Flood Diversion Research Articles

Rangia cuneata clam decline in Lake Pontchartrain from 2001 to 2014 due to an El Niño Southern Oscillation shift coupled with a period of high hurricane intensity and frequency

The clam, Rangia cuneata, occurs in low salinity zones of Atlantic and Gulf of Mexico estuaries. Prior to 2001, it was abundant in Lake Pontchartrain, a large and shallow oligohaline estuary, located north of New Orleans. However, density abruptly decreased by 96% after an extreme drought from an El Nino Southern Oscillation (ENSO) shift (1998—2000). Stable higher salinities resulted in the establishment of higher salinity communities. The hooked mussel, Ischadium recurvum, increased abruptly and colonized live R. cuneata. Competition from I. recurvum and the R. cuneata decline occurred at the end of the drought, despite a decrease in salinity. After the drought, there was a period of high hurricane intensity and frequency which stifled clam recovery. Their densities remained relatively low due to declines from hurricane disturbances in 2005, 2008 and 2012. In 2014, after two years without severe hurricane effects, density and biomass recovered to baseline years (1954 and 1997). Barrier island erosion caused by Hurricane Georges in 1998 and adverse effects of the ENSO drought on wetlands may have set the stage for increased effects of subsequent hurricanes. High relative sea level rise, wetland loss and erosion of barrier islands, which occurred with each successive storm, potentially increased the size of surges. Surges resuspended sediments which buried clams and abruptly increased salinity and lowered dissolved oxygen. Salinity stratification persisted after storms and caused hypoxia in bottom waters. Storm surge interactions with discharges from the Bonnet Carre Spillway, a Mississippi River flood diversion structure, and the MRGO, a ship channel, also exacerbated hurricane effects.

Inexact Probabilistic Optimization Model and Its Application to Flood Diversion Planning in a Dynamic and Uncertain Environment

AbstractFlood management systems involve a variety of complexities, such as multiple uncertainties and their interdependences, as well as multiregion and dynamic features. This paper thus presents an inexact two-stage mixed-integer programming with random coefficients (ITMP-RC) model for flood management in a dynamic and uncertain environment. ITMP-RC is capable of addressing dual uncertainties expressed as random boundary intervals that exist in the coefficients of the objective function. A case study of flood diversion planning is used to demonstrate the applicability of the proposed methodology. Results indicate that total system costs would be rising gradually with increased probabilities of occurrence, implying a trade-off between economic objective and system safety. A variety of decision alternatives can be obtained under different policy scenarios, which are useful for decision makers to formulate appropriate flood management policies according to practical situations. The performance of ITMP-RC i...

Experimental study of flood diversion in the middle and lower Han River, China

River flood control plays an important and essential role to prevent the loss of life and property along the riverbank. This study designed a bend flume experiment to investigate the effects of flood diversion in the middle and lower of Han River using the method of passive control. The diversion breach evolution and the relations between the diversion flow through the breach and the influencing factors were analyzed. Four stages of the entire flood diversion process of non-cohesive dikes, namely overtopping, groove formation, breach stretching and stability stages, were proposed. The research results indicated that the particle size had an obvious effect on the erosion rate during the initial flood diversion, and little influence on the maximum diversion discharge. In addition, the water head between the inside and outside of river had a significant effect on the initial flow diversion. The greater the water head, the greater the diversion discharge that occurs.

Anthropogenic effects and climate change threats on the flood diversion of Erchung Floodway in Tanshui River, northern Taiwan

The Erchung Floodway, one of the successful measures of the Taipei Flood Prevention System, was constructed to mitigate the Tanshui River floods in the Taipei metropolitan area. The Taipei metropolitan area is the most crowded region in Taiwan. More than one-third of the total population of the country resides in this area. However, its function has changed due to urban development and natural alterations over time. The main concerns of this study are to investigate the current diversion capacity and the current vulnerability of the Taipei Flood Prevention System in accordance with influential environmental factors, including anthropogenic effects and climate change threats. Thirty-two scenarios were established for sensitivity analysis using HEC-RAS model. The results indicate that the capacity of the Erchung Floodway diversion has noticeably decreased from 9,200 to 6,300 m3/s under a 200-year recurrence flood. Three vulnerable locations have been identified: Shihtzutou, Shezi, and Wugu. It was also found that the Taipei Flood Prevention System will encounter challenges if the roughness of the riverbed within the Erchung Floodway increases by over 50 %, the roughness of the riverbed within the Tanshui River increases by over 25 %, the water stage at the river mouth rises to 5.03 m, or the 200-year recurrence flood increases to 28,300 m3/s. Two proposed cost-effective mitigation strategies in the present study are: (1) to remain or decrease the riverbed elevation and roughness within the Tanshui River (Taipei Bridge section); (2) to decrease the riverbed roughness by at least 25 % within the upstream and midstream of the Erchung Floodway.

Spectroscopic measurements of estuarine dissolved organic matter dynamics during a large-scale Mississippi River flood diversion

The Mississippi River Flood of 2011 prompted the opening of the Bonnet Carré Spillway (BCS) in southeastern Louisiana to protect the City of New Orleans. The BCS diverted approximately 21.9km3 of river water into the oligohaline Lake Pontchartrain Estuary over the course of 43days. We characterized estuarine dissolved organic matter (DOM) dynamics before, during, and after the diversion in order to better understand the biogeochemical dynamics associated with these immense freshwater inflows. Dissolved organic carbon (DOC) exhibited a large degree of variability during and after the period of elevated primary productivity that occurred following the diversion. Furthermore, DOC analysis provides limited insight into carbon cycling during these dynamic periods. In order to overcome the limitations of DOC, spectroscopic methods were used to gain insights into chemical composition dynamics. Both ultraviolet visible (A254, A350, SUVA254, spectral slope, and normalized UV/Vis) and fluorescence spectroscopy (excitation emission matrices and fluorescence and biological indices) were used to study the compositional changes of DOM over time. Collectively, our results document a perturbation in DOM chemistry in Lake Pontchartrain due to the diversion and a subsequent return toward pre-diversion conditions. Immediate increases in A350 indicate that BCS freshwater contained elevated concentrations of lignin of terrestrial origin. Ensuing declines in A350, along with changes in the fluorescence and biological indices, indicate that DOM rapidly became more microbial in composition. Our results provide insights into estuarine DOM dynamics relevant to systems receiving flood pulses of freshwater due to either hydrologic manipulation or precipitation events.

Discussion of “Hydraulic Principles of the 2,268-Year-Old Dujiangyan Project in China” by Shanghong Zhang, Yujun Yi, Yan Liu, and Xingkui Wang

Discussion of “Hydraulic Principles of the 2,268-Year-Old Dujiangyan Project in China” by Shanghong Zhang, Yujun Yi, Yan Liu, and Xingkui Wang

Closure to “Hydraulic Principles of the 2,268-Year-Old Dujiangyan Project in China” by Shanghong Zhang, Yujun Yi, Yan Liu, and Xingkui Wang

Closure to “Hydraulic Principles of the 2,268-Year-Old Dujiangyan Project in China” by Shanghong Zhang, Yujun Yi, Yan Liu, and Xingkui Wang

Efficient GIS-based model-driven method for flood risk management and its application in central China

Abstract. In recent years, an important development in flood management has been the focal shift from flood protection towards flood risk management. This change greatly promoted the progress of flood control research in a multidisciplinary way. Moreover, given the growing complexity and uncertainty in many decision situations of flood risk management, traditional methods, e.g., tight-coupling integration of one or more quantitative models, are not enough to provide decision support for managers. Within this context, this paper presents a beneficial methodological framework to enhance the effectiveness of decision support systems, through the dynamic adaptation of support regarding the needs of the decision-maker. In addition, we illustrate a loose-coupling technical prototype for integrating heterogeneous elements, such as multi-source data, multidisciplinary models, GIS tools and existing systems. The main innovation is the application of model-driven concepts, which put the system in a state of continuous iterative optimization. We define the new system as a model-driven decision support system (MDSS ). Two characteristics that differentiate the MDSS are as follows: (1) it is made accessible to non-technical specialists; and (2) it has a higher level of adaptability and compatibility. Furthermore, the MDSS was employed to manage the flood risk in the Jingjiang flood diversion area, located in central China near the Yangtze River. Compared with traditional solutions, we believe that this model-driven method is efficient, adaptable and flexible, and thus has bright prospects of application for comprehensive flood risk management.

多孔分洪闸调度方案优化探讨——以洞庭湖澧南垸为例

闸门启闭是水闸控制运用的关键。而科学合理的闸门控制调度方案，对于实现最好的分洪效果，保障闸门安全，有着十分重要的意义。以澧水津市站1998年及2003年洪水过程为基础资料，通过同频率控制放大得到设计洪水过程。对现有调度方案进行了评价，结果表明，现有调度方案分洪效果并不理想。根据最大削峰准则与最小成灾历时准则建立了澧南垸洪水闸优化调度目标函数及约束条件。依据所建目标函数，以频率5%的设计洪水过程线为例，制定了洪水闸优化调度方案。对所制定调度方案进行了评价，分析表明，此调度方案能达到较好分洪效果和安全保障。 Opening and closing is the key of floodgate control and application. Scientific and reasonable control scheme, to achieve the best flood diversion effect and ensure gate security, has very important significance. According to the 1998 and 2003 flood process data of Li river of Jinshi hydrological station, through the same frequency control amplifier, design flood process is obtained. The scheduling scheme is evaluated, and results show that, the existing scheduling scheme of flood diversion effect is not good. Floodgate optimization objective function has been established. On the basis of the objective function, with a frequency of 5% of the designed flood hydrograph for example, a floodgate optimization control scheme has been developed. Analysis shows that the floodgate control scheme can achieve better flood diversion effect and safety.

Improvement of a drainage system for flood management with assessment of the potential effects of climate change

Runoff discharge in the Tuku lowlands, Taiwan, has increased with land development. Frequent floods caused by extreme weather conditions have resulted in considerable economic and social losses in recent years. Currently, numerous infrastructures have been built in the lowland areas that are prone to inundation; the measures and solutions for flood mitigation focus mainly on engineering aspects. Public participation in the development of principles for future flood management has helped both stakeholders and engineers. An integrated drainage–inundation model, combining a drainage flow model with a two-dimensional overland-flow inundation model is used to evaluate the flood management approaches with damage loss estimation. The proposed approaches include increasing drainage capacity, using fishponds as retention ponds, constructing pumping stations, and building flood diversion culverts. To assess the effects on the drainage system of projected increase of rainfall due to climate change, for each approach simulations were performed to obtain potential inundation extent and depth in terms of damage losses. The results demonstrate the importance of assessing the impacts of climate change for implementing appropriate flood management approaches.Editor Z.W. KundzewiczCitation Chang, H.-K., Tan, Y.-C., Lai, J.-S., Pan, T.-Y., Liu, T.-M., and Tung, C.-P., 2013. Improvement of a drainage system for flood management with assessment of the potential effects of climate change. Hydrological Sciences Journal, 58 (8), 1581–1597.

Application of localized meshless methods to 2D shallow water equation problems

This study aims to apply the meshless local radial-basis-function differential quadrature (LRBFDQ) method to solve the shallow water equations (SWE). This localized approach is developed from the differential quadrature (DQ) method by employing the radial-basis functions (RBFs) as the trial functions. Comparing with global-type meshless methods, the present method is more appropriate to large-scale problems with complex shapes. Moreover the drawbacks rising from the poor selection of shape parameter and also the full resultant matrix with high condition number are reduced. For real hydraulic-engineering applications located in irregular domains, the LRBFDQ method is very suitable to solve these kinds of shallow-water problems. In this work, the numerical models are applied to simulate three typical 2D SWE problems: (1) a tidal-wave propagation, (2) a dam-break problem and (3) an inverse engineering problem: the numerical analysis of the inflow discharge of the Yuanshantze Flood Diversion (YFD) project in Taiwan. As a result, the adopted meshless method not only shows its algorithm superiority over other mesh-dependent numerical schemes, but also brings more efficiency than several conventional mesh or meshless methods. The application of YFD project also delivers its applicability of this meshless scheme to solve real-world engineering projects.

Analysis on Flood Control Unified Regulation of Baiyangdian Wetland and its Upstream Reservoir Group

Baiyangdian wetland is the end of defence line to middlestream and downstream of Daqing river, and its geographic position has decided its critical function to flood control of Daqing river watershed. Therefore, according to the flood regulating ability of Baiyangdian, when the basin occur 50 year frequency flood, joint operation programs have been determined firstly, then the joint operation of Baiyangdian and multi-reservoir in parallel upstream have been presented through the pre-discharge regulation and real-time control discharge regulation, through comparison we determined the optimal combination scheme: joint scheduling with Wangkuai, Xidayang and Longmen upstream reservoirs,the storing water of reservoir can appropriately increased by reservoirs flood control capacity, thus we can not diversion flood to Wenanwa by Xiaoguan floodway, it can reduce the flood diversion of 1.62×109 m3; and compared with conventional scheduling, we can reduce 8.57×108 m3 flood diversion to the East wetland through Zaolinzhuang discharge gate. Therefore the flood flow into the flood diversion area reduced significantly, which have great practical significance to the safety of Baiyangdian wetlands surrounding areas and the important cities and towns downstream.

Estuarine ecosystem response to three large-scale Mississippi River flood diversion events

Large inflows of nitrogen (N)-rich freshwater to estuaries can lead to expressions of eutrophication including harmful algal blooms of cyanobacteria (CyanoHABs). Lake Pontchartrain is a large, oligohaline estuary that occasionally receives episodic diversions of N-rich Mississippi River water via the Bonnet Carré Spillway to alleviate flood threats to New Orleans, LA. The extreme flood stage of the Lower Mississippi River in May 2011 prompted the tenth opening of the spillway since 1937. The 2011 opening occurred later in the season than the previous two lower discharge events (1997 and 2008) and was characterized by dissolved inorganic N loads 1.7 and 2.6 times greater than the 1997 and 2008 events, respectively. Rapid depletion of riverine nitrate (21days) occurred post-spillway closure in 2011 with no associated CyanoHAB and was followed by an internal pulse of phosphorus (P) from sediments to restore N-limitation. Our analysis of recent spillway openings indicates that there is not a simple stimulus–response relationship between N loading and CyanoHAB formation. We investigate the systemic causal relationships that determine ecosystem response to these nutrient-rich freshwater inflows and highlight several important parameters including: external N loading, timing, magnitude, plume hydrodynamics, nutrient molar ratios, internal P loading, weather, and northern tributary discharge. Our results suggest that the turbulent, fluctuating environment and nutrient composition during diversions does not favor CyanoHAB formation and that the immense size and timing of the 2011 diversion may have resulted in near complete post-diversion CyanoHAB suppression by hydraulic flushing.

Stranding of Spawning Run Green Sturgeon in the Sacramento River: Post‐Rescue Movements and Potential Population‐Level Effects

AbstractThe lower portion of the Sacramento River, California, has been highly engineered to protect low‐lying surrounding communities from annual flood events. While engineered floodplains have provided adequate protection for the surrounding communities, there remain unintended consequences to migratory fish that become stranded during high flow events. In April 2011, we rescued 24 threatened Green Sturgeon Acipenser medirostris that were stranded in two flood diversions along the Sacramento River. We tagged these 24 Green Sturgeon with acoustic tags and analyzed their survival and migration success to their spawning grounds. Additionally, we provided a population viability analysis to show the potential impacts of stranding and the benefits of conducting rescues at the population level. We found that 17 of these 24 individuals continued their upstream migration to the spawning grounds. Modeling suggests that recurrent stranding of a similar magnitude without rescue could affect the long‐term viability of Green Sturgeon in the Sacramento River. Population viability analyses of rescue predicted a 7% decrease below the population baseline model over 50 years as opposed to 33% without rescue. Despite the mitigated impact to the population with rescue, fish passage improvements should be considered as a long‐term goal for preventing population risks at flood control diversions.Received May 4, 2012; accepted December 6, 2012

Research on the Influence in Complex River Network Area for Waterway Regulation

In order to study the influence of the navigation improvement project in the Qingyi River, on flood control of the complex river network, the water level variation of the key control stations in Shuiyang, Qingyi and Zhanghe river basins, flood diversion variation of middle reach of Shuiyang stem and flow pattern in the flow field before and after construction of the project using Mike11 model, under the conditions of designed flood and excessive standard flood. The results show that after construction of the project,the water levels at the control stations are decreasing or constant and the flood diversion of middle reach of Shuiyang stem decreases. So the project is beneficial to the flood control of the basins.

A dual two-stage stochastic model for flood management with inexact-integer analysis under multiple uncertainties

This study introduces a hybrid optimization approach for flood management under multiple uncertainties. An inexact two-stage integer programming (ITIP) model and its dual formation are developed by integrating the concepts of mixed-integer and interval-parameter programming techniques into a general framework of two-stage stochastic programming. The proposed approach provides a linkage to pre-defined management policies, deals with capacity-expansion planning issues, and reflects various uncertainties expressed as probability distributions and discrete intervals for a flood management system. Penalties are imposed when the policies are violated. The marginal costs are determined based on dual formulation of the ITIP model, and their effects on the optimal solutions are investigated. The developed model is applied to a case study of flood management. The solutions of binary variables represent the decisions of flood-diversion–capacity expansion within a multi-region, multi-flow-level, and multi-option context. The solutions of continuous variables are related to decisions of flood diversion toward different regions. The solutions of dual variables indicate the decisions of marginal costs associated with the resources of regions’ capacity, water availability, and allowable diversions. The results show that the proposed approach could obtain reliable solutions and adequately support decision making in flood management.

Comprehensive flood risk assessment based on set pair analysis-variable fuzzy sets model and fuzzy AHP

On the basis of the disaster system theory and comprehensive analysis of flood risk factors, including the hazard of the disaster-inducing factors and disaster-breeding environment, as well as the vulnerability of the hazards-bearing bodies, the primary risk assessment index system of flood diversion district as well as its assessment standards were established. Then, a new model for comprehensive flood risk assessment was put forward in this paper based on set pair analysis (SPA) and variable fuzzy sets (VFS) theory, named set pair analysis-variable fuzzy sets model (SPA-VFS), which determines the relative membership degree function of VFS by using SPA method and has the advantages of intuitionist course, simple calculation and good generality application. Moreover, the analytic hierarchy process (AHP) was combined with trapezoidal fuzzy numbers to calculate the weights of assessment indices, thus the weights for flood hazard and flood vulnerability were determined by the fuzzy AHP procedure, respectively. Then SPA-VFS were applied to calculate the flood hazard grades and flood vulnerability grades with rank feature value equation and the confidence criterion, respectively. Under the natural disasters risk expression recommended by the Humanitarian Affairs Department of United Nations, flood risk grades were achieved from the flood hazard grades and flood vulnerability grades with risk grade classification matrix, where flood hazard, flood vulnerability and flood risk were all classified into five grades as very low, low, medium, high and very high. Consequently, integrated flood risk maps could be carried out for flood risk management and decision-making. Finally, SPA-VFS and fuzzy AHP were employed for comprehensive flood risk assessment of Jingjiang flood diversion district in China, and the computational results demonstrate that SPA-VFS is reasonable, reliable and applicable, thus has bright prospects of application for comprehensive flood risk assessment, and moreover has potential to be applicable to comprehensive risk assessment of other natural disasters with no much modification.

Roller-compacted concrete dams: a brief history and their advantages

Roller-compacted concrete has been rapidly developing over the past 35 years and is now commonly used for mass concreting operations typically in a gravity dam application. This paper reviews the advantages of roller-compacted concrete over some of the other forms of dam construction, including advantages in reducing the cost of flood diversions.

Optimal control of flood diversion in watershed using nonlinear optimization

This study aims to develop a simulation-based optimization model applicable to mitigate hazardous floods in storm events in a watershed which consists of a complex channel network and irregular topography. A well-established model, CCHE1D, is used as the simulation model to predict water stages and discharges of unsteady flood flows in a channel network, in which irregular (i.e. non-rectangular and non-prismatic) cross-sections are taken into account. Based on the variational principle, the adjoint equations are derived from the nonlinear hydrodynamic equations of CCHE1D, which are to establish a unique relationship between flood control variables and hydrodynamic variables. The internal conditions at the confluence in channel network for solving the adjoint equations in a watershed are obtained. An implicit numerical scheme (i.e. Preissman’s scheme) is implemented for discretizing and solving the adjoint equations with the derived internal conditions and boundary conditions. The applicability of this integrated optimization model is demonstrated by searching for the optimal diversion hydrographs for withdrawing flood waters through a single floodgate and multiple floodgates into detention basins. Numerical optimization results show that this integrated model is efficient and robust. It is found that the single-floodgate control leads to an unfavorable speed-up in river flow which may create extra erosions in the channel bed; and multiple-floodgates diversion control diverts less flood waters, therefore can be a cost-effective control action. This simulation-based optimization model is capable of determining the optimal schedules of diversion discharge, optimal floodgate locations, minimum capacities of flood water detention basins in rivers and watersheds.

Flood management selections for the Yangtze River midstream after the Three Gorges Project operation

Summary After the Yangtze River was closed by the Three Gorges Project (TGP) in 2003, erosion occurred from the dam site to the river mouth, especially in the middle and lower reaches of the Yangtze River. However, in some local areas of Chenglingji reach which holds the key position for flood management, there is actually deposition in contrast to the expected erosion. In this paper, a one dimensional mathematical model of the river network with sediment transport is used as the tool to simulate flow and fluvial processes. The calculation domain is from Yichang, which is downstream of the dam, to Hankou, the controlling node of flood management, 694 km long in total. The model is calibrated based on the field data of hydrology and sediment transport during the period from October 2003 to October 2008. Then the model is utilized to simulate the erosion and deposition of the middle and lower reaches of the Yangtze River in the next two decades, and produce the results of a new river channel after river bed deformation occurs. The typical flood processes of 1954 and 1998 in the Yangtze River basin are used to check the flood management scheme for the research area, and results show that water storage of Three Gorges Reservoir (TGR) and a flood diversion program downstream of the Yangtze River should be taken into consideration.