scholarly journals Advanced Operating Technique for Centralized and Decentralized Reservoirs Based on Flood Forecasting to Increase System Resilience in Urban Watersheds

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1533 ◽  
Author(s):  
Lee
Keyword(s):  
Flood Forecasting ◽  
Flood Damage ◽  
Urban Watersheds ◽  
Urban Drainage ◽  
Rainfall Events ◽  
Artificial Rainfall ◽  
Operating Technique ◽  
Structural Measures ◽  
Mixed Measure ◽  
System Resilience

The frequency of inundation in urban watersheds has increased, and structural measures have been conducted to prevent flood damage. The current non-structural measures for complementing structural measures are mostly independent non-structural measures. Unlike the current non-structural measures, the new operating technique based on flood forecasting is a real-time mixed measure, which means the combination of different non-structural measures. Artificial rainfall events based on the Huff distribution were used to generate preliminary and dangerous thresholds of flood forecasting. The new operation for centralized and decentralized reservoirs was conducted by two thresholds. The new operation showed good performance in terms of flooding and resilience based on historical rainfall events in 2010 and 2011. The flooding volume in the new operation decreased from 6617 to 3368 m3 compared to the current operation in 2010, and the flooding volume in 2011 decreased from 664 to 490 m3. In the 2010 event, the results of resilience were 0.831835 and 0.866566 in current and new operations, respectively. The result of resilience increased from 0.988823 to 0.993029 in the 2011 event. This suggestion can be applied to operating facilities in urban drainage systems and might provide a standard for the design process of urban drainage facilities.

scholarly journals Effect of tillage, slope, and rainfall on soil surface microtopography quantified by geostatistical and fractal indices during sheet erosion

2020 ◽  
Vol 12 (1) ◽  
pp. 232-241
Author(s):  
Na Ta ◽  
Chutian Zhang ◽  
Hongru Ding ◽  
Qingfeng Zhang
Keyword(s):  
Surface Roughness ◽  
Fractal Dimension ◽  
Soil Surface ◽  
Rainfall Events ◽  
Tillage Practices ◽  
Surface Microtopography ◽  
Artificial Rainfall ◽  
Soil Surface Roughness ◽  
The Difference ◽  
Sheet Erosion

AbstractTillage and slope will influence soil surface roughness that changes during rainfall events. This study tests this effect under controlled conditions quantified by geostatistical and fractal indices. When four commonly adopted tillage practices, namely, artificial backhoe (AB), artificial digging (AD), contour tillage (CT), and linear slope (CK), were prepared on soil surfaces at 2 × 1 × 0.5 m soil pans at 5°, 10°, or 20° slope gradients, artificial rainfall with an intensity of 60 or 90 mm h−1 was applied to it. Measurements of the difference in elevation points of the surface profiles were taken before rainfall and after rainfall events for sheet erosion. Tillage practices had a relationship with fractal indices that the surface treated with CT exhibited the biggest fractal dimension D value, followed by the surfaces AD, AB, and CK. Surfaces under a stronger rainfall tended to have a greater D value. Tillage treatments affected anisotropy differently and the surface CT had the strongest effect on anisotropy, followed by the surfaces AD, AB, and CK. A steeper surface would have less effect on anisotropy. Since the surface CT had the strongest effect on spatial variability or the weakest spatial autocorrelation, it had the smallest effect on runoff and sediment yield. Therefore, tillage CT could make a better tillage practice of conserving water and soil. Simultaneously, changes in semivariogram and fractal parameters for surface roughness were examined and evaluated. Fractal parameter – crossover length l – is more sensitive than fractal dimension D to rainfall action to describe vertical differences in soil surface roughness evolution.

Accounting for sensor calibration, concentration heterogeneity, measurement and sampling uncertainties in monitoring urban drainage systems

2003 ◽  
Vol 47 (2) ◽  
pp. 95-102 ◽  
Author(s):  
J.-L. Bertrand-Krajewski ◽  
J.-P. Bardin ◽  
M. Mourad ◽  
Y. Béranger
Keyword(s):  
Performance Indicator ◽  
Sensor Calibration ◽  
Urban Drainage ◽  
Experimental Conditions ◽  
Flow Rates ◽  
Rainfall Events ◽  
Drainage Systems ◽  
Methods And Techniques ◽  
Urban Drainage Systems ◽  
Online Measurements

Assessing the functioning and the performance of urban drainage systems on both rainfall event and yearly time scales is usually based on online measurements of flow rates and on samples of influent and effluent for some rainfall events per year. In order to draw pertinent scientific and operational conclusions from the measurement results, it is absolutely necessary to use appropriate methods and techniques in order to i) calibrate sensors and analytical methods, ii) validate raw data, iii) evaluate measurement uncertainties, iv) evaluate the number of rainfall events to sample per year in order to determine performance indicator with a given uncertainty. Based on previous work, the paper gives a synthetic review of required methods and techniques, and illustrates their application to storage and settling tanks. Experiments show that, despite controlled and careful experimental conditions, relative uncertainties are about 20% for flow rates in sewer pipes, 6-10% for volumes, 25-35% for TSS concentrations and loads, and 18-276% for TSS removal rates. In order to evaluate the annual pollutant interception efficiency of storage and settling tanks with a given uncertainty, efforts should first be devoted to decrease the sampling uncertainty by increasing the number of sampled events.

scholarly journals Real-Time Integrated Operation for Urban Streams with Centralized and Decentralized Reservoirs to Improve System Resilience

Water ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 69 ◽  
Author(s):  
Eui Hoon Lee ◽  
Young Hwan Choi ◽  
Joong Hoon Kim
Keyword(s):  
Urban Areas ◽  
Urban Streams ◽  
Urban Drainage ◽  
Require Time ◽  
Impervious Area ◽  
The Status ◽  
Resilience Index ◽  
Integrated Operation ◽  
System Resilience ◽  
Integrated Operations

Recently, the number of extreme rainfall events has increased because of climate change. The ever-widening impervious area in urban watersheds also continuously augments runoff volume. Most measures to prevent urban inundation are structural, such as the construction, rehabilitation, and replacement of urban drainage facilities. Because structural measures require time and money, nonstructural measures are also required for the efficient prevention of urban inundation. Current operations in Korea focus on the individual operation of urban drainage facilities while neglecting the status of effluent streams. A study on urban drainage facilities that considers the status of urban streams is necessary to improve the operation of drainage facilities in urban areas. A revised resilience index is suggested to evaluate measures. For the historical rainfall event in 2010, the system resilience for current and integrated operations was 0.199 and 0.238, respectively. For the 2011 event, the system resilience for current and integrated operations was 0.064 and 0.235, respectively. The integrated operation exhibited good performance for the 2010 and 2011 events. Based on the results of this study, an operation as a nonstructural measure for the total management of urban areas is proposed. The revised resilience index could support decision-making processes for flood-management plans.

Uncertainty in urban flood damage assessment due to urban drainage modelling and depth-damage curve estimation

2010 ◽  
Vol 61 (12) ◽  
pp. 2979-2993 ◽  
Author(s):  
G. Freni ◽  
G. La Loggia ◽  
V. Notaro
Keyword(s):  
Computational Cost ◽  
Flood Damage ◽  
Hydraulic Model ◽  
Data Availability ◽  
Urban Drainage ◽  
Damage Estimation ◽  
Total Uncertainty ◽  
Hydraulic Models ◽  
Functional Relationships ◽  
Flooding Events

Due to the increased occurrence of flooding events in urban areas, many procedures for flood damage quantification have been defined in recent decades. The lack of large databases in most cases is overcome by combining the output of urban drainage models and damage curves linking flooding to expected damage. The application of advanced hydraulic models as diagnostic, design and decision-making support tools has become a standard practice in hydraulic research and application. Flooding damage functions are usually evaluated by a priori estimation of potential damage (based on the value of exposed goods) or by interpolating real damage data (recorded during historical flooding events). Hydraulic models have undergone continuous advancements, pushed forward by increasing computer capacity. The details of the flooding propagation process on the surface and the details of the interconnections between underground and surface drainage systems have been studied extensively in recent years, resulting in progressively more reliable models. The same level of was advancement has not been reached with regard to damage curves, for which improvements are highly connected to data availability; this remains the main bottleneck in the expected flooding damage estimation. Such functions are usually affected by significant uncertainty intrinsically related to the collected data and to the simplified structure of the adopted functional relationships. The present paper aimed to evaluate this uncertainty by comparing the intrinsic uncertainty connected to the construction of the damage-depth function to the hydraulic model uncertainty. In this way, the paper sought to evaluate the role of hydraulic model detail level in the wider context of flood damage estimation. This paper demonstrated that the use of detailed hydraulic models might not be justified because of the higher computational cost and the significant uncertainty in damage estimation curves. This uncertainty occurs mainly because a large part of the total uncertainty is dependent on depth-damage curves. Improving the estimation of these curves may provide better results in term of uncertainty reduction than the adoption of detailed hydraulic models.

scholarly journals Sustainable Urban Drainage: a brief review of the compensatory techniques of structural and non-structural measures

2019 ◽  
Vol 23 ◽  
pp. 35
Author(s):  
Mariana Borges Albuquerque ◽  
Angélica Ardengue de Araújo ◽  
Carlos Eduardo Nunes Medina Martinez ◽  
Frederico Fábio Mauad ◽  
Cristhiane Michiko Passos Okawa
Keyword(s):  
Surface Runoff ◽  
Sustainable Management ◽  
Hydrological Cycle ◽  
Urban Drainage ◽  
Urban Water ◽  
Urban Water Management ◽  
Negative Effects ◽  
Cultural Aspects ◽  
Structural Measures ◽  
Negative Impacts

The accelerated disorderly and unplanned growth of cities has had negative impacts, such as the inability of the rainwater collection network to drain the area, causing flooding. Developing sustainable urban drainage projects, integrated urban water management and compensatory techniques in urban drainage are alternatives used to reduce the negative effects of urbanization on the hydrological cycle. Planning the surface runoff of urban water should go beyond structural projects, we must consider technical, financial, political and cultural aspects, among others, which makes this process complex, although very necessary. The aim of this paper is to undertake a brief literature review presenting the main urban drainage compensatory techniques used to promote sustainable management of rainwater. It concludes that there are many compensatory techniques that can be applied to promote and make sustainable urban drainage possible, whether through structural or non-structural measures.

scholarly journals Improving predictions of the effects of extreme events, land use, and climate change on the hydrology of watersheds in the Philippines

2016 ◽  
Vol 373 ◽  
pp. 147-151 ◽  
Author(s):  
Rubianca Benavidez ◽  
Bethanna Jackson ◽  
Deborah Maxwell ◽  
Enrico Paringit
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Ecosystem Services ◽  
Real Time ◽  
Flood Forecasting ◽  
The Philippines ◽  
Flood Mitigation ◽  
Extreme Rainfall Event ◽  
Management Interventions ◽  
Structural Measures

Abstract. Due to its location within the typhoon belt, the Philippines is vulnerable to tropical cyclones that can cause destructive floods. Climate change is likely to exacerbate these risks through increases in tropical cyclone frequency and intensity. To protect populations and infrastructure, disaster risk management in the Philippines focuses on real-time flood forecasting and structural measures such as dikes and retaining walls. Real-time flood forecasting in the Philippines mostly utilises two models from the Hydrologic Engineering Center (HEC): the Hydrologic Modeling System (HMS) for watershed modelling, and the River Analysis System (RAS) for inundation modelling. This research focuses on using non-structural measures for flood mitigation, such as changing land use management or watershed rehabilitation. This is being done by parameterising and applying the Land Utilisation and Capability Indicator (LUCI) model to the Cagayan de Oro watershed (1400 km2) in southern Philippines. The LUCI model is capable of identifying areas providing ecosystem services such as flood mitigation and agricultural productivity, and analysing trade-offs between services. It can also assess whether management interventions could enhance or degrade ecosystem services at fine spatial scales. The LUCI model was used to identify areas within the watershed that are providing flood mitigating services and areas that would benefit from management interventions. For the preliminary comparison, LUCI and HEC-HMS were run under the same scenario: baseline land use and the extreme rainfall event of Typhoon Bopha. The hydrographs from both models were then input to HEC-RAS to produce inundation maps. The novelty of this research is two-fold: (1) this type of ecosystem service modelling has not been carried out in the Cagayan de Oro watershed; and (2) this is the first application of the LUCI model in the Philippines. Since this research is still ongoing, the results presented in this paper are preliminary. As the land use and soil parameterisation for this watershed are refined and more scenarios are run through the model, more robust comparisons can be made between the hydrographs produced by LUCI and HEC-HMS and how those differences affect the inundation map produced by HEC-RAS.

scholarly journals Hydraulic characteristics of stepped spillway dropshafts for urban deep tunnel drainage systems: the case study of Chengdu city

2019 ◽  
Vol 80 (8) ◽  
pp. 1538-1548
Author(s):  
Lei Liao ◽  
Ruidong An ◽  
Jia Li ◽  
Wenmin Yi ◽  
Xiaofan Liu ◽  
...  
Keyword(s):  
Extreme Rainfall ◽  
Stepped Spillway ◽  
Urban Drainage ◽  
Deep Tunnel ◽  
Hydraulic Characteristics ◽  
Extreme Rainfall Events ◽  
Rainfall Events ◽  
Fluctuating Pressure ◽  
Air Explosion

Abstract Cities in southwestern China experience urban drainage and overflow pollution after extreme rainfall events, which are major problems. In this study, a type of stepped spillway dropshaft suitable for drainage by deep tunnels in Chengdu was proposed and the hydraulic characteristics were investigated experimentally. The results showed that the nappe flow and strong turbulent deflected jet flow in the stepped spillway allowed the dropshaft to greatly dissipate energy. According to the distribution of the time-averaged pressure on the steps, the flow on the steps could be divided into a recirculating region, a wall-impinging region and a mixing region. The time-averaged pressure on the outside of the step was higher than that on the inside due to the centrifugal force effect of the water. The fluctuating pressure distribution of the step approximated the normal distribution. It was acceptable to calculate the minimum pressure with 3 times the root mean square (RMS). The vibration of the flow on the stepped spillway did not resonate with the step. When the outflow tunnel was under submerged outflow conditions, the aeration in the stepped spillway was exhausted through air holes and only a small amount of air entered the outflow tunnel, thereby avoiding an air explosion.

scholarly journals A Non-Linear Programming Approach to Floodplain Management With Non-Structural Alternatives

1975 ◽  
Vol 7 (2) ◽  
pp. 1-7 ◽  
Author(s):  
Jawahar L. Kaul ◽  
Cleve E. Willis
Keyword(s):  
A Priori ◽  
Flood Damage ◽  
Programming Approach ◽  
Floodplain Management ◽  
Connecticut River ◽  
Non Linear Programming ◽  
Sense Of Security ◽  
Structural Measures ◽  
False Sense

There is apparently a growing awareness of the role of non-structural measures as an important part of an overall flood damage reduction program. This awareness has come in part with the realization that structural measures often provide a false sense of security to floodplain occupants and can, then, result in increased food damages — contrary to their intended purpose. To be sure, restrictions prohibiting all development in flood prone areas is a polar case (which will eliminate all damages). There are no a priori reasons to believe that all uses should be prohibited from all floodplain areas. Some of these areas can, in fact, be put to economic use by land use management such that benefits derived outweigh costs associated with such development.The objectives underlying this investigation, then, are (i) to develop a methodology useful to planners at several levels for efficient floodplain management, considering both structural and non-structural measures and (ii) to demonstrate the usefulness of the methodology by applying it to a selected floodplain in the Connecticut River Basin.

scholarly journals Flood Proofing Decisions Under Uncertainty

1973 ◽  
Vol 2 (2) ◽  
pp. 235-249 ◽  
Author(s):  
Cleve E. Willis ◽  
Petros Aklilu
Keyword(s):  
Flood Control ◽  
Flood Damage ◽  
Decision Makers ◽  
Control Measures ◽  
Decisions Under Uncertainty ◽  
Damage Reduction ◽  
Structural Measures ◽  
Flood Damages

Flood proofing first entered the flood damage reduction literature with the pioneering work of John Sheaffer. Prior to this, flood control measures considered were predominantly structural – consisting of dams, levees, dikes, channel improvements, etc. The addition of flood proofing to other flood damage reduction measures has broadened the choice among the existing alternatives for decision makers. Unlike the structural measures, flood proofing measures do not actually reduce flood stage or prevent the water from reaching the structures, but rather are as considered by Sheaffer, “adjustments to structures and contents which are designed and/or adopted primarily to reduce flood damages”.

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