a) and TSS is 0. 729～1. 808 t/ (hm² ·a) in the Dianchi Lake catchments. Throughout the year, COD_cr and TSS caused by rainfall runoff account for 10. 96 %～15. 35 % and 25. 73 %～35. 89 % of the total catchment area of emission pollution load, respectively. Control of rainfall runoff pollution is one of the ways to mitigate non-point source pollution of suburb in the Dianchi Lake catchments.

Abstract:As a current community-wide hot issue, soil and water conservation eco-compensation has aroused extensive attention. Based on the analysis and discrimination of the current theory and practice of soil and water conservation eco-compensation, we further define the core of soil and water conservation eco-compensation, i. e., the basis of compensation, the subjects of compensation, the objects of compensation, and the standards of compensation, as well as the way of soil and water conservation eco-compensation, i. e., the policy compensation, project compensation, financial compensation, in-kind compensation, training compensation, employment compensation, moral compensation, etc. In addition, we analyze and assess the main practices of soil and water conservation compensation currently adopted in Yellow River basin, which are setting the concepts and senses of conservation and protection of resources, promoting the sustainable development of ecological environment and enterprises, establishing the mechanism of soil and water conservation eco-compensation initially, providing a model for soil and water conservation eco-compensation, and so on.

Abstract:The morp hological anatomy of stems and leaves of Artemisia sacrorum Ledeb. var . messerschmidtiana at 200 mg/ L of lead was studied. The changes were manifested as follows : For the stems of non-mining area eco-type at 200 mg/ L of lead, there were few changes in the organizational structure. The stems of mining area eco-type showed the adaptability to lead : both the thickness of epidermal and cell wall increased.The thickness of catheter of xylem increased and there was black substance in the catheter . For the leaves of non-mining area eco-type, there were great changes by lead stress. The entire structure of organization was loose; the shape of cell was irregular ; the sizes of cells were not the same ; some cells appeared disintegration in the organization ; and the chloroplast contained in the whole cells decreased significantly. But for t he leaves of mining area eco-type, the organization was completed ; the cells arranged closely ; the shapes of cells were regular ; and the sizes of cells were the same. Mining area eco-type appeared strong adaptability to lead st ress, which provides an excellent germplasm resource for the theory and practice of phytoremediation of lead contaminated soil .

Abstract:Land conversion is an inevitable phenomenon in the process of economic development . As to the economic development, land conversion is an input factor and however, in different stages of economic development, the factor has different effects on economic development . In order to explain the relationship between the spatial difference of land conversion and the stages of economic development, this paper adopts the change rate of arable land occupation and imbalance index of land conversion. Results show that the rate of farmland conversion is gradually descending, among all land categories and the change rate of arable land occupation in city construction, industry, and mining is the fastest . At the same time, the imbalance of land conversion relative to GDP and non-agricultural sectors is increasing and the imbalance relative to labor of non-agricult ural sectors is decreasing. On the whole, spatial difference of land conversion in J iangsu Province is basically in conformity with the level of economic development .

Abstract:In order to increase the livability and survival rate of young apple trees in the loess hilly and gully areas of Northern Shaanxi Province, soil physical properties and young apple tree growth were monitored by the three treatments of soil preparation by digging hole before rainy season, after rainy season, and in spring. Results showed that soil bulk density was decreased and soil total porosity and soil non-capillary porosity were increased after soil preparation by digging hole. For the treatment of soil preparation by digging hole before rainy season, soil moisture was increased in spring and tree growth prophase period ; soil temperature difference between daily max-temperature and daily min-temperature was decreased; tree livability was increased ; and tree growth was promoted. However, for the treatments of soil preparation by digging hole after rainy season and in spring, soil moisture was decreased ; soil temperature difference was increased ; tree livability was reduced ; tree growth was weakened ; ground subsidence depth was deepened in plant year ;branch water content was reduced in the winter and spring ; branch shriveling index was increased ; and tree survival rate was decreased. Soil preparation by digging hole before rainy season is suggested when apple trees were planted in the loess hilly and gully area of Northern Shaanxi Province.

Abstract:According to forest resources inventory of the Tenth Five-year Plan in and by taking Xishan Forest Farm of Beijing City as an example, a rapid assessment indicator system of forest ecosystem health is established based on the integrality indicator, stability indicator, and sustainability indicator. Indicator weight is determined by applying the method of AHP. By using forest health assessment model, the health assessment in Xishan Forest Farm at subplot scale is studied. Results show that there are 367 subplots in Xishan For est Farm and 70. 3% of them are in sub-health condit ion. The eight indexes determined can reflect the forest ecosystem health statement of Xishan Fo rest Farm and they are easy to use, with a certain degree of science and operation.

Abstract:Road networks may greatly influence hydrologic and geomorphic processes in a watershed. The relationship between road distribution pattern and landuse type is crucial for the quantization of road network characteristics in a small watershed. This study was conducted to explore the manner in which landuse type affects road network distribution pattern. Road networks in different periods( 1982 and 2002) were extracted based on high resolution remote sensing images of Zhifanggou watershed in the central Loess Plateau. In turn, the road networks were overlaid with the landuse types in corresponding periods. GIS spatial analysis and statistic methods were used to study the correlation of road segment position and length with the changed landuse types. Results show that in a watershed, the changed landuse may influence road netw ork significantly. Nevertheless, roads in different levels receive different effects from changed landuse type. Roads of the third and forth levels are influenced more greatly than the second level roads. Linear function may be used to describe the relationship between the forth level road length and the area of land blocks. An equation optimized by the landuse type affection degree to human activity is proposed to get road length based on land block areas.

Abstract:The returning farmland to fo rest project has brought important effects on the succession of regional agricultural eco-economic system. By analyzing the implementation effects of the project in Mizhi County of high population density over the past 10 years, it is found that vegetation is restored and forest coverage is increased by 13. 85%. Soil and water loss is controlled effectively and the degree of soil and water loss control is enhanced by 12.73% . Farmers income has been raised, their lifestyle and ideas have been changed notably, and regional industrial structure has been optimized. It also proves that ecology can be coordinated with economy in the development of the loess hilly area.

Abstract:This paper classifies the types of land evaluation units using a four hierarchy of indexes step by step and evaluates the land suitability for reclamation of bauxite region in Pingguo County of Guang xi Zhuang A uto nomous Region by the way of sum of weig hing and indexes. Results are as follows: ( 1) The best suitability of the thick platform non-polluted, which is composed of top soil and surface soil and the ratio of top soil to surface soil is 4:1, is the third-class dryland. ( 2) The best suitability of the thick platform non-polluted, which is composed of bottom soil and fly ash and the ratio of bottom soil to fly ash is 3:1, is the seco ndclass dryland. ( 3) The best suitability of the thin slop non-polluted, which is composed of top soil and surface soil and the ratio is 4:1, is the first-class garden plot. ( 4) The best suitability of the thin slop non-polluted, which is composed of bottom soil and fly ash and the ratio is 3:1, is the woodland o f the third grade.The result may provide a scientific basis of reclamation planning for mining enterprises and it is beneficial for reducing cost and the sustainable development and utilization of land resources in bauxite region in Pingguo County.

Abstract:Taking the Mountain Lianhua Natio nal Nature Reserve in Gansu Province as its object and conducting the sample field investigation, this research was carried out with an attempt to study the recreational impact on vegetation in the Mountain Lianhua .Results show that in terms of the recreational impact on vegetation, the investigated sites are in the order of the Zixiao Palace >the Nature Reserve Administ ration >Tangfang Beach-Shahe Beach >the Lianhua Palace .Analysis shows that among the four investigated sites, the Zixiao Palace has a sharp difference compared with the others .As the research indicates, the recreational activities have caused some impacts on vegetation in some scenic sites and some parts in the Mountain Lianhua National Nature Rese rve, but the impact on the entire ecolog ical environment of the nature reserve is not much .

Abstract:The Rock-art Protection Zone of Helan Mountains is the Chinese culture and art treasures for thousands of years. It is located on both the pluvial fan and the ent rance of Helan Valley, a typical debris flow valley in Helan Mountains, and is of ten damaged by debris flow. Based on both the environmental background of Helan Valley and the feature analysis of debris flow ravine, some suggestions are put out to solve the problems of debris flow to the Helan Rock-art and ancient village relics. The suggestions are the combination of hazard defense and partition governance, the integration of project arrangement and biological measures, and the cooperation of disaster reduction and emergency system.

Abstract:Based on the historical data of cultivated land and economic development in 1990 - 2006, the paper analyzed the spatiotemporal change characteristics of cultivated land in Changsha City. The main factors to driving forces in cultivated land change were then analyzed by the principal component analysis and multiple regression analysis. Results showed that (1) the cultivated land in Changsha City presented a downward trend in 1990 —2003 and a slight rising trend in 2003 - 2006. The annual decline percentage between 1990 and 2006 was about0. 26 %. (2) Regional difference between regions was obvious. (3) The principal component analysis indicated that economic factor and agricultural factor could be summed up as the two main factors to reducing cultivated land in Changsha City and the economic factor was the key one. (4) Multiple regression analysis also indicated that the economic factor was the most important influence factor to the change of cultivated land in Changsha City.

Abstract:To evaluate the quality of ecoenvironment in Shaanxi water source area in the middle route of the south??to??north water transfer project objectively can provide the decision??making and reference for the implementation of the project . Under the guidance of ecological system theory and by using remote sensing techniques and the analysis methods of geographic information systems, the paper extracts six factor layer data affecting environmental quality in the study area, then stacks them to be the integrated environmental index layer data, and finally divides it into four environment divisions. From the result of spatial statistical analysis, the first and the second integrated natural indexes are the best, account ing for 64. 69 percent of the total water area; the third is better, accounting for 31. 52 percent ; and the forth is poor, accounting for 3. 79 percent. To evaluate and study the eco-environmental quality in Shaanxi Province comprehensively can provide a data support and a decision??making basis for ecological compensation and soil and water conservation in the middle route of the south??to??morth water transfer project.

Abstract:Based on the current reclamation conditions in Chenzhou City, we located storeho use and wasted area at Chang cheng Mountains lead-zinc polymetallic mine in Yizhang County and carried out a series of researches on soil pollution and its reclamation. Evaluation on the current pollution situation of the storehouse and wasted area in the mine was mainly made. Results showed that the pollution of mullock and soils in the mining area was serious. The main pollutants were As in mullock and As and Cd in soils. Based on the evaluation results, some suggestions were proposed for the reclamation of seriously polluted mining area during the service time and the end of service time.

Abstract:Undergraduate training objective is key to undergraduate education. On the basis of the analysis for the advantages and disadvantages of current undergraduate education objectives of the soil & water conservation and desertification control major, four aspects about scientific personnel training orientation, supply and demand relationship, professional and discipline relationship, and relatively stable clientele are discussed and improved subsequently. The new training objectives are initially identified. With the new training objectives, the students graduated from the major can master the basic theories, knowledge, and skills of soil and water conservation and desertification control, possess the related knowledge of biology, geography, water conservancy engineering, environmental science and engineering, agronomy, agricultural resources utilization, animal science, forestry, management and law, and have the solid background for continuation education or become the specialized personnel capable of wo rking on the research, teaching, planning, design, construction, controlling, monitoring, and management of soil and water conservation in the department of water administration and related departments.