Journal of Earth Science

Environmental Impacts of the Yangtze Three Gorges Project: An Overview of the Chinese-German Research Cooperation

Günter Subklew, Julia Ulrich, Leander Fürst, Agnes Höltkemeier

2010, 21(6): 817-823. doi: 10.1007/s12583-010-0133-x

[Abstract](727) [FullText HTML] (83) [PDF 200KB](29)

Abstract:
The construction of the Three Gorges Dam on the Yangtze River in China has a great influence on the ecosystems involved. In order to investigate these environmental effects in the Yangtze catchment area as well as downstream of the dam, Forschungszentrum Jülich has organized a research network for the Chinese and German partners. In the research fields of (1) interaction water/sediment/contaminants, (2) vegetation/biodiversity, (3) changing land use/erosion/mass movements, and (4) atmosphere, the partners have accumulated a great deal of expertise in handling major issues and also in developing models and recommendations for action. The following provides an overview of the research network and the research tasks. On the German side, five projects in research field (3) have been in operation since 2008. The results are reported in contributions by Ehret et al., Jaehnig and Cai, Schönbrodt et al., and Seeber et al.. Another five projects in research field (1) have started by September 2010. The research tasks undertaken in these five projects are presented below.

Frequency Ratio Analysis of Mass Movements in the Xiangxi Catchment, Three Gorges Reservoir Area, China

Dominik Ehret, Joachim Rohn, Christian Dumperth, Susan Eckstein, Stefanie Ernstberger, Karel OTTE, René Rudolph, Johannes Wiedenmann, Wei Xiang, Renneng Bi

2010, 21(6): 824-834. doi: 10.1007/s12583-010-0134-9

[Abstract](777) [FullText HTML] (95) [PDF 570KB](33)

Abstract:
In 2003, the Three Gorges Project (TGP, China), currently the world's largest hydroelectric power plant by total capacity, went into operation. Due to large-scale impoundment of the Yangtze River and its tributaries and also due to resettlement, extensive environmental impacts like land use change and increase of geohazards are associated with the TGP. Within the Yangtze Project, we investigate these effects for the Xiangxi (香溪) catchment which is part of the Three Gorges Reservoir. The aim of this study is to evaluate the susceptibility for mass movement within the Xiangxi River backwater area using geographic information system (GIS). We used existing mass movements and the conditioning factors (geology, elevation, slope, curvature, land use, and land use change) for analyzing mass movement susceptibility. Mass movements and geology were mapped in the field to establish a mass movement inventory and a geological map. Land use and digital elevation model (DEM) were obtained from remote-sensing data. We determined the relation between mass movements and the conditioning factors by using the frequency ratio method and found strong relation between mass movements and both natural and human-influenced conditioning factors.

Assessing the Usle Crop and Management Factor C for Soil Erosion Modeling in a Large Mountainous Watershed in Central China

Sarah Schönbrodt, Patrick Saumer, Thorsten Behrens, Christoph Seeber, Thomas Scholten

2010, 21(6): 835-845. doi: 10.1007/s12583-010-0135-8

[Abstract](904) [FullText HTML] (161) [PDF 770KB](26)

Abstract:
Due to the impoundment of the Yangtze River, the Three Gorges Dam in China fosters high land-use dynamics. Soil erosion is expected to increase dramatically. One of the key factors in soil erosion control is the vegetation cover and crop type. However, determining these factors adequately for the use in soil erosion modeling is very time-consuming especially for large mountainous areas, such as the Xiangxi (香溪) catchment in the Three Gorges area. In our study, the crop and management factor C was calculated using the fractional vegetation cover (C_FVC) based on Landsat-TM images from 2005, 2006, and 2007 and on literature studies (C_LIT). In 2007, the values of CFVC range between 0.001 and 0.98 in the Xiangxi catchment. The mean C_FVC value is 0.05. C_LIT values are distinctly higher, ranging from 0.08 to 0.46 with a mean value of 0.32 in the Xiangxi catchment. The mean potential soil loss amounts to 120.62 t/ha/a in the Xiangxi catchment when usingC_LIT for modeling. Based on C_FVC, the predicted mean soil loss in the Xiangxi catchment is 11.50 t/ha/a. Therefore, C_LIT appears to be more reliable than the C factor based on the fractional vegetation cover.

Land Use Change and Causes in the Xiangxi Catchment, Three Gorges Area Derived from Multispectral Data

Christoph Seeber, Heike Hartmann, Wei Xiang, Lorenz King

2010, 21(6): 846-855. doi: 10.1007/s12583-010-0136-7

[Abstract](963) [FullText HTML] (104) [PDF 946KB](29)

Abstract:
The construction of the Three Gorges Dam on the Yangtze River has extensive impact on the ecosystems and the population of the Three Gorges Area (TGA). Inundation and resettlement have induced far-reaching land use and land cover change (LUCC). The areas that are affected by measures of resettlement are in a tense situation between the implementation of various governmental tasks addressing sustainable land use and water retention and the fulfilment of the population's economic needs, which primarily depend on agricultural production. Destabilization of slopes and soil erosion are immediate hazards induced by the impoundment. Farming is a very important source of income and has to persist on the one hand to assure the income of the rural population. On the other hand, the environment has to be protected from runoff, soil erosion and instabilities connected to relief, geology and hydraulic influences. In this study, supervised classifications are performed using Landsat-TM (1987 and 2007) and ASTER (2007) images. LUCC is assessed by post-classification change analysis. On the catchment scale, arable land has decreased significantly, while garden land (citrus orchards) and woodland have increased. LUCC mainly affects the area surrounding the reservoir ("backwater") of the Xiangxi (香溪) River, driven by local resettlement, newly built infrastructure, relocation of land cultivation, and conversion of arable land to garden land. In the hinterland, LUCC occurs in form of abandonment of land cultivation as a consequence of the Grain-for-Green programme.

Applicability of Time Domain Reflectometry for Yuhuangge Landslide Monitoring

Echuan Yan, Kun Song, Honggang Li

2010, 21(6): 856-860. doi: 10.1007/s12583-010-0137-6

[Abstract](872) [FullText HTML] (98) [PDF 401KB](23)

Abstract:
Yuhuangge (玉皇阁) landslide in Wushan (巫山), Chongqing (重庆), is one of the focal monitoring geological hazards in the Three Gorges Reservoir. Time domain reflectometry (TDR) and in-place inclinometers were arranged to monitor the deep deformation. Time domain reflectometry is based on transmitting an electromagnetic pulse into a coaxial cable grouted in rock or soil mass and watching for reflections of this transmission due to cable deformity induced by the ground deformation. Comparing the monitoring data of No. 5 Station, in the middle profile of the landslide, from June to December of 2008, the depth of slip surface determined by TDR is −33.58 m, which is consistent with the geological condition of the borehole nearby. The deformation curve trend of the TDR and inclinometer is similar, and it is uniform with the deformation caused by the Three Gorges Reservoir 175 m experimental impoundment. Further, TDR can monitor the tiny deformation accurately. Therefore, TDR is applicable to monitor the Yuhuangge landslide deep deformation and reflect the deformation characteristics well. It is significant to promote the application of TDR in landslide monitoring.

Ferrybox: Using Automated Water Measurement Systems to Monitor Water Quality: Perspectives for The Yangtze River and Three Gorges Dam

Carsten Frank, Friedhelm Schroeder, Wilhelm Petersen

2010, 21(6): 861-869. doi: 10.1007/s12583-010-0138-5

[Abstract](846) [FullText HTML] (105) [PDF 459KB](21)

Abstract:
The building of the Three Gorges Dam (Hubei (湖北) Province, China) has transformed a region with an economy based on sustainable agriculture for millennia into an entirely different environment within an exceptionally short time. This disrupts the natural biogeochemical cycles of carbon, nutrients, and metals and possibly will affect the whole catchment including downstream ecosystems, such as wetlands, estuaries, deltas, and adjacent sea areas. Starting from changes that have already been documented, this article concentrates on the possible use of a "FerryBox", which is an automated water quality measurement system on board a ship or on shore, to monitor the short and long term development of the quality of the river water in the backwater area and downstream of the dam. While there are already research programmes running to monitor the water quality of the river and the backwater area, these programs are limited to ship campaigns with sampling and laboratory analysis. The spatial and temporal resolution of such measurements is not sufficient for an overall assessment of the water quality and for prognoses in the context of anthropogenic and climate change. Therefore, a concept of applying regular automated observations by a FerryBox is presented. It is shown that such systems are very well suited to give feedback for the assessment of measures to improve the water quality.

Mechanism of Reservoir Water in the Deformation of Hefeng Landslide

Tingting Zhang, Echuan Yan, Jiangtao Cheng, Wei Xiang

2010, 21(6): 870-875. doi: 10.1007/s12583-010-0139-4

[Abstract](849) [FullText HTML] (111) [PDF 555KB](28)

Abstract:
The trial impoundment was carried on in Three Gorges Reservoir from September 27, 2008. There were strong deformation and failure in Hefeng (鹤峰) landslide when the reservoir water level descended from the altitude of 173 m. It indicates that the deformation is closely related to reservoir water fluctuation. For this reason, the effect of reservoir water in the deformation was studied, taking Hefeng landslide as an example in this article. First, the geological characteristics and deformation situation of strong deformation region are analyzed to disclose the intrinsic factors and the pattern of the deformation under the condition of water level fluctuation. Second, the stabilities of the landslide are calculated during the rising and descending processes, and the corresponding relationship between reservoir water level fluctuation and landslide deformation is further identified. At last, the seepage fields and the force condition of landslide body below the phreatic line are analyzed to reveal the effect of reservoir water. Moreover, it can be concluded that for better permeable reservoir landslide, during reservoir water rising, the favorable effect of seepage force weakens the unfavorable effect of uplift force, so the rising of reservoir water has little effect on the stability, and no deformation is caused; but during the descending of reservoir water, the unfavorable effect of seepage force is superimposed on the unfavorable effect of the uplift force, which causes the stability to dramatically decrease and leads to the failure of the accumulation body in front of the landslide.

River Water Quality Assessment in Selected Yangtze Tributaries: Background and Method Development

Jähnig Sonja C, Qinghua Cai

2010, 21(6): 876-881. doi: 10.1007/s12583-010-0140-y

[Abstract](963) [FullText HTML] (86) [PDF 362KB](25)

Abstract:
Water pollution is among the most severe environmental problems in China, particularly in the vicinity of residential and urban areas. In almost all Asian countries, river monitoring is predominantly based on the analysis of chemical data. However, biological data are a worthwhile addition for the determination of the long-term ecological status of rivers and are particularly well-suited in case of steep pollution and disturbance gradients. A tool for river water quality assessment using benthic invertebrates has been developed for selected tributaries of the middle reach of the Yangtze River. Site selection was supported by a preclassification considering physico-chemical and hydromorphological conditions. Following a stratified sampling design, 34 samples were taken in small and large streams in the subtropical mountainous area of western Hubei (湖北) (China) covering a pollution gradient, accompanied by an extensive field protocol on stream characteristics and (physico-) chemical water analyses. The proposed assessment system is computed as an average score per taxon. The challenge to further consider the additional impact from global change into the development of such tools is discussed.

Theory and Practice of Ionic Soil Stabilizer Reinforcing Special Clay

Wei Xiang, Deshan Cui, Qingbing Liu, Xuesong Lu, Lijing Cao

2010, 21(6): 882-887. doi: 10.1007/s12583-010-0141-x

[Abstract](878) [FullText HTML] (132) [PDF 189KB](27)

Abstract:
The change in the thickness of water films of special clay particles such as sliding clay, red clay, and expansive clay is an important factor in producing geological disasters and geological environmental damage. In order to reduce the thickness of water films, ionic soil stabilizer (ISS) is used to treat sliding clay, red clay, and expansive clay. Direct shear test of sliding clay and shrinkage, free swell rate, zeta potential, and cation-exchange capacity of red clay and expansive clay are carried out. The results show that as the plastic indexes of special clay soil decrease, the shear strength of sliding clay increases, the shrinkage and free swell rate of red clay and expansive clay decrease, and the thickness of the water film thins after treatment with the ionic soil stabilizer. Therefore, the geological engineering disasters caused by changes in the thickness of water films of special clay can be effectively inhibited.

Soil Stabilizing Capability of Three Plant Species Growing on the Three Gorges Reservoir Riverside

Tenten Norbert, Bo Zeng, Marian Kazda

2010, 21(6): 888-896. doi: 10.1007/s12583-010-0142-9

[Abstract](740) [FullText HTML] (76) [PDF 622KB](24)

Abstract:
Plant regrowth capacity and soil protection were investigated using three flooding-tolerant Yangtze River riverside species (Arundinella anomala, Hemartria compressa and Cynodon dactylon). The root and leaf surface growth, the plant regrowth capacity and the mitigation of soil runoff were analyzed using potted plants that were covered with 5, 10 and 18 cm new sediments, respectively. A. anomala reacted most slowly to the recovery from new sediments, while H. compressa had the highest recovery rates. The latter could produce 24 times the initial root length and 41 times its original leaf surface during the growth period of 12 weeks. C. dactylon showed no significant change in growth in relation to the rising sediment thickness, which means that even 18 cm of new sediments were tolerated by C. dactylon. Erosion tests showed that all three plant species can reduce the soil runoff by more than 63%. Compared to other species, A. anomala was less capable of stabilizing new sediments. The soil protecting abilities of H. compressa decreased after more than 10 cm of new sediments. C. dactylon showed the best soil retention compared to the other species examined, since it could reduce the soil runoff up to 87%. Consequently, C. dactylon was found to be significantly better for soil-protection plant species than A. anomala and H. compressa given the conditions at the Three Gorges Reservoir.

Estimation of Throughfall Erosivity in a Highly Diverse Forest Ecosystem Using Sand-Filled Splash Cups

Geissler Christian, Peter Kühn, Xuezheng Shi, Thomas Scholten

2010, 21(6): 897-900. doi: 10.1007/s12583-010-0132-y

[Abstract](830) [FullText HTML] (167) [PDF 326KB](29)

Abstract:
Sand-filled splash cups were used to study the erosive power of rainfall and throughfall in the humid subtropics of Southeast China. The splash cup measurements yielded precise and reproducible results under both open field conditions and forest vegetation. The splash cups were exposed to specific forest stands of different ages and to selected species (Schima superba, Castanopsis eyrei, Daphniphyllum oldhamii, Lithocarpus glaber) in the Gutianshan (古田山) National Nature Reserve (GNNR). The results of the measurements under forest vegetation show that the erosive power of throughfall drops to be 2.59 times higher compared to the open field. This accentuates the importance of shrub, herb and litter layers in forest ecosystems to protect the soil against erosion. Coalescing drops from leaves and branches (drips) are responsible for this notable gain in erosive power. Moreover, differences in sandloss between the investigated tree species (deciduous, evergreen) revealed that the erosion potential and the spatial heterogeneity of throughfall are species-specific. This highlights the importance of selecting specific species for afforestation projects considering the prevention of soil erosion.

A Seismically Triggered Landslide in the Niujuan Valley near the Epicenter of the 2008 Wenchuan Earthquake

Fangqiang Wei, Chernomorets Sergey, Aristov Konstantin, Petrakov Dmitry, Tutubalina Olga, Pengcheng Su, Yuhong Jiang, Aisong Xu, Petrasov Alexey

2010, 21(6): 901-909. doi: 10.1007/s12583-010-0143-8

[Abstract](985) [FullText HTML] (77) [PDF 1616KB](23)

Abstract:
The Wenchuan (汶川) earthquake on 12 May 2008 induced a large number of landslides, collapses, and rockfalls along the Longmenshan (龙门山) fault. The landslide in Niujuan (牛圈) Valley (named Niujuan landslide), close to the epicenter, is one that travelled a long distance with damaging consequences. Using QuickBird satellite images and GIS tools, the seismogenic mass movements are analyzed, and the movement phases, travel path, and post-catastrophic processes of Niujuan landslide are described and discussed. Image interpretation and a GPS survey showed that the mass movements denuded 37% of the research area. The Niujuan landslide moved 1 950 m along the Lianhuaxingou (莲花心沟) stream, transformed to a debris avalanche, and accumulated in the downstream bed of Niujuan Valley, where they formed a dam 30 m in height, blocking the Niujuan stream and creating a barrier lake basin with 0.11 million m³ storage capacity. Subsequent to the Niujuan landslide, debris flows have been more active in Lianhuaxingou and Niujuan valleys because of the accumulated mass of debris.

Focusing Seismic Energy along Faults through Time-Variable Rupture Modes: Wenchuan Earthquake, China

Kusky Timothy M, Abduwasit Ghulam, Lu Wang, Jianguo Liu, Zhongquan Li, Xiao Chen

2010, 21(6): 910-922. doi: 10.1007/s12583-010-0144-7

[Abstract](864) [FullText HTML] (125) [PDF 3185KB](23)

Abstract:
Field analysis and differential interferometry derived from Synthetic Aperture Radar (PALSAR) of the epicentral area of the May 12 2008 M_w 8.0 Wenchuan (汶川) earthquake zone reveal details about fault ruptures and ground displacements, with field-documented vertical offsets reaching 12 m along the trace of the main fault rupture, and PALSAR-measured horizontal displacements reaching 12.3 m. We document slip indicators on the fault scarp that show initially sub-horizontal then progressively steeper slip increments with time along the same fault during the 2 min earthquake, suggesting that the rupture propagated as a mixed Mode II–III fracture, with strike-slip movement at the tip directing energy from the initial rupture to points north of the epicenter, followed by vertical displacement in the interior of the slipped region. Field, seismic, and PALSAR-measured displacements are dominantly thrust near the epicentral region, and dextral in northeasterly areas, showing that slip was partitioned along the fault in space and time during the earthquake. The changing slip directions may correlate with three main pulses of energy release at 0, 23, and 57 s during the earthquake as recorded by seismograms. The earthquake generated massive landslides > 100 km north of the epicenter along the trace of the fault. These massive sturzstroms formed where entire mountainsides collapsed and moved at high velocity down populated mountain valleys, jumping smaller mountains and ricocheting off steep canyon walls. These avalanches rode on cushions of water and compressed air that generated air blasts from beneath the debris, knocking down trees high on opposing mountain slopes. The concentration of massive landslides and ground deformation so far north of the epicenter was related to the Mode II-III fracture propagation focusing seismic energy along the fault towards the north, explaining why so much devastation occurred > 100 km from the epicenter, such as in the destroyed city of Beichuan (北川). Understanding near-surface earthquake processes and geological hazards associated with massive earthquakes in populated mountainous areas has the potential to save many lives in the future.

Saturated Hydraulic Conductivity from Field Measurements Compared to Pedotransfer Functions in a Heterogeneous Arable Landscape

Florian Winter, Markus Disse

2010, 21(6): 923-930. doi: 10.1007/s12583-010-0145-6

[Abstract](808) [FullText HTML] (115) [PDF 691KB](24)

Abstract:
A high degree of uncertainty with regard to soil parameterisation limits the significance of physically-based simulation of distributed flood control measures, which affect the runoff generation process, such as land-use changes or differing soil tillage practices. In this study, the soil measurement data from the hillslope scale at the Scheyern research farm were compared to demonstrate this uncertainty. To account for the spatial variability of soils in the investigation area of Scheyern, different approaches were applied to estimate soil hydraulic properties and saturated hydraulic conductivity, and were compared to field measurements.

Numerical Modelling of Seismic Site Effects Incorporating Non-linearity and Groundwater Level Changes

Dominik Ehret, Joachim Rohn, Dieter Hannich, Carlos Grandas, Gerhard Huber

2010, 21(6): 931-940. doi: 10.1007/s12583-010-0146-5

[Abstract](859) [FullText HTML] (134) [PDF 845KB](23)

Abstract:
In the past decades, the necessity for detailed earthquake microzonation studies was recognized worldwide. Therefore, different approaches were established and applied. Unfortunately, the majority of these approaches are not based on pre-existing field data but require extensive seismic measurements and investigations. Furthermore, these approaches incorporate non-linearity inadequately and cannot take groundwater level changes into account. For this purpose, notably numerical models are most suitable. These models require a good knowledge of the local geological conditions (especially of the uppermost unconsolidated units), information about the geotechnical parameters of these units, and a hydrogeological model of the investigated area. Most of this information can be obtained from geotechnical investigations and surveys that have already been carried out in most densely populated areas. In a case study for Bucharest City, non-linear analyses were performed using software that is based on the visco-hypoplastic constitutive law. The results indicate that groundwater level changes have an important influence on duration and amplitude of ground response and thus should be considered for seismic microzonation studies. This approach can be used to display site effects and to identify different microzones taking different earthquake magnitudes and groundwater levels into account.

Assessment of Soil Erosion and Sediment Yield in Liao Watershed, Jiangxi Province, China, Using USLE, GIS, and RS

Li Hui, Chen Xiaoling, Kyoung Jae Lim, Cai Xiaobin, Myung Sagong

2010, 21(6): 941-953. doi: 10.1007/s12583-010-0147-4

[Abstract](994) [FullText HTML] (208) [PDF 921KB](36)

Abstract:
Soil erosion by water is a serious problem all over the world. In China, about 1 790 000 km² of land suffers from water erosion, which accounts for 18.3% of China's total area. This study was conducted in the Liao (潦) watershed in Jiangxi (江西) Province to assess annual soil erosion and sediment yield using the Universal Soil Loss Equation (USLE). A geographic information system (GIS) was used to generate maps of the USLE factors, which include rainfall erosivity (R), soil erodibility (K), slope length and steepness (LS), cover (C), and conservation practice (P) factors. By integrating these factors in a GIS, a spatial distribution of soil erosion over the Liao watershed was obtained. The soil erosion was found to vary from nil for flat and well-covered areas to more than 500 t/ha/a in mountainous places with sparse vegetation. The average soil erosion is 18.2 t/ha/a with a standard deviation of 109.3 t/ha/a. The spatial distribution of erosion classes was estimated. About 39.5% of the watershed is under the tolerant erosion rate, and 60.5% of the study area experienced erosion to different extents. A spatially distributed sediment delivery ratio (SDR) module was developed to account for soil erosion and deposition. It was found that the SDR value at the outlet of the Liao watershed was 0.206, and the sediment yield was 1.32 million t/a, which was 20% higher than the measured sediment. The results can be used to identify the soil erosion hot spots and develop the best soil erosion management practices and help estimate the quantity of soil that was transported into the downstream Poyang (鄱阳) Lake.

Pyrite in Sliding Mud: A Potential Indicator of Landslide Development

Guodong Zheng, Shouyun Liang, Yuhua Lang, Xiangxian Ma, Mingliang Liang, Wei Xiang

2010, 21(6): 954-960. doi: 10.1007/s12583-010-0148-3

[Abstract](678) [FullText HTML] (104) [PDF 953KB](30)

Abstract:
A new principle of geochemical conditions within a landslide slip zone is presented based on the concept of a self-sealing closed system for which newly formed pyrite should be considered as a potential indicator. Once slip zones occur, a series of water-rock interactions may take place, particularly, a change in redox conditions simultaneously with progression of the landslide. This change induces weathering of the debris and bed rocks, and leads to accumulation of newly formed sliding mud within the slip zone. Pyrite formation along with clay mineral accumulation occurs under a weak alkaline-strong reducing environment along with landslide development. Thus, formation of neogenetic pyrite, iron speciation, and clay mineralization are all important factors for a better understanding of landslide progression.

Complex Effective Relative Permittivity of Soil Samples from the Taunus Region (Germany)

Lauer Katja, Albrecht Christian, Christina SALAT, Felix-Henningsen Peter

2010, 21(6): 961-967. doi: 10.1007/s12583-010-0149-2

[Abstract](756) [FullText HTML] (124) [PDF 1304KB](26)

Abstract:
The most important parameter affecting ground-penetrating radar (GPR) measurements is the complex effective relative permittivity ε_{r, eff}^* because it controls the propagation velocity and the reflection of GPR pulses. Knowing ε_{r, eff}^* of soils passed through by electromagnetic waves increases accuracy in soil thickness and interface identification. Complex effective relative permittivity ε_{r, eff}^* =ε_{r, eff}^' − jε"_{r, eff}^* of 25 soil samples with textures ranging from loamy sand to silty clay was measured using the two-electrode parallelplate method. The measurements were conducted at defined water contents for frequencies from 1 MHz to 3 GHz. The results confirm the frequency dependence of ε_{r, eff}^* and show that the dielectric behavior of soil-water mixtures is a function of water content. Applying the experimental data of this study with predictions based on the empirical model by Topp et al. (1980), we find that Topp et al.'s curve tends to underestimate the real part of ε_{r, eff}^* measured. Along with frequency and water content, soil texture and organic matter affect soil permittivity. Moreover, the real part of ε_{r, eff}^* increases at higher dry bulk densities. Output from our calibration model enables us to predict ε_{r, eff}^* for the soil samples which were tested under the actual in situ soil water content. This results in high accuracy of soil thickness prediction.

Situation and Prevention of Loess Water Erosion Problem along the West-to-East Gas Pipeline in China

Jing'e Wang, Wei Xiang, Xu Zuo

2010, 21(6): 968-973. doi: 10.1007/s12583-010-0150-9

[Abstract](732) [FullText HTML] (126) [PDF 700KB](31)

Abstract:
Loess water erosion constitutes a great threat to the safety of the West-to-East Gas Pipeline in China. Through aerial-photo interpretation and investigation of the typical region (Zichang (子长)-Yongping (永坪) Section) where the loess water erosion problem is intensely developed, the influence of water erosion on the pipeline in the loess area can be manifested as the following 3 aspects: (1) surface and gully erosion causes the base overhead and pipeline exposure; (2) underground erosion forms caves, which may cause surface subsidence and foundation failure; (3) water erosion of loess may destroy the balance of slopes and cause geological hazards like landslide, collapse and debris flow. Presently, the controlling methods are mainly concrete or grouted rubble protection. These methods are not only high in cost but also have poor effect and poor durability. This article suggests a method of controlling the loess water erosion problem with soil solidified material. Then, related tests are conducted. The results of uniaxial compression, permeability, and anti-erosion ability tests indicate that the mechanical properties and anti-erosion ability of solidified loess were improved significantly.

A Setup for a Scenario-Driven Water Balance at Landscape Scale—Assessment with AKWA-M^®-Embedded in a Model Framework for Land-Use Planning's Decision Support in Mountainous Southwest China

Wahren Andreas, Berkhoff Karin, Münch Albrecht, Herrmann Sylvia, Karl-Heinz Feger

2010, 21(6): 974-978. doi: 10.1007/s12583-010-0151-8

[Abstract](804) [FullText HTML] (102) [PDF 545KB](21)

Abstract:
Land-cover changes cause a loss of natural vegetation in many parts of the world. In the Xishuangbanna (西双版纳) district (Yunnan (云南) Province), rubber plantations replace tropical rainforests covering already an area of about 10% of the study area (2007). There, land-use allocation is mostly driven by economic considerations. Thus, local planning authorities need decision support for land-use planning issues, which integrate socio-economic and ecological aspects. Within the NabanFrame, an agro-economic, ecological and social model was applied, which, altogether, interacted with a land allocation model via defined interfaces. Effects on the water cycle, ecological conditions as well as socio-economic should be considered by integrating the spatially distributed rainfall-runoff and water balance model AKWA-M® in the model setup.

2010 Vol. 21, No. 6

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