Climate and land-use changes affecting river sediment and brown trout in alpine countries—a review

Background, aim, and scope

Catch decline of freshwater fish has been recorded in several countries. Among the possible causes, habitat change is discussed. This article focuses on potentially increased levels of fine sediments going to rivers and their effects on gravel-spawning brown trout. Indications of increased erosion rates are evident from land-use change in agriculture, changes in forest management practices, and from climate change. The latter induces an increase in air and river water temperatures, reduction in permafrost, changes in snow dynamics and an increase in heavy rain events. As a result, an increase in river sediment is likely. Suspended sediment may affect fish health and behaviour directly. Furthermore, sediment loads may clog gravel beds impeding fish such as brown trout from spawning and reducing recruitment rates. To assess the potential impact on fine sediments, knowledge of brown trout reproductive needs and the effects of sediment on brown trout health were evaluated.

Approach

We critically reviewed the literature and included results from ongoing studies to answer the following questions, focusing on recent decades and rivers in alpine countries.

Have climate change and land-use change increased erosion and sediment loads in rivers?

Do we have indications of an increase in riverbed clogging?

Are there indications of direct or indirect effects on brown trout from increased suspended sediment concentrations in rivers or from an increase in riverbed clogging?

Results

Rising air temperatures have led to more intensive precipitation in winter months, earlier snow melt in spring, and rising snow lines and hence to increased erosion. Intensification of land use has supported erosion in lowland and pre-alpine areas in the second half of the twentieth century. In the Alps, however, reforestation of abandoned land at high altitudes might reduce the erosion risk while intensification on the lower, more easily accessible slopes increases erosion risk. Data from laboratory experiments show that suspended sediments affect the health and behaviour of fish when available in high amounts. Point measurements in large rivers indicate no common lethal threat and suspended sediment is rarely measured continuously in small rivers. However, effects on fish can be expected under environmentally relevant conditions. River bed clogging impairs the reproductive performance of gravel-spawning fish.

Discussion

Overall, higher erosion and increased levels of fine sediment going into rivers are expected in future. Additionally, sediment loads in rivers are suspected to have considerably impaired gravel bed structure and brown trout spawning is impeded. Timing of discharge is put forward and is now more likely to affect brown trout spawning than in previous decades.

Conclusions

Reports on riverbed clogging from changes in erosion and fine sediment deposition patterns, caused by climate change and land-use change are rare. This review identifies both a risk of increases in climate erosive forces and fine sediment loads in rivers of alpine countries. Increased river discharge and sediment loads in winter and early spring could be especially harmful for brown trout reproduction and development of young life stages. Recently published studies indicate a decline in trout reproduction from riverbed clogging in many rivers in lowlands and alpine regions. However, the multitude of factors in natural complex ecosystems makes it difficult to address a single causative factor.

Recommendations and perspectives

Further investigations into the consequences of climate change and land-use change on river systems are needed. Small rivers, of high importance for the recruitment of gravel-spawning fish, are often neglected. Studies on river bed clogging are rare and the few existing studies are not comparable. Thus, there is a strong need for the development of methods to assess sediment input and river bed clogging. As well, studies on the effects to fish from suspended sediments and consequences of gravel beds clogging under natural conditions are urgently needed.     

Pharmaceutical residues in tidal surface sediments of three rivers in southeastern China at detectable and measurable levels

Pharmaceutical compounds were increasingly detected in environmental matrices but little is known whether these compounds would transport to coastal zones via watersheds. Three typical tidal rivers in southeastern China were selected and 15 surface sediment samples (0–10 cm) were collected along a 50-km tidal section of each river. Surface sediment samples were frozen-drying and then extracted for pharmaceutical compounds by an accelerated solvent extraction system. The pharmaceutical compounds in extracts were scanned using a high-performance liquid chromatography/tandern mass spectrometry (HPLC-MS/MS). Three hundred and thirty compounds from nine pharmaceutical groups were detected with signal-to-noise above three (detectable level) in the surface sediments, of which 186 compounds were with a signal-to-noise above ten (measurable level). Of all, 291 and 80 compounds were detectable and measurable in all the three rivers, respectively. The Jiulong River showed a high load of pharmaceutical compounds in surface sediment than other two rivers. Of the nine pharmaceutical groups, the antihistamines and detoxification group and anti-infective drug group contributed five dominant compounds in the surface sediments in all the three rivers. Natures of pharmaceutical compounds rather than the sediment properties (pH, EC, and total carbon content) might influence their residues. The incredible number and intensity of pharmaceutical residues were detected in tidal surface sediments of the three rivers indicating that the pharmaceutical contamination should be strongly considered in China. Source identification and eco-toxicity assessment should be taken into account in the future study. Therapeutic medicine managements need to be strictly improved at a watershed scale to reduce loads of pharmaceuticals into aquatic ecosystems.     

Influence of hydropower dams on the composition of the suspended and riverbank sediments in the Danube

Large hydropower dams have major impacts on flow regime, sediment transport and the characteristics of water and sediment in downstream rivers. The Gabcikovo and Iron Gate dams divide the studied Danube transect (rkm 1895-795) into three parts. In the Gabcikovo Reservoir (length of 40km) only a part of the incoming suspended sediments were deposited. Contrary to this, in the much larger Iron Gate backwater zone and reservoir (length of 310km) all riverine suspended sediments were deposited within the reservoir. Subsequently, suspended sediments were transported by tributaries into the Iron Gate backwater zone. Here they were modified by fractional sedimentation before they transgressed downstream via the dams. Compared with undammed Danube sections, Iron Gate reservoir sediment and suspended matter showed higher clay contents and different K/Ga and Metal/Ga ratios. These findings emphasize the importance of reservoir-river sediment-fractionation.     

The influence of the scale of mining activity and mine site remediation on the contamination legacy of historical metal mining activity

Globally, thousands of kilometres of rivers are degraded due to the presence of elevated concentrations of potentially harmful elements (PHEs) sourced from historical metal mining activity. In many countries, the presence of contaminated water and river sediment creates a legal requirement to address such problems. Remediation of mining-associated point sources has often been focused upon improving river water quality; however, this study evaluates the contaminant legacy present within river sediments and attempts to assess the influence of the scale of mining activity and post-mining remediation upon the magnitude of PHE contamination found within contemporary river sediments. Data collected from four exemplar catchments indicates a strong relationship between the scale of historical mining, as measured by ore output, and maximum PHE enrichment factors, calculated versus environmental quality guidelines. The use of channel slope as a proxy measure for the degree of channel-floodplain coupling indicates that enrichment factors for PHEs in contemporary river sediments may also be the highest where channel-floodplain coupling is the greatest. Calculation of a metric score for mine remediation activity indicates no clear influence of the scale of remediation activity and PHE enrichment factors for river sediments. It is suggested that whilst exemplars of significant successes at improving post-remediation river water quality can be identified; river sediment quality is a much more long-lasting environmental problem. In addition, it is suggested that improvements to river sediment quality do not occur quickly or easily as a result of remediation actions focused a specific mining point sources. Data indicate that PHEs continue to be episodically dispersed through river catchments hundreds of years after the cessation of mining activity, especially during flood flows. The high PHE loads of flood sediments in mining-affected river catchments and the predicted changes to flood frequency, especially, in many river catchments, provides further evidence of the need to enact effective mine remediation strategies and to fully consider the role of river sediments in prolonging the environmental legacy of historical mine sites.     

Fish Migration, Dams, and Loss of Ecosystem Services in the Mekong Basin

The past decade has seen increased international recognition of the importance of the services provided by natural ecosystems. It is unclear however whether such international awareness will lead to improved environmental management in many regions. We explore this issue by examining the specific case of fish migration and dams on the Mekong river. We determine that dams on the Mekong mainstem and major tributaries will have a major impact on the basin’s fisheries and the people who depend upon them for food and income. We find no evidence that current moves towards dam construction will stop, and consider two scenarios for the future of the fisheries and other ecosystems of the basin. We conclude that major investment is required in innovative technology to reduce the loss of ecosystem services, and alternative livelihood strategies to cope with the losses that do occur.     

Assessing the effect of natural controls and land use change on sediment yield in a major Andean River: the Magdalena drainage basin, Colombia

The Magdalena River, a major fluvial system draining most of the Colombian Andes, is a world-class river, in the top 10 in terms of sediment load (approximately 150 MT/yr). In this study, we explore the major natural factors and anthropogenic influences behind the patterns in sediment yield on the Magdalena basin and reconstruct the spatial and temporal pattern of deforestation and agricultural intensification across the basin to test the relationships between land use change and trends in sediment yield. Our results show that sediment yield for the whole Magdalena catchment can be explained by natural variables, including runoff and maximum water discharge. These two estimators explain 58% of variance in sediment yield. Temporal analyses of sediment discharges and land use show that the extent of erosion within the catchment has increased over the last 10 to 20 years. Many anthropogenic influences, including a forest decrease by 40% in a 20-year period, an agriculture and pasture increase by 65%, poor soil conservation and mining practices, and increasing rates of urbanization, may have accounted for the overall increasing trends in sediment yield on a regional scale.     

Assessment of denitrification process in lower Ishikari river system,Japan

Sediment denitrification rate and its role in removal of dissolved nitrate load in lower Ishikari river system were examined. Denitrification rate were measured using acetylene inhibition technique on the sediment samples collected during August 2009–July 2010. The denitrification rate varied from 0.001 to 1.9 μg N g⁻¹ DM h⁻¹ with an average value of 0.21 μg N g⁻¹ DM h⁻¹ in lower Ishikari river system. Denitrification rate showed positive correlation with dissolved nitrate concentration in the river basin, indicating overlying water column supplied nitrate for the sediment denitrification processes. Nutrient enrichment experiments result showed that denitrification rate increased significantly with addition of nitrate in case of samples collected from Barato Lake however no such increase was observed in the samples collected from Ishikari river main channel and its major tributaries indicating that factors other than substrate concentration such as population of denitrifier and hydrological properties of stream channel including channel depth and flow velocity may affects the denitrification rate in lower Ishikari river system. Denitrification rate showed no significant increase with the addition of labile carbon (glucose), indicating that sediment samples had sufficient organic matter to sustain denitrification activity. The result of nutrient spiraling model indicates that in- stream denitrification process removes on an average 5% d⁻¹ of dissolve nitrate load in Ishikari river. This study was carried out to fill the gap present in the availability of riverine denitrification rate measurement and its role in nitrogen budget from Japanese rivers characterize by small river length and high flow rate.     

How do long-term development and periodical changes of river-floodplain systems affect the fate of contaminants? Results from European rivers

In many densely populated areas, riverine floodplains have been strongly impacted and degraded by river channelization and flood protection dikes. Floodplains act as buffers for flood water and as filters for nutrients and pollutants carried with river water and sediment from upstream source areas. Based on results of the EU-funded “AquaTerra” project (2004-2009), we analyze changes in the dynamics of European river-floodplain systems over different temporal scales and assess their effects on contaminant behaviour and ecosystem functioning. We find that human-induced changes in the hydrologic regime of rivers have direct and severe consequences on nutrient cycling and contaminant retention in adjacent floodplains. We point out the complex interactions of contaminants with nutrient availability and other physico-chemical characteristics (pH, organic matter) in determining ecotoxicity and habitat quality, and draw conclusions for improved floodplain management.     

Contamination of rivers in Tianjin, China by polycyclic aromatic hydrocarbons

Tianjin urban/industrial complex is highly polluted by some persistent organic pollutants. In this study, the levels of 16 priority polycyclic aromatic hydrocarbons (PAHs) were tested in sediment, water, and suspended particulate matter (SPM) samples in 10 rivers in Tianjin. The total concentration of 16 PAHs varied from 0.787 to 1943 microg/g dry weight in sediment, from 45.81 to 1272 ng/L in water, and from 0.938 to 64.2 microg/g dry weight in SPM. The levels of PAHs in these media are high in comparison with values reported from other river and marine systems. Variability of total concentrations of PAHs in sediment, water, and SPM from nine different rivers is consistent with each other. No obvious trends of total PAHs concentration variations were found between upstream and downstream sediment, water, and SPM samples for most rivers, which indicate local inputs and disturbances along these rivers. The spatial distributions of three-phase PAHs are very similar to each other, and they are also similar to those found in topsoil. However, their chemical profiles are significantly different from that of topsoil. The change of profiles is consistent with the different aqueous transport capability of 16 PAHs. Low molecular weight PAHs predomination suggests a relatively recent local source and coal combustion source of PAHs in the study area.     

Cumulative effects of climate warming and other human activities on freshwaters of Arctic and subarctic North America

Despite their generally isolated geographic locations, the freshwaters of the north are subjected to a wide spectrum of environmental stressors. High-latitude regions are especially sensitive to the effects of recent climatic warming, which have already resulted in marked regime shifts in the biological communities of many Arctic lakes and ponds. Important drivers of these limnological changes have included changes in the amount and duration of snow and ice cover, and, for rivers and lakes in their deltas, the frequency and extent of spring floods. Other important climate-related shifts include alterations in evaporation and precipitation ratios, marked changes in the quality and quantity of lake and river water inflows due to accelerated glacier and permafrost melting, and declining percentages of precipitation that falls as snow. The depletion of stratospheric ozone over the north, together with the clarity of many Arctic lakes, renders them especially susceptible to damage from ultraviolet radiation. In addition, the long-range atmospheric transport of pollutants, coupled with the focusing effects of contaminant transport from biological vectors to some local ecosystems (e.g., salmon nursery lakes, ponds draining seabird colonies) and biomagnification in long food chains, have led to elevated concentrations of many persistent organic pollutants (e.g., insecticides, which have never been used in Arctic regions) and other pollutants (e.g., mercury). Rapid development of gas and oil pipelines, mining for diamonds and metals, increases in human populations, and the development of all-season roads, seaports, and hydroelectric dams will stress northern aquatic ecosystems. The cumulative effects of these stresses will be far more serious than those caused by changing climate alone.     

Water level response to hydropower development in the upper Mekong River

Environmental changes and their transboundary influences on the Mekong watercourse system have been an international research focus in recent years, but the opinions and results related to the impacts of upper Mekong River dams are quite different. In this paper, based on the records of water levels from 1960 to 2003 at three mainstream sites in the upper Mekong River, a quantitative examination has been undertaken into characteristics of the mainstream water-level process at multiple timescales and its response to cascade development. The major results are: i) Annual mean, wet period mean, and the mean water levels during the period between March and April (PBMA period) exhibit a significant increasing trend at Jiuzhou and Yunjinghong sites, which are influenced by large-scale factors such as climate change and solar activity. ii) The interdecadal and interannual variations of annual mean, annual maximum, and wet period mean water levels at three sites show similar features during the dam construction period. iii) The interdecadal variations of PBMA period water level show a gradual increase at Gajiu and Yunjinghong sites but a falling trend at Jiuzhou; these trends confirm that there is some regulation on the flow in the dry season caused by the two existing dams. iv) The downstream effects of the present dams on water levels are very limited at the annual mean and wet season mean levels, not apparent at the monthly and yearly timescales, and relatively significant at daily and hourly timescales.     

Polychlorinated dibenzo-p-dioxins and dibenzofurans in River Po sediments

The River Po is the main Italian river draining one of the most populated and industrialised regions in Italy. As part of a monitoring project to assess environmental quality in the River Po, we measured the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in bottom sediments collected along the whole course of the river, from the spring to the delta, downstream from the confluence of its main tributaries. The aim was to investigate the level of contamination in the main Italian river and the contribution of contaminant loads from the subbasins. Composite sediment samples were collected in summer and winter surveys in low-flow water conditions and analysed by HRGC-HRMS for PCDD and PCDF homologue groups and for the 2,3,7,8-substituted congeners. The spatial trend observed in the Po River for PCDD and PCDF concentrations varied depending on the load of contaminants received from the tributaries and the processes of sedimentation. The sum of PCDD and PCDF concentrations, and the toxic equivalent content, ranged from 121 to 814 and from 1.3 to 13 ng/kg dry weight sediment, respectively. These levels of contamination seem lower than in the sediments of rivers draining highly industrialised areas. The PCDD and PCDF homologue profiles in all the samples were very similar, suggesting a common source of this contamination in the River Po. Principal component analysis suggested that widespread sources, such as urban runoff and domestic wastewaters, are probably the main cause of these levels of PCDDs and PCDFs.     

Occurrence, distribution, and sources of six phenolic endocrine disrupting chemicals in the 22 river estuaries around Dianchi Lake in China

The objectives of this study are to track the occurrence, distribution, and sources of phenolic endocrine disrupting compounds (EDCs) in the 22 rivers around Dianchi Lake in China, to estimate the input and output amounts of phenolic EDCs in the water system, and to provide more comprehensive fundamental data for risk assessment and contamination control of phenolic EDCs in aquatic environment. Six phenolic EDCs were systematically evaluated in water and surface sediment in the estuaries of those rivers. The water and sediment samples were preconcentrated by solid-phase extraction system and microwave-assisted extraction system, respectively. Phenolic EDCs were analyzed by GC-MS (Thermo Fisher Scientific, USA) after derivatization. Phenolic EDCs were found ubiquitously in the aquatic environment. The total concentrations ranged from 248 to 4,650 ng/L in water, and 113 to 3,576 ng/g dry weight in surface sediment. The residue amount of phenolic EDCs in Dianchi Lake was 258 kg/a. Concentrations of the phenolic EDCs in the Lake decreased with increase in distance to the estuaries of those rivers which run through urban and industrial areas. The rivers seriously contaminated by phenolic EDCs were Xin River, Yunliang River, Chuanfang River, Cailian River, Jinjia River, Zhengda River, and Daqing River which run through the old area of Kunming City. Satisfying correlations were observed between the concentrations of the target compounds in water and in surface sediment. NP1EO, NP2EO, and BPA were identified as the three predominant phenolic EDCs. There were significant correlations between phenolic EDCs and many basic water quality parameters. Urban and industrial areas are the major contributors for phenolic EDCs, especially in Kunming City. Compositional profiles of phenolic EDCs in surface sediment were similar to those in river water. The concentrations of phenolic EDCs in the rivers located in the northwest part of the valley were very high, and posed a potential risk to aquatic organisms and even human. The concentrations of NP2EO, NP1EO, and BPA were at moderate levels of other areas. The basic water quality parameters (TOC, TN, DO, and pH) play important roles on the distribution, fate, and behavior of phenolic EDCs in the valley.     

Occurrence and distribution of pharmaceuticals in surface water, suspended solids and sediments of the Ebro river basin, Spain

The occurrence of 43 pharmaceuticals belonging to predominant therapeutic classes and their distribution in surface water, suspended solids and sediments has been investigated in the Ebro river basin in the Northeast of Spain. WWTP effluents were found to be a main source of contamination and the spatial distribution was affected by the river flow at the sampling point and corresponding dilution factor, resulting in higher concentrations and higher loads in small tributary rivers than in the Ebro river. The study showed that some compounds are preferentially found bound to suspended solids and not detected in river water. Generally, compounds with basic characteristics (pKa > 7) showed higher tendency to bind to suspended solids. The sediment samples generally presented lower concentrations than suspended solids.     

Evaluation of fecal pollution of river sediment by detection of urobilin

In this study, we attempted to establish a new indicator for fecal pollution of river sediment using a sensitive detection method for urobilin. Urobilin contained in sediment was extracted with an alkaline buffer solution. The suitable buffer solution for extraction of urobilin consisted of 0.1 M Tris-HCl buffer (pH 10.0) containing 0.1 m sodium chloride. The ratio of sediment to buffer was 1:10. The distribution of urobilin in river sediment was studied by this method. The amount of urobilin in the river sediment of Tokyo (urban) and the Miura peninsula (rural) area was surveyed. Large quantities of urobilin were detected in the sediments of the urban rivers, but it was scarce in the rural rivers. Urobilin showed a higher content in sediment than in water. Urobilin in river sediment is distributed in large amounts in the lower reaches, where the water is polluted with domestic sewage and industrial waste, but is scarce in the upper streams. The amount of urobilin decreases to the lower layers.     

Technogenic load in small river watersheds in the Hibiny Mountains

Pollution loads and morphological changes in the Hibiny mountains ecosystems, one of the most industrially developed regions of the Russian North, were studied using landscape geochemical methods. Principal pollutants come from the local apatite-nepheline ore mining and processing industry which is responsible for mechanical disturbances as well. Some pollutants (Cu, Ni, Co, sulphur etc.) reach the territory because of long-range air transport from the Monchegorsk smelters. Different environmental media were sampled. Seven hydrochemical regions were distinguished, based on chemical composition of local small rivers. Hydrochemical composition of the most polluted of them is controlled by industrial polluted water discharges. The most polluted rivers are: B.Belaya, the lower parts of Loparskaya, Juksporiok etc. Lakes Umb and Imandra receive high amounts of different polluters with river waters. Pollutant loads at small river watersheds depend on height and aspect of mountain slopes. The internal mountain watersheds are the cleanest as a rule. Heightened air pollutant accumulation is typical for the height of 600-800 and 500 m due to atmospheric circulation patterns. Using GIS technologies, a synthetic map of technogenic loads in the Hibiny mountain region was compiled.     

Dynamic modeling of organophosphate pesticide load in surface water in the northern San Joaquin Valley watershed of California

The hydrology, sediment, and pesticide transport components of the Soil and Water Assessment Tool (SWAT) were evaluated on the northern San Joaquin Valley watershed of California. The Nash-Sutcliffe coefficients for monthly stream flow and sediment load ranged from 0.49 to 0.99 over the watershed during the study period of 1992-2005. The calibrated SWAT model was applied to simulate fate and transport processes of two organophosphate pesticides of diazinon and chlorpyrifos at watershed scale. The model generated satisfactory predictions of dissolved pesticide loads relative to the monitoring data. The model also showed great success in capturing spatial patterns of dissolved diazinon and chlorpyrifos loads according to the soil properties and landscape morphology over the large agricultural watershed. This study indicated that curve number was the major factor influencing the hydrology while pesticide fate and transport were mainly affected by surface runoff and pesticide application and in the study area.     

Spatial and temporal variations and possible sources of dichlorodiphenyltrichloroethane (DDT) and its metabolites in rivers in Tianjin, China

Water, suspended solid (SS) and sediment samples were collected from nine water courses in Tianjin, China and analyzed for dichlorodiphenyltrichloroethane (DDT) and its metabolites (DDXs, including o,p'-,p,p'-DDT, DDD and DDE). The average DDX concentrations in water, SS and sediment were 59+/-30 ng l(-1), 2690+/-1940 ng g(-1)dry wt. and 340+/-930 ng g(-1)dry wt., respectively. Due to the termination of the extensive agricultural application and industrial manufacture, DDXs in river sediment decreased by one order of magnitude since 1970's and low DDT fractions in these sediments were observed. Still, DDXs in the sediments near the outlets of the major manufacturers remained relatively high attributed to the historic input. DDXs in sediment were also positively correlated with organic matter content. Spatial distributions of DDXs in SS and water was different from that in sediment. For SS, a negative correlation between DDX concentration and SS content indicated a dilution effect in many rivers. Dissolved organic carbon content was the major factor affecting DDX concentrations in water phase. Wastewater discharged from dicofol manufacturers and likely illegal agricultural application were the primary reasons causing high DDT (DDE+DDD) ratios in SS and water.     

Distribution and fate of organochlorine pesticide residues in sediments from the selected rivers in Taiwan

The contamination of organochlorine pesticides (OCPs) in sediments from selected rivers in Taiwan was investigated to evaluate the pollution potentials and hazard in river sediments. Da-han River and Erh-jen River were selected as the target rivers due to their serious pollution. A total of 40 surface sediment samples were collected at five sampling stations along the rivers. Results showed that the concentrations of various pesticides in sediments were in the range of 0.57-14.1 ng/g for sigmaHCH, 0.05-0.15 ng/g for aldrin, 0.12-5.8 ng/g for dieldrin, 0.22-0.64 for endrin, 0.24-6.37 ng/g for endosulfan and 0.21-8.81 ng/g for EDDT (p,p'-DDD, p,p'-DDE, p,p'-DDT). Among the OCPs, sigmaHCH, endosulfan and sigmaDDT were the most dominant compounds in the river sediments. Endosulfan sulfate was the most frequent detected compound in the sediments from the selected rivers. Also, sigmaDDT, dieldrin and beta-HCH were in abundance. Different contamination patterns between the selected river sediments were also observed. Da-han River was mainly contaminated with endosulfan sulfate and sigmaDDT. Whereas the main pesticides in Erh-jen River were beta-HCH and sigmaDDT. Among the cyclodiene compounds, dieldrin was in abundance in most of the sediments. Moreover, the frequencies of detection of the metabolites were higher than those of parent compounds, depicting that the sediments have contaminated for a long time. The results obtained in this study showed that there still exist a variety of OCP residues in the river sediments in Taiwan.     

面向城市水系环境需水的再生水空间配置——以深圳市宝安区为例

以深圳市宝安区为例,探讨以再生水满足城市水系环境需水的方法.应用一维恒定与非恒定水质模型计算了4种补水水质方案下该区10条主要河流的环境需水量,从水量平衡角度提出全区再生水BOD5的平均值,并进一步分析了补水水质与河流环境需水量的关系.结合该区水系与污水处理系统空间位置,提出3种再生水的空间配置方法.结果表明:茅洲河和...