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1.
Influence of Three Gorges Dam on streamflow and sediment load of the middle Yangtze River, China 总被引：2，自引：2，他引：0
Qiang Zhang Vijay P. Singh Xiaohong Chen 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(4):569-579
Using updated hydrological datasets from three stations, including Cuntan, Yichang and Hankou, covering the period of January
1992–December 2008, the influence of Three Gorges Dam (TGD) on streamflow and sediment load of the Yangtze River was investigated.
Results indicated that TGD did not seem to exert a significant influence on streamflow occurring at three stations and changes
in streamflow can be mainly attributed to streamflows of tributaries. However, a sharp decrease in the sediment load after
the impoundment of TGD was observed. Clear water after the impoundment caused erosion of riverbed and resulted in more sediment
at the Hankou station than at the Yichang station. No distinct changes in the annual and monthly maximum sediment loads were
observed before and after the impoundment. Therefore, annual and monthly maximum sediment load changes should be subjected
mainly to river hydraulics. This study has practical relevance for understanding the influence of large hydraulic structures
on the hydrological processes of large rivers. 相似文献
2.
水利工程兴建后洞庭湖径流与泥沙的变化 总被引：12，自引：6，他引：6
本文根据1951—1988年洞庭湖及其入湖河流的水文泥沙资料,研究大型水利工程兴建后洞庭湖径流与泥沙的变化。研究表明,近40年来洞庭湖的径流量减少了29.2％,输沙量减少了48.7％。引起水沙变化的主要原因是荆江四口分流河床的淤积,使荆江入湖的径流量与输沙量减少。1966—1972年下荆江三个弯道裁弯取直,使荆江河床下切,导致荆江及其分流水位的下降,也促使荆江分流的流量与输沙量的减少。40年来洞庭湖水流变化的趋势对洞庭湖、江汉平原与长江中下游的防洪较为有利。 相似文献
3.
《水文科学杂志》2013,58(6)
Abstract Abstract The prediction and estimation of suspended sediment concentration are investigated by using multi-layer perceptrons (MLP). The fastest MLP training algorithm, that is the Levenberg-Marquardt algorithm, is used for optimization of the network weights for data from two stations on the Tongue River in Montana, USA. The first part of the study deals with prediction and estimation of upstream and down-stream station sediment data, separately, and the second part focuses on the estimation of downstream suspended sediment data by using data from both stations. In each case, the MLP test results are compared to those of generalized regression neural networks (GRNN), radial basis function (RBF) and multi-linear regression (MLR) for the best-input combinations. Based on the comparisons, it was found that the MLP generally gives better suspended sediment concentration estimates than the other neural network techniques and the conventional statistical method (MLR). However, for the estimation of maximum sediment peak, the RBF was mostly found to be better than the MLP and the other techniques. The results also indicate that the RBF and GRNN may provide better performance than the MLP in the estimation of the total sediment load. 相似文献
4.
Revisiting lake sediment budgets: How the calculation of lake lifetime is strongly data and method dependent 
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下载免费PDF全文 Hanibal Lemma Teshager Admasu Mekete Dessie Derbew Fentie Jozef Deckers Amaury Frankl Jean Poesen Enyew Adgo Jan Nyssen 《地球表面变化过程与地形》2018,43(3):593-607
Lake sedimentation has a fundamental impact on lake lifetime. In this paper, we show how sensitive calculation of the latter is to the quality of data available and assumptions made during analysis. Based on the collection of a large new dataset, we quantify the sediment masses (1) mobilized on the hillslopes draining towards Lake Tana (Ethiopia), (2) stored in the floodplains, (3) transported into the lake, (4) deposited in the lake and (5) delivered out from the lake so as to establish a sediment budget. In 2012–2013, suspended sediment concentration (SSC) and discharge measurements were made at 13 monitoring stations, including two lake outlets. Altogether, 4635 SSC samples were collected and sediment rating curves that account for land cover conditions and rainfall seasonality were established for the 11 river stations, and mean monthly SSC was calculated for the outlets. Effects of the floodplain on rivers' sediment yield (SY) were investigated using measurements at both sides of the floodplains. SY from ungauged rivers was assessed using a model that includes catchment area and rainfall, whereas bedload and direct sediment input from lake shores were estimated. As a result, the gross annual SY was c. 39.55 (± 0.15) Mt, dominantly from Gilgel Abay and Gumara Rivers. The 2.57 (± 0.17) Mt sediment deposited in floodplains indicate that the floodplains serve as an important sediment sink. Moreover, annually c. 1.09 Mt of sediment leaves the lake through the two outlets. Annual sediment deposition in the lake was c. 36.97 (± 0.22) Mt and organic matter accumulation was 2.15 Mt, with a mean sediment trapping efficiency of 97%. Furthermore, SSC and SY are generally higher at the beginning of the rainy season because soils in cultivated fields are bare and loose due to frequent ploughing and seedbed preparation. Later in the season, increased crop and vegetation cover lead to a decrease in sediment production. Based on the established sediment budget with average rainfall, the lifetime of Lake Tana was estimated as 764 to 1032 years, which is shorter than what was anticipated in earlier studies. The sedimentation rate of Lake Tana (11.7 ± 0.1 kg m?2 yr?1) is in line with the sedimentation rates of larger lakes in the world, like Lake Dongting and Lake Kivu. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
5.
[专稿]近年长江中下游径流节律变化、效应与修复对策 总被引：1，自引：0，他引：1
近十余年长江上游大量兴建大型水库,蓄水、调节和拦沙对中下游河川径流和泥沙产生了深刻影响.河川径流减少,径流季节提前,伏秋（特别是10月）流量显著降低、变差系数增大,97%严重干旱频率情景变成80%~85%.同时,宜昌和出海输沙量分别减少93%和70%,中下游河槽冲刷下降1~3 m,三峡蓄水后仅13年清水冲刷幅度和范围已超过三峡预期30年的冲刷上限,目前仍呈加速趋势.干流各站平均水位下降2~4 m,与此同时河道同流量洪水位反而升高.水库调节是水位降低的主要原因,河道冲刷更加剧水位降低,当前水位变化对防洪和生态都不利.汛后流量和干流水位提前降低使洞庭湖和鄱阳湖（两湖）提前干枯、松滋等"三口"入湖水量减少,伏秋高热季节两湖生态环境面貌发生了根本变化.汛后流量减少甚至显著增加长江大通十月流量小于15000 m3/s几率和上海长江水源受咸潮影响风险,10月咸潮入侵变成最严重时段必须引起高度重视.我们认为,径流和径流节律变化是当前长江生态环境最主要问题之一.建议以"水资源工程"重新定位上游大型工程、以"水资源优先"优化流域管理和切实回归既定三峡工程运行原则等统一调度和改善中下游水情;通过水库挖泥等措施修复长江物质通量,抑制中下游剧烈冲刷和稳定河流格局;加强中下游蓄滞洪区等防洪能力建设,为最大限度降低上游水库防洪和蓄水压力创造条件;主要通过改善上游水库调度维护两湖环境条件,"引清水入洞庭"和"增加供水设施建设"加强两湖适应能力.这是长江修复和保护重点. 相似文献
6.
The Mekong Basin in southeast Asia is facing rapid development, impacting its hydrology and sediment dynamics. Although the understanding of the sediment transport rates in the Mekong is gradually growing, the sediment dynamics in the lower Mekong floodplains (downstream from Kratie) are poorly understood. The aim of this study is to conduct an analysis to increase the understanding of the sediment dynamics at the Chaktomuk confluence of the Mekong River, and the Tonle Sap River in the Lower Mekong River in Cambodia. This study is based on the data from a detailed field survey over the three hydrological years (May 2008–April 2011) at the two sites (the Mekong mainstream and the Tonle Sap River) at the Chaktomuk confluence. We further compared the sediment fluxes at Chaktomuk to an upstream station (i.e. Mukdahan) with longer time series. Inflow sediment load towards the lake was lower than that of the outflow, with a ratio on average of 84%. Although annually only a small amount of sediment load from the Tonle Sap contributes to the delta (less than 15%), its share is substantial during the February–April period. The annual sediment load transport from the confluence to the delta in 2009 and 2010 accounted for 54 and 50 Mt, respectively. This was on average only 55% of the sediment fluxes measured at Mukdahan, a more upstream station. Furthermore when compared to sediment loads further downstream at the Cambodia–Vietnam border, we found that the suspended sediment flux continued to decline towards the South China Sea. Our findings thus indicate that the sediment load to the South China Sea is much lower than the previous estimate 150–160 Mt/yr. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
为探索三峡水库运行前后长江中下游干流及两湖径流过程的变化及其驱动因素,利用宜昌、监利、大通、七里山、湖口共5个水文站的流量资料,分析了各站径流过程的变化特征及其成因。结论:(1)各站年径流量均减少,但除七里山站之外,其它各站减少比例均小于10%且变化不显著;(2)干流各站月径流量最大减幅发生在10月,而七里山站、湖口站分别发生在7月、4月;(3)干流各站月径流量最大增幅发生在3月,而七里山站、湖口站分别发生在1月、6月;(4)宜昌站,1—4月径流量增加是三峡水库入库径流增加和水库调度的共同作用结果,6—8月径流量减少的主因是三峡水库入库径流量减少,5、9、10月径流量变化的主因是三峡水库调度;(5)监利站,径流量的变化与宜昌站表现出高度的一致性,但冬季各月径流量的增幅均大于宜昌站;(6)大通站,4—6月径流量变化方向与湖口站一致,其它月份变化方向均与宜昌站一致。(7)七里山站,7月径流量减少的主因是洞庭湖流域来水减少,9、10月径流量减少的主要原因是荆江分流减少,但洞庭湖流域来水减少也是重要原因。(8)湖口站,4、5月径流量减少的主因是流域降水减少,9、10月径流量减少的主要原因是鄱阳... 相似文献
8.
The peak in sediment transport in alluvial rivers generally lags behind the peak in discharge. It is thus not clear how the hysteresis in the sediment/discharge relationship may be impacted by damming, which can fundamentally alter the water and sediment regimes in the downstream reaches of the river. In this study, a total of 500 flood events in the Yichang–Chenglingji Reach (YCR) of the Middle Yangtze River immediately downstream of the Three Gorges Dam (TGD) are analysed to study the impacts of dam operations on the hysteresis of suspended sediment transport. Sediment rating curves, hysteresis patterns, as well as lag times, are investigated to determine the relationship between suspended sediment concentration (SSC) and flow discharge (Q) at different temporal scales, from inter-annual to individual flood events, for the pre- and post-TGD period from 1992 to 2002 and from 2003 to 2017, respectively. The results showed that the TGD operation decreased the frequency and magnitude of floods. The decrease in peak flow and increase in base flow weakened the flood contribution to the annual discharge by nearly 20%. However, the relative suspended sediment load contribution during flood events was much higher than the discharge contribution, and was little impacted by the dam. At seasonal and monthly scales, more than 80% of the suspended sediment was transported by ~65% of the water discharge in the summer and early autumn. The monthly SSC–Q relationship changed from a figure-eight to an anti-clockwise pattern after the construction of the TGD. For single flood events, the TGD operations significantly modified the downstream SSC–Q hysteresis patterns, increasing the frequency of anti-clockwise loops and the lag time between peak Q and peak SSC. These adjustments were mainly caused by differences in the propagation velocities of flood and sediment waves and the sediment ‘storage–mobilization–depletion’ process, whereas the influence of lateral diversions was small. © 2020 John Wiley & Sons, Ltd. 相似文献
9.
ABSTRACTSedimentation in navigable waterways and harbours is of concern for many water and port managers. One potential source of variability in sedimentation is the annual sediment load of the river that empties in the harbour. The main objective of this study was to use some of the regularly monitored hydro-meteorological variables to compare estimates of hourly suspended sediment concentration in the Saint John River using a sediment rating curve and a model tree (M5?) with different combinations of predictors. Estimated suspended sediment concentrations were multiplied by measured flows to estimate suspended sediment loads. Best results were obtained using M5? with four predictors, returning an R2 of 0.72 on calibration data and an R2 of 0.46 on validation data. Total load was underestimated by 1.41% for the calibration period and overestimated by 2.38% for the validation period. Overall, the model tree approach is suggested for its relative ease of implementation and constant performance.
EDITOR M.C. Acreman; ASSOCIATE EDITOR B. Touaibia 相似文献
10.
Doan Van Binh Sameh A. Kantoush Tetsuya Sumi Nguyen Phuong Mai Trieu Anh Ngoc La Vinh Trung Tran Dang An 《水文研究》2021,35(2):e14030
The hydrogeomorphology of the Vietnamese Mekong Delta (VMD) has been significantly altered by natural and anthropogenic drivers. In this study, the spatiotemporal changes of the flow regime were examined by analysing the long-term daily, monthly, annual and extreme discharges and water levels from 1980 to 2018, supported by further investigation of the long-term annual sediment load (from the 1960s to 2015), river bathymetric data (in 1998, 2014 and 2017) and daily salinity concentration (from the 1990s to 2015) using various statistical methods and a coupled numerical model. Then, the effects of riverbed incision on the hydrology were investigated. The results show that the dry season discharge (i.e., in March–June) of the Tien River increased by up to 23% from the predam period (1980–1992) to the postdam period (1993–2018) but that the dry season water level at My Thuan decreased by up to −46%. The annual mean and monthly water levels in June at Tan Chau and in January and June–October at My Thuan in the Tien River decreased statistically, even though the respective discharges increased significantly. These decreased water levels instead of the increased discharges were attributed to the accelerated riverbed incision upstream from My Thuan, which increased by more than three times, from a mean rate of −0.16 m/year (−16.7 Mm3/year) in 1998–2014 to −0.5 m/year (−52.5 Mm3/year) in 2014–2017. This accelerated riverbed incision was likely caused by the reduction in the sediment load of the VMD (from 166.7 Mt/year in the predam period to 57.6 Mt/year in the postdam period) and increase in sand mining (from 3.9 Mm3 in 2012 to 13.43 Mm3 in 2018). Collectively, the decreased dry season water level in the Tien River is likely one of the main causes of the enhanced salinity intrusion. 相似文献
11.
Abstract A measurement campaign was carried out in the Upper Tana basin (Kenya) to quantify soil erosion and reservoir sedimentation rates, including a bathymetric reservoir survey and sediment load sampling during one year. Then, distributed soil erosion modelling was performed to study sediment budgets throughout the basin and to evaluate the potential of upstream erosion control through vegetated contour strips and check dams. Finally, the areas where these measures would be most effective were identified and local stakeholder associations to implement them were prioritized. The influence of the scale of implementation was evaluated by using the model to consider three adoption scenarios. This study illustrates the relevance of distributed erosion models to target erosion control measures when sufficient information on the eroding areas is available from field surveys. Bathymetric surveys were fundamental to validate the long-term model response, while point measurements were valuable to verify the spatial variability of model predictions. Editor Z.W. Kundzewicz; Associate editor G. Mahé Citation Hunink, J.E., Niadas, I.A., Antonaropoulos, P., Droogers, P., and de Vente, J., 2013. Targeting of intervention areas to reduce reservoir sedimentation in the Tana catchment (Kenya) using SWAT. Hydrological Sciences Journal, 58 (3), 600–614. 相似文献
12.
近30年洞庭湖季节性水情变化及其对江湖水量交换变化的响应 总被引：1，自引：1，他引：0
江湖水量交换的变化影响着通江湖泊洞庭湖的水情,进而影响湖区社会经济及生态的可持续发展.以洞庭湖城陵矶站、南咀站以及长江干流宜昌站、螺山站1981-2012年逐日水位、流量观测数据为基础,采用单位根检验、方差分析和水位-流量绳套曲线等方法对洞庭湖季节性水情变化特征进行提取,并探究江湖水量交换变化对其产生的影响.研究表明:近30年来洞庭湖水情呈阶段性特征,与相对稳定的1981-2002年相比,2003-2012年湖泊水位总体呈下降趋势,年均水位下降0.43 m;枯、涨、丰、退水期各季水情变化特征为:2003年以后洞庭湖丰水期水位平均下降0.60 m,呈现出"高水不高"现象;退水期水位平均下降1.49 m,退水加快;枯水期水位略有上升,平均上升0.18 m;涨水期水位变化不明显.湖泊退水期水位降幅最为明显,尤其是10月大幅下降,平均下降2.03 m,有提前进入枯水期的趋势.水情变化与江湖水量交换变化密切相关:丰水期,三口(松滋、太平和藕池)分流量减小在一定程度上降低湖泊水位;退水期,三口分流量减小叠加城陵矶出口长江水位下降对洞庭湖产生拉空作用,湖泊出流加快水位被拉低;枯水期,主要是1 3月,城陵矶出口长江水位上升对湖泊顶托作用增强,湖泊出流减缓水位略有抬升. 相似文献
13.
In-depth studies of water and sediment fluxes from rivers into the sea are very important for understanding the interactions between land and sea. This paper is concerned with identifying the changes in the time series of water and sediment fluxes from Feiyun River in Zhejiang Province, China. Inter- and intraannual variability in the water discharge and sediment load of the Feiyun River into the sea are analyzed using the observed data of runoff (1956–2008) and sediment (1957–2008) at Xuekou Station, which is in the main channel. The results show that there is a good peak–valley correlation between the water discharge and sediment load, and there are obvious seasonal variations, with a 65.7% water discharge and 89.2% sediment load during the flooding periods. Water discharge is mainly controlled by natural rainfall, but the construction of the upstream reservoirs in 1997 increased the discharge amount in the dry season and decreased the amount in the flooding season. Sediment loads were reduced after a huge flood in 1990 and construction of upstream reservoirs, while the latter also decreased the sediment load during the typhoon flooding period. Furthermore, the correlation between water discharge and sediment load is also affected by the flood and reservoir construction. There are some differences in the regression equations of sediment load and water discharge for 1957–1989, 1991–1996, and 1997–2008. 相似文献
14.
The sedimentology of proglacial Silt Lake was assessed by lake sediment coring and monitoring of lacustrine processes during a late‐summer period of high glacier melt to characterize sediment delivery from the heavily glacierized catchment and investigate the sediment trapping dynamics of this upland lake. A complete varve chronology was established for a distal basin of the lake which was exposed by Lillooet Glacier retreat between 1947 and 1962. The varve record showed decreasing sedimentation rates in the basin while the glacier retreated, and as the lake became free of ice contact in the early 1970s. Although recession has continued over recent decades, and glacier proximity to the lake has, therefore, continued decreasing, lacustrine sedimentation rates are now accelerating due to changing basin morphometry caused by delta progradation. Over shorter time scales, lake sedimentation patterns respond to changing runoff conditions, including late‐summer glacier melt intensity, intra‐annual flooding events, diumal runoff fluctuations, and within‐lake turbidity currents. Turbidity currents included quasi‐regular flows during high diurnal discharges and an episodic flushing of temporarily stored sediment from the sandur or delta at a time of low stage. Suspended sediment yield to Silt Lake is estimated to exceed 103 Mg km?2 a?1, a magnitude that surpasses previous local and regional yield estimates for the glacierized headwaters of the Lillooet River valley. Since Silt Lake currently traps a significant prooportion of that upland sediment supply, and the trapping efficiency of the basin has been variable at decadal time scales, the formation and continued development of Lilt Lake has likely had a significant influence on downstream sediment delivery. Lacustrine sediment‐based proxies of long‐term hydroclimatic variability being developed in glacially distal settings should include provisions for dynamic sediment trapping effects in upstream water bodies that often form in the active proglacial environment. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
15.
Mediterranean lake–wetland systems are threatened by climate change and intensive human impacts. Individual lake responses to these threats are poorly known but urgently required to steer preservation strategies. The dramatic water-level fall (~8 m since 1987) of Lake Megali Prespa endangers this global biodiversity hotspot and the wider catchment’s water resources. Annual lake fluctuations are found to be strongly related to wet-season (Oct.–Apr.) precipitation variability, which is linked to the North Atlantic Oscillation. The lake primarily adjusts to sustained inflow changes through amending surface evaporation. Cumulative water abstraction since 1951 (~19 × 106 m3/year: ~0.006% of lake volume) explains ~70% of the long-term decrease in surface evaporation; climate variability explains the remainder. Persistent low lake levels after 1995 are caused by water abstraction. Compared to 1952/53–1977/78, the period 1978/79–2003/04 experienced significant decreases in wet-season precipitation, snowfall and discharge; the number of very dry years increased.
EDITOR A. Castellarin; ASSOCIATE EDITOR D. Gerten 相似文献
16.
湖泊沉积物储存着长时期的流域环境信息,是百年尺度湖泊环境演变研究的高分辨率记录器。本文通过210Pbex、137Cs组合定年法,分析放射性核素剖面特征,研究沉积速率时空变化规律,并解析沉积物粒度指示的环境信息,揭示百年尺度湖泊沉积环境演变。结果表明:洞庭湖210 Pbex剖面分布呈现多段衰变型、混合—衰变—平衡型、衰变—本底型和无沉积型4种类型。3大湖体200 cm的沉积深度对应的年代跨度为127～162年,构建了洞庭湖沉积物深度—年代关系。洞庭湖平均质量沉积速率为1.47～3.11 g/(cm2·a),整体上呈现南洞庭湖>西洞庭湖>东洞庭湖的空间特征;自1900年后,质量沉积速率增加了3～7倍,呈时序增加趋势。沉积年代上,沉积物粒度特征表明洞庭湖沉积环境呈3个阶段2个过渡期的演变特征,与同时期区域内毁林开荒、水利建设、植树造林等人为活动有较好的对应关系,说明近百年来人为活动是洞庭湖泥沙沉积的重要因素。本研究结果可为强化湖泊及其流域生态环境保护... 相似文献
17.
《水文科学杂志》2013,58(4):777-792
Abstract Based on data from five hydrometric stations, Pingshan station on the Jinshajiang River, Gaochang station on the Minjiang River, Wulong station on the Wujiang River, Wusheng station on the Jialingjiang River and Yichang station on the Yangtze River, a study has been made of the temporal variation in grain size of suspended sediment load in the upper Yangtze River. The results show that in the past 40 years, the grain size of the suspended sediment load in the main stem and major tributaries of the upper Yangtze River has had a decreasing trend, that can be explained by the effect of reservoir construction and implementation of soil conservation measures. The reservoirs in the upper Yangtze River Basin, all used for water storage for hydro-electric generation and/or irrigation, have trapped coarse sediment from the drainage area above the dam and, thus, the sediment released now is much finer than before the construction of the reservoirs. The downstream channels are all gravel-bedded or even in bedrock, with little fine sediment, and thus, the released flow can hardly get a supply of fine sediment through eroding the bed. Then, after the downstream adjustment, the grain size of suspended sediment is still fine. Large-scale soil conservation measures have significantly reduced sediment yield in some major sediment source areas. The relatively coarse sediment is trapped and, thus, the sediment delivered to the river becomes finer. 相似文献
18.
太湖上游流域经济发展对废水排放及入湖总磷的影响 总被引：5，自引：3，他引：2
为探索太湖流域水环境质量随经济发展的变化趋势,利用环境库兹涅茨曲线模型模拟1978-2012年太湖上游流域人均GDP与废水排放量、入湖总磷负荷的关系.结果表明:以1978年为计算基期,太湖上游流域人均GDP年均增速为10.3%~11.8%;1990-2012年,太湖上游流域年均工业废水排放量和废水排放总量分别为64799×104、93707×104t,与人均GDP均呈倒U型关系,从2006-2007年、2008-2009年呈下降趋势;入湖总磷负荷与太湖上游流域废水排放总量呈显著正相关,且与人均GDP呈倒U型关系,从2007-2008年呈下降趋势,在1990s以前为850~1200 t/a,1990s以后为1300~2000 t/a.该研究为从经济学角度评估太湖上游流域废水排放、入湖总磷负荷及其变化趋势提供科学依据. 相似文献
19.
Maochuan Hu Takahiro Sayama Weili Duan Kaoru Takara Bin He Pingping Luo 《水文科学杂志》2017,62(8):1255-1265
A suite of extreme indices derived from daily precipitation and streamflow was analysed to assess changes in the hydrological extremes from 1951 to 2012 in the Kamo River Basin. The evaluated indices included annual maximum 1-day and 5-day precipitation (RX1day, RX5day), consecutive dry days (CDD), annual maximum 1-day and 5-day streamflow (SX1day, SX5day), and consecutive low-flow days (CDS). Sen’s slope estimator and two versions of the Mann-Kendall test were used to detect trends in the indices. Also, frequency distributions of the indices were analysed separately for two periods: 1951–1981 and 1982–2012. The results indicate that quantiles of the rainfall indices corresponding to the 100-year return period have decreased in recent years, and the streamflow indices had similar patterns. Although consecutive no rainfall days represented by 100-year CDD decreased, continuous low-flow days represented by 100-year CDS increased. This pattern change is likely associated with the increase in temperature during this period.
EDITOR D. KoutsoyiannisASSOCIATE EDITOR E. Gargouri 相似文献
20.
Abstract The study of sediment load is important for its implications to the environment and water resources engineering. Four models were considered in the study of suspended sediment concentration prediction: artificial neural networks (ANNs), neuro-fuzzy model (NF), conjunction of wavelet analysis and neuro-fuzzy (WNF) model, and the conventional sediment rating curve (SRC) method. Using data from a US Geological Survey gauging station, the suspended sediment concentration predicted by the WNF model was in satisfactory agreement with the measured data. Also the proposed WNF model generated reasonable predictions for the extreme values. The cumulative suspended sediment load estimated by this model was much higher than that predicted by the other models, and is close to the observed data. However, in the current modelling, the ANN, NF and SRC models underestimated sediment load. The WNF model was successful in reproducing the hysteresis phenomenon, but the SRC method was not able to model this behaviour. In general, the results showed that the NF model performed better than the ANN and SRC models. Citation Mirbagheri, S. A., Nourani, V., Rajaee, T. & Alikhani, A. (2010) Neuro-fuzzy models employing wavelet analysis for suspended sediment concentration prediction in rivers. Hydrol. Sci. J. 55(7), 1175–1189. 相似文献