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831.
832.
Characteristics of Non—Point Source Pollution in the Watershed of Miyun Reservoir,Beijing,China 总被引:1,自引:0,他引:1
Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir,a very important drinking water source of Bijing,China,and they are mainly from non-point sources.The watershed in Miyun County was selected as the study region with a totoal area of 1400km^2.Four typical monitoring catchments and two experimental units were used to monitor the precipitation,runoff,sediment yield and pollutant loading related to various land uses in the meantime.The results show that the total nutrient loss amounts of TN and TP are 898.07t/a,and 40.70t/a,respectively,in which nutrients N and P carried by runoff are 91.3% and 77.3%,respectively.There is relatively heavier soil eroson in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir.Different land uses would influence the loss amounts of non-point source pollutants.The amount of nutrient loss from the agricultural land per unit is highest,that from forestry comes next that from grassland is lowest.However,due to the variability of land use areas,agricultural land contributes a lot to TP and forestry lands to TN. 相似文献
833.
834.
Nutrient Loss from Various Land-Use Areas in Shixia Small Watershed of Miyun County,Beijing China 总被引:1,自引:0,他引:1
In the Shixia small watershed,twenty experimental plots and two monitoring channels,the residential area and livestock areas were used to monitor the flow,runoff and erosion,Nitrogen and phosphorous concentrations associated with various land uses were analyzed at the same time.The results are presented as follows:(1)TP ,TN and COD concentrations of runoff samples in the residential area and livestock arease are nearly 10 times those in other land-use areas.High nutrient loads are associated with village land use,which is due to unsuitable livestock rising.These areas should be treated as the critical areas of non-point source pollution.(2)Different land use influences intensity the loss nutrients,especially slope tillings in agricultural land.The amount of nutrient loss from agricultural land per unit is highest,that from forestry is intermediated and that frompastures is lowest,However,in consideration of the variability of land-use areas,agricultural land contributes the greatest to TP and forestry land to TN.(3)The concentrations of TN and TP in sediments from gangues are highest ,those in forestry land are intermediate,and those in agricultural land are lowest.Nutrient loss from hilly areas in much greater than from mountainous areas. 相似文献
835.
836.
水库诱发地震机制和实例 总被引:3,自引:0,他引:3
由诱震的内因和外因两大个因素入手,论述水库诱发地震形成的机制。通过百余座水库地震实例,总结出水库诱发地震的一些基本特征,可供同行参考。 相似文献
837.
大桥水库诱发地震前的小震群 总被引:1,自引:2,他引:1
2002年3月3日大桥水库诱发了Ma4.6级地震,根据大桥台网7年多库区地震观测记录,在2001年9~11月库区内有密集分布的高频次近地表的小震群活动,以致库区内地震存在6值与叩值等地震学参数异常。这个小震群震级小、频次高,分布在一个震源深度浅地域小的空间范围内。小震群的震中分布与安宁河东支断裂和库水位有关。借用基于GIS的地震分析预报系统对天然构造活动引起的震群分析方法和指标,对该小震群进行分析后认为:小震群为典型的前兆震群。 相似文献
838.
839.
The Gru?a Reservoir (located at 238…269 m a. s. l., volume 64.6 · 106 m3, surface 934 ha, drainage area 318 km2, max. depth 31 m, mean theoretical retention time 22 months) was investigated during the years 1996 to 2001. The obtained values of trophic state parameters (9…200 μg L?1 total phosphorus, 3…99 μg L?1 chlorophyll‐a, and 0.5…2 m transparency) indicate that water of the Gru?a Reservoir is eutrophic according to three types of classification: Carlson, OECD, and Jones and Lee. It was noticed that values of average biomass abundance are large in the Gru?a Reservoir, and they could indicate a richer trophic state. When these indices are cited in connection with parameters of the trophic state, it is apparent that the Gru?a Reservoir can be classified as a eutrophic water on the basis of total phosphorus content of chlorophyll‐a and hypertrophic water with respect to transparency. 相似文献
840.
重庆小南海水库地震堆积坝体帷幕灌浆试验研究 总被引:3,自引:0,他引:3
赵元弘 《水文地质工程地质》2005,32(3):89-93
小南海地震堆积坝体孤块石多,孔隙率大,局部架空现象明显,防渗整治难度较大。灌浆试验采用硬质合金或金刚石钻头回转钻进、泥浆护壁的钻孔方法,采用孔口封闭、自上而下分段、孔内循环式的灌浆方法,使用水泥粘土浆液,适当提高中排孔的灌浆压力,可以较好地解决堆积坝体的渗漏问题。从灌浆试验成果、检查孔压水试验及岩芯采取情况分析,灌浆效果明显,达到了试验的预期目的。 相似文献