Reservoir Routing Research Articles

Streamflow simulation improvements enabled by a state‐of‐the‐art algorithm for reservoir routing in the U.S. National Water Model

AbstractThis study investigates whether improvements could be achieved for the United States National Water Model (NWM) by using a data‐driven reservoir operation simulation algorithm, that is, the generic data‐driven reservoir operation model (GDROM), to replace the existing reservoir representation in NWM for reservoir routing in streamflow simulation. The evaluations of NWM versus NWM + GDROM are conducted using 41‐year NWM retrospective simulation products during 1979 to 2020. The results show that NWM + GDROM exhibits significant improvement to NWM in both the entire Contiguous U.S. (CONUS) and various regions. It is found that the accuracy of reservoir inflow and storage values affects the NWM + GDROM improvement. When driven by observed storage (which is usually more accurate than modeled storage) or more accurately simulated inflow, NWM + GDROM produces more significant improvements in reservoir outflow simulations in all the study CONUS regions. Especially, since high flows are more accurately simulated by NWM than low flows, NWM + GDROM has larger improvement for the simulation of high flows than low flows.

An analytical two-stage risk analysis model in the real-time reservoir operation

Flood risk analysis is vital for real-time reservoir operation. The reservoir operation horizon (OH) is generally longer than the streamflow forecast horizon (FH), while the gap between the FH and the OH was seldom considered in analytical flood risk models. This study develops an analytical two-stage risk model covering the period within the FH (the first stage) and from the FH to the OH (the second stage). In the first stage, the errors in forecasted streamflow and reservoir water level-storage relationships are considered using the multinormal distribution within the FH. In the second stage, design flood hydrographs are used to estimate the flood risk by conducting reservoir routing. Finally, the total flood risk is calculated by using the copula method to combine the flood risks from the first and second stages. Results for a case study using China’s Three Gorges Reservoir indicate that an effective FH can be identified to minimize flood risk, and balance between the forecast accuracy and length of the horizon. The length of the effective FH is not fixed and depends on reservoir inflow. Moreover, larger errors will not always lead to greater flood risks. The proposed method provides useful information on flood risk for real-time reservoir operation.

Penentuan Initial Elevation untuk Mendukung Operasi Early Release Bendungan Sadawarna

Modifications of Sadawarna Dam include the addition of a sluice gate that is placed on the right side of the spillway which functions as an early release facility along with an intake to lower the reservoir water level before the flood comes. Implementation of early release on reservoir routing requires an initial elevation that is different from the initial elevation in general. The aim of this research is to determine the new initial elevation to support early release operations for the Sadawarna Reservoir. This research was conducted by calculating return flood discharge and flood routing in reservoir with 3 (three) scenarios of initial elevation. The method used for analysis of return flood discharge is SCS (Soil Conservation Service). The reservoir routing method uses level pool routing with the HEC-HMS application. Initial elevation is determined by 3 (three) scenarios that started from initial elevation +75,25 masl, +77,00 masl, and +78,50 masl. The results of 3 (three) scenarios showed that the optimal initial elevation that can be used in early release operations is at an elevation of +77,00 masl. The results of the reservoir flood routing simulation with initial elevation resulted reduction flood discharge up to return period of 50 years and resulted in the fastest reservoir water level recovery

Refined Reservoir Routing (RRR) and Its Application to Atmospheric Carbon Dioxide Balance

Reservoir routing has been a routine procedure in hydrology, hydraulics and water management. It is typically based on the mass balance (continuity equation) and a conceptual equation relating storage and outflow. If the latter is linear, then there exists an analytical solution of the resulting differential equation, which can directly be utilized to find the outflow from known inflow and to obtain macroscopic characteristics of the process, such as response and residence times, and their distribution functions. Here we refine the reservoir routing framework and extend it to find approximate solutions for nonlinear cases. The proposed framework can also be useful for climatic tasks, such as describing the mass balance of atmospheric carbon dioxide and determining characteristic residence times, which have been an issue of controversy. Application of the theoretical framework results in excellent agreement with real-world data. In this manner, we easily quantify the atmospheric carbon exchanges and obtain reliable and intuitive results, without the need to resort to complex climate models. The mean residence time of atmospheric carbon dioxide turns out to be about four years, and the response time is smaller than that, thus opposing the much longer mainstream estimates.

A New Vision for Reservoir Routing with Different Scenarios: A Case Study of Haditha Dam Reservoir /Western Iraq.

A New Vision for Reservoir Routing with Different Scenarios: A Case Study of Haditha Dam Reservoir /Western Iraq.

Development of non-data driven reservoir routing in the routing application for parallel computatIon of discharge (RAPID) model

Dams and reservoirs predictably alter the discharge of a river often confounding large-scale flow simulations. The Routing Application for Parallel computatIon of Discharge (RAPID) model has been widely used operationally. Until recently, RAPID could only represent reservoir outflow by directly specifying discharges from dams. Herein, we develop a non-data driven reservoir routing approach within RAPID. Results are comprehensively evaluated across the entire Mississippi River Basin (MRB). The reservoir routing resulted in considerable improvement in the Lower Mississippi and Arkansas-White-Red regions. Further, the accuracy of estimated reservoir releases also benefits when the inflow estimation improves. Simulation of the reservoir release with observed reservoir inflow resulted in highest Kling-Gupta efficiency (KGE) among all experiments. Inclusion of reservoir routing in RAPID will enhance the utility of this model in basins where dams exist and more importantly, improves streamflow predictions by providing better hydrological information for decision makers.

Development of A Two-storage Reservoir Operation Rules for Flood Control Case Study of Wonogiri Multipurpose Reservoir, Central Java, Indonesia

Wonogiri Reservoir, one of the large reservoirs in Indonesia, regulates water for flood control, irrigation, domestic use, and hydropower. It is located at the upper part of Bengawan Solo River Basin, Central Java. A closure dike has recently been constructed as a countermeasure against severe sedimentation that separates the reservoir into two parts, i.e., Sediment Storage Reservoir (SSR) and Main Reservoir (MR). A two-gate spillway was constructed in the SSR to facilitate sediment flushing and sluicing. During flood events, it controls reservoir water level jointly with the MR spillway. This brings the need for an update on the reservoir operation rules, especially on the gates opening of the new spillways to maintain the flood control performance. An assessment of reservoir routing simulation results was carried out by considering the overflow from SSR to MR, or vice versa with two options of Control Water Level (CWL), i.e. +135.8 m and +136.3 m. The flood control performance of the new reservoir operation rules was evaluated by considering the reservoir water level recovery, the maximum total outflow discharge, and the dam safety due to the risk of overtopping. These assessments give a foundation for the selection of CWL and the spillway operation to ascertain an optimal flood control of the reservoir.

Estimating Reservoir Inflow and Outflow From Water Level Observations Using Expert Knowledge: Dealing With an Ill‐Posed Water Balance Equation in Reservoir Management

AbstractQuantifying reservoir water balance is an essential process for the efficient management of water resources. Water level records are often the only data available for reservoir analysis, which causes an ill‐posed problem in water resource system planning. This study proposes an analytical framework to estimate reservoir inflow and outflow from water level observations using hydrological models and reasoning carefully derived from expert knowledge and soft data. Partial reservoir inflow hydrographs were constructed from water level observations using a continuity equation and knowledge‐based constraints developed for periods of no spillway discharge. A bucket‐type rainfall‐runoff model was then calibrated to the partial inflow hydrographs. Finally, a complete reservoir inflow hydrograph was constructed using the calibrated models, which were then employed to estimate detailed reservoir outflow components under a full water balance relationship between inflow, outflow, water levels, and reservoir operation rules. The proposed solution for the ill‐posed water balance equation outperformed conventional (benchmark) approaches in accuracy and uncertainty in its application to agricultural reservoirs. This study demonstrates how hydrological modeling and reasoning, which are discreetly designed based on expert knowledge, can help to solve the ill‐posed water balance equation by creating supplementary information regarding the problem. The proposed framework is expected to assist in reconstructing reservoir routing processes using water level observations for hydrological analysis and water resource management planning.

WEB.BM – a web-based river basin management model with multiple time-step optimization and the SSARR channel routing options

ABSTRACT This paper presents the WEB.BM model for multipurpose multireservoir river basin management that uses Mixed Integer Linear Programming (MILP) solver to optimize basin operation over single or multiple time steps, with flexible time step length and optional use of both reservoir and hydrological channel routing. The principal novelty is the capability of the model to solve multiple time step optimization while simultaneously properly accounting for hydrological channel routing as constraints to optimization, which is demonstrated on two numerical tests presented in this paper, which can be used as benchmark by other researchers. There are no other known optimization-based river basin management models with this capability. The model can include multiple reservoirs, hydropower plants, environmental flow targets, return flows from irrigation, diversion volume licences, apportionment agreements between neighbouring states and net evaporation. Operating priorities among users are represented by a selection of user-defined weight factors. The model can be accessed at www.riverbasinmanagement.com.

Analisis Ketersediaan Air Waduk Gadjah Mungkur dengan Adanya Pembangunan Intake dan Jaringan Pipa Trasmisi Wosusokas

Gadjah Mungkur Reservoir is one of the multipurpose reservoirs built by damming the flow of the Bengawan Solo River. The Gadjah Mungkur Reservoir has existed for a long time with the main purpose of controlling flooding, but over time, this reservoir is also useful as a hydropower plant, irrigation, and also to meet the raw water needs of Wonogiri City. The potential of the Gadjah Mungkur Reservoir itself in meeting the needs of drinking water is an essential function in the people’s life around the reservoir. Therefore, the expansion of the scope of providing drinking water can be used to develop the potential of the Gadjah Mungkur Reservoir. This coverage expansion was realized through the construction of the Wosusokas intake and transmission pipeline network to drinking water receiving areas, namely Wonogiri, Sukoharjo, Solo, and Karanganyar, with service coverage of drinking water access resepectively ±78,38, ±70,97%, ±81,85%, and ±70,97%. This study aims to analyze the water availability of the Gadjah Mungkur Reservoir with additional coverage for drinking water services. The method used is a simple reservoir routing calculation by processing secondary data obtained in the form of inflow, outflow, and reservoir storage characteristics. The results of the analysis show that elevation variations with the construction of the Wosusokas intake and transmission pipeline have an annual average of +132,56 m in 2017, with a reservoir storage volume reaching 216,27 MCM and +134,29 m in 2018, with a reservoir storage volume reaching 284,92 MCM. However, there are some elevation values that exceed +138,0 m, namely at February to March 2018. However, overall, the results of the analysis show that the Wosusokas construction can increase the potential utilization of the Gadjah Mungkur Reservoir without endangering the reservoir with water level fluctuations that can still be controlled and in accordance with the regulation of reservoir water level.

A Framework of Dam-Break Hazard Risk Mapping for a Data-Sparse Region in Indonesia

This paper introduces a new simple approach for dam-break hazard mapping in a data-sparse region. A hypothetical breaching case of an earthen dam, i.e., the Ketro Dam in Central Java, (Indonesia) was considered. Open-access hydrological databases, i.e., TRMM and CHIRPS, were collected and compared with the rainfall ground station data to ensure data quality. Additionally, the 3-h rainfall distribution of the TRMM database was employed and validated with the measured data to establish the 24-h rainfall distribution of the probable maximum precipitation. The probable maximum flood discharge was computed with the SCS method, and the reservoir routing computation was conducted to determine the possible breaching mechanisms. The result shows that the Ketro Dam proves safe against overtopping, and thus only the piping mechanism has been taken into consideration. Using the breaching hydrograph, the open-access Digital Elevation Model MERIT Hydro, and the high-performance shallow water model NUFSAW2D, the flood propagation to the downstream part of the dam was simulated, enabling fast computations for different scenarios. The quantification of the susceptibility rate of urban areas was eased with overlay analysis utilizing InaSAFE, a plugin for the QGIS model. This study shows that even for a data-sparse region, the recent open-access databases in terms of hydrological and hydraulic aspects may be used to generate a dam-break hazard map. This will benefit the related stakeholders to take proper action to reduce the loss of life.

The Impact of the Construction of a Dam on Flood Management

A possible strategy to mitigate the effects of flooding from an area identified as having high runoff potential will reduce the volumes of water that overflow the drainage area and build a system of a storage location in the coastal city of Tangier. The study is based on two main axes: (i) the extreme flow frequency analysis, using eight probability laws adjusted by the Maximum Likelihood method, and (ii) the estimation of the flood outflows at the dam outlet using the routing method in order to assess the effect of detention dams on water flood. Annual (Maximum) series based flood sampling procedure is adopted for constructing the Flood Frequency analysis. A numerical comparison of AIC criteria and BIC has allowed a proceeding to the selection of the most fitted law distributions. The result shows that the Gumbel law is best adapted to the predetermination of the extreme flow estimation in the Mghogha watershed for different return periods. The reservoir routing method along with rainfall-runoff processes were applied by the mean of the HEC-HMS model. The model was run under two different scenarios. Scenario 1 simulates the Mghogha basin with the absence of the reservoir. Meanwhile, scenario 2 simulates the same basin by taking into account the existence of the Ain Mechlawa reservoir within different return periods of from 2 to 200 years. Peak discharges downstream have been dramatically attenuated and water volumes have been decreased with the prolongation of the return period. For the 100 and 200 return periods, the peak discharge of flood reduction for scenario 1 and scenario 2 were 52.06 and 52.17 %, respectively, and for the flood volume was 22.46 and 22.82% respectively. Finally, the results of investigations showed a good performance of the model in the estimation of outflow peak discharge of the Ain Mechlawa Dam. Doi: 10.28991/cej-2021-03091658 Full Text: PDF

Dam break analysis of Situ Gintung Dam collapse reconstruction

On March, 27th 2009 Situ Gintung dam collapsed. Situ Gintung dam failure has been analyzed based on the condition of watershed, reservoir, and embankment on March, 27 2009. Hydrological analysis and slope stability analysis are combined to analyze the major causes gintung collapse. Watershed analysis using ARC-GIS software, routing in reservoir using HEC-HMS model, and stability condition was strudied using Geo-Slope. Input data, parameters, and model assumptions are very important to get the right results. Hydrological analysis results show that rain occurred on March 26, 2009 with a rainfall intensity of 111 mm/day was only classified as rainfall with a return period of 5 years. Reservoir routing show that water level elevation on March, 27 2009 was only 70 cm above the spillway crest or 1,3 m below the embankment crest with a peak flow of 36,2 m3/s, so it didn’t cause overtopping on the embankment. Slope stability analysis results show that the factor of safety of 1,19 < 1,5 (standard), it show that there was the weakening of the dam, such as scouring, erosion, and cracks. It can be concluded that the main factor of the collapsed was caused by scouring and cracks.

Improving Reservoir Outflow Estimation for Ungauged Basins Using Satellite Observations and a Hydrological Model

AbstractNowadays, most of rivers globally are regulated by dams and reservoirs, which have substantially altered natural streamflow regimes. Understanding the impacts of these dams and reservoirs on streamflow is essential for water resources management. In situ reservoir release data or actual reservoir operating rules are difficult to obtain, particularly for transboundary rivers, resulting in the tremendous difficulty of simulating exact reservoir behaviors. This study aims to use easy‐to‐obtain satellite observations combined with a distributed hydrological model to estimate reservoir releases at the daily time scale. The developed Satellite‐Based Reservoir routing Scheme (SBRS) was applied to two individual reservoirs in the United States and Thailand and cascade reservoirs on the Lancang River in China. The normalized root‐mean‐square error (NRMSE), correlation coefficient (CC), and hydrographs of daily regulated streamflow simulations were used to assess the performance of the reservoir release simulations. The SBRS was compared with four other global reservoir operation schemes and showed better overall performance with higher CC and lower NRMSE. In addition, the SBRS performed better for the individual reservoirs (CC &gt; 0.6, NRMSE &lt; 0.2) than the cascade reservoirs, which is attributed to the uncertainty in the simulation of inflow and reservoir storage changes and to the lack of remote sensing data for all the cascade reservoirs. This study explores the potential of satellite observations combined with hydrological modeling in elucidating reservoir behaviors in ungauged and/or transboundary river basins. A better understanding of reservoir behaviors serves as a basis for water resources management and provides a more cooperative environment for all stakeholders of a basin.

A Model Tree Generator (MTG) Framework for Simulating Hydrologic Systems: Application to Reservoir Routing

Data-driven algorithms have been widely used as effective tools to mimic hydrologic systems. Unlike black-box models, decision tree algorithms offer transparent representations of systems and reveal useful information about the underlying process. A popular class of decision tree models is model tree (MT), which is designed for predicting continuous variables. Most MT algorithms employ an exhaustive search mechanism and a pre-defined splitting criterion to generate a piecewise linear model. However, this approach is computationally intensive, and the selection of the splitting criterion can significantly affect the performance of the generated model. These drawbacks can limit the application of MTs to large datasets. To overcome these shortcomings, a new flexible Model Tree Generator (MTG) framework is introduced here. MTG is equipped with several modules to provide a flexible, efficient, and effective tool for generating MTs. The application of the algorithm is demonstrated through simulation of controlled discharge from several reservoirs across the Contiguous United States (CONUS).

Susceptibility of Water Resources and Hydropower Production to Climate Change in the Tropics: The Case of Lake Malawi and Shire River Basins, SE Africa

The sensitivity of key hydrologic variables and hydropower generation to climate change in the Lake Malawi and Shire River basins is assessed. The study adapts the mesoscale Hydrological Model (mHM) which is applied separately in the Upper Lake Malawi and Shire River basins. A particular Lake Malawi model, which focuses on reservoir routing and lake water balance, has been developed and is interlinked between the two basins. Climate change projections from 20 Coordinated Regional Climate Downscaling Experiment (CORDEX) models for Africa based on two scenarios (RCP4.5 and RCP8.5) for the periods 2021–2050 and 2071–2100 are used. An annual temperature increase of 1 °C decreases mean lake level and outflow by 0.3 m and 17%, respectively, signifying the importance of intensified evaporation for Lake Malawi’s water budget. Meanwhile, a +5% (−5%) deviation in annual rainfall changes mean lake level by +0.7 m (−0.6 m). The combined effects of temperature increase and rainfall decrease result in significantly lower flows in the Shire River. The hydrological river regime may change from perennial to seasonal with the combination of annual temperature increase and precipitation decrease beyond 1.5 °C (3.5 °C) and −20% (−15%). The study further projects a reduction in annual hydropower production between 1% (RCP8.5) and 2.5% (RCP4.5) during 2021–2050 and between 5% (RCP4.5) and 24% (RCP8.5) during 2071–2100. The results show that it is of great importance that a further development of hydro energy on the Shire River should take into account the effects of climate change, e.g., longer low flow periods and/or higher discharge fluctuations, and thus uncertainty in the amount of electricity produced.

Effect of reservoir models and climate change on flood analysis in arid regions

Dams are built in arid regions across watersheds for flood control among other purposes. Capacity-elevation (C-E) curves are vital for reservoir routing and dam operation. Different models are available for representing C-E relationships. Power and logarithmic laws are evaluated and tested for reservoir routing. The evaluation is based on the analysis of 136 reservoirs across different regions of Saudi Arabia (SA). The analysis revealed that 75.7% of the reservoirs are of flood plain foothill type. A case study on Al-Lith dam basin is utilized for application based on measured events. The resulting routed outflow hydrographs showed that the logarithmic law is better to represent the reservoir than the power law. With respect to the climate change effect, the results show that the predicted rainfall from Representative Concentration Pathways scenario (RCP4.5) increased by about 20 to 31.4% from 5 to 100 years return periods respectively with an average of 27%. While for scenario RCP8.5, the predicted rainfall increased by 42% to about 55% from 5 to 100 years return periods respectively with an average of 49%. For the RCP4.5 scenario, the peak flows, Qp, and volumes, W, increased by an average of 69% and 67% respectively. While for the RCP8.5 scenario, the same parameters increased by an average of 139% and 134% respectively. The effect of transmission losses in the results seems to be minor with respect to climate change signal (for RCP4.5, Qp and W are lowered on average by 2% and 0.5% respectively, and for RCP8.5, Qp and W are lowered on average by 4.5% and 1.3% respectively). The results of this research recommend to use the logarithmic law and to take into account the effect of climate change on future dam projects in SA.

Considering different streamflow forecast horizons in the quantitative flood risk analysis for a multi-reservoir system

The flood risk analysis of a multi-reservoir system is based on the forecasted streamflow, whose time length is the forecast horizon (FH). FHs are generally different for each reservoir while the operation horizon (OH) is the same in a multi-reservoir system. To bridge the gap between the FHs and the OH of the multi-reservoir system, this study aims to develop a two-stage flood risk analysis method, specifically considering different FHs of each reservoir. In the first stage (the time period within the FHs), multinormal distribution of multi-reservoir storage was deduced by using the multivariate autoregressive model. In the second stage (the time period between the FHs and the OH), flood risk was calculated by using the reservoir routing for design flood hydrographs. The total flood risk within the OH incorporated the risks in the first and second stages. Finally, the joint effective FHs corresponding to the minimum total flood risk could be identified by numerical experiments. The results for the case study indicate that: (1) the proposed two-stage flood risk analysis utilizes different FHs in the multi-reservoir system and bridge the gap between the FHs and the OH; (2) the joint effective FHs are not constants and change with inflow conditions.

A unified approach for hydrological modeling of arid catchments for flood hazards assessment: case study of wadi Itwad, southwest of Saudi Arabia

A unified and systematic approach for hydrological modeling is presented for assessing flood hazards in arid and semi-arid regions with wadi Itwad as a case study. The approach consists of the following steps: (1) estimation of the design storm duration, (2) estimation of the design rainfall depth, (3) development of the design storm hyetograph, (4) setup of the watershed hydrological system, (5) infiltration tests for estimate of soil characteristics, (6) land use and land cover analysis for curve number estimation, (7) how to incorporate dams (if any) and their reservoir characteristics for reservoir routing analysis, and (8) performing hydrological modeling under different scenarios, namely: lumped with and without the effect of dams and routed scenarios. An emphasis is made on the comparison between the SCS unit hydrograph and the unit hydrograph (UH) estimated for stream flow data. The UH method produces hydrographs that are typical of arid regions. It is characterized by a steep rising limb with a short time to peak, a rapid recession to zero base flow, and less flood volume due to transmission losses. The scenarios show that the lumped case overdesigns the protection schemes, while the lumped central basin with detention dams storing the flood water completely leads to underdesign in the downstream area. The routed scenario is more realistic, since it considers the detention dams with an overflow. The runoff volume (66.6 MCM) of the 10-year return period of the routed scenario is in the order of magnitude within the observed historical data (50 to 100 MCM) reported in the literature. The study concludes that the proposed approach is robust and takes into account the Saudi arid environment while performing flood risk assessment in KSA.

Comparison of generalized non-data-driven lake and reservoir routing models for global-scale hydrologic forecasting of reservoir outflow at diurnal time steps

Abstract. Large-scale hydrologic forecasts should account for attenuation through lakes and reservoirs when flow regulation is present. Globally generalized methods for approximating outflow are required but must contend with operational complexity and a dearth of information on dam characteristics at global spatial scales. There is currently no consensus on the best approach for approximating reservoir release rates in large spatial scale hydrologic forecasting, particularly at diurnal time steps. This research compares two parsimonious reservoir routing methods at daily steps: Döll et al. (2003) and Hanasaki et al. (2006). These reservoir routing methods have been previously implemented in large-scale hydrologic modeling applications and have been typically evaluated seasonally. These routing methods are compared across 60 reservoirs operated by the U.S. Army Corps of Engineers. The authors vary empirical coefficients for both reservoir routing methods as part of a sensitivity analysis. The method proposed by Döll et al. (2003) outperformed that presented by Hanasaki et al. (2006) at a daily time step and improved model skill over most run-of-the-river conditions. The temporal resolution of the model influences model performances. The optimal model coefficients varied across the reservoirs in this study and model performance fluctuates between wet years and dry years, and for different configurations such as dams in series. Overall, the method proposed by Döll et al. (2003) could enhance large-scale hydrologic forecasting, but can be subject to instability under certain conditions.