Responses of consumers and food resources to a high magnitude,unpredicted flood in the upper Mississippi River basin

The Mississippi and Missouri Rivers experienced flooding in 1993 that fell outside the annual predictable flood period of spring and early summer. Flooding began in late June, peaked in late July (25 232 m³/s on the upper Mississippi and 21 240 m³/s on the Missouri) and remained at or near flood stage into October 1993. This study was performed to determine if disturbance by an unpredicted flood event would alter trophic dynamics of river–floodplain systems by creating shifts in the composition of organic matter available to consumers. The Ohio River, which did not flood during the same period, was examined for comparison. Stable isotopic ratios of carbon and nitrogen from samples collected in 1993 and 1994 were used to characterize potential food sources and determine linkages between food sources and invertebrate and fish consumers. Pairwise contrasts, performed separately for each river, indicated there were few interannual differences in δ¹³C and δ¹⁵N of organic matter sources and consumers. Between sample period (flood year versus normal water year) trends in both flooded rivers were similar to between‐year trends observed for the Ohio River. Trophic structure of the Mississippi and Ohio Rivers was similar in both years, with fine and ultra‐fine transported organic matter and dissolved organic matter representing the major sources of organic matter. Overlapping isotopic signatures in the Missouri River made tracking of sources through the consumers difficult, but similarities in δ¹³C and δ¹⁵N between years indicated trophic structure did not change in response to the flood. The results suggest that consumers continued to rely on sources of organic matter that would be used in the absence of the unpredicted 1993 flood. It is proposed that trophic structure did not change in response to flooding in the Mississippi and Missouri Rivers because both rivers exhibited the same trends observed in the Ohio River. Copyright © 2001 John Wiley & Sons, Ltd.     

Downstream channel changes after a small dam removal: Using aerial photos and measurement error for context; Calapooia River,Oregon

Dam removal is often implemented without adequate baseline monitoring to distinguish background variability from channel changes due to the removal. This study evaluated aerial photos as substitutes for multiple‐year pre‐removal field data to assess downstream channel changes associated with a small dam removal. The Brownsville Dam, a 2.1 m tall concrete dam on the Calapooia River, Oregon, was removed in 2007. We mapped bars and the low flow channel downstream from the dam and in an upstream control reach using aerial photos (1994–2008) and in the field prior to (2007) and following (2008) removal. The locations and magnitudes of changes in bar area and wetted width, relative to errors, indicate that downstream channel changes were a result of the removal. The maximum changes (?3520 ± 1460 m² for bar area, 32 ± 8 m for wetted width) observed prior to dam removal with aerial photos were far downstream. In contrast, the maximum changes after removal were immediately below the dam (200 ± 90 m² for bar area, ?11 ± 3 m for wetted width), and small in the upstream control (?150 ± 130 m² for bar area, 9 ± 4 m for wetted width). The dominant errors were photo specific: exposure error for spring to summer comparisons, position error for photos not processed for this study and identification error for small scale photos not scanned from film. We found aerial photos to be an acceptable but coarse substitute for multi‐year pre‐removal field data, and suggest best practices to minimize errors. Copyright © 2009 John Wiley & Sons, Ltd.     

Flow and water temperature simulation for habitat restoration in the Shasta River,California

Low instream flows and high water temperatures are two factors limiting survival of native salmon in California's Shasta River. This study examines the potential to improve fish habitat conditions by better managing water quantity and quality using flow and water temperature simulation to evaluate potential restoration alternatives. This analysis provides a reasonable estimate of current and potential flows and temperatures for a representative dry year (2001) in the Shasta River, California. Results suggest restoring and protecting cool spring‐fed sources provides the most benefit for native salmon species from a broad range of restoration alternatives. Implementing a combination of restoration alternatives further improves instream habitat. Results also indicate that substituting higher quality water can sometimes benefit native species without increasing environmental water allocations. This study shows the importance of focusing on the limitations of specific river systems, rather than systematically increasing instream flow as a one size fits all restoration approach. Copyright © 2009 John Wiley & Sons, Ltd.     

穿堤涵闸防渗帷幕的方案研究

在长江中游干流和支流的河堤上建有众多的穿堤涵闸。因大多数河堤建在二元地层结构上，在粘土覆盖较薄、江河水位较高情况下，河堤背水坡坡肢附近争生渗透变形。在修建穿堤涵闸时，因开挖进、出水口，不仅削弱堤身且扰动了弱透水性的覆盖层，使穿堤涵闸在汛期比河堤更易发生渗透破坏。针对这种情况，介绍了几种常用的；穿堤涵闸防渗加固措施，并论述了不同条件下穿堤涵闸防渗帷幕的设计方案，以湖北省公安县刘家湾闸为例，说明防帷幕     

杨家河水力发电规划对民生改善的促进

杨家河水力发电规划的实施,不仅对纳雍县"大力发展水电,着力改善民生,促进经济可持续发展"起到积极的推动作用,而且将加快毕节地区农村电气化建设和小水电代燃料工程的进程。     

大朝山水电站工程截流概况

大朝山水电站工程是澜沧江上继漫湾之后的第二座大型水电部工程，１９９７年１１月１０日安全圆满实现大江截流。本文就工程截流的总体实施情况做一简要回顾     

黄河上游水文情报预报的发展与应用

黄河上游流域人烟稀少，经济不发达，６０年代前水文站网寥寥无几。７０、８０年代，黄委会上游水文水资源局，在该地区的黄河干流上恢复，新建了一批水文站，并在其主要支流设立了水文站。这些站网现控制站康乃亥以上流域的广大地区。     

现代治黄思路研讨

“治黄”包括整个黄河流域的开发利用 ,属于区域经济研究范围 .文中所述“治黄”只以河道演变规律和整治方针为主要内容 .“现代治黄思路”的含义包括 :经过近 50年的治理 ,黄河的面貌和基本属性起了变化 ,现代黄河既保持其原有特点 ,又区别于传统的黄河 ;应以最先进的科学技术和思维方式去观察分析 .文中阐明了世纪之交黄河的重大变化 ,并综合评述各种治黄思路的目标、观点和方法 .     

海河流域水资源现状与可持续利用对策

海河流域水资源严重短缺、水污染严重,节水效率有待进一步提高,水资源长期过度开发,流域用水量大大超过了流域水资源承载能力并造成生态环境严重恶化.通过对水资源供需矛盾的分析,提出了进一步加强水资源统一管理,促进水资源优化配置,全面建设节水型社会,确保水资源可持续利用的对策.