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Since the construction of the Gezhouba Dam in the 1980s, the number of Chinese sturgeon in the Yangtze River has been rapidly declining. The Gezhouba Dam has cutoff the migration path of these sturgeon, resulting in an overall reduction of suitable sturgeon habitat. This paper describes a habitat suitability index model that is used to evaluate the impacts of the Gezhouba Dam and Three Gorges Project on Chinese sturgeon spawning sites. Based on research concerning the reproduction characteristics of Chinese sturgeon, ten major ecological factors that influence reproduction were analyzed, including: water temperature, velocity, water depth, substrate, suspended sediment concentration, and the amount of egg predatory fish. The suitability index (SI) curves based on these ten ecological factors were obtained, and a habitat suitability function was developed. A two-dimensional mathematical model was also created to simulate and predict physical habitat situation (such as hydraulic, sediment, and substrate) of the Chinese sturgeon. By coupling the habitat suitability function and a two-dimensional mathematical model, a habitat suitability index model for Chinese sturgeon was established. The habitat suitability index model was validated by comparing measured data with predictions from the model. These comparisons showed that the computed results agreed well with the measured results, and the high calculated habitat suitability index (HSI) corresponded to high measured quantity of eggs per unit (1000 m3) discharge (CPUEd). The calculated habitat suitability index for Chinese sturgeon also showed that the habitat suitability index was better in 1999, before the impoundment of the Three Gorges Project, compared with the habitat suitability in 2003. Simulation results of different discharges from Gezhouba Dam predicted that flow discharges between 10,000 and 30,000 m3/s were most suitable for sturgeon spawning.

Stream networks and knickpoints in the Sanjiangyuan RegionThe source area of the Lancang (Mekong), Yangtze and Yellow rivers is named in Chinese Sanjiangyuan (source of three rivers). Geographical characteristics of these rivers, and various rivers at the margin of the Qinghai-Tibetan Plateau (Jialing, Minjiang, Dadu, Yalong and Jinsha) are summarized from field investigations along with digital elevation model (DEM) analyses and satellite images. Uplift of the Qinghai-Tibetan Plateau has resulted in an asymmetrical distribution of tributaries for stream networks at the margins of the plateau. Almost all tributaries join the trunk stream from the northwest. Three types of drainage network are evident: plume, nervation and dendritic. In general, plume networks have a large number of first order streams. Nervation networks have a main stream and parallel tributaries. Dentritic networks are characrterized by continuous bifurcation and have a branch-like appearance. Most stream networks in the Sanjiangyuan region are of the nervation type. Several large knickpoints are evident along the longitudinal profiles of the Yellow and Yangtze Rivers. Channel aggradation immediately upstream of these knickpoints marks a transition in river processes from vertical bed evolution (i.e. incision) to horizontal channel adjustment (and associated braided and anabranching channels).

Sediment deposition in reservoirs has caused the loss of 66% of the reservoir capacity in China. The main sedimentation control strategies are: 1) storing the clear water and releasing the turbid water; 2) releasing turbidity currents; 3) Draw-down flushing and empty flushing; and 4) dredging. The paper summarizes these strategies with examples. Sediment transport in many Chinese rivers occurs mostly during the 2–4 month flood season, that is, 80–90% of the annual sediment load is transported with 50–60% of the annual runoff. By storing the clear water after the flood season and releasing the turbid water during the flood season, less sediment deposits in the reservoir while the reservoir is still able to store enough water for power generation in the low flow season. The Three Gorges and Sanmenxia reservoirs apply this strategy and control sedimentation effectively. Turbidity currents have become the main sedimentation control strategy for the Xiaolangdi Reservoir. Empty flushing involves reservoir draw-down to temporarily establish riverine flow along the impound reach, flushing the eroded sediment through the outlets. Case studies with the Hengshan Reservoir and Zhuwo Reservoir are presented. Jet dredgers have been used to agitate the reservoir deposit so that the deposit is released from the reservoir with currents. The sediment releasing efficiency is 30–100% for storing the clear and releasing the turbid; 6–40 % for turbidity current; and 2,400–5,500% for empty flushing. Empty flushing causes high ecological stress on the ecosystem to the downstream reaches. Storing the clear and releasing the turbid is the best strategy to control reservoir sedimentation while achieving hydro-power benefit and maintain ecological stability.

The Wenchuan earthquake on May 12, 2008 triggered numerous avalanches and landslides and created many quake lakes. This paper studies the stability of mass movement deposits and quake lakes and the relation of the mass movements and quake lakes with riverbed incision by field investigations, satellite images and data analysis. The mass movements induced by the Wenchuan earthquake released different degrees of potential energy. Landslides which occurred within quaternary deposits released most of their energy and had the highest stability and safety post‐event. The avalanche deposits along the Minjiang River had the lowest stability and are dangerous because the slopes are still steep. The essential cause of the mass movement was riverbed incision. From the viewpoint of river training and management, some landslides might be prevented if riverbed incision were controlled. Two strategies are applied to manage the quake lakes: (1) to preserve the quake lakes; and (2) to remove the quake lakes. The T...

In northwest China, an area of more than 11 000 km2 is covered by Pisha Sandstone, a kind of loosely bonded sandstone formed during the Tertiary period. Pisha Sandstone is hard when it is dry but becomes loose when it is wet. Due the nature of this sandstone, this area of northwest China is plagued with a high erosion rate (over 20 000 t/km2 yr) as well as poor vegetation. In order to reforest gullies and to control erosion in the area, seabuckthorn (Hippophae rhamnoides Linn) was successfully used to reduce the erosion rate and help encourage vegetation growth in this area. Field investigations have been carried out in the Xizhao gully to study the effects of the species on sediment trapping and ecological improvement. Through these investigations, it was discovered that seabuckthorn encouraged the growth of Clinelymus dahurcus Turcz, and consequently, the two species form a dense double-layer of vegetation with well-developed middle and understory plant communities. The forest was planted in the late 1990s (first introduced in 1995), with a measured rate of sediment trapping efficiency of more than 90%. Rainstorm water was also stored in the gully within the trapped sediment. The water content in the reforested gully was approximately twice as high as the non-vegetated gully. Soil organic matter content was higher in the gully planted with seabuckthorn than compared with a non-vegetated gully. The understory community was evaluated by the taxa richness, the thickness-coverage and the Simpson diversity of the sub-layer vegetation. The understory community patterns found in the seabuckthorn vegetation was much better compared with those found in areas forested with poplar or willow vegetation.

Field experiments were conducted on bed load transport in the Diaoga River, a mountain stream in southwest China, to study the variation of bed load transport with varying sediment supply. The rate of bed load transport is greatly affected by incoming sediment (load and size). Under the same flow conditions, bed load transport rates may differ by three orders of magnitude depending on whether measurements were taken before or after the first flood of the year. The relation of the “bed load transport rate versus flow intensity” appears to have similar characteristics as a clockwise looped-rating curve. Experiments also were conducted during the non-flood season to study bed load transport processes with different incoming load from an upstream section. Bed load with different sizes can be grouped into two types: traveling bed load and structural bed load. Traveling bed load is composed of sediment finer than a critical size, Dc, and its transport rate depends mainly on the incoming sediment rate. The incoming sediment rate can alter the rate of bed load transport by three orders of magnitude. Structural bed load is composed of coarser sediment and its transport rate closely relies on the flow intensity.

The formation and geomorphic evolution of the Jiuduansha Shoal are investigated over the past 50 years in this paper. The sedimentary processes, formation, and geomorphic evolution of the Jiuduansha Shoal in the Yangtze River Estuary, eastern China, are analyzed based on digitized sea maps from 1945 to 2001, satellite images from 1975 to 2001, and field survey data in the spring-neap tidal cycle in the dry and flood seasons in 2003. The suspended sediment concentration and hydrodynamics of the North Passage and South Passage during the dry and flood seasons in the spring-neap tidal cycle in 2003 were investigated, and relations between the North Passage and South Passage of the Jiuduansha Shoal are analyzed. Results show that seasonal and spring-neap tidal cycle variations in sediment and water discharge from the drainage basin correspond to erosion and deposition on the Jiuduansha Shoal. The results and data can provide useful information for the management of the Yangtze River Estuary and restoration of the estuarine tidal flat ecology.

This paper presents a three-dimensional (3D) mathematical model for suspended load transport in turbulent flows. Based on the stochastic theory of turbulent flow proposed by Dou, numerical schemes of Reynolds stresses for anisotropic turbulent flows are obtained. Instead of a logarithmic law, a specific wall function is used to describe the velocity profile close to wall boundaries. The equations for two-dimensional suspended load motion and sorting of bed material have been improved for a 3D case. Numerical results are in good agreement with the measured data of the Gezhouba Project. The present method has been employed to simulate sediment erosion and deposition in the vicinity of the Three Gorges Dam. The size distribution of the deposits and bed material, and flow and sediment concentration at different times and elevations, are predicted. The results agree well with the observations in physical experiments. Thus, a new method is established for 3D simulation of sediment motion in the vicinity of dams.

The ecological and hydraulic features of step-pool systems are studied by field investigation, measurement, sampling, and analysis. The study is done on Shengou and Jiuzhai Creeks, where step-pool systems have developed, Fork Gully, where a step-pool system is developing, and the Jinsha River and Jiangjia and Xiaobaini Ravines, where there is no step-pool system. Boulders, cobbles, and gravel tightly interlock and form the steps having an inherent stability that only extreme floods are likely to disturb. Gravel and sand deposit in the pools behind the steps. These steps and pools provide high diversity of habitat for the stream biocommunity. The density of benthic macroinvertebrates in streams with step-pool systems is several 100 times higher than neighboring streams without step-pool systems. A new habitat diversity index is proposed considering the spatial distribution of various substrates, velocity, and water depth. The study reveals that the biodiversity of benthic macroinvertebrates increases with habitat diversity. Measurements with a specially designed instrument were done to study the development of step-pool systems and its effects on resistance to the flow and stream bed stability. A step-pool system maximizes the flow resistance and protects the bed sediment from erosion. Thus, the riverbed and bank slope are stabilized. The development degree of step pools is proportional to the streambed slope. The bed resistance increases with the development degree of step pools. Riverbed inertia represents the stability of the streambed. The development of step-pool systems greatly increases the riverbed inertia, and, therefore, maximizes streambed stability.

Benthic macroinvertebrates have been commonly used as indicator species for assessment of aquatic ecology. Streambed sediment, or substrate, plays an important role in habitat conditions for macroinvertebrate communities. Field investigations were done to study the benthic diversity and macroinvertebrate compositions in various stream substrata. Sampling sites with different bed sediment, latitude, and climate were selected along the Yangtze River, the Yellow River, the East River, and the Juma River, in China. The results show that benthic community structures found in different substrata clearly differ, while those found in substrata of similar composition and flow conditions but in different macroclimates are similar. The study, thus, demonstrates that the benthic macroinvertebrate community is mainly affected by substrate composition and flow conditions, but is generally unaffected by latitudinal position and macroclimate. Taxa richness of the macroinvertebrate community was found to be the highest on hydrophyte-covered cobbles, high on moss-covered bedrock, and low on clay beds and cobble beds devoid of plant biomass. Sandy beds are compact and unstable, thus, no benthic macroinvertebrates were found colonizing such substrata. Aquatic insects account for most of the macroinvertebrates collected in these rivers. Different insects dominate in different types of substrata: mainly EPT species (Ephemeroptera, Plecoptera, Trichoptera) in cobble, gravel, and moss-covered bedrock; and Chironomidae larvae in clay beds. The relation between the number of species in the samples and the size of the sampling area fits a power function of the species area. One square meter (1m2) is suggested as the minimum sampling area. A substrate suitability index is proposed by integrating the suitability of sediment, periphyton, and benthic organic materials for macroinvertebrates. The biodiversity of macroinvertebrates increases linearly with the substrate suitability index. Benthic taxa richness increases linearly with the suitability index.

Reservoirs play a vital role in economic development and flood control. Nevertheless, both human and natural factors may lead to dam failures with catastrophic consequences. Analyzing the data of dam failure events from 1954 to 2003 and using the method of energy spectrum analysis, this paper studies the periodicity of dam failures. The rate of failure of different dam ages is analyzed. The climate is the main factor affecting the rate of dam failure. Climate diagrams are used to analyze the spatial distribution of dam failure events in China. High rate of dam failure occurs with 25-year and 12.5-year periods. The distribution of the percentage of dam failure shows an L-shape as a function of service age. The first 5 years of operation is known as the ‘infant period’, during which, the probability of dam failure is much higher than during any other periods. The failure rate in areas near or north to the 400 mm annual isopluvial line is notably higher than other areas. In areas with high temperature difference among seasons have a high annual average dam failure rate.

Suspended sediment adsorbs pollutants from flowing water in rivers and deposits onto the bed. However, the pollutants accumulated in the river bed sediment may affect the bio-community through food chain for a long period of time. To study the problem the concentration of heavy metals (Cr, Cd, Hg, Cu, Fe, Zn, Pb and As) in water, sediment, and fish/invertebrate were investigated in the middle and lower reaches of the Yangtze River during 2006-2007. The concentrations of heavy metals were 100-10,000 times higher in the sediment than in the water. Benthic invertebrates had relatively high concentrations of heavy metals in their tissues due to their proximity to contaminated sediments. Benthic invertivore fish had moderately high concentrations of heavy metals whereas phytoplanktivore fish, such as the silver carp, accumulated the lowest concentration of heavy metals. The concentrations of Cu, Zn, and Fe were higher than Hg, Pb, Cd, Cr, and As in the tissue samples. The concentration of heavy metals was lower in the river sediments than in the lake sediments. Conversely, the concentration of heavy metals was higher in river water than in lake water. While a pollution event into a water body is often transitory, the effects of the pollutants may be long-lived due to their tendency to be absorbed in the sediments and then released into the food chain. The heavy metals were concentrated in the following order: bottom material > demersal fish and benthic fauna > middle-lower layer fish > upper-middle layer fish > water.

Regional environmental evaluation often requires a large amount of spatial information. Remote sensing (RS) and geographic information systems (GIS) are capable of managing large amounts of spatially related datum, and providing the ability to integrate multiple layers and to derive additional information. A methodological reference framework, using RS, GIS, and AHP (the analytic hierarchy process), is developed for environmental vulnerability assessment. Using this proposed method, we carried out a case study in the Tibetan Plateau. An environmental vulnerability index (EVI) proposed incorporates 15 factors covering natural conditions, environmental issues, and human activities. According to the EVI values, the vulnerability was classified into five levels: slight (EVI 3.4). The case study showed that the majority of the area in the Tibetan Plateau is ecologically lightly (light level; 22% of the total area), moderately (moderate level; 27%), and heavily (heavy level: 30%) vulnerable. Except for a clearly horizontal distribution, the environmental vulnerability increased clearly with increasing elevation (vertical distribution). The case study verified the usefulness and feasibility of the methods developed, for the results gained reflect the reality of the Tibetan environment closely. Further use in other regions should pay attention to what factors seem to be important in determining the local environmental vulnerability, and how is the impact of each factor on the complex environment. (c) 2008 Elsevier Ltd. All rights reserved.

A vegetation-erosion model was developed to assess the extent of soil erosion and development trend of vegetation in the context of existing and contemplated vegetation-based soil erosion controls under different climatic, topographical and soil conditions. The model recognizes four vegetation-mediated soil erosion states: (i) an expanding vegetation coverage coupled with reduced erosion (C), (ii) a deteriorating vegetation coverage coupled with increased erosion (A), (iii) two transitional states between A and C, one with increasing erosion and vegetation coverage (B) and the other with decreasing erosion and vegetation coverage (D). With the model, the vegetation-erosion state of any particular area can be quantitatively described, by way of a vegetation-erosion chart, for varying climate, soil and topographic conditions, as demonstrated for the Xishan region, the East River basin, the Wangjiagou and Anjiagou watersheds (Loess Plateau), and the Xiaojiang watersheds (hot and dry valleys in the upper Yangtze River basin) in China. This paper presents the principles and results of area-specific investigations that track the fractions of the areas covered by vegetation and experiencing soil erosion (with soil loss determined in t/km2yr). This is done within the context of local soil erosion control initiatives via re-vegetation efforts, or the lack thereof, over the course of 30 years. The effectiveness of reforestation and erosion-control measures vary under different climatic, topographical and soil conditions. The vegetation may be quickly restored in the hot and wet East River basin but is very difficult on the dry and cold Loess Plateau. In the hot and dry valleys the vegetation can be restored if erosion is controlled and intensive reforestations for small watersheds are performed.

The stream ecology of the East River is studied using benthic macro-invertebrates as indicator species. Samples were taken from 12 selected sites with different environmental conditions, from the upper reaches to the lower reaches. Four sites were selected to assess restoration strategies. The taxon richness, number density, biodiversity, and bio-community indices of benthic invertebrates remain at a relatively high level in the upper and middle reaches of the East River, but reduce to nearly zero in the lower reaches. The main ecological stresses are loss of habitat because of reclamation and the separation of riparian waters from the river. An important restoration strategy is to create multiple habitats with high habitat diversity, such as riparian lakes, wetlands, backwaters and sluggish flow zones, and to reconnect separated oxbow lakes with the river. Riparian waters should be managed in a similar way in Zengjiang Bay, allowing river flow to carry fine sediments into the riparian waters. Consequently, the fine sediment can deposit to form a mud layer. Fishes and invertebrates may live and spend parts of their life cycle in riparian waters. The Fengshuba Dam causes instantaneous fluctuation in flow discharge, and the aquatic ecology in the downstream reaches is impacted. A restoration strategy is required to adjust the operation scheme of the reservoir. Slope erosion and landslides also impact the stream ecology; the main restoration strategy for this is reforestation.

Reforestation is one of the most important and efficient measures of water and soil conservation. Based on field investigations in the Shangyang Soil Conservation and Reforestation Station in Huizhou, Guangdong Province, China, we studied the variation in vegetation development, vegetation succession processes and soil erosion. The regional vegetation consists mainly of monsoon evergreen broad-leaved forests (MEBF). The area was deforested and became a denuded hill area with extremely high soil erosion in the 1960s and 1970s. Then, the area was closed in order to allow recovery of the vegetation. Under natural conditions the vegetation development and succession processes were slow during which soil erosion and strong sunshine and evaporation slowed down the development of the vegetation. About 25 years later, the vegetation cover was still merely 35% or so. The dominant vegetation types were heliophilous herbage and shrubs which formed a poorly developed shrub-herbage community and erosion remained high. In contrast, reforestation with selected tree species dramatically speeded up the vegetation succession process. About 12 years after reforestation, vegetation cover of the Acacia auriculiformis plantations in the Shangyang Station was 90% and erosion was under control. After 23 years, understory vegetation, consisting of indigenous species, had developed in the plantations. The planted trees and naturally developing herbage, shrubs, bamboo, local trees and liana formed a complex vegetation community in three layers. It will take 60 years for the vegetation to succeed from bare land to a secondary growth forest under natural conditions. Reforestation may speed up the vegetation succession process. The time may be reduced to 20 years. Reforestation is the most effective measure of vegetation restoration and erosion control in this area.

In this paper we carry out a theoretical analysis based on the general one-dimensional morphodynamic model for rivers in order to show how the morphological equilibrium of a river is influenced by water and sediment diversion/supply along the river. The results of the analysis show that large scale water diversions, like those along the Lower Yellow River, can cause the development of a convex riverbed profile in the long-term. Deposition will take place along the whole reach of the river, with an increasing deposition depth from downstream to upstream. The slope of the river bed increases from upstream to downstream. Furthermore, an analysis on the morphological time scale shows that this development in the Lower Yellow River will take a time period on the order of decades to centuries. The results of the analysis have been compared with observations in the Lower Yellow River. Since the second half of the 1980's large scale water diversions from the Yellow River have been taking place. The observations show that this has indeed led to significant sedimentation along the river.

In this paper, the changes in the annual runoff and sediment transport have been assessed by using the long term observation data from 10 gauging stations on 10 large rivers across China from far north to far south. It is found that the annual sediment yield has generally had a decreasing trend in the past half century. According to the changes in annual runoff and the sediment yield per area, rivers in China can be classified into the following three groups: 1) rivers with decreasing annual sediment transport and stable runoff; 2) rivers with both decreasing annual sediment transport and runoff and 3) rivers with greatly reduced annual sediment transport and decreasing annual runoff. The results indicate that, in all southern rivers (to the south of the Huaihe River including the Huaihe River), there has been little change in average annual runoff but a dramatic decrease in annual sediment transport. In the northern rivers, however, both the annual sediment yield and the runoff show significant evidence of reduction. To further investigate the recent changes in annual runoff and sediment transport, the short-term observation data from these 10 gauging stations in the recent 10 years have been assessed. Results show that both the annual sediment transport and the runoff have decreased significantly in the northern rivers in the past 10 years. Using the Yellow River at the Lijin Station as an example, the average annual runoff for the last 10 years is only 1/3 of the long term average value and the average annual sediment yield of the last 10 years is only 1/4 of the long term average value. More unusually, in the Yongding River the annual sediment yield has approached zero and the runoff has decreased significantly. In addition, the impacts of human activities on the changes in both runoff and sediment transport have been discussed.

Macroinvertebrates are important components of stream ecosystems, and are often used as indicator species for the assessment of river ecology. Numerous studies have shown that substrate is the primary physical environmental variable affecting the taxa richness and density of macroinvertebrates. The aim of this work is to study the effects of the characteristics of streambed substrate, such as grain size, shape, and roughness, on the composition and biodiversity of macroinvertebrates. A field experiment was done on the Juma River, a second-order mountain stream in northern China. Substrata of cobbles, hewn stones, pebbles, coarse sand, and fine sand were used to replace the original gravel and sand bed in a stretch of 30 m in length. The sampling results indicated that the macroinvertebrate assemblage is significantly affected by the grain size, porosity and interstitial dimension of the substrate, while it is rarely affected by the shape and the surface roughness of the experimental substrata. Macroinvertebrate compositions in cobbles and hewn stones were stable and changed least over time. The taxa richness and density of individuals in the substrata of cobbles, hewn stones, and pebbles are much higher than in those of the coarse sand and fine sand.

Based on field investigations in the East River basin in Guangdong Province, south China, the processes of vegetation development and vegetation succession on bare slopes with high erosion rates are studied. Different reforestation measures have been applied to the slopes, which have resulted in very different processes of vegetation development and succession. On an experimental plot with burned forest but surviving roots, the vegetation restored naturally and quickly because there was little soil erosion. However, in the plots suffering from long-term severe soil erosion, natural vegetation recovery on these barren slopes is very slow. After 26 years, a barren slope has only been partly colonized by poorly developed vegetation composed of heliophilous herbages and scattered shrubs. On the other hand, plantation of some selected wood species on the slope land has dramatically accelerated the vegetation recovery and succession. The plots were reforested with plantation of Acacia auriculiformis in the early 1980s. Twelve years later, the vegetation cover of the artificial forests reached 90% and an understory vegetation community consisting of local species had naturally developed. Reforestation with suitable strategies may control erosion and greatly accelerate vegetation succession in the eroded slope land in the subtropical zones.

The fluvial and morphological processes induced by impoundment of the Sanmenxia Reservoir and relevant human activities on the Yellow River and its tributaries are complex. The long‐term annual sediment load of the Yellow River was 1.6 billion tons, ranking first of all the world's rivers. In 1960, Sanmenxia Dam began filling. Sediment transport in the river then was greatly disturbed and a new cycle of the fluvial processes was induced. First, the dam caused not only anticipated sedimentation in the reservoir, but also serious sedimentation in the largest tributary of the river (the Weihe River). The response of fluvial process to the dam closure varies in space and time. Second, the downstream reaches of the dam experienced erosion and resiltation, changes of river pattern, and development of meanders. Moreover, the downstream reaches of the dam have experienced more and more water diversion, which has induced readjustment of the longitudinal profile of the river. The study reveals that sedimentation in the Sanmenxia Reservoir enhanced the bed elevation at Tongguan, where the Weihe River flows into the Yellow River. The rising Tongguan's elevation caused retrogressive siltation waves in the Weihe River, which propagated at a speed of about 10 km/yr. An equilibrium sedimentation model is proposed, which agrees well with the data of sedimentation in the Weihe River. In the reaches below the dam the river changes from braided to wandering, or from wandering–braided to wandering–meandering. The discharge released to the downstream reaches has been regulated by the reservoir and it decreases along the course because the quantity of water diversions is more than the inflow from tributaries. The reduction in discharge causes readjustment of the longitudinal bed profile. By using the minimum stream power theory, we prove that the riverbed profile is developing toward an “S‐shape” profile.

We present an independent assessment of the health and water sustainability of the East River (Dongjiang) in South China, which is the source of nearly 80% of Hong Kong's water supply. Field measurements show that the water quality in the upper and middle reaches is generally good and well exceeds the drinking quality standard, with high bio-diversity. The streamflow of the East River Basin is satisfactorily simulated using both the distributed MIKE-SHE model and the lumped HSPF model. With an average streamflow of 760 m3/s, the River is able to satisfy the current water demand. Using the HSPF model, the water quality is found to have deteriorated in recent years. In addition to water supply, the River also supports a variety of needs such as hydro-power generation, waste assimilation, navigation, habitat for aquatic life, and expulsion of sea water intrusion. Using the projected need of 150 m3/s for water supply, the instream flow requirement based on hydrological and water quality simulation is estimated to be 467 m3/s in 2010. This suggests that the water sustainability of the East River requires alternative strategies, which may include integrated water resources management, provision of better wastewater treatment, and water and soil conservation.

Efficient carbon-14 labeling of four potent and selective DP1 antagonists is reported. The synthetic sequence began with α-hydroxylation, reduction of an ester, followed by oxidative diol cleavage and aldehyde reduction. The resulting alcohol 4 was converted to a mesylate then nucleophilic substitution with [14C]-sodium cyanide was performed to yield a nitrile, which upon basic hydrolysis provided the carbon-14 labeled acid 1. Compound 2 was obtained from the same alcohol intermediate 4 and two diastereomeric compounds 6 and 7 were easily prepared from compound 2. Carbon-14 synthesis of compounds 1, 2, 6 and 7 were achieved in good yields, high radiochemical purity (>99%) and with high specific activity (45 mCi/mmol). Copyright © 2006 John Wiley & Sons, Ltd.

Metabolites of the potent DP antagonist, MK-0524, were generated using in vitro systems including hepatic microsomes and hepatocytes. Four metabolites (two hydroxylated diastereomers, a ketone and an acyl glucuronide) were characterized by LC-MS/MS and 1H NMR. Larger quantities of these metabolites were prepared by either organic synthesis or biosynthetically to be used as standards in other studies. The propensity for covalent binding was assessed and was found to be acceptable (50 pmol-equiv/mg protein).

A universal and label-free photoelectrochemical cytosensing strategy was designed based on resonance energy transfer (RET) between carbon dots and cysteamine capped gold nanoparticles. RET promoted photo-to-current conversion efficiency and enhanced detection sensitivity. This proposed photoelectrochemical cytosensing platform exhibited a good performance for the assay of tumor cells with overexpressed receptors on cells.

Carbon materials on the nanoscale exhibit diverse outstanding properties, rendering them extremely suitable for the fabrication of electrochemical biosensors. Over the past two decades, advances in this area have continuously emerged. In this review, we attempt to survey the recent developments of electrochemical biosensors based on six types of carbon nanomaterials (CNs), i.e., graphene, carbon nanotubes, carbon dots, carbon nanofibers, nanodiamonds and buckminsterfullerene. For each material, representative samples are introduced to expound the different roles of the CNs in electrochemical bioanalytical strategies. In addition, remaining challenges and perspectives for future developments are also briefly discussed.

DNA–RNA heteroduplexes have been used as templates for copper nanocluster (CuNC) formation for the first time. Taking advantage of the electrocatalysis of CuNCs, quantitation of miRNA can thus be accomplished. More importantly, by simply operating several rounds of CuNC formation, repeated detection of miRNA has further been realized, which is rare in miRNA biosensors.

The biological community of a river ecosystem is determined by the characteristics of both terrestrial and aquatic ecosystems. The terrestrial ecosystem depends mainly on the plant community and the aquatic ecosystem comprises aquatic plants, benthic invertebrates, and vertebrates. The main ecological functions of rivers are habitat, conduit, filter, barrier, source, and sink. Ecological stresses are defined as the disturbances that bring changes to river ecosystems. The ecological stresses are natural events or human-induced activities that occur separately or simultaneously. The structure of a system and its capability of carrying out important ecological functions may be changed by stresses, regardless of whether they act individually or in combination. Damming, gravel and sand mining, channelization, water diversion, habitat fragmentation, exotic species, landslides and debris flows, and intensive fluvial processes are the most common stresses on stream ecology.

An incised river is defined as a river that is experiencing bed-level lowering. From the viewpoint of geomorphological process, mountain rivers either were or are incised rivers. Large rivers may be incised rivers in the upper reaches, but fluvial rivers in the lower reaches. The development of channel incision in mountainous areas depends on the rainfall, watershed vegetation, and soil and rock compositions. Incision may cause landslides, debris flows, and riverbed scour and in conjunction with bank erosion, provides sediment to the flow. A step-pool system is a geomorphologic phenomenon occurring in highgradient mountain streams with alternating steps and pools. Cobbles and boulders generally compose the steps, which alternate with finer sediments in pools to produce a repetitive, staircase like longitudinal profile in the stream channel. The tight interlocking of particles in steps gives them an inherent stability that only extreme floods are likely to disturb. Step-pool system maximizes the resistance, and, thus, controls riverbed incision. A bedrock channel has bedrock exposed along the channel bed or walls for at least approximately half its length, or has bedrock limits to the magnitude and location of bed scour and bank erosion during floods. Bedrock channels most commonly occur in regions of high topographic relief. Relief may be a product of recent tectonic uplift, as in the Himalayan Mountains of central Asia. The exposed bedrock implies that the channels may be particularly sediment-starved during floods and subjects to long term incision. The causes and evolution process of incised rivers and control strategies of channel bed incision are also discussed in this chapter.

Management of the Yellow River is presented as a case study for alluvial river management. The river is difficult to manage because it carries a heavy sediment load and used to be the most disastrous river in China. The river has successfully been kept flowing within the Grand Levees for a half century. But new problems have attracted the attention of society, for example, the water diversion to meet increasing water demand has caused the river to run dry for parts of the year, and floodplain reclamation and sedimentation of the channel have resulted in historically high water stage. Integrated river management is more necessary than before to coordinate various efforts of river training and management.

The golden mussel (Limnoperna fortunei) is a filter-collector macroinvertebrate species originating from southern China. It easily invades water transfer tunnels and attaches onto tunnel walls and structures with extremely high density, resulting in biofouling, pipe clogging, structure corrosion, a decrease in water transfer efficiency, and water pollution. It has become a prevalent problem and has caused concern all over the world. However, an effective and environment friendly method of controlling golden mussel invasion has not yet been approved. This study is aimed to propose measures for preventing golden mussel invasion and biofouling in the water transfer tunnels of the East River Water Source Project (ERWSP), which transfers water from the East River to Shenzhen, southern China for 10 million people. Long-term samplings and observations of the East River water were performed to study the golden mussel's invading pattern. Flume experiments were done to study the golden mussel's attachment on 14 different materials and performance in turbulent flows. An integrated ecological prevention pool was designed and constructed based on the flume experimental results for preventing the golden mussel invasion in the scale model tunnels of the ERWSP. The major technology of the ecological pool was preventing the golden mussel from entering the tunnels by attracting veligers to attach on geotextile cloth, attracting mussels to attach on bamboo, and killing veligers with high-frequency turbulence. An eight-month application experiment showed that the ecological pool successfully controlled the golden mussel invasion and biofouling in the scale model tunnels. The mussel density on the attachment materials decreased sharply as the distance of the materials from the pool entrance increased; the turbulence was effective in killing veligers that escaped from the attachment materials. No mussel was found on the model tunnels. Thus, the integrated ecological prevention pool is recommended as a successful measure for controlling the golden mussel invasion and biofouling in water transfer tunnels., Facultad de Ciencias Naturales y Museo

Sediment is transported by river flow in the forms of suspended load and bed load. The fluvial process is a result of sediment deposition and erosion. Flood, avulsion and sediment transportation and deposition are the natural processes in alluvial rivers and water diversion, channelization, and navigation are human disturbances to rivers. The fluvial process is the macroscopic view and long-term consequence of sediment movement. This chapter introduces the basic knowledge of sediment movement and fluvial processes, paying attention to the fall velocity of sediment particles, flow resistance, bed forms, and the rate of sediment transportation, hyperconcentrated floods, river patterns, and unsteady sediment transportation. This knowledge is useful for alluvial river management.

Traditional river management has usually been specific purpose-oriented to achieve water security, economic benefits, or habitat restoration and paid attention to only a short period, such as a few decades. Integrated river management aims for long-term stability and sustainable development, and coordination of various aspects of the river system, including morphology and landscape, river uses, and ecology. Four principles for river management are proposed: (1) extending the duration of water flowing in rivers, which may be achieved by extending the river course or reducing the flow velocity; (2) controlling various patterns of erosion and reducing the sediment transportation in rivers; (3) increasing the diversity of habitat and enhancing the connectivity between the river and riparian waters; and (4) restoring natural landscapes.

A landslide is a mass movement occurring on steep slopes under the action of gravity. Debris flow is a distinct type of mass movement commonly triggered by intense rainfall and/or melting snow on steep hill slopes. It differs from landslide in its “flowing” feature. Flow means relative movement in numerous layers of the medium, whereas a slide occurs only along one or several interfaces or beds. The main causes of landslides and avalanches are earthquakes and rainstorms. Disaster chains are initiated by landslides and avalanches. Great landslides resulted in barrier lakes. The stability of a landslide dam depends on the development degree of the step-pool system in the spillway channel on the landslide dam and the highest stream power of flow. Preserved landslide dams may develop into a knickpoint and become a key factor for river pattern establishment and river stability.

Basic concepts are introduced in this chapter to help the readers understand the contents of the other chapters in this book. The water cycle and modes of stream network development, Horton’s laws, sediment and sediment load, and various river patterns are defined and presented. Concepts of the water environment and stream ecology are briefly introduced. The major river management issues, such as water resources management, flood defense, reservoir management, river bed incision and geological disasters, erosion control, and river uses are also discussed.

This chapter begins by describing some general water quality management problems and the definition of pollution from environmental and economic perspectives. The chapter then focuses on four of the major water pollution problems facing rivers throughout the world: dissolved oxygen (DO), nutrients, waterborne and water contact diseases, and sediment contamination. The DO relations are described through the simple Streeter-Phelps concept relating carbonaceous biochemical oxygen demand (BOD) to DO and the extensions of this concept to nitrogeneous BOD, benthic processes, and photosynthesis and respiration. Dispersion effects on BOD and DO are discussed and then the total, simplified DO balance is presented. Dissolved oxygen standards and the linkage between these standards and habitat are presented. Finally, remedial methods to improve low DO concentrations are discussed.

Deltas are classified into river-, wave-, and tide- dominated deltas according to the dominant forces; or fan deltas and braided deltas according to their geomorphic settings. Large river deltas can also be classified into male deltas and female deltas. Estuary floods are due to 1) subsidence of the land or islands; 2) tsunamis, hurricanes and storm surges; and 3) heavy rainstorms. The flooding risk and flood defense strategies are discussed with the Venice Lagoon, Indian Ocean Tsunami, Hurricane Kartrina and New Orleans, and Hong Kong as examples. Human activities pose a serious threat to the health of estuaries and coastal waters. In particular, semi-enclosed estuaries are often under pressure to serve as wastewater disposal areas, leading to a high risk of eutrophication and algal blooms. Wastewater is flushed through repeated exchange of the intertidal water volume between the embayment and the open water body: clean water entering the embayment during flood tide fills the intertidal volume, mixing with the existing water in the embayment and, as the tide falls, the intertidal volume of water discharges out of the embayment, removing the dissolved substance. Tidal flushing time is taken as the time required for a tracer mass to reduce to a certain level of the initial mass. Wetlands along coastal shorelines serve as natural barriers against flood damage and erosion due to wind, waves and currents. Mangrove plants are capable of transferring oxygen from the atmosphere to the roots and creating an oxygenated zone for nitrification around the roots while the surrounding sediments are reduced thus favoring de-nitrification. Various techniques of wastewater outfalls, protection of wetlands, and prediction of algal blooms are also discussed in this chapter.

In a broad sense, all rivers develop from rills and gullies in the process of erosion. Erosion is classified according to agents causing erosion into water erosion, wind erosion, gravity erosion, glacier erosion and cultural erosion. Water erosion occurs in different forms: splash erosion, sheet erosion, rill erosion, gully erosion and channel erosion. Grain erosion is defined as the phenomenon of breaking down of bare rocks under the action of sun exposure and temperature changes, detachment of grains by wind, flow of grains down the slope under the action of gravity, and accumulation of eroded material at the toe of the mountain forming a deposit fan. Vegetation is the most important factor affecting the erosion process and development of rills. Vegetation, fluvial-geomorphic processes and landforms are inextricably interconnected parts of the landscape. Vegetation-erosion dynamics studies the laws of evolution of watershed vegetation under the action of various ecological stresses. Vegetation and erosion are a pair of competing and mutually interacting aspects of a watershed. For a watershed, vegetation and erosion may reach an equilibrium state if the circumstances remain unchanged for a long period of time. However, the equilibrium may not be stable. Ecological stresses, especially human activities, may disturb the balance and initiate a new cycle of dynamic processes. Studies considering both geomorphology and vegetation in the watershed are uncommon yet may provide important information regarding geomorphological and ecological processes.

A novel indole series of PGD2 receptor (DP receptor) antagonists is presented. Optimization of this series led to the identification of potent and selective DP receptor antagonists. In particular, antagonists 35 and 36 were identified with Ki values of 2.6 and 1.8 nM, respectively. These two antagonists are also potent in a DP functional assay where they inhibit the PGD2 induced cAMP production in platelet rich plasma with IC50 values of 7.9 and 8.6 nM, respectively. The structure–activity relationships of this indole series of DP receptor antagonists will also be discussed.

Nicotinic acid (NA) is commonly used to treat dyslipidemia, but it elicits an adverse effect, termed flushing, which consists of cutaneous vasodilation with associated discomfort. An animal model of NA-induced flushing has been established in mice. As in humans, NA stimulated vasodilation in a dose-dependent manner, was associated with an increase of the vasodilatory prostaglandin (PG) D 2 in plasma and could be blocked by pretreatment with aspirin. Two PGD 2 receptors have been identified: PGD 2 receptor 1 (DP1, also called DP) and PGD 2 receptor 2 (DP2, sometimes termed CRTH2). DP2 does not mediate NA-induced vasodilation; the DP2-specific agonist DK-PGD 2 (13,14-dihydro-15-keto-PGD 2 ) did not induce cutaneous vasodilation, and DP2 −/− mice had a normal vasodilatory response to NA. By contrast, BW245C, a DP1-selective agonist, induced vasodilation in mice, and MK-0524, a DP1-selective antagonist, blocked both PGD 2 - and NA-induced vasodilation. NA-induced vasodilation was also studied in DP1 +/+ , DP1 +/− , and DP1 −/− mice; although NA-induced vasodilation depended almost completely on DP1 in female mice, it depended only partially on DP1 in male mice. The residual NA-induced vasodilation in male DP −/− mice was aspirin-sensitive. Thus, in the mouse, DP1 appears to be an important component involved in NA-induced vasodilation, but other cyclooxygenase-dependent mechanisms also may be involved. A clinical study in healthy men and women demonstrated that treatment with MK-0524 reduced the symptoms of flushing and the increase in skin perfusion after the administration of NA. These studies suggest that DP1 receptor antagonism may be an effective means to suppress NA-induced flushing in humans.

The concentration of dissolved ions, including K+, Na+, Ca2+, Mg2+, Cl−, SO4 2−, HCO3 −, CO3 2−, is an important index for river water quality. By employing the data of measured ions in the Weihe River basin, relationships between the concentration of ions and water discharge and sediment loads are revealed. Generally one of the most important factors affecting the concentration of ions is water dilution, which results in a continuous reduction in the concentration of ions following increasing flow discharge. In a dry season, the concentration of ions decreases with water discharge and sediment concentration; whereas in a wet season, however, the relationships are more complex because the soil erosion can be extremely intensive and sources of ions are rather diverse. Lithology and climate are the two most important influencing factors for these relationships. The Jinghe River and Bahe River are two typical tributaries of the Weihe River. The Jinghe River is from the Loess Plateau and carries extr...

TGP project ‐ the Three Gorges Project on the Yangtze River ‐ is the largest hydro‐project in China. This paper outlines the environmental and ecological impacts of the project. Cumulative sedimentation in the reservoir will reach an equilibrium in 100 years with a total volume about 16 billion m3. The planned Xiangjiaba and Xiluodu reservoirs, which will be located at 1020 km and 1180 km upstream of the TGP dam, can be used to trap sediment and thus reduce the sedimentation rate of TGP reservoir in the first 90 years. Experimental studies showed that impoundment of TGP reservoir will cause sediment deposition at the apron of the Chongqing harbor and even change the stem flow from the west channel to the east channel. Building spur dykes and groins to regulate the flow can solve the problem. Calculation with 1‐D models show that the released water from the dam will scour 2.5 billion tons of sediment from the downstream channels in 40 years, which will result in channel degradation. The flood stag...

A series of substituted 5-, 6-, and 7-azaindoles were prepared via the Hemetsberger-Knittel reaction. In general, better yields were obtained at higher temperatures and shorter reaction times than required for the formation of the analogous indoles, and in some cases, only decomposition occurred below a minimum temperature. The resulting templates offer up to five sites for subsequent functionalization to allow a wide range of chemical diversity.

Debris flows are often triggered by heavy rainfall and flash floods in mountainous areas. Generally, debris flows are the most disastrous event associated with floods and cause most of the fatalities resulting from flood events. This paper reports a study of debris flows by filed investigations at the Xiaojiang watershed, which is in the upper Yangtze River basin, and flume experiments. Two types of debris flows—viscous debris flows and two-phase debris flows — occur on the Yunnan Plateau in south China. Viscous debris flows consist of clay, silt, sand, and gravel. This kind of flow is non-Newtonian and often develops into roll waves. They sometimes exhibit drag reduction and extremely high super-elevation. The drag reduction is mainly due to the effects of air cushions and the bed smoothening. Two-phase debris flows consist of gravel and boulders and show obvious relative movement between the solid particles and the liquid. Flume experiments show that debris flows may be triggered by torrential ...

This paper presents a study of the variation of the elevation of Tongguan, which is located in the backwater zone of the Sanmenxia Reservoir, in response to changes in flow runoff. The analysis indicated that the rise of the elevation of Tongguan, which is defined as the stage corresponding to a discharge of 1000 m3/s at Tongguan station, is controlled by the stream energy. A close relationship existed between the elevation of Tongguan and the superimposed stream energy that integrates the current and the preceding years’ flow and dam operation conditions. When the flow runoff remains relatively constant and the pool level of the dam has a relatively large range of variations, then the elevation of Tongguan is primarily controlled by the dam operation conditions. On the other hand, if the flow runoff has a relatively large range of variations and the pool level of the dam remains relatively constant, then the elevation of Tongguan is primarily controlled by the flow conditions. These findings are of importance for optimizing the dam operation in order to lower and control the elevation of Tongguan, and therefore to minimize the backwater effect of the dam operation.

Vegetation and erosion are a pair of competing and interactive factors that affect the quality of watershed ecosystems. The objective of this study is to develop an innovative approach for conceptualizing and simulating the vegetation-erosion dynamics. Differential equations of vegetation-erosion dynamics have been developed to describe the relevant vegetation processes, with the relevant solution methods being provided. Based on the developed model, a vegetation-erosion chart can be produced for predicting the tendencies of vegetation and erosion under different land-use conditions. Thus decision supports in terms of desired measures to improve the system conditions can be provided. In general, vegetation of a watershed may exist in three states, including (1) vegetation-developing and erosion-reducing; (2) vegetation-deteriorating and erosion-increasing; and (3) transitional state between states (1) and (2). Humans may change a watershed system from one state into another. The effort needed for such a change depends on the distance between the present position and the destination one as shown on the vegetation-erosion chart. The developed model has been applied to three regions, including the Xiaojiang, Heishui, and Shengou Watersheds in China. The results demonstrate that the proposed vegetation-erosion dynamics is a powerful tool for simulating and predicting vegetation evolutions in the watersheds. Generally, reforestation and erosion-control measures would improve vegetation coverage slowly in the first 10 years, but become much faster in the second 10 years; this implies that a long-term strategy is needed. The results also indicate that, for revegetating hilly areas, erosion control is critical; merely planting trees and shrubs is insufficient for greening the exposed land.

A series of 2-substituted N-benzyl benzimidazole containing molecules has been synthesized and its structure-activity relationship for the human DP receptor has been evaluated. Selective DP antagonists with nanomolar potency for the DP receptor were identified in this novel series of benzimidazoles.

Sediment management is always most challenging in the hydraulic engineering on sediment‐laden rivers. Chinese people have accumulated abundant experiences in solving the problems like watershed erosion, heavily sediment‐laden rivers, reservoir sedimentation, estuarine and coastal sedimentation, and debris flows and control strategies. This paper summarizes the sediment issues, research approaches and management strategies. The paper outlines a vision for the future sediment research in the new century, especially reporting on an ambitious plan of validation of sediment studies performed for the Three Gorges Project. The need for multidisciplinary approaches to conducting research is also discussed.

The SAR from our peptide libraries was exploited to design a series of potent deoxybenzoin PTP-1B inhibitors. The introduction of an ortho bromo substituent next to the difluoromethylphosphonate warhead gave up to 20-fold increase in potency compared to the desbromo analogues. In addition, these compounds were orally bioavailable and active in the animal models of non-insulin dependent diabetes mellitus (NIDDM).

Most rivers in China carry high sediment loads, and therefore develop deltas. Many cities have consequently developed near river mouths and have become centers of commerce within China. The increasing population pressure poses new problems and the need for new river basin management strategies. This paper discusses such deltaic processes and the corresponding management strategies for the Yangtze, Yellow and Haihe River deltas, with these being three typical examples. The Yangtze River carries large amounts of water and sediment into the East China Sea. Deltaic islands and shores develop continuously at the river mouth, leading to bifurcations of the channels. Navigation channel dredging and land creation projects are being implemented in the estuary, with these projects intended to narrow and stabilize the river mouth. The present Yellow River delta has developed over the past 147 years as a consequence of siltation and avulsions of the river channel, flooding and sedimentation. Human activities...