Qingshui River Research Articles

Discovery and Significance of Malan Loess on the Piedmont Plain in Pinggu District, Beijing

The platforms on both sides of the Malangou River (a lateral ditch of the Qingshui River that is a tributary of the Yongding River) where Malan Village in Zhaitang Town of Mentougou District of Beijing is located are the place of China's typical section of the Quaternary Malan loess. During the investigation in the eastern suburbs of Beijing City, the authors not only clarified 5 grades of terraces on the Pinggu piedmont plain, but also found a clayey silt section mixed with a small amount of alluvial-diluvial gravel layers at a height of 15–25 m above the river level near a Fishpond in Xinli Village of Nandule Town. Results of the study of grain size of the section document that the loess mostly is silty soil (0.05–0.005 mm), and that the grain size probability cumulative curves of the section are dominated by single-peak, coarse-grained segment I and coarse-grained segment II types, reflecting that its depositional environment is similar to eolian phase. Identification results of heavy minerals from the section show that their contents account for 0.01%–0.11%, averaging 0.04%. There are 24 kinds of heavy minerals, most of which are stable heavy minerals, and the clay minerals mostly are illite, which is consistent with the Malan loess on the Loess Plateau. The chemical composition data reflect that the source area of the loess is relatively arid. The six grade classification of sporopollen in the section further shows the subdivision of the history of alternating warm and humid phases in this geological period. The thermoluminescence dating results range from 21.0 ka to 59.2 ka, convincingly demonstrating that the section indeed consists of Malan loess. The above studies provide a new basis for overall understanding of the distribution of the Malan loess at the northeast margin of the North China Plain and its environment change in the Late Pleistocene.

Practice of Slip Surface Depth of Highway Slope Determined by Synthetic Survey Method

The excavation roadbed was used in K29+450～900 sections of secondary highway from Gengma to Qingshui River. The design roadbed width was 12m, and after an excavation, the inclination of side slope was between 27 to 50 °. It is Nanting River below bed and the vertical distance is 20m between them. Under actions of external load, mountain slipping and river scouring, there appears an instable phenomenon in slope. The pile board wall had inclined which is located in the central section of one side of roadbed and close to K29+900 section after construction. The inclining range was larger and the inclination that was serious at pile head at the top reached about 2m. The research was focused on a side slope engineering in K29+450~900 sections and through site survey, the topography and geological features of slope were known and mastered. By drilling, high-density electric method and numerical simulation method, the depth and scope of slip surface were determined to provide a basis for governance programme of engineering reinforcement.

Static Load Test and Modal Analysis of Qingshui River Bridge

A load test on a multi-girder concrete bridge of 30m Span having a non-composite deck slab is described. The bridge was designed to have eight simple supported spans, each consisting of a cross section with six RC T beam. Through analyzing the static and dynamic character of bridge structures, calculating efficiency ratio of load test, picking up the results of observation points, it was determined that the girders were acting non-compositely with the concrete deck and that significant restraint was being developed at the bearing supports. Modal analysis and identification ascertain the characteristic properties of bridges from their response. The damage in bridges may be reflected in the changes of their natural frequencies or modes of natural vibration.

Full-Scale Dynamic Testing of Qingshui River Bridge

Both ambient vibration testing and vehicle impact testing are carried out on a concrete multi-girder bridge. Ambient vibration testing is relatively easier to conduct and can provide detailed vibrating information of the structure. However vehicle impact testing is indispensable to obtain the impact factor of the traffic load. The measured vibration frequencies compare well to those of calculated values. This means that the finite element model may enable good predictions of the actual behavior of the bridge.

Landslide hazard mapping using GIS and weight of evidence model in Qingshui River watershed of 2008 Wenchuan earthquake struck region

Tens of thousands of landslides were triggered by May 12, 2008 earthquake over a broad area. The main purpose of this article is to apply and verify earthquake-triggered landslide hazard analysis techniques by using weight of evidence modeling in Qingshui (清水) River watershed, Deyang (德阳) City, Sichuan (四川) Province, China. Two thousand three hundred and twenty-one landslides were interpreted in the study area from aerial photographs and multi-source remote sensing imageries post-earthquake, verified by field surveys. The landslide inventory in the study area was established. A spatial database, including landslides and associated controlling parameters that may have influence on the occurrence of landslides, was constructed from topographic maps, geological maps, and enhanced thematic mapper (ETM+) remote sensing imageries. The factors that influence landslide occurrence, such as slope angle, aspect, curvature, elevation, flow accumulation, distance from drainages, and distance from roads were calculated from the topographic maps. Lithology, distance from seismogenic fault, distance from all faults, and distance from stratigraphic boundaries were derived from the geological maps. Normalized difference vegetation index (NDVI) was extracted from ETM+ images. Seismic intensity zoning was collected from Wenchuan (汶川) Ms8.0 Earthquake Intensity Distribution Map published by the China Earthquake Administration. Landslide hazard indices were calculated using the weight of evidence model, and landslide hazard maps were calculated from using different controlling parameters cases. The hazard map was compared with known landslide locations and verified. The success accuracy percentage of using all 13 controlling parameters was 71.82%. The resulting landslide hazard map showed five classes of landslide hazard, i.e., very high, high, moderate, low, and very low. The validation results showed satisfactory agreement between the hazard map and the existing landslides distribution data. The landslide hazard map can be used to identify and delineate unstable hazard-prone areas. It can also help planners to choose favorable locations for development schemes, such as infrastructural, buildings, road constructions, and environmental protection.

An integrated simulation-monitoring framework for nitrogen assessment: A case study in the Baixi watershed, China

Abstract As the deterioration of drinking water quality has become increasingly severe worldwide, there is a considerable need to accurately identify variable pollution sources. Currently, simulation programs have been shown to be less effective in short-term and detailed simulations. Therefore, this study advanced an integrated framework for simulation by combining the modelling and monitoring methods. A case study was conducted to identify the spatial and temporal distribution of nitrogen (N) in the upstream watershed of a typical drinking water reservoir, in the city of Ningbo, Zhejiang province, China. In this study, a watershed model, Soil and Water Assessment Tool (SWAT), was used to estimate N load for the 254 km2 upper stream watershed; while storm runoff samples were also collected to illuminate more detailed processes in the storm event. Based on the model output, the critical N source in Baixi watershed was identified as the forest. The potential nonpoint source (NPS) pollution risk areas were also illustrated as Sub-basin 21, 20 and 26. In addition, the model simulation proved that the Qingshui River contributed more N load than the other two tributaries. Conversely, the short-term and detailed trends were obtained through storm sampling. By analyzing the storm samples, it was clear that the N load into the drinking water reservoir results from a combination of land-use, agricultural activities, as well as atmospheric deposition, especially in the acid rain control region. It could be further inferred that modelling and monitoring could serve as a framework to provide information for N load prediction and protection of drinking water. Using the integrated simulation-monitoring framework, the SWAT model could be used as an effective tool to foretell the potential risk of detrimental NPS conditions, while monitoring could provide an inventory and detailed means to further study short-term trends.

Warming effects on permafrost under earthquake motions and seismic stability of pile foundation of dry bridge

A series of shaking table tests for the 1∶100 scaled model of the pile foundation in the Qingshui river Bridge along the Qinghai–Tibet Railroad were conducted on condition that the soil temperature around pile was below 0°C. The change of temperature around the pile foundation during the earthquake motions was monitored, and the warming effects on the permafrost were obtained. Applying dynamic finite element analysis method, the characteristics of seismic response of the pile foundation were analysed. In the dynamic time history analysis, the artificial seismic waves were used as the input ground motions. The effects of the peak acceleration and frequency characteristic of input ground motions on seismic stability of the pile foundation of bridges at the unstable permafrost areas of high temperature and high ice content were determined. The distributions of dynamic displacement, acceleration and earth pressure were studied and the dynamic stability of the pile foundation of bridges was evaluated.

Relationship between the variation of water quality in rivers and the characteristics of watershed at Miyun, Beijing, China

Based on the characteristics of land use and drainage network of the upper watershed of the Miyun Reservoir, Beijing, 26 monitoring and sampling sites were selected in different sub-catchments. Temporal and spatial variations in nutrient loss were dealt with in this paper in terms of the monitoring data on the water quality of the main tributaries flowing into the Miyun Reservoir. In combination with the monitoring data on water quality, the impacts of watershed characteristics including land-use type, landscape pattern, and drainage density were assessed. The concentrations of nutrients in the rainy season are higher than those in other seasons, and the concentrations of NO3−-N are linearly related to those of total N which is the main form of nitrogen present in the river water. The concentrations of nitrogen become higher toward the reservoir along the main rivers. The seasonal variation of nitrogen in the watershed affected by intensive human activities is very obvious; in the watershed with steady or low water flow, the seasonal variation of nitrogen is less obvious. Forest land and grassland can trap and filter nitrogen effectively. Land-use pattern also has important impacts on the loss of nitrogen. The concentrations of nitrogen and phosphorus in the water bodies show great temporal and spatial variations. On a temporal scale, the concentrations of TN and TP in the rainy reason are higher than those in other seasons. On a spatial scale, the concentrations of TN and NO3−-N in the Qingshui River and Chaohe River are highest all the time. The spatial variation of TP is distinct, being obvious at sampling sites near villages. The form of nitrogen and phosphorus loss varies in different hydrological seasons. Dissolved nitrogen and phosphorus are the main forms in streams in non-rainy seasons, the dissolved nitrogen and total nitrogen decrease in percentage in the rainy season. Particulate nitrogen and phosphorus are the main forms in some rivers. The concentrations of TN and NO3−-N from orchards and villages are high whereas those from forest land are lowest. Land-use pattern has impacts on TN and NO3−-N losses, at the sampling sites near the source landscape, the concentrations are higher than those at the sampling sites near the sink landscape. Water quality of the rivers which flow into the Miyuan Reservior is influenced by the composition of adjacent soils.