侵蚀地区植被生态动力学模型

研究侵蚀地区的植被在水力侵蚀和各种生态应力以及人类活动影响下的演变规律 ,建立了植被生态动力学模型。将作用于植被的各种生态应力分成长期、短期和瞬时应力 ,给出了它们的定量表达式 ,并且统一在植被生态动力学方程中 ;同时进一步得出了动力学耦合方程组的理论解。该模型应用于金沙江支流小江流域 ,结果较好地描述了流域的植被生态演变过程与侵蚀过程的关系 ,说明了治理强度和控制侵蚀对植被发育的重要性。

高侵蚀性地区使用水泥电杆的问题

焉耆县地处是新疆巴州地区，是鱼米之乡，博斯腾湖盛产鱼类，一望无际的芦苇是造纸的优质原料。然而邻近公路的高压输电线路水泥电杆上的铁抱箍由于盐碱的腐蚀，电杆纵裂严重，已影响到线路的安全运行。

伊盟灌木草地在侵蚀丘陵沟壑地区水土保持中的作用

在伊盟1.3亿亩的土地上,丘陵沟壑区草地占25%,约3000多万亩,主要分布在准格尔旗、东胜市、达拉特旗南部。这些地区近百年来。

模袋混凝土在堤防工程中的实践与应用——以博斯腾湖大小湖隔堤模袋试验段为例

模袋混凝土工程是一项从国外引进的新技术,主要适用于护坡、水库建设等,它具有外型美观、坚固耐久、施工方便等特点。在博斯腾湖大小湖隔堤护坡工程中,成功应用模袋充填高性能混凝土的护坡结构形式,为其在西北严寒强侵蚀地区的推广应用提供了成功的经验。

Effect of Soil Erosion on Productivity of Sloping Field in a Micro-plot Experiment

[Objective] This study aimed to explore the effects of soil erosion on the productivity of sloping field. [Method] Through removing of and covering with topsoil in a micro-plot experiment, the effect of soil erosion on productivity of sloping field was studied. [Result] The results showed that there was extremely significantly posi- tive correlation between the thicknesses of covered topsoil with either the yield of maize seeds or the yield of maize stalks, which indicated that the yields of maize seeds and maize stalks decreased extremely significantly with the increase of the amount of surface soil loss caused by erosion on the sloping field. The yields of maize seeds and maize stalks decreased by 29.62% and 24.46% respectively in the treatment with removal of a 15 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks decreased by 17.31% and 20.14% re- spectively in the treatment with removal of a 10 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks decreased by 12.69% and 11.51% respectively in the treatment with removal of a 5 cm thick layer of ma- ture topsoil in the plow layer; the yields of maize seeds and maize stalks increased by 10.00% and 9.35% respectively in the treatment with covering with a 5 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks increased by 15.77% and 16.19% respectively in the treatment with covering with a 10 cm thick layer of mature topsoil in the plow layer; the yields of maize seeds and maize stalks increased by 17.69% and 25.18% respectively in the treat- ment with covering with a 15 cm thick layer of mature topsoil in the plow layer. [Conclusion] This study provides a basis for assessing the effect of soil erosion on sloping field.

Synthesis Analysis of Soil Erosion for Three-River Headwater Region Based on GIS

In this paper,based on the common soil erosion model,the Three-River Headwaters region was select for study object. GIS methods are applied to conduct Semi-quantitative assessment for different types of soil erosion,and some results are concluded. The water erosion occurs in High Mountain and extra-high mountain of Yushu,Nangqian,Banma and Jiuzhi County in the southeast and south of the Three-River Headwaters region. The degree of erosion is prone to topography,precipitation,river and human activity. The freeze-thaw erosion mainly distributes in the northwest of the Three-River Headwaters region. The area of middle and above middle erosion degree accounts for roughly 50%.

Application of Remote Sensing in Study of Slope Land Use and Soil Erosion in Subtropic Region of China

This paper introduces briefly two remote sensing case studies on land use in the subtropic region of China. One is on slope land use in the Yangtze River Three Gorges area. This is a large area of 60497 km2.First of all, geometric correction and supervised classification were conducted for ten scenes of Landsat-5 TM or MSS images. The resolution of the processed images is 50 m ×50 m on ground. By the classification the land use/cover categories in this area were discriminated. Then the croplands including rice fields and upland fields were extracted from the land use/cover maps. Simultaneously the slope grade maps were prepared based on the topographic maps. Overlaying the slope grade maps and the cropland maps, the area and percentage of the croplands in different slope grades were determined. This case study indicated that 71.5% of the uplands was situated on the slope above 15° and 25% on the slope above 25° in this area. It is dangerous, and urgent cultivation or engineering measures should be taken. Another case study is on soil erosion in Linshan County of Guangxi Province. Airphoto interpretation and supervised classification of a Landsat TM image were carried out for discriminating land cover/use categories in an area of 3557.8 km2.And the soil erosion intensity grades were determined according to the land cover/use maps and slope maps.It wed discovered that the land suffering soil erosion accounted for 2404.0 km2, 67.6% of the total area of the county. Necessary measures to control soil erosion should be taken also.

Methodological Framework for a Multi-Scale Study on Hydrological Processes and Soil Erosion in Subtropical Southeast China

This paper introduces and illustrates the concepts of geoecological process combinations and geographical or landscape dimensions by outlining the methodology of a Sino-German cooperative project in Southeast China and presents the first results of the modelling process for the catchment scale. The project equipped a catchment in subtropical Southeast China from plot scale to catchment scale in order to study the hydrological and soll erosion processes. Distinct spatial differences in principal water and soil material fluxes were quantified. Deep drainage peaks occurred in May, June and July and even in August and November. Measurements in erosion plots as well as sedimentary deposits revealed that there was soil erosion connected with overland flow. Consistent with the results from the regular catenary variations of soil colors, textural stratification and hydrograph analysis, there was also a clear indication of interflow from measured soil moisture data. The experimental set up has the potential to further deepen the understanding of small-scale processes involved in lateral water fluxes and soil erosion. The expected results and interpretations will lead to a further integration of the collected data. In the future, to understand matter transfer in and between landscape ecological units, agricultural influence on nutrient status and flux data will be incorporated.

The Typical Watershed of the Three Gorges Reservoir Area Soil Erosion Diversity Change on Different Slope Gradients Taking the Meixi River Watershed as an Example

[Objective] The diversity of soil erosion in the Meixi River watershed of the Three Gorges Reservoir Region was analyzed, in order to provide references for governance and protection of ecological environment of the study area. [Method] The soil erosion diversity index and evenness index of the Meixi River watershed in the Three Gorges Reservoir Region were studied based on the TM images in the year of 1988, 1999 and 2010, supported by GIS technology to extract various types of soil erosion in the area with different slope gradients and calculate soil erosion di- versity index and evenness index. [Result~ As slope gradients grew, the diversity in- dex and evenness index of soil erosion decrease after increasing with a turning point from 25~ to 35~. [Conchlsion] The proportion of light-erosion in the study area is 15.57%. Hence, the increase of diversity index and evenness index with gradients of 5^-35~ shows that the higher erosion intensity, the more uniform erosion types and the indexes decreased in gradients higher than 35°, suggesting that the lower erosion intensity, the better environment. Distribution and variation of different land types have close relation with soil erosion diversity and evenness indexes. Though soil erosion problems have been alleviated, by comparing soil erosion diversity index and evenness index, it can be concluded that changes of indexes are lower than 0.02, and soil erosion should be continued to be well controlled.

Using ^(137)Cs Tracer Technique to Evaluate Erosion and Deposition of Black Soil in Northeast China

Soil and water losses through erosion have been serious in the black soil region of Northeast China. Therefore, a sloping cultivated land in Songnen Plain was selected as a case study to： 1） determine the ^137Cs reference inventory in the study area; 2） calculate erosion and deposition rates of black soil on different slope locations; 3） conduct a sensitivity analysis of some model parameters; and 4） compare overall outputs using four different models. Three transects were set in the field with five slope locations for each transect, including summit, shoulder-slope, back-slope, foot-slope, and toe-slope. Field measurements and model simulation were used to estimate a bomb-derived ^137Cs reference inventory in the study area. Soil erosion and deposition rates were estimated using four ^137Cs models and percentage of ^137Cs loss/gain. The ^137Cs reference value in the study area was 2 232.8 Bq m^-2 with ^137Cs showing a clear topographic pattern, decreasing from the summit to shoulder-slope, then increasing again at the foot-slope and reaching a maximum at the toe-slope, Predicted soil redistribution rates for different slope locations varied. Among models, the Yang Model （YANG-M） overestimated erosion loss but underestimated deposition. However, the standard mass balance model （MBM1） gave predictions similar to a mass balance model incorporating soil movement by tillage （MBM2）. Sensitivity analysis of the proportion factor and distribution pattern of ^137Cs in the surface layer demonstrated the impact of ^137Cs enrichment on calculation of the soil erosion rate. Factors influencing the redistribution of fallout ^137Cs in landscape should be fully considered as calculating soil redistribution rate using ^137Cs technique.

Gully Erosion Regionalization of Black Soil Area in Northeastern China

Gully erosion is the frequent and main form of soil erosion in the black soil area of the northeastern China, which is one of the most important commodity grain production bases in China. It is encroaching upon the fertile farmland there. Regionalization of gully erosion can reveal the spatial distribution and regularity of the development of gully erosion. Based on the eco-geographical regional background features of the black soil area, this study combined the regionalization with influencing factors of the development of gully erosion. GIS spatial analysis, geostatistical analysis, spatial statistics, reclassification, debris polygon processing and map algebra methods were employed. As a result, the black soil area was divided into 12 subregions. The field survey data on type, length, volume and other characteristics indicators of gully erosion were used to calibrate the results. Then the features of every subregion, such as where the gully erosion is, how serious it is, and why it happens and develops, were expounded. The result is not only an essential prerequisite for gully erosion surveys and monitoring, but also an important basis for gully erosion prevention.

The Effects of Land Uses on Purplish Soil Erosion in Hilly Area of Sichuan Province,China

In order to evaluate the soil erosion rate for different land uses and make recommendations on land-use alternatives for erosion control in hilly and mountain areas on a Purplish soil (Regosols in FAO taxonomy), experimental data were obtained from three continuously monitored sites located at Yanting, Nanbu and Pengxi of Sichuan province. The data showed that the rank of erosion rate is farmland > unfenced grassland > fenced grassland > forestland. The erosion rate of farmland was more than 3 times higher than that of forestland and fenced grassland, indicating that restricting human activity is crucial for over-erosion. The erodibility was higher at the initial period of rainy season for all the three types of land use. The erosion rates of fenced grassland and mature afforestation land were not proportional to rainfall intensity because these land uses changed impact energy of the rainfall. This research showed that restricting human activity, intensifying the management of initial period of rainy season, and increasing the cover rate of land surface are the three major measures for soil erosion prevention. It is recommended that farmers should cease cultivation on farmland at the top of hills and steep slope land return those lands back to grassland or forestland.

The characteristics of gully erosion over rolling hilly black soil areas of Northeast China

In this study,short-term gully retreat was monitored from the active gullies selected in representative black soil area,using differential global positioning system(GPS).With the support of geographic information system(GIS),multi-temporal digital elevation models(DEM) were constructed from the data collected by GPS and used for further analysis.Based on the analysis of multi-temporal DEM,we discussed the erosion-deposition characteristics within gully and a developing model for black soil gully area of Northeast China was proposed.The results are:(1) The analysis of the monitored gully data in 2004 indicated that the retreat of gully head reached more than 10 m,gully area extended 170-400 m2,net gully eroded volume 220-320 m3,and gully erosion modulus 2200-4800 t?km?2?a?1.(2) Compared with the mature gully the initial gully grows rapidly,and its erosion parameters are relatively large.The erosion parameters have not only to do with flow energy,but also with the growth phase.(3) There are significant seasonal differences in gully erosion parameters.The extension of gully area and width dominates in winter and spring without marked net erosion while changes mainly occur in gully head and net erosion in rainy season.(4) It is remarkable for freeze-thaw erosion in the black soil area of NE China.The gully wall of SG2 extended 0.45 m under freeze-thaw effect in 2004,and the distance of gully head retreated maximally 6.4 m.(5) Due to freeze-thaw action and snowmelt,gully is primarily in the interior adjustment process in winter and early spring.There are much more depositions compared with that during rainy season,which can almost happen throughout the gully,while erosion mostly occurs near head,esp.for gullies having a relatively long history of development.On the other hand,the process of energy exchange with exterior dominates in rainy season.It is considered that this cyclic process is an important mechanism for gully growth in high latitude or/and high attitude regions.

Snake Model for the Extraction of Loess Shoulder-line from DEMs

Shoulder lines are the most important landform demarcations for geographical analysis,soil erosion modeling and land use planning in the Loess Plateau area of China.This paper proposes an automatic,effective and accurate method of determining loess shoulder line from DEMs by integrating a hydrological D8 algorithm and a snake model.The watershed boundary line is adopted as the initial contour which evolves to identify the exact position of loess shoulder-line by the guidance of an external force of snake model from DEMs.Experiments show that the method overcomes the difficulties in both threshold selection for edge detection and the disconnecting issues in former extraction approaches.The accuracy evaluation of shoulder-line maps from the two test sites of the loess plateau area show obvious improvements in the extraction.The average contour matching distance of the new method is 12.0 m on 5 m resolution DEM,and shows improvement in the accuracy and continuity.The comparisons of accuracy evaluations of the two test sites show that the snake model method performs better in the loess plain area than in the area with high gully density.

Spectral Response of Different Eroded Soils in Subtropical China: A Case Study in Changting County, China

Hyper-spectral data is widely used to determine soil properties. However, few studies have explored the soil spectral characteristics as response to soil erosion. This study analysed the spectral response of different eroded soils in subtropical China, and then identify the spectral characteristics and soil properties that better discriminate softs with different erosion degrees. Two methods were compared： direct identification by inherent spectral characteristics and indirect identification by predictions of critical soft properties. Results showed that the spectral curves for different degrees of erosion were similar in morphology, while overall reflectance and characteristics of specific absorption peaks were different. When the first method is applied, some differences among different eroded groups were found by integration of associated indicators. However, the index of such indicators showed apparent mixing and crossover among different groups, which reduced the accuracy of identification. For the second method, the correlation between critical soil properties, such as soil organic matter （SOM）, iron and aluminium oxides and reflectance spectra, was analysed. The correlation coefficients for the moderate eroded group were primarily between -0.3 to -0.5, which were worse than the other twogroups. However, the maximum value of R2 was obtained as 0.86 and 0.94 for the non-apparent eroded and the severe group. Furthermore, these two groups also showed some differences in the spectral response of iron complex state （Fep）, Aluminium amorphous state （Alo） and the modelling results for soil organic matter （SOM）. The study proved that it is feasible to identify different degrees of soil erosion by hyperspectral data, and that indirect identification by modelling critical soil properties and reflectance spectra is much better than direct identification. These results indicate that hyper-spectral data may represent a promising tool in monitoring and modelling soil erosion.

^(137)Cs and^(210)Pb_(ex) as Soil Erosion Tracers in the Hilly Sichuan Basin and the Three Gorges Area of China

Accelerated soil erosion and land degradation represent major environmental problems for agricultural lands.Reliable information on the rates of soil loss is urgently needed.The traditional techniques for documenting rates of soil loss may meet this need,but face many limitations.The fallout radionuclides,especially 137 Cs and 210 Pb ex,are increasingly used as effective tracers to quantify soil erosion rates,and they represent a valuable complement to the existing classical methods.This paper aims to introduce the basis for assessing soil erosion rates on cultivated and uncultivated slopes by using 137 Cs and 210 Pb ex measurements,to compare the 137 Cs and 210 Pb ex reference inventories,and to report several case studies undertaken in the hilly area of Sichuan Basin and the Three Gorges area of China.

Characteristics of modern sedimentation in Qingdao bays

With available survey data and 237surface sediment samples,the modern sedimentation in Qingdao bays is studied.The research result shows that the east area is shallower(16.4 m) than that in the west(45.8 m).The geography was formed by a symmetric wave in a sequence of bank-offshore depression-platform-tidal channel-platform-offshore depression-foreshore from south to north.Flood sedimentary systems were formed from inlet of the Jiaozhou Bay in the west to the barrier bar in the east.Lateral sedimentation includes mainly tidal current ridges in two tidal channels.Gravel sandy sediments formed by wave lie in midland of from seashore to wave base.Dynamic functions are mainly tide and wave.Tidal current moves sediment in vertical and horizontal directions,sorting sediments and providing materials for coastwise beaches.The sources of sediment are mainly from eroded headland rocks.In general,grain sizes in this area from the inlet of the Jiaozhou Bay in the west(120°17') to the barrier bar outside in the east(120°35') are coarse-fine-coarse,forming gravel-gravelly sand(G-S),sand(S),gravel clay silt(G-YT),clay silt(YT),gravelly silty sand(G-TS),silty sand(TS),gravelly sandy silt(G-ST),and sandy silt(ST) in turn.

Estimating Soil Erosion in Northeast China Using ^(137)Cs and ^(210)Pbex

Evaluation of soil erosion in agricultural fields is valuable to develop conservation practices for reducing agricultural nonpoint source pollution. Soil erosion rates were quantified using the fallout radionuclide tracer technique in Mojiagou Basin located on the outskirts of Changchun in Northeast China. The calculated soft erosion rates in the study area were 1.99 and 1.85 mm year-1 using 137Cs and excess 210pb （210Pbex） measurements, respectively. Both fallout radionuclides showed a similar tendency at downslope sites. All measured sites have experienced net erosion during the past 50 to 100 years. 137Cs and 210Pbex measurements were useful to quantify soil erosion rates on field and small basin scales. At this rate of erosion, the current fertile topsoil layer would be entirely removed within 70 years.

^(137)Cs Redistribution in Thin Stony Soil of a Carbonate Rock Slope in Southwest China

The fallout radionuclide cesium-137(137 Cs) has been widely employed as a tracer for assessment of soil loss from thick uniform soils;however,few studies have been conducted on thin stony soils on slopes underlain by carbonate rocks which are widely distributed in karst areas.Information derived from 137 Cs measurement of soil samples collected along a carbonate rock slope with thin stony soil where neither soil erosion nor deposition occurred was used to investigate the characteristics of 137 Cs redistribution in a karst area of Southwest China.The results indicated that the 137 Cs inventories of the surface soil on the slope studied were much lower than that of the local 137 Cs reference inventory and the 137 Cs activities were much higher than those on slopes with thick uniform soils.The spatial distribution of 137 Cs inventories was characterized by considerable variation.The high 137 Cs depletion in the stony soil of the slope studied was mainly because a considerable proportion of the fallout input of 137 Cs could be lost with runoff and the dissolution of carbonate particles in the soil promoted the loss of 137 Cs.These demonstrated that the rates of soil loss could not be estimated from the degree of depletion of the 137 Cs inventory relative to the local reference inventory for the thin stony soil of the rocky slope underlain by carbonate rocks in the study area in the way that has been widely used in areas with thick uniform soils.

An Integrated Quantitative Method to Simultaneously Monitor Soil Erosion and Non-Point Source Pollution in an Intensive Agricultural Area

In China, some areas with intensive agricultural use are facing serious environmental problems caused by non-point source pollution(NPSP) as a consequence of soil erosion(SE). Until now, simultaneous monitoring of NPSP and SE is difficult due to the intertwined effects of crop type, topography and management in these areas. In this study, we developed a new integrated method to simultaneously monitor SE and NPSP in an intensive agricultural area(about 6 000 km2) of Nanjing in eastern China, based on meteorological data,a geographic information system database and soil and water samples, and identified the main factors contributing to NPSP and SE by calculating the NPSP and SE loads in different sub-areas. The levels of soil total nitrogen(TN), total phosphorus(TP), available nitrogen(AN) and available phosphorus(AP) could be used to assess and predict the extent of NPSP and SE status in the study area.The most SE and NPSP loads occurred between April to August. The most seriously affected area in terms of SE and NPSP was the Jiangning District, implying that the effective management of SE and NPSP in this area should be considered as a priority. The sub-regions with higher vegetation coverage contributed to less SE and NPSP, confirming the conclusions of previous studies, namely that vegetation is an effective factor controlling SE and NPSP. Our quantitative method has both high precision and reliability for the simultaneous monitoring of SE and NPSP occurring in intensive agricultural areas.