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751.
752.
V. Sridhar Amy L. Sansone Jonathan LaMarche Tony Dubin Dennis P. Lettenmaier 《Journal of the American Water Resources Association》2004,40(1):197-213
ABSTRACT: Removal of streamside vegetation changes the energy balance of a stream, and hence its temperature. A common approach to mitigating the effects of logging on stream temperature is to require establishment of buffer zones along stream corridors. A simple energy balance model is described for prediction of stream temperature in forested headwater watersheds that allows evaluation of the performance of such measures. The model is designed for application to “worst case” or maximum annual stream temperature, under low flow conditions with maximum annual solar radiation and air temperature. Low flows are estimated via a regional regression equation with independent variables readily accessible from GIS databases. Testing of the energy balance model was performed using field data for mostly forested basins on both the west and east slopes of the Cascade Mountains, and was then evaluated using the regional equations for low flow and observed maximum reach temperatures in three different east slope Cascades catchments. A series of sensitivity analyses showed that increasing the buffer width beyond 30 meters did not significantly decrease stream temperatures, and that other vegetation parameters such as leaf area index, average tree height, and to a lesser extent streamside vegetation buffer width, more strongly affected maximum stream temperatures. 相似文献
753.
Colin W. Krause Brendan Lockard Tammy J. Newcomb David Kibler Vinod Lohani Donald J. Orth 《Journal of the American Water Resources Association》2004,40(6):1645-1658
ABSTRACT: Watershed and aquatic ecosystem management requires methods to predict and understand thermal impacts on stream habitat from urbanization. This study evaluates thermal effects of projected urbanization using a modeling framework and considers the biological implications to the fish community. The Stream Network Temperature Model (SNTEMP) was used in combination with the Hydrologic Simulation Program Fortran (HSPF) to assess changes in stream thermal habitat under altered stream‐ flow, shade, and channel width associated with low, medium, and high density urban developments in the Back Creek watershed (Roanoke County, Virginia). Flow alteration by the high density development scenario alone caused minimal heating of mean daily summer base flow (mean +0.1°C). However, when flow changes were modeled concurrently with reduced shade and increased channel width, mean daily temperature increased 1°C. Maximum daily temperatures exceeding the state standard (31°C) increased from 1.1 to 7.6 percent of the time using summer 2000 climatic conditions. Model results suggest that additional urban development will alter stream temperature, potentially limiting thermal habitat and shifting the fish community structure from intolerant to tolerant fish species in Back Creek. More research is needed on the sub‐lethal or chronic effects of increased stream temperature regimes on fish, particularly for those species already living in habitats near their upper limits. 相似文献
754.
江津润湿时间的温度分布研究 总被引:3,自引:1,他引:2
采用直接读取、4点统计、24点统计三种方法研究了江津试验站1998年的润湿时间的温度分布,研究表明,可以利用全年每天2、8、14、20点的4个数据统计年润湿时间的温度分布;江津地区润湿时间的温度分布特征主要为:(1)99%的年润湿时间是在5℃至30℃温度范围,每月润湿时间的温度波动一般为15℃;(2)在(0~5)℃、(5~10)℃、(10~15)℃、(15~20)℃、(20~25)℃、(25~30)℃、(30~35)℃区间内,4点统计法各区间润湿时间的百分比分别为0.34%、13.4%、24.5%、18.3%、26.0%、17.4%、0.0%。 相似文献
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756.
DDS系列煤炭自燃阻化剂实验研究 总被引:11,自引:0,他引:11
为寻找高效阻化剂以防止煤炭自热引燃,在控温炉中对DDS系列煤自燃阻化剂的阻化效果进行了实验研究,并与经前的阻化剂做了比较。实验采用烟煤作为试样,借助于著名的Frank-Kamenetskii模型,利用4,6,8和10厘米立方体阻化煤磁地60-220℃温度范围估测其氧化反应的活化能。 相似文献
757.
758.
用Na_2CO_3催化焙烧法将CuS转化为Cu。最佳的转化条件;反应温度为750℃,CuS:Na_2CO_3(摩尔比)为1:2,在空气中反应90min。CuS的转化率可达到99%。 相似文献
759.
Khalique A Ahmad S Anjum T Jaffar M Shah MH Shaheen N Tariq SR Manzoor S 《Environmental monitoring and assessment》2005,108(1-3):45-57
The temporal turbidity and surface temperature changes and effects of the 17 August 1999 earthquake in the İzmit Gulf, Turkey have been investigated using Landsat TM/ETM data. The gulf is in the Mediterranean–Black Sea transition climatic zone and is partially surrounded by green vegetation cover and degraded and densely urbanized-industrialized areas. Landsat TM/ETM data acquired in 1990–1999 confirms increase in turbidity. Turbidity is always low in the southern part and high in the northern part of the gulf, because the more urbanized and industrialized areas are located in the northern part. The Landsat-7 ETM data acquired in the same year (1999) shows seasonal changes in turbidity. Moreover, the two high turbidity and surface temperature anomalies, one of which is parallel to the 17 August 1999 earthquake surface rupture (east–west) and the other which is in the northwest–southeast direction were mapped from Landsat-5 TM data acquired the day (18.08.1999) following the earthquake in the east end of the gulf. On the basis of turbidity implying the sea bottom movement, it is possible to state that a second rupture in the northwest and southeast direction could have occurred at the sea bottom during the earthquake. The distribution of the seismicity centers and the orientation of the lineaments in the area support this finding. 相似文献
760.