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1.
Purpose
The aim of this work was to develop a comprehensive fluvial suspended sediment budget for a large regulated river, the lower River Ebro (NE Spain).Materials and methods
The sediment loads of the Ebro mainstem and its main tributaries were estimated from continuous records of water discharge and turbidity (appropriately transformed to suspended sediment concentrations). Records were obtained at ten monitoring sections during the relatively dry 2008–2011 period.Results and discussion
The sediment load estimated for the River Ebro upstream of the Mequinenza Reservoir is remarkable (i.e. mean suspended load of 0.6?×?106?t?year?1), despite the fact that the site is already affected by a sediment deficit due to upstream reservoirs. Further downstream, and owing to their humid characteristics, the contribution of the Pyrenean tributaries (Segre and Cinca Rivers) is much larger compared with their Iberian Massif counterparts (Matarranya and Algars Rivers), with sediment loads of 0.49?×?106 and 2,260 t, respectively. The suspended sediment load trapped in the Mequinenza-Ribarroja-Flix Dam Complex for the study period was estimated at 2.3?×?106?t. Below the dams, the sediment load was reduced by 95 % but increased gradually in a downstream direction due to the erosion processes that clear water (i.e. very low sediment concentrations) flood flows exert on the river bed and banks and the episodic contribution from ephemeral tributaries.Conclusions
Reservoirs have reduced the overall sediment load and the natural variability of flow and sediment transport in the River Ebro. In addition, the sediment budget revealed that floods were not the only drivers of the sediment dynamics in the lower Ebro. For instance, the particular location of the monitoring sections showed that episodic contributions from small tributaries alter the general sediment load of the river during certain torrential events. 相似文献2.
Background, Aim and Scope Past and present management of the Ebro catchment have altered water, sediment and nutrient fluxes of the lower Ebro River
and its delta. The construction of the Mequinensa and Riba-Roja dams during the 1960s disrupted the sediment transport continuity.
As a result, the lower Ebro River and its delta are facing a reduction in sediment delivery which is estimated to be up to
99% of its original yield (about 3 × 107 t/yr). Consequently, about 45% of the emerged delta will be under the mean sea level by 2100 due to subsidence and sea level
rise, whereas the delta coast is retreating at a rate of several meters per year in the mouth area. This paper aims to establish
the basis for a sediment management plan directed to offset the effects of the sediment delivery deficit of the Ebro delta.
Main Features A new management plan named ‘Integrated Plan for the Protection of the Ebro Delta’ (PIPDE) is being presently elaborated in
order to develop sustainable management of the Ebro River and delta through an integrated management of water, sediment and
habitats, in order to achieve European Union (EU) Water Framework Directive (WFD) requirements. Among other aspects, the plan
aims to restore the sediment flux of the lower Ebro River by means of both the removal of the sediment trapped behind the
dams and the transport of the sediment downstream of the reservoirs to the river mouth and delta plain.
Results Preliminary studies show that the ‘flushing flood’ method has lower costs and is the most adapted method to transfer the sediments
retained into the Riba-Roja dam. The required sediment load to stop coastal retreat in the mouth area and to compensate relative
sea level rise represents 10 times the present suspended load (0.021 g/l), but is 10 times lower than the total volume of
sediment delivered to the sea under natural conditions. Sediment delivery to the delta plain can be accomplished through the
rice irrigation system, a method used prior to dam construction.
Discussion Problems of achieving a sustainable management of water and sediment are mostly linked to reservoir management. Technical
problems associated with by-passing sediments through the reservoirs can be solved through operational and structural changes.
Benefits of sediment flow recovery are multiple, including maintenance of the reservoir capacity, possible decline of invasive
species, reduction of elevation loss and coastal retreat in the delta.
Conclusions The partial restoration of sediment fluxes in the lower Ebro River and its delta is technically feasible and environmentally
desirable, but further detailed studies need to be carried out before the plan can be implemented.
Perspectives Overall, the sustainability of the lower Ebro River and delta can only be guaranteed by the implementation of a new reservoir
management concept where the ecological and morphological values, as well as the economical and social values, have to be
taken into consideration. 相似文献
3.
Purpose
Dominant discharges and associated sediment dynamics of the River Isábena, a 445-km2 catchment in the central Pyrenees of Spain that is punctuated by badlands, are analysed.Materials and methods
Calculations of suspended sediment loads are based on continuous records of discharge and turbidity obtained at the basin outlet for the period 2005–2010.Results and discussion
Dominant discharges for sediment load (i.e. effective discharge) present a bimodal distribution, with one peak falling in the range of low flows and the other associated to less frequent but higher magnitude floods (i.e. bankfull). The highly suspended sediment availability in the badlands, together with the high connectivity between the badlands and the stream network and the important in-channel fine sediment storage, causes both large and small events to remobilize fines. Baseflows, despite their low competence, generate resuspension and massive sediment loads. Thus, effective discharge (i.e. the discharge which transports most of the sediment) is not solely associated with bankfull (i.e. the discharge that dominates channel form), but to a wider range of discharges. Consequently, this river channel is not specifically adjusted to convey most of the sediment load during high floods, as in many other rivers, but instead large volumes of sediment are transferred downstream at an almost constant rate.Conclusions
Results suggest that dominant discharge may play a lesser role in terms of (suspended) sediment load in non-supply-limited fluvial systems and/or in rivers that permanently work close to, or at, full transport capacity, as is the case of the Isábena. 相似文献4.
Gateuille David Owens Philip N. Petticrew Ellen L. Booth Barry P. French Todd D. Déry Stephen J. 《Journal of Soils and Sediments》2019,19(9):3357-3373
Purpose
Sediment dynamics in most large river basins are influenced by a variety of different natural and anthropogenic pressures, and disentangling these cumulative effects remains a challenge. This study determined the contemporary and historical sources of fine-grained (<?63-μm) sediment in a large, regulated river basin and linked changes in sources to activities in the basin. The river has seen declines in chinook salmon, sockeye salmon, and the endangered Nechako white sturgeon populations, and sediment (both fine-grained and sands) transport and deposition have been identified as potential causes of these declines.
Materials and methodsSamples of suspended sediment and potential source materials were collected from numerous sites distributed throughout the upper Nechako River Basin in British Columbia, Canada. A floodplain sediment core was also collected in order to reconstruct sediment sources over the last ~?70 years. Discriminating fingerprint properties were used within the MixSIAR model to apportion sources among sub-basins and land-use types. Results were compared to records of precipitation and Nechako River discharge trends, and to changes in landscape development.
Results and discussionContributions from the erosion of channel banks dominated the suspended sediment load at most sites. Changes in sediment sources during the 2015 field season reflected snowmelt and patterns of water release from the Nechako Reservoir that affected the sediment-carrying capacity of tributaries and the Nechako River main stem. Spatial variations in 2015 also reflected the distribution of land use (e.g., forested or agricultural land) as well as topography (e.g., slope steepness). Over the last ~?70 years, variations in sediment sources and the characteristics of the sediment (e.g., organic matter content and particle size composition) were linked to the construction of the Kenney Dam (operational in 1954) and the impacts of deforestation by the forestry and agricultural industries. Superimposed on these have been wildfires and a major mountain pine beetle infestation leading to higher erosion rates in the affected areas.
ConclusionsThe sediment source fingerprinting technique, in combination with historical information on the hydrometeorology and the land use and river management in the basin, has provided valuable information with which to understand sediment dynamics in the Nechako River Basin. Such an approach can help to disentangle how large river systems respond to a combination of natural and anthropogenic pressures.
相似文献5.
Jiongxin Xu 《CATENA》2002,49(4)
According to the yearly maximum suspended sediment concentrations (SSC) in the Yellow River and its tributaries, the rivers are divided into three types of more than 300, 20–300, and less than 20 kg/m3. The middle Yellow River basin is located in the transitional zone from subhumid to semiarid climates, and covered by a thick loess mantle. Neighboring on the desert areas to the northwest, the surface material of the Loess Plateau exhibits some marked areal differentiation in grain size and forms three zones covered by sandy loess, (typical) loess and clayey loess from northwest to southeast. Controlled by these physico-geographical conditions, the grain size of river-transported sediment shows some particular characteristics; at small water discharge or SSC, the grain size of suspended sediment abruptly decreases to a minimum with increasing water discharge or SSC. At water discharge of more than ca. 40 m3/s or at SSC of more than ca. 40 kg/m3, the grain size increases with water discharge or SSC.During the low-stage season, the relatively clear baseflow may scour the coarse bed materials, so the suspended sediment is relatively coarse. In the rainy season, rainstorm runoff washes out fine loess materials to the river, making suspended sediment fine. During relatively strong rainstorms, there often occur hyperconcentrated flows at SSC of more than 300 kg/m3. The relatively coarse grains could then remain suspended in the mixture of water and fine suspended sediment. 相似文献
6.
Samples of suspended and fine channel bed sediment were used to examine the spatial and temporal variability in the amount of fine-grained sediment and associated contaminants temporarily stored in the Na Borges River (319 km2) in Mallorca and the relationship of such channel storage to the fluxes of fine sediment and associated contaminant through the system. This Mediterranean groundwater-dominated river drains a predominantly agricultural catchment, although urbanisation during the twentieth century has changed the catchment hydrology. A re-suspension technique was used to obtain estimates of channel storage at monthly intervals during the 2004–2005 hydrological year at eight locations along the main stem of the stream (i.e. 26 km). The estimates of fine sediment storage ranged between 0 and 13,000 g m− 2, with a mean value of 2400 g m− 2. Only Cu exceeded the critical threshold (36 μg g− 1), established by existing guidelines for the contaminant content of fluvial sediment. The results demonstrated significant spatial and temporal variability, in response to the influence of urban point sources, agricultural practises, seasonal groundwater interactions and the first-flush effect. The amount of fine sediment entering storage during the study period was 515.2 t, representing the net increase in storage over the study period. As a result, the mean specific storage was 21 t km− 1. Suspended-sediment load and temporary fine sediment storage are the two basic components of the channel sediment budget that interact to determine sediment transport through a channel system, and they can therefore be used to compute the total input of sediment and associated contaminants to the system. Accordingly, storage values were compared with estimates of suspended sediment load and associated contaminant load values at three measuring stations along the river. During the study period, storage in the main channel system represented 87% of the sediment input and 68% of the contaminant input, indicating that deposition was more important than transport. The low gradient of the main channel and the low return period (i.e. 0–2.5 years) of the flood events that occurred during the study period meant that remobilised bed sediment and associated contaminants were redeposited downstream rather than being flushed to the catchment outlet as suspended sediment. Furthermore, the river bed is dry during the summer months, allowing sealing and crusting processes to stabilise the sediment deposited during the wet season and thereby reduce its availability for remobilisation at the beginning of the next wet season. Together, these factors promote sediment deposition and storage, with the result that sediment progressively accumulate over several hydrological years until a major flood event (i.e. return period ≈ 5 years) evacuates the stored sediment. 相似文献
7.
The sediment, budget of a reservoir on the Neckar River, Germany, was investigated by means of experimental and numerical methods. Field measurements of channel bathymetry show that. sedimentation and erosion occur primarily in the lower backwater-influenced section of the reservoir, which stores approximately 350,000 m3 of fine-grained deposits. Sediment load balances for two major storm events in Dec. 1993 and Apr. 1994 showed net erosion of 32,000 ±10,000 tonnes and 24,000 ± 5,000 tonnes of sediment, respectively. A balanced sediment budget, was found for a minor flood in Jan. 1995. In agreement with the field data, numerical simulation of sediment transport. over a period of 45 years demonstrates that the river reservoir served initially as a sediment trap from 1950 to 1978, and since then as a temporary storage basin for sediment. 相似文献
8.
Fernando Jaramillo Matthieu Baccard Pramenath Narinesingh Susan Gaskin Vincent Cooper 《Land Degradation \u0026amp; Development》2016,27(4):1064-1074
Impact assessments on river systems of the combined effect of bed and suspended sediment loads from quarries are difficult to find. In this study, bed and suspended loads were measured to determine the impact of a 20‐ha limestone quarry on the river system of its 5,000‐ha steep, diverse land use/land cover but mostly forested catchment. A network of hydrologic and sediment monitoring instruments was deployed over the catchment during two separate study periods when sediment loadings were measured from captured storms. Results showed that the quarry stood to make a disproportionately large contribution to the catchment's estimated 2·1 Mg ha−1 yr−1 suspended sediment load. Large storm events contributed most of the loadings with five events supplying 92% of total loadings at the outlet. A paired method approach to compare suspended sediment loads between two subcatchments showed that during eight storm events, the quarry yielded between 2 and 49·2 Mg ha−1 per event, whereas the forest never yielded more than 0·1 Mg ha−1. Furthermore, the contribution of sediments from the quarry to bed load was more than 75% at a section located 1·2 km downstream. Future management activities to reduce sediment and bed loads, not only from this catchment but also from all others with similar land use/land covers, should focus on improving quarry operations. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
9.
[目的]解决黄河三角洲地区盐碱地改良造林绿化的难点。[方法]分析黄河三角洲目前的盐碱地资源和特点,阐述盐碱地改良与造林绿化现状。在此基础上,依据前人的技术和研究成果,结合作者多年来盐碱地生态改良的研究与实践。[结果]提出了适宜黄河三角洲盐碱地造林绿化的关键技术:(1)利用传统方法造林绿化改良盐碱地;(2)重视新技术和新成果的应用。[结论]利用盐碱地造林绿化关键技术,实现黄河三角形洲滨海盐碱地改良是切实可行的。 相似文献
10.
Characteristics of bacterial community in the water and surface sediment of the Yellow River,China, the largest turbid river in the world 总被引：1，自引：0，他引：1
Na Xia Xinghui Xia Ting Liu Lijuan Hu Baotong Zhu Xiaotian Zhang Jianwei Dong 《Journal of Soils and Sediments》2014,14(11):1894-1904
Purpose
Few studies have described the bacterial community structures of turbid rivers. In this paper, the characteristics of the bacterial community in the water and surface sediment of the Yellow River, China, the largest turbid river in the world, were studied.Materials and methods
Water and sediment samples were collected from six sites along the river. Bacterial community composition was determined using the 16S ribosomal RNA (rRNA) gene clone library technique. The relationship between environmental parameters and bacterial diversity was analyzed.Results and discussion
A total of 1,131 gene sequences were obtained and clustered into 639 operational taxonomic units (at the 97 % identity level), with Proteobacteria as the predominant phylum. The Shannon index for water samples ranged from 3.39 to 4.40 and was generally higher than that in other rivers; this was probably due to the high suspended particulate sediment (SPS) concentration in the Yellow River, which can provide more habitats for both aerobic and anaerobic bacteria. Also, the bacterial diversity of the water samples was slightly higher than that of the surface sediment samples. The bacterial diversity of water increased along the river in the downstream direction, while there was no trend for the sediment. Redundancy analysis indicated that pH, dissolved organic carbon (DOC), and SPS were the main factors controlling the water bacterial community in the Yellow River, and pH, nitrate–nitrogen, and water content were the main factors for the surface sediment bacterial community.Conclusions
This study indicated that the bacterial diversity of the Yellow River is generally higher than that in other rivers, suggesting that SPS plays an important role in regulating bacterial diversity and community structure in aquatic environments. 相似文献11.
引用黄河泥沙对下游平原土地质量及其演变的影响 总被引：4，自引：3，他引：4
通过 5 0年来引黄用沙的总量及其分布研究 ,在结合野外调查采样分析的基础上 ,系统研究了泥沙对土壤质地、肥力、盐分运移规律及其景观的影响 ,并提出在欣赏引黄成就的同时 ,应密切关注泥沙堆占土地、次生沙化、次生盐碱化、淤塞排泄河道等问题。 相似文献
12.
[目的]河道演变是水流、泥沙与河床边界相互作用的结果,对水利工程的安全、洪涝灾害的防控有显著的影响。黄河中游府谷—龙门段位于晋陕峡谷地带,以黄土高原沟壑侵蚀地貌为主,流经的黄土高原地区是黄河泥沙的主要来源,因此研究该河段的河道冲淤特征及影响因素对控制黄河中游水土流失有重要意义。[方法]基于府谷、吴堡、龙门3个典型水文站径流泥沙及河道断面数据,分析了2007—2017年府谷—龙门段河道冲淤特征及相关影响因素。[结果](1)近11年来府谷—龙门段河道整体表现为冲刷,其中府谷—吴堡段表现为河道冲刷量逐渐减小,吴堡—龙门段表现为河道冲刷逐年加剧。(2)府谷—吴堡段呈水减沙增的趋势,吴堡—龙门段整体表现为水多沙少,两河段河道冲淤量与水流含沙量变化同步。(3)府谷—吴堡段悬移质泥沙中值粒径呈增加趋势,河道冲刷变缓;吴堡—龙门段悬移质泥沙中值粒径呈减小趋势,加剧河道侵蚀。(4)府谷站入黄泥沙量增加,河道侵蚀力降低,河道冲刷变缓;吴堡站入黄泥沙量减少,河道侵蚀力增强,河道处于冲刷的状态。[结论]径流泥沙的变化在很大程度上影响了府谷—龙门段河道冲淤。在生态环境有所改善的背景下,研究该河段河道冲淤特征及动... 相似文献
13.
Evaluation of suspended load changes using AnnAGNPS and SWAT semi-empirical erosion models 总被引：3，自引：0，他引：3
Simulation models are frequently used tools for suspended sediment load quantification in mesoscale catchment areas. To improve the simulation results, it is important to compare and verify different models using measured data. In this study, we tested two continuous simulation, semi-distributed erosion and sediment transport models AnnAGNPS and SWAT for the period of 1995–2004 in the Blšanka river basin. The catchment (374 km2) is an agricultural hop-growing region in the north-western part of the Czech Republic. Both models were calibrated using the first 5 years of data, and then validated using the second 5 years of daily discharge and suspended sediment yield values. For the long-term continuous simulation, the results of SWAT model simulation showed a better agreement to the measured data, while for short-term rainfall-runoff event simulation, especially short duration intensive rainfall events, suspended load was more accurately predicted by AnnAGNPS. Land use changed significantly in parts of the river basin during the observation period. Many hop-gardens were dismantled and arable land was partially converted to grassland and pasture. This enabled us to test the applicability of AnnAGNPS and SWAT models under changing land use conditions. According to both models, suspended sediment load was reduced after the land use changes by 10%–30%, which was in agreement with decreasing sediment discharge observed at the watershed outlet. 相似文献
14.
Research on the sedimentation and erosion problem of the Ergene River Basin in Western Turkey and precautions to control it 总被引：1，自引：0，他引：1
The objective of this study was to asses the rainfall-runoff-sedimentation relationship from directly measured data since 1972, to find out the effect of the present land use and soil cultivation techniques on the sediment yield, and to offer practical solutions to the problems in the Ergene River Basins located in the European Part of Turkey. The suspended sediment yield was calculated by multiplying the daily average discharged water by the average sediment concentration, while the eroded coarse sediment yield was computed using a regression equation developed by the Japanese Ministry of Construction. The relationship between the runoff and suspended sediment rates was explained exponentially as S = 1.99 Q A 1.62 (P > 0.01 and R 2 = 0.846) (S is the suspended sediment rate in t d?1, and Q A is the average daily runoff rate in m3 s?1). The suspended sediment rates of the Ergene Basin can then be predicted from the flow rate at any time of the year using this produced regression equation. According to the results, 70% of the basin’s soil (9534 km2 and occupying 81.76% of the total area of the region) is under erosion hazard varying in intensity, namely, 25.3% light, 34.6% moderate, 8.6% strong, and 1.5% very strong. 47.09% of the average 604 mm precipitation falls in the critical period of October–January in terms of the sedimentation. The coarse and suspended sediment yield was 74.040 t km?2 per year, which was well below the average for Turkey. However, it was 2 and 2.5 times larger than the average for Europe and Africa, respectively. Because 76.93% of the eroded land is in the 1rst, 2nd, and 3rd class, the severity of the sedimentation situation is proved. The causes of the high sediment yield were identified, and a series of precautions were suggested to minimize them. 相似文献
15.
Cristina Buendia Dami Vericat Ramon J. Batalla Chris N. Gibbins 《Land Degradation \u0026amp; Development》2016,27(4):1045-1063
Elucidating the links between catchment and channel geomorphic processes helps the understanding of landscape evolution and the geomorphic development of river basins, and then the land degradation processes. In this study, we analyse suspended sediment dynamics and its relationship with rainfall, discharge and in‐channel sediment storage in a highly dynamic Mediterranean montane catchment (the River Isáben, Southern Pyrenees, NE Iberian Peninsula). The aim is to assess hydrological controls on and temporal patterns of the suspended sediment load. High loads in this basin occur as a consequence of intense erosion in badlands located in the middle of the catchment. This study focuses on a reach located downstream from the main badland areas, where rainfall, discharge (Q), sediment transport (SSC) and in‐channel sediment storage were monitored for a 1‐year period. Marked seasonality in water and sediment load was observed; whereas most of the discharge occurred in winter and spring, most of the sediment was transported during summer and autumn. Q‐SSC hysteretic loops revealed the importance of sediment availability (whether stored in the channel or originating from wider catchment source areas) in the river's sedimentary response. Clockwise loops dominated during winter and spring, whereas counter‐clockwise loops occurred mostly in summer and autumn, when in‐channel storage reached its maximum. There were significant correlations between rainfall intensity in the sediment source areas, in‐channel sediment storage and sediment yield. These correlations emphasize the importance of understanding sediment availability when analysing the temporal dynamics of sediment transport, especially in catchments where different source areas (slopes and riverbed) may contribute to the load to differing degrees and at different times of the year. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
17.
[目的] 分析不同区域冰川河流的水沙关系、输沙量及其对气候变化的响应,并对泥沙侵蚀强度进行评估,为高寒山区冰川河流的水沙动态研究提供理论基础。[方法] 选取绒布河和科其喀尔河作为研究对象,在消融期间（2018年5—10月）对冰川河进行野外观测和水样采集。考虑气温和降水的影响,采用水文模型法对绒布河径流量进行模拟,结合水沙关系曲线、泥沙滞后环及回归模型对冰川河流的悬移泥沙输移及其影响因素进行分析。[结果] 气温是影响高寒山区冰川河流悬移泥沙运输的主要因素;绒布河和科其喀尔河消融期的径流模数约7.36×105,6.82×105 m3/（km2·a）,输沙模数分别为200 t/（km2·a）和890 t/（km2·a）。[结论] 绒布冰川对气候变化更加敏感,消融强度大,泥沙主要来源于融水与降水对河道底部与坡面的侵蚀,但是可侵蚀沉积物和水力条件不足,造成该地区输沙模数低于其他冰川;科其喀尔河地处西北干旱区,泥沙输移量主要是由泥沙来源决定的,随着气温的升高,大量冰碛物被输送到下游,侵蚀强度明显高于其他大多数冰川。 相似文献
18.
Brian Kronvang Hans E. Andersen Søren E. Larsen Joachim Audet 《Journal of Soils and Sediments》2013,13(1):230-241
Purpose
The importance of bank erosion was quantified during three periods (October 2006–April 2007, May 2007–April 2008 and May 2008–April 2009) in the 486 km2 catchment area of River Odense, Denmark. A catchment sediment budget was established including other sediment sources such as tile drains and surface runoff, in-channel and overbank sinks and storage and the resulting bed load and suspended sediment load exported from the catchment.Material and methods
Bank erosion and sedimentation were measured using ca. 3,000 erosion pins established in 180 pin plots, each consisting of three vertical lines of pins. Thirty-six representative reaches, each with a length of 100 m, were selected by a stratified random procedure in GIS. Bed load and suspended sediment export from the catchment were measured using a bed load sampler and from continuous measurements of turbidity at the outlet gauging station.Results and discussion
The gross sediment input from bank erosion during the three study periods amounted to 21,100–25,200 t in the River Odense catchment, which is considerably higher than the estimated input of sediment from tile drains and surface runoff, which amounted to 220–500 t and 0–100 t, respectively. The measured bed load (20–490 t) was five to 60 times lower than the suspended sediment export from the catchment (1,240–2,620 t) during the three study periods, with the largest difference occurring in the driest year. Sediment sinks and storage were of high importance for the catchment sediment budget as the measured in-channel storage of sediment on stream banks was as high as 16,200–20,100 t, and the overbank sediment sink was estimated at 360–3,100 t.Conclusions
Bank erosion was the dominant sediment source (90–94 %) in the River Odense catchment during the three study years. In-channel and overbank sediment sinks and storage dominated the sediment budget as 79–94 % of the sediment input from all sources was not exported from the catchment during the three study years. Such a large attenuation of sediment in river channels and on floodplains is extremely important for fluvial habitats and ecology. Moreover, it has strong implications for attempts to document changes in sediment export following implementation of mitigation measures. 相似文献19.
为了解冲积性河流塑槽输沙需水量,合理调配水资源,以内蒙古河段为例,依据挟沙水流能量平衡方程,研究了冲积性河流挟沙水流的能量耗散原理及水流塑槽和输沙能量的分配模式,给出了反应冲积性河流冲淤状态的塑槽输沙需水量计算方法,由平滩流量、河道来沙量和冲淤量三者组成的关系确定塑槽输沙需水量。利用内蒙古河段1960-2013年实测资料,计算得到内蒙古河段塑槽输沙水量,汛期来沙量0.7～1.1亿t,塑造2 000～3 000 m~3/s的中水河槽、淤积水平控制30%以下,需要的汛期塑槽输沙水量为94.6～141.2亿m~3;分析了不同条件下汛期塑槽输沙水量变化规律:来沙量一定,同样的中水河槽规模,控制淤积水平越低,需要的塑槽输沙水量越大;来沙量一定,同样的淤积水平,塑造中水河槽规模越大,需要的塑槽输沙水量越大;控制同样淤积水平,塑造同样中水河槽规模,汛期来沙量越大,需要的塑槽输沙水量越大。内蒙古河段塑槽输沙需水量计算结果和结果变化规律可为黄河上游内蒙古河段水资源配置提供参考。 相似文献
20.
利用1950—2005年黄河干流泥沙分布特征值资料与干流任意河段年平均泥沙加入公式对黄河干流宁蒙河段年平均泥沙加入进行了计算分析。结果表明,1950—2005年宁蒙河段每年都有大量泥沙加入,并且加入量随时间呈波动变化。通过数据分析与实地调查发现,造成该河段泥沙大量加入以及随时间呈波动变化的原因主要是宁蒙河段穿越腾格里沙漠、河东沙地、乌兰布和沙漠以及库布齐沙漠,沙漠与河流交互作用,使其具备风沙直接入黄以及支流泥沙入黄的条件;尤其以"十大孔兑"河道上游比降大,河道两岸地表沙物质易蚀性高,从而导致大量泥沙通过洪水过程进入黄河。黄河宁蒙河段的泥沙防治关键在于减少入黄泥沙量,特别是要加强"十大孔兑"地区的水土保持综合防治力度。 相似文献