Flood Control Mechanism of Multiple Dams Constructed in a Series Based on Cascade Method

2015 ◽  
Vol 10 (3) ◽  
pp. 475-485
Author(s):  
Hideo Oshikawa ◽  
◽  
Toshimitsu Komatsu ◽  
Keyword(s):  
Conventional Method ◽  
Flood Control ◽  
Control Mechanism ◽  
Water Discharge ◽  
High Water ◽  
Control Approach ◽  
Flood Peak ◽  
Control Concept ◽  
Control Capability ◽  
Cascade Method

Using numerical simulation, we clarified the mechanism that the flood control capability is dramatically strengthened by using multiple serial dams efficiently, based on a new flood control concept that let dams overflow through emergency spillways. Numerical analysis results for a group of dry dams were used to quantitatively evaluate this effect and to derive an empirical formula. The conventional flood control approach sets the design high water discharge of individual dams, even when dams are constructed serially, ensuring that no overflows occurs in any of the dams, here called the “conventional” method. By comparing the group of dry dams based on the conventional method and a method on the same scale but set based on a new concept that we called Cascade method, we found that when the flood peak is cut in conventional control, the latter half of the cutoff flood peak must be cut again, making flood control redundant. The Cascade method avoids this redundancy in storage use and cuts the flood peak efficiently and linearly.

An Experimental Study on Flood Control Capability of Dry Dams Constructed in a Series

2015 ◽  
Vol 10 (3) ◽  
pp. 467-474 ◽  
Author(s):  
Hideo Oshikawa ◽  
◽  
Yuka Mito ◽  
Toshimitsu Komatsu ◽  
◽  
...  
Keyword(s):  
Experimental Study ◽  
Flood Control ◽  
Laboratory Experiments ◽  
Slide Gate ◽  
Reservoir Capacity ◽  
Control Effect ◽  
Flood Disasters ◽  
Control Capability ◽  
Cascade Method ◽  
Large Dam

The new Cascade concept of flood control is demonstrated in laboratory experiments in which upstream dams in a series of dams constructed along a river overflow from emergency spillways while the final downstream dam is required only to use its normal spillway and never do its emergency spillway. Multiple small dry dams lacking a slide gate in a normal spillway should be constructed in a series rather than as a single large dam to prevent flood disasters and to preserve the natural environment. Dry dams for flood control have recently been reviewed, planned, and built at sites in Japan. In this paper, we compare the Cascade method to conventional flood control in laboratory experiments conducted based on the condition that dams all have the same reservoir capacity. Results have shown that the Cascade method using multiple dry dams was considerably more effective than conventional flood control. Furthermore, the additional flood control effect of a dry dam equipped with closable and openable gate in its regular spillway was experimentally confirmed although there is no such kind of the gate on an ordinary dry dam. This new dry dam should be constructed in the river’s upper reaches away from the existing downstream storage dam needing still more its capacity for water utilization, thus ensuring the amount of water available by closing the regular spillway after the dry dam is filled to capacity. The flood control capacity of dams including the new dry dam is stronger than that of an ordinary storage dam thanks to the dry dam’s storage function.

Evaluation of nutrient runoff from the kako river by continuous daily sampling

1996 ◽  
Vol 34 (12) ◽  
pp. 67-72
Author(s):  
Yukio Komai
Keyword(s):  
Suspended Solids ◽  
Water Discharge ◽  
Electronic Conductivity ◽  
High Water ◽  
Nutrient Loads ◽  
Discharge Condition ◽  
Nutrient Runoff ◽  
Average Value ◽  
Daily Sampling ◽  
A Site

A water sample was taken once a day for 15 months at a site near an estuary of the Kako River, Japan, to estimate nutrient loads from rivers to the sea. Total phosphorus (T-P), total nitrogen (T-N), suspended solids (SS) and electronic conductivity (EC) were measured. T-P and SS concentrations varied in proportion to the discharge, and T-P concentrations increased with those of SS, too. EC varied inversely with the discharge, but the fluctuations of T-N concentrations were less than those of T-P and SS concentrations. Water quality remained, for the most part, constant throughout the day. T-P, T-N and SS load were 181t/year, 2320t/year and 51000t/year in 1992, respectively, 54% of T-P load, 47% of T-N load and 80% of SS loads outflowed in those cases where the discharge was more than 100 m3/s, which were 36 days in 1992. 79% of T-P load, 69% of T-N load and 92% of SS load outflowed in periods of high water discharge, which were 88 in 1992. T-P and T-N loads calculated by using one day's data in every month were 151t/year and 2450t/year. But nutrient loads calculated by using the average value of data from an ordinary discharge were two or three times lower than calculated yearly loads. These results showed the importance of estimating the yearly load considering the discharge condition and sampling at a time of high water discharge.

scholarly journals Hydraulic Evaluation of the Levee System Evolution on the Kurobe Alluvial Fan in the 18th and 19th Centuries

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4406
Author(s):  
Tadaharu Ishikawa ◽  
Hiroshi Senoo
Keyword(s):  
Channel Capacity ◽  
Flood Control ◽  
River Flow ◽  
Global Climate ◽  
Flow Simulation ◽  
Japan Sea ◽  
Main Channel ◽  
Alluvial Fan ◽  
Flood Peak ◽  
Levee System

The development process and flood control effects of the open-levee system, which was constructed from the mid-18th to the mid-19th centuries, on the Kurobe Alluvial Fan—a large alluvial fan located on the Japan Sea Coast of Japan’s main island—was evaluated using numerical flow simulation. The topography for the numerical simulation was determined from an old pictorial map in the 18th century and various maps after the 19th century, and the return period of the flood hydrograph was determined to be 10 years judging from the level of civil engineering of those days. The numerical results suggested the followings: The levees at the first stage were made to block the dominant divergent streams to gather the river flows together efficiently; by the completed open-levee system, excess river flow over the main channel capacity was discharged through upstream levee openings to old stream courses which were used as temporary floodways, and after the flood peak, a part of the flooded water returned to the main channel through the downstream levee openings. It is considered that the ideas of civil engineers of those days to control the floods exceeding river channel capacity, embodied in their levee arrangement, will give us hints on how to control the extraordinary floods that we should face in the near future when the scale of storms will increase due to the global climate change.

Simulation of karst floods with a hydrological model improved by meteorological model coupling

2021 ◽  
Keyword(s):  
Flood Control ◽  
Underground Structure ◽  
Wrf Model ◽  
Precipitation Forecast ◽  
Karst Area ◽  
Peak Time ◽  
Flood Prediction ◽  
Meteorological Model ◽  
Flood Peak ◽  
Flood Warning

Abstract Karst basins are prone to rapid flooding because of their geomorphic complexity and exposed karst landforms with low infiltration rates. Accordingly, simulating and forecasting floods in karst regions can provide important technical support for local flood control. The study area, the Liujiang karst river basin, is the most well-developed karst area in South China, and its many mountainous areas lack rainfall gauges, limiting the availability of precipitation information. Quantitative precipitation forecast (QPF) from the Weather Research and Forecasting model (WRF) and quantitative precipitation estimation (QPE) from remote sensing information by an artificial neural network cloud classification system (PERSIANN-CCS) can offer reliable precipitation estimates. Here, the distributed Karst-Liuxihe (KL) model was successfully developed from the terrestrial Liuxihe model, as reflected in improvements to its underground structure and confluence algorithm. Compared with other karst distributed models, the KL model has a relatively simple structure and small modeling data requirements, which are advantageous for flood prediction in karst areas lacking hydrogeological data. Our flood process simulation results suggested that the KL model agrees well with observations and outperforms the Liuxihe model. The average Nash coefficient, correlation coefficient, and water balance coefficient increased by 0.24, 0.19, and 0.20, respectively, and the average flood process error, flood peak error, and peak time error decreased by 13%, 11%, and 2 hours, respectively. Coupling the WRF model and PERSIANN-CCS with the KL model yielded a good performance in karst flood simulation and prediction. Notably, coupling the WRF and KL models effectively predicted the karst flood processes and provided flood prediction results with a lead time of 96 hours, which is important for flood warning and control.

scholarly journals Effects of high water discharge from Alcalá dam on fish larval stages of Guadalquivir estuary

2016 ◽  
Vol 3 ◽  
Author(s):  
Miró Juan Miguel ◽  
Megina César ◽  
Donázar-Aramendía Iñigo ◽  
Sánchez-Moyano Emilio ◽  
García-Asencio Isabel ◽  
...  
Keyword(s):  
Water Discharge ◽  
High Water ◽  
Guadalquivir Estuary ◽  
Larval Stages

scholarly journals ECOSYSTEM SERVICE ASSESSMENT IN AGRICULTURAL WATERSHED BY USING TOPMODEL

AGROFOR ◽  
2018 ◽  
Vol 2 (3) ◽  
Author(s):  
Kosuke MUKAE ◽  
Koji MIWA ◽  
Hiromu OKAZAWA ◽  
Tomonori FUJIKAWA
Keyword(s):  
Land Use ◽  
River Discharge ◽  
Flood Control ◽  
Human Life ◽  
Water Discharge ◽  
Heavy Rain ◽  
Agricultural Watershed ◽  
Sudden Increase ◽  
Millennium Ecosystem Assessment ◽  
Different Types

In Millennium Ecosystem Assessment established by the United Nations, theecosystem services (ES) provide benefits for human life as well as theenvironment. There is “regulating services” among all the supporting services. As aregulatory service, forests alleviate the flood risk after heavy rain by storingrainfall temporarily into forestlands and prevent the sudden increase in riverdischarge. The purpose of this research is to develop a hydrological modelling toassess this service in a watershed where consists of not only forestland but alsograssland. TOPMODEL is applied for the quantification. This model was inventedto forecast river discharge in watersheds where the land use is uniform. However,the model has not been applied to a watershed where agricultural and forest areaare mixed in Japan. This research aimed to develop TOPMODEL to apply to suchcomplexed land use. Because the targeted watershed is consisted of two land-usetypes, TOPMODEL was applied in each grassland and forestland. It predicted theriver discharge by combining the predicted discharge from the different types ofland calculated by TOPMODEL. The result confirmed that by developing themodel, it was able to assess the water discharge from the both grassland andforestland in a watershed. The developed model also showed the betterreproducibility of river-discharge prediction than the conventional TOPMODEL.In addition, it clarified that the forestland stores more water than grassland into theground. Therefore, the effect of flood control which is the regulatory service of ESwas assessable through the developed model.

scholarly journals Artificial Neural Network Model for Estimation of Suspended Sediment Load in Krishna River Basin, India

2020 ◽  
Vol 9 (3) ◽  
pp. 3701-3705
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Water Level ◽  
Suspended Sediment ◽  
River Basin ◽  
Flood Control ◽  
Sediment Load ◽  
Water Discharge ◽  
Suspended Sediment Load ◽  
Artificial Neural

The correct assessment of amount of sediment during design, management and operation of water resources projects is very important. Efficiency of dam has been reduced due to sedimentation which is built for flood control, irrigation, power generation etc. There are traditional methods for the estimation of sediment are available but these cannot provide the accurate results because of involvement of very complex variables and processes. One of the best suitable artificial intelligence technique for modeling this phenomenon is artificial neural network (ANN). In the current study ANN techniques used for simulation monthly suspended sediment load at Vijayawada gauging station in Krishna river basin, Andhra Pradesh, India. Trial & error method were used during the optimization of parameters that are involved in this model. Estimation of suspended sediment load (SSL) is done using water discharge and water level data as inputs. The water discharge, water level and sediment load is collected from January 1966 to December 2005. This approach is used for modelled the SSL. By considering the results, ANN has the satisfactory performance and more accurate results in the simulation of monthly SSL for the study location.

scholarly journals River hydrology and recent suspended sediment flux in the Red River: implication for assessing soil erosion and sediment transport/deposition processes

2016 ◽  
Vol 54 (5) ◽  
pp. 614
Author(s):  
Dang Thi Ha ◽  
Alexandra Coynel
Keyword(s):  
Particulate Matter ◽  
Suspended Particulate Matter ◽  
Water Discharge ◽  
River System ◽  
Deposition Process ◽  
High Water ◽  
Sediment Flux ◽  
Red River ◽  
Hydrological Conditions ◽  
Suspended Particulate

Based on a database of daily water discharge and daily suspended particulate matter concentrations along the Red River and at the outlet of the main tributaries (Da and Lo) during the 2005-2010 period, covering contrasting hydrological conditions, the water and sediment fluxes transported by the Red River system were determined. The results showed that only 21% of the discharge is derived from the upper Red River, 54% and 25% being derived from the Da and the Lo Rivers, respectively. In contrast, the distribution of suspended particulate matter (SPM) load is very different of that observed for water discharge: most SPM were eroded from the upstream catchment located in China (78%). Moreover, annual SPM fluxes (FSPM) showed a strong spatial variability between upstream watershed and the outlet of the river. The mean inter-annual FSPM was 30 Mt/yr (i.e. specific flux of 741 t/km²/yr) at the LaoCai site, 38 Mt/yr (i.e. 792 t/km²/yr) at the PhuTho gauging site, 29 Mt/yr (i.e. 193 t/km²/yr) at the SonTay gaugng station. Its values were 4.1 Mt/yr (i.e. 80 t/km²/yr) and 6.6 Mt/yr (i.e. 191 t/km²/yr) for the Da and Lo rivers, respectively. Between the LaoCai and PhuTho sites, both erosion and sedimentation processes occurred together, but strongly depended on the hydrological conditions. Between the PhuTho and SonTay sites, the important loss of SPM flux suggested a dominant deposition process in the floodplain during high water before the delta. These results proved the complex processes of erosion/sedimentation occurring on the Red River watershed.

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