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通过渭南市东雷抽黄大型灌溉泵站的更新改造设计,提出泵站在改造设计中应注意的几个重要环节,以期为其他大型灌排泵站的更新改造提供参考与帮助。 相似文献
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随着当今社会的飞速发展,城市化进程的不断加剧,浑河作为沈阳一水相系的母亲河,其生态发展变化与沈阳城市建设发展休戚相关,因此更显得尤为重要.本文从浑河的历史变革情况、生态水利设施的建设情况等角度阐述了沈阳浑河生态发展变化的历程,并总结出了现有的成功的建设方案及其所呈现的生态效果,同时也展望了沈阳浑河未来生态建设发展方向的... 相似文献
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以黄河下游,尤其是游荡型河段的研究资料为背景,通过模型试验,在分析河势变化过程的基础上,运用数学统计与理论探讨,研究了不同水沙条件下河湾中心角、河湾半径和河湾跨度的变化趋势,初步揭示了随水沙、比降条件的改变,河势的变化过程,总结出河流在边界条件改变后河势演变的特点,对预测河道演变趋势,有效地河道整治具有一定的意义。 相似文献
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Temperature is one of the most important environmental variables in stream ecosystems because it affects the growth, survival and distribution of stream biota. This study examined if the spatial variability of thermal regimes and 18 other environmental variables were associated with fish communities in watersheds throughout the Great Lakes Basin (GLB), Ontario. The thermal regimes were defined as regimes 1, 2 and 3 and had maximum water temperatures of 26.4, 28.4 and 23.5°C, and spring warming rates of 0.20, 0.12 and 0.10 °C d?1, respectively. The spatial variability of the thermal regimes (VTR) within the watersheds was summarized into four VTR groups: S1, S2, M23 and M123. Stream sites in S1 watersheds had temperatures characteristic of regime 1 whereas stream sites in S2 watersheds followed regime 2. M23 watersheds had sites with a mix of regimes 2 and 3 whereas M123 watersheds had all three thermal regimes at sites throughout watersheds. Canonical correspondence analysis (CCA) indicated that 16% of the variation in fish communities was related to the spatial VTR in the watersheds. Forward selection CCA indicated that elevation, the S1 VTR group, sparse forest cover, wetland area, base flow index (groundwater discharge potential), flow and industrial stress explained 42% of the variance in the fish communities. Simplified indicator species analysis (ISA) showed that different species could be used as indicators for each of the VTR groups. Human activities such as industrial development, deforestation, groundwater withdrawal and flow alteration all may affect the environmental variables related to stream fish communities. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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The Sanaga River is one of Sub‐Saharan Africa's largest and greatly regulated rivers. Available flow data for this hydrosystem largely cover the pre‐ and post‐regulation periods. From comparisons between unregulated (hypothetical) and observed scenarios, it has been possible to separate and to quantify hydro‐climatic (groundwater + rainfall) change effects from anthropogenic impacts (especially dam‐related alterations). To appreciate shifts in the river regime, discontinuity detection tests and the IHA model were applied to discharge data series reflecting average and extreme flow conditions, respectively. Results obtained principally from the Hubert segmentation method reveal that a major discontinuity occurred in 1970–1971 separating a surplus phase between 1945–1946 and 1969–1970, and a deficient and much contrasted one, from 1971/1972. This implies that the Sanaga catchment is dominantly affected by hydro‐climatic changes. However, wide land cover/land use changes experienced here since 1988 have resulted in an increase in surface runoff. Additional quickflows linked to these changes may have partly compensated for the substantial decline in the dry season rainfall and groundwater inputs observed from this date. Although at the monthly scale, dam‐related impacts on average flows increase with stage of regulation, the seasonal variability of the river regime remains generally unaffected. A comparison of the IHA statistics, calculated from unregulated and observed streamflow data, show that hydrologic shifts occurring in maximum and minimum discharges are mostly significant from 1971/1972 and are mainly due to the action of dams. Minimum flows appear, however, widely impacted, thus reflecting the prime objective assigned to the existing reservoirs, constructed to supplement flows for hydroelectricity production during the dry season. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献