The Experts below are selected from a list of 3528 Experts worldwide ranked by ideXlab platform
Tao-chang Yang - One of the best experts on this subject based on the ideXlab platform.
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Using synthetic Flow Duration Curves for rainfall–runoff model calibration at ungauged sites
Hydrological Processes, 2000Co-Authors: Tao-chang YangAbstract:The primary objective of the study is to propose a strategy for rainfall–runoff model calibration at ungauged sites. This strategy comprises two main components: (1) development of the regional analysis method to synthesize the Flow Duration Curves at ungauged sites; and (2) utilization of the synthetic Flow Duration Curves for model calibration. Since the regional analysis method can synthesize the Flow Duration Curves at ungauged sites, the continuous rainfall–runoff model coupled with a global optimization method were applied in southern Taiwan using the synthetic Flow Duration Curve as an objective for model calibration. The results reveal that the regional Flow Duration Curve and the strategy for model calibration at ungauged sites have good performances in the study area. Copyright © 2000 John Wiley & Sons, Ltd.
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Synthetic regional Flow Duration Curve for southern Taiwan
Hydrological Processes, 1996Co-Authors: Tao-chang YangAbstract:The primary purpose of this study is to develop the regional Flow Duration Curves for southern Taiwan. To define homogeneous regions for developing regional Flow Duration Curves, multivariate statistical analysis (principal component and cluster analysis) was applied to daily Flow data from 34 stream-gauged stations in southern Taiwan. Two kinds of clustering variables, the dimensionless Flow Duration Curve and specific Flow Duration Curve, were compared in this study. It was found that three homogeneous regions delineated by specific Flow Duration Curves as clustering variables have more reasonable results. The three homogeneous regions not only have well-defined geographical boundaries, but also correspond to the rainfall and geology characteristics of the regions. It seems that the technique of cluster analysis can reasonably define the homogeneous regions. In each homogeneous region, the synthetic regional Flow Duration Curves were developed by a family of parametric Duration Curves. This approach has the advantage of being simple and needing only the basin area as an index. The performance of the regional Flow Duration Curve was verified by the comparison of areas under the actual and synthetic Flow Duration Curves ; the latter were generated from the regional Flow Duration Curve. Almost all the 34 stream-gauged stations had less than 25% absolute error.
Francis H S Chiew - One of the best experts on this subject based on the ideXlab platform.
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comparing Flow Duration Curve and rainfall runoff modelling for predicting daily runoff in ungauged catchments
Journal of Hydrology, 2015Co-Authors: Yongqiang Zhang, Jai Vaze, Francis H S ChiewAbstract:Summary Predicting daily runoff time series in ungauged catchments is both important and challenging. For the last few decades, the rainfall–runoff (RR) modelling approach has been the method of choice. There have been very few studies reported in literature which attempt to use Flow Duration Curve (FDC) to predict daily runoff time series. This study comprehensively compares the two approaches using an extensive dataset (228 catchments) for a large region of south-eastern Australia and provides guidelines for choosing the suitable method. For each approach we used the nearest neighbour method and two weightings – a 5-donor simple mathematical average (SA) and a 5-donor inverse-distance weighting (5-IDW) – to predict daily runoff time series. The results show that 5-IDW was noticeably better than a single donor to predict daily runoff time series, especially for the FDC approach. The RR modelling approach calibrated against daily runoff outperformed the FDC approach for predicting high Flows. The FDC approach was better at predicting medium to low Flows in traditional calibration against the Nash–Sutcliffe-Efficiency or Root Mean Square Error, but when calibrated against a low Flow objective function, both the FDC and rainfall–runoff models performed equally well in simulating the low Flows. These results indicate that both methods can be further improved to simulate daily hydrographs describing the range of Flow metrics in ungauged catchments. Further studies should be carried out for improving the accuracy of predicted FDC in ungauged catchments, including improving the FDC model structure and parameter fitting.
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A new regionalization approach and its application to predict Flow Duration Curve in ungauged basins
Journal of Hydrology, 2010Co-Authors: Quanxi Shao, Lu Zhang, Francis H S ChiewAbstract:Summary Prediction in ungauged basins is an important task for water resources planning and management and remains a fundamental challenge for the hydrological community. Regionalization is typically used to estimate parameter values of hydrological predictive tools for catchments without observed streamFlow. This study proposes a new regionalization method, called the index model. The index model establishes a nonparametric relationship between each parameter of predictive tools and a linear combination of predicators. This method is able to describe a wide range of functions, linear or nonlinear, and avoids the potential misspecification which usually occurs as a result of using the ordinary linear regression. We illustrate the method by predicting Flow Duration Curves at 227 unimpaired catchments in southeast Australia. This study also compares results from regional models based on the linear regression, nearest neighbour and hydrological similarity. The results show that the index model produces the most accurate prediction with highest coefficients of efficiency, followed by the linear regression. In particular, the index model improves the model performance substantially at catchments where the linear regression is a fair to poor fit. The index model was also interpretable and showed that potential evapotranspiration and summary statistics of rainfall are predominant in prediction.
Ilyas Masih - One of the best experts on this subject based on the ideXlab platform.
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regionalization of a conceptual rainfall runoff model based on similarity of the Flow Duration Curve a case study from the semi arid karkheh basin iran
Journal of Hydrology, 2010Co-Authors: Ilyas Masih, S Uhlenbrook, Shreedhar Maskey, Mobinuddin AhmadAbstract:Summary The study examines the possibility of simulating time series of streamFlows for poorly gauged catchments based on hydrological similarity. The data of 11 gauged catchments (475–2522 km 2 ), located in the mountainous semi-arid Karkheh river basin of Iran, is used to develop the procedure. The well-known HBV model is applied to simulate daily streamFlow with parameters transferred from gauged catchment counterparts. Hydrological similarity is defined based on four similarity measures: drainage area, spatial proximity, catchment characteristics and Flow Duration Curve (FDC). The study shows that transferring HBV model parameters based on the FDC similarity criterion produces better runoff simulation compared to the other three methods. Furthermore, it is demonstrated that the FDC based regionalization of HBV model parameters works reasonably well for streamFlow simulations in the data limited catchments in the mountainous parts of the Karkheh river basin. In addition, it could be demonstrated that the parameter uncertainty of the model has little impact on the FDC based regionalization approach. The methodology presented in this paper is easy to replicate in other river basins of the world, particularly those facing decline in streamFlow monitoring networks and with a limited number of gauged catchments.
Mobinuddin Ahmad - One of the best experts on this subject based on the ideXlab platform.
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regionalization of a conceptual rainfall runoff model based on similarity of the Flow Duration Curve a case study from the semi arid karkheh basin iran
Journal of Hydrology, 2010Co-Authors: Ilyas Masih, S Uhlenbrook, Shreedhar Maskey, Mobinuddin AhmadAbstract:Summary The study examines the possibility of simulating time series of streamFlows for poorly gauged catchments based on hydrological similarity. The data of 11 gauged catchments (475–2522 km 2 ), located in the mountainous semi-arid Karkheh river basin of Iran, is used to develop the procedure. The well-known HBV model is applied to simulate daily streamFlow with parameters transferred from gauged catchment counterparts. Hydrological similarity is defined based on four similarity measures: drainage area, spatial proximity, catchment characteristics and Flow Duration Curve (FDC). The study shows that transferring HBV model parameters based on the FDC similarity criterion produces better runoff simulation compared to the other three methods. Furthermore, it is demonstrated that the FDC based regionalization of HBV model parameters works reasonably well for streamFlow simulations in the data limited catchments in the mountainous parts of the Karkheh river basin. In addition, it could be demonstrated that the parameter uncertainty of the model has little impact on the FDC based regionalization approach. The methodology presented in this paper is easy to replicate in other river basins of the world, particularly those facing decline in streamFlow monitoring networks and with a limited number of gauged catchments.
Jan Seibert - One of the best experts on this subject based on the ideXlab platform.
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Prediction of hydrographs and Flow-Duration Curves in almost ungauged catchments : Which runoff measurements are most informative for model calibration?
Journal of Hydrology, 2017Co-Authors: Sandra Pool, Daniel Viviroli, Jan SeibertAbstract:Applications of runoff models usually rely on long and continuous runoff time series for model calibration. However, many catchments around the world are ungauged and estimating runoff for these catchments is challenging. One approach is to perform a few runoff measurements in a previously fully ungauged catchment and to constrain a runoff model by these measurements. In this study we investigated the value of such individual runoff measurements when taken at strategic points in time for applying a bucket-type runoff model (HBV) in ungauged catchments. Based on the assumption that a limited number of runoff measurements can be taken, we sought the optimal sampling strategy (i.e. when to measure the streamFlow) to obtain the most informative data for constraining the runoff model. We used twenty gauged catchments across the eastern US, made the assumption that these catchments were ungauged, and applied different runoff sampling strategies. All tested strategies consisted of twelve runoff measurements within one year and ranged from simply using monthly Flow maxima to a more complex selection of observation times. In each case the twelve runoff measurements were used to select 100 best parameter sets using a Monte Carlo calibration approach. Runoff simulations using these ‘informed’ parameter sets were then evaluated for an independent validation period in terms of the Nash-Sutcliffe efficiency of the hydrograph and the mean absolute relative error of the Flow-Duration Curve. Model performance measures were normalized by relating them to an upper and a lower benchmark representing a well-informed and an uninformed model calibration. The hydrographs were best simulated with strategies including high runoff magnitudes as opposed to the Flow-Duration Curves that were generally better estimated with strategies that captured low and mean Flows. The choice of a sampling strategy covering the full range of runoff magnitudes enabled hydrograph and Flow-Duration Curve simulations close to a well-informed model calibration. The differences among such strategies covering the full range of runoff magnitudes were small indicating that the exact choice of a strategy might be less crucial. Our study corroborates the information value of a small number of strategically selected runoff measurements for simulating runoff with a bucket-type runoff model in almost ungauged catchments.