长江上游水资源开发利用研究——以重庆市为例

介绍了长江上游地区水资源开发利用情况，并以重庆市为例，从重庆市水资源实际情况和开发利用现状出发，针对水资源在开发利用中存在的问题，提出了相应的对策措施，其中涵盖了三峡库区的水生态环境保护问题，以期为重庆市水资源规划和管理提供参考。     

Occurrence of Sediment-Bound Pyrethroids in Danish Streams and their Impact on Ecosystem Function

In a total of 189 water samples collected from Danish streams no traces of the pyrethroid esfenvalerate were detected. However, pyrethroids have previously been found in sediments in 9 out of 30 streams investigated. We found that the shredding activity of the Trichopteran Sericostoma personatum and the amphipod Gammarus pulex was significantly reduced with increased concentration of the pyrethroid lambda-cyhalohtrin adsorbed to the leaves on which they fed. Predation rate on the Plecopteran Leuctra nigra by the leech Erpobdella octoculata increased significantly with increasing concentration of lambda-cyhalothrin on the leaves on which L. nigra was fed. Our results clearly indicate that the ongoing monitoring of pesticides is likely to underestimate pyrethroid occurrence and that sediment-bound pyrethroids have a potential negative impact on ecosystem function and biotic interactions in streams.     

HOW RIPARIAN ECOSYSTEMS ARE PROTECTED AT LAKE TAHOE1

Riparian ecosystems are designated for special protection from development and disturbance at Lake Tahoe. The Tahoe Regional Planning Agency (TRPA) required protection of Stream Environment Zones (SEZs) in its Regional Plan for the Lake Tahoe Basin in 1987. These zones are identified by the presence of key indicators such as the evidence of surface water flow, riparian vegetation, near‐surface ground water, designated floodplain, and alluvial soils. They are mapped on each potential building site and assigned a setback that is also off limits to building construction. The SEZs are protected to maintain their functions and values, including flood attenuation, water quality enhancement, and wildlife habitat. Strict regulations control use or disturbance of SEZs on public and private property throughout the watershed. The TRPA has set restoration targets to increase the acreage of naturally functioning SEZs in the Tahoe Basin. Many SEZ restoration projects have been designed and implemented, but SEZ restoration targets have not been met. More SEZ restoration projects are being designed and funded each year. Restoration designers would benefit from increased effectiveness monitoring of completed projects and Web‐based dissemination of monitoring results.     

REMOTE SENSING OF RIPARIAN BUFFERS: PAST PROGRESS AND FUTURE PROSPECTS1

Riparian buffer zone management is an area of increasing relevance as human modification of the landscape continues unabated. Land and water resource managers are continually challenged to maintain stream ecosystem integrity and water quality in the context of rapidly changing land use, which often offsets management gains. Approaches are needed not only to map vegetation cover in riparian zones, but also to monitor the changes taking place, target restoration activities, and assess the success of previous management actions. To date, these objectives have been difficult to meet using traditional techniques based on aerial photos and field visits, particularly over large areas. Recent advances in remote sensing have the potential to substantially aid buffer zone management. Very high resolution imagery is now available that allows detailed mapping and monitoring of buffer zone vegetation and provides a basis for consistent assessments using moderately high resolution remote sensing (e.g., Landsat). Laser‐based remote sensing is another advance that permits even more detailed information on buffer zone properties, such as refined topographic derivatives and multidimensional vegetation structure. These sources of image data and map information are reviewed in this paper, examples of their application to riparian buffer mapping and stream health assessment are provided, and future prospects for improved buffer monitoring are discussed.     

Stream and riparian management for freshwater turtles

The regulation and management of stream ecosystems worldwide have led to irreversible loss of wildlife species. Due to recent scrutiny of water policy and dam feasibility, there is an urgent need for fundamental research on the biotic integrity of streams and riparian zones. Although riverine turtles rely on stream and riparian zones to complete their life cycle, are vital producers and consumers, and are declining worldwide, they have received relatively little attention. I review the literature on the impacts of contemporary stream management on freshwater turtles. Specifically, I summarize and discuss 10 distinct practices that produce five potential biological repercussions. I then focus on the often-overlooked use of riparian zones by freshwater turtles, calculate a biologically determined riparian width, and offer recommendations for ecosystem management. Migration data were summarized on 10 species from eight US states and four countries. A riparian zone encompassing the majority of freshwater turtle migrations would need to span 150 m from the stream edge. Freshwater turtles primarily chose high, open sandy habitats to nest. Nests in North America contained eggs and hatchlings during April through September and often through the winter. In addition, freshwater turtles utilized diverse riparian habitats for feeding, nesting, and overwintering. Additional documentation of stream and riparian habitat use by turtles is needed.     

Influence of Restoration Age and Riparian Vegetation on Reach‐Scale Nutrient Retention in Restored Urban Streams

In urban watersheds, stormwater inputs largely bypass the buffering capacity of riparian zones through direct inputs of drainage pipes and lowered groundwater tables. However, vegetation near the stream can still influence instream nutrient transformations via maintenance of streambank stability, input of woody debris, modulation of organic matter sources, and temperature regulation. Stream restoration seeks to mimic many of these functions by engineering channel complexity, grading stream banks to reconnect incised channels, and replanting lost riparian vegetation. The goal of this study was to quantify these effects by measuring nitrate and phosphate uptake in five restored streams in Charlotte and Raleigh, North Carolina, with a range of restoration ages. Using nutrient spiraling methods, uptake velocity of nitrate (0.02‐3.56 mm/min) and phosphate (0.14‐19.1 mm/min) was similar to other urban restored streams and higher than unimpacted forested streams with variability influenced by restoration age and geomorphology. Using a multiple linear regression approach, reach‐scale phosphate uptake was greater in newly restored sites, which was attributed to assimilation by algal biofilms, whereas nitrate uptake was highest in older sites potentially due to greater channel stability and establishment of microbial communities. The patterns we observed highlight the influence of riparian vegetation on energy inputs (e.g., heat, organic matter) and thereby on nutrient retention.     

Risk factors for elevated Enterococcus concentrations in a rural tropical island watershed

Associations were examined between riparian canopy cover, presence of cattle near streams, and month of year with the concentration of Enterococcus (Most Probable Number (MPN)/100 ml) in surface water at Waipā watershed on the North Side of the Hawaiian island Kaua'i. Each one percent decrease in riparian canopy cover was associated with a 3.6 MPN/100 ml increase of waterborne Enterococcus. Presence of cattle near monitoring sites was associated with an increase of 99.3 MPN/100 ml of Enterococcus in individual grab samples. Lastly, summer samples (July) were substantially higher in concentration of Enterococcus than winter collected samples (February) in Enterococcus in sampled streams. These results suggest that reducing canopy cover and introduction of cattle into riparian zones may contribute to increases of Enterococcus concentrations in stream water.     

Understanding the Factors That Influence Headwater Stream Flows in Response to Storm Events1

Stanfield, Les W. and Don A. Jackson, 2011. Understanding the Factors That Influence Headwater Stream Flows in Response to Storm Events. Journal of the American Water Resources Association (JAWRA) 1‐22. DOI: 10.1111/j.1752‐1688.2010.00518.x Abstract: Headwater drainage features (first‐ to second‐order streams) are the capillaries of the landscape that, among other things, moderate the timing and volumes of water available to the riparian and aquatic ecosystems. How these features respond to summer rainfall is poorly understood. We studied how geology and an index of land use/land cover influenced peak flows following rainfall events in 110 headwater stream sites that were studied over a four‐month period during a drought year. Highest peak flows were observed in the most urbanized catchments and in poorly drained soils, but specific responses were variable depending on both geology and land disturbance. Redundancy analysis indicated that both surficial geology and land disturbance were important factors influencing peak flows under drought conditions. We conclude that responses of these headwater streams to individual storms during drought conditions are unpredictable from data collected using our methods, but increased peak flows were associated with increased urban and agricultural development, but mitigated by surficial geology. These findings demonstrate the challenges to accurately predict flow conditions in headwater streams during periods of extreme weather that concurrently have the greatest potential effect on biota. The combination of these challenges and importance of such events indicates the need to develop new approaches to study and manage these resources.     

Biophysical‐Regulatory Classification and Profiling of Streams Across Management Units and Ecoregions1

Caruso, Brian S. and Joshua Haynes, 2011. Biophysical‐Regulatory Classification and Profiling of Streams Across Management Units and Ecoregions. Journal of the American Water Resources Association (JAWRA) 00(0):1‐22. DOI: 10.1111/j.1752‐1688.2010.00522.x Abstract: Aquatic resources management in the United States (U.S.) under Clean Water Act Section 404 has become more complex after recent Supreme Court decisions and U.S. Army Corps of Engineers and Environmental Protection Agency (USEPA) guidance. Many intermittent/ephemeral and headwater streams may not be jurisdictional if they lack a significant nexus with navigable waters. Streams in semiarid USEPA Region 8 were classified based on hydrologic permanence and stream order using National Hydrography Dataset (NHD) Plus and GIS to provide information across broad spatial scales to aid with jurisdictional determinations (JDs). Four classes were developed for profiling across management units and ecoregions. Based on medium‐resolution NHDPlus data, intermittent streams comprise >¾, and first order streams constitute >½ of the total stream length in Region 8. Mountain states and ecoregions have the largest percentage of perennial first order streams, whereas the Dakotas, plains, and desert ecoregions have the greatest percentages of intermittent first order and intermittent higher order streams. In the Upper Colorado River Basin, >50% of reaches are intermittent first order, and 9% are perennial first order. NHDPlus data can significantly underestimate the length of headwater and intermittent streams, but can still be a valuable tool to help develop stream classes and for regional JD planning and analysis. Refinement of the stream classes using high resolution NHD data and other key catchment parameters can improve their utility for JDs.     

Effect of Flow Depth and Velocity on Nitrate Loss Rates in Natural Channels1

Carleton, James N. and Yusuf M. Mohamoud, 2012. Effect of Flow Depth and Velocity on Nitrate Loss Rates in Natural Channels. Journal of the American Water Resources Association (JAWRA) 1‐12. DOI: 10.1111/jawr.12007 Abstract: Loss rates of nitrate from streams and rivers are governed by movement of the ion from water column to anoxic bed sediments. Quantitative representations of nitrate in streams and rivers have often treated such losses as governed by first‐order mechanisms that are invariant with respect to potential modulating factors other than temperature. Results of studies in recent years, however, suggest that rates of water column‐sediment mass transfer are influenced by stream geometry and associated hydraulics. We develop expressions for the instream nitrate loss rate coefficient, k, as a function of water velocity and depth, using hydraulic geometry to empirically relate velocity to depth for two cases: (1) variability in mean conditions among reaches; and (2) temporal variability in conditions at a single reach, under changing flow. The result is expressions for k as functions of water column depth. Measured stream k values reported in the literature are shown to be well represented by expressions developed for the first case, and the potential for application to probabilistic analysis is briefly examined. We explore the latter case using the Hydrologic Simulation Program – FORTRAN (HSPF) model, modified to incorporate the dependence of k on instantaneous stream depth. In example simulations of two nitrate‐exporting watersheds, the incorporation of depth‐dependence of k produces improvement in the model’s ability to match observed stream nitrate concentrations.