Journal articles: 'GAMMA HYDROGRAPH'

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Gądek, Wiesław, Beata Baziak, and Tamara Tokarczyk. "Strupczewski Method for Parametric Design Hydrographs in Ungauged Cross-Sections." Archives of Hydro-Engineering and Environmental Mechanics 64, no. 1 (June 27, 2017): 49–67. http://dx.doi.org/10.1515/heem-2017-0004.

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AbstractNonparametric hydrographs, constructed by the method suggested by Archer, are usually used for developing parametric design hydrographs. Flow changes in time are described by the UPO ERR Gamma complex function, which denotes a Gamma curve reformulated to have a Unit Peak at the Origin (abbreviated to UPO), supplemented by the Exponential Replacement Recession (ERR) curve. It may be observed, that this solution does not work in some areas of the upper Vistula and middle Odra catchments when the times of the rising limb of a hydrograph are higher than the times of the falling limb, i.e. when the skewness coefficient approximates 0.5 or higher values. Better results can be achieved with the function suggested by Strupczewski in 1964. It is a solution which uses two parameters of the flood hydrograph. The objective of the present paper is to assess the Strupczewski method by comparing it with a complex UPO ERR Gamma function for gauged cross-sections in the upper Vistula and middle Odra catchments. The assessment was carried out for 30 gauged cross-sections (15 in each river catchment). The parameters were optimized for width-hydrograph descriptors W75 and W50, designed by the Archer method, and for the skewness coefficient s. Optimization using only two width-hydrograph descriptors aims to test how the Strupczewski method works for cross-sections for which the values of width-hydrograph descriptors W75 and W50 are known. The assessment of both methods was carried out with reference to a nonparametric hydrograph constructed by the Archer method. The results of these assessments suggest that the Strupczewski method may be used not only for gauged cross-sections, but also for ungauged ones.

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Szeląg, Bartosz, and Maciej Mrowiec. "The methods of evaluating storage volume for single-chamber reservoir in urban catchments." Archives of Environmental Protection 42, no. 2 (June 1, 2016): 20–25. http://dx.doi.org/10.1515/aep-2016-0016.

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Abstract The article presents a method of designing single-chamber rectangular detention reservoirs based on nomographs connecting the parameters and the shape of the inflow with the reservoir hydrograph (triangular, described by the power function and described by the gamma distribution) as well as the hydraulic characteristics of the accumulation chamber and the orifice. The preparation of nomographs involved using the SWMM (Storm Water Management Model) program with the application of numerical calculations’ results of a differential equation for the stormwater volume balance. The performed analyses confirm a high level of similarity between the results of calculating the reservoir volume obtained by using the above mentioned program and using the developed nomographs. The examples of calculations presented in the paper confirm the application aspects of the discussed method of designing the detention reservoir. Moreover, based on the conducted analyses it was concluded that the inflow hydrograph described by the gamma distribution has the greatest impact on the reservoir’s storage volume, whereas the hydrograph whose shape in the rise and recession phases is described by the power function has the smallest effect.

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Bhunya, P. K., S. K. Mishra, and Ronny Berndtsson. "Simplified Two-Parameter Gamma Distribution for Derivation of Synthetic Unit Hydrograph." Journal of Hydrologic Engineering 8, no. 4 (July 2003): 226–30. http://dx.doi.org/10.1061/(asce)1084-0699(2003)8:4(226).

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Aranda, Jose, and Rafael García-Bartual. "Synthetic Hydrographs Generation Downstream of a River Junction Using a Copula Approach for Hydrological Risk Assessment in Large Dams." Water 10, no. 11 (November 2, 2018): 1570. http://dx.doi.org/10.3390/w10111570.

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Peak flows values (Q) and hydrograph volumes (V) are obtained from a selected family of historical flood events (period 1957–2017), for two neighboring mountain catchments located in the Ebro river basin, Spain: rivers Ésera and Isábena. Barasona dam is located downstream of the river junction. The peaks over threshold (POT) method is used for a univariate frequency analysis performed for both variables, Q and V, comparing several suitable distribution functions. Extreme value copulas families have been applied to model the bivariate distribution (Q, V) for each of the rivers. Several goodness-of-fit tests were used to assess the applicability of the selected copulas. A similar copula approach was carried out to model the dependence between peak flows of both rivers. Based on the above-mentioned statistical analysis, a Monte Carlo simulation of synthetic design flood hydrographs (DFH) downstream of the river junction is performed. A gamma-type theoretical pattern is assumed for partial hydrographs. The resulting synthetic hydrographs at the Barasona reservoir are finally obtained accounting for flow peak time lag, also described in statistical terms. A 50,000 hydrographs ensemble was generated, preserving statistical properties of marginal distributions as well as statistical dependence between variables. The proposed method provides an efficient and practical modeling framework for the hydrological risk assessment of the dam, improving the basis for the optimal management of such infrastructure.

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Jin, Chang-Xing. "A deterministic gamma-type geomorphologic instantaneous unit hydrograph based on path types." Water Resources Research 28, no. 2 (February 1992): 479–86. http://dx.doi.org/10.1029/91wr02577.

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Singh, Sushil K. "Time Base as an Invertible Function of the Parameters of Gamma Unit Hydrograph." Journal of Irrigation and Drainage Engineering 135, no. 6 (December 2009): 802–5. http://dx.doi.org/10.1061/(asce)ir.1943-4774.0000105.

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Gnecco, Ilaria, Anna Palla, and Paolo La Barbera. "A dimensionless approach for the runoff peak assessment: effects of the rainfall event structure." Hydrology and Earth System Sciences 22, no. 2 (February 2, 2018): 943–56. http://dx.doi.org/10.5194/hess-22-943-2018.

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Abstract. The present paper proposes a dimensionless analytical framework to investigate the impact of the rainfall event structure on the hydrograph peak. To this end a methodology to describe the rainfall event structure is proposed based on the similarity with the depth–duration–frequency (DDF) curves. The rainfall input consists of a constant hyetograph where all the possible outcomes in the sample space of the rainfall structures can be condensed. Soil abstractions are modelled using the Soil Conservation Service method and the instantaneous unit hydrograph theory is undertaken to determine the dimensionless form of the hydrograph; the two-parameter gamma distribution is selected to test the proposed methodology. The dimensionless approach is introduced in order to implement the analytical framework to any study case (i.e. natural catchment) for which the model assumptions are valid (i.e. linear causative and time-invariant system). A set of analytical expressions are derived in the case of a constant-intensity hyetograph to assess the maximum runoff peak with respect to a given rainfall event structure irrespective of the specific catchment (such as the return period associated with the reference rainfall event). Looking at the results, the curve of the maximum values of the runoff peak reveals a local minimum point corresponding to the design hyetograph derived according to the statistical DDF curve. A specific catchment application is discussed in order to point out the dimensionless procedure implications and to provide some numerical examples of the rainfall structures with respect to observed rainfall events; finally their effects on the hydrograph peak are examined.

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Gądek, Wiesław, Beata Baziak, Tamara Tokarczyk, and Wiwiana Szalińska. "A Novel Method of Design Flood Hydrographs Estimation for Flood Hazard Mapping." Water 14, no. 12 (June 9, 2022): 1856. http://dx.doi.org/10.3390/w14121856.

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Flood hazard mapping requires knowledge of peak flow as well as flood wave volume and shape, usually represented as a design flood hydrograph (DFH). Statistical approaches for DFH development include nonparametric and parametric methods. The former are developed from long-term flow observations and are thus related to the physio-hydro-climatological catchment properties, but not applicable for ungauged catchments. The alternative parametric DFH can be estimated for any river cross-section, but its links with catchment characteristics are limited. The goal of this study was to introduce a novel hybrid approach for DFH estimation, where the parametric DFH is estimated from the selected properties of the nonparametric DFH (hydrograph width at the levels of 50% and 75% of the peak flow and skewness coefficient) that can be related to the catchment characteristics. The model that offers effective parameter estimation and best correspondence to the reference observation-based hydrograph was selected from among Gamma distribution, Strupczewski and Baptista candidates. The method was validated for 34 catchments of the upper Vistula River and Middle Odra water regions (Poland) based on data from the 1964–2010 period. The Baptista method was found to provide the best model for hybrid DFH construction according to the applied quality measures.

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Rai, R. K., S. Sarkar, and H. G. Gundekar. "Adequacy of two-parameter beta distribution for deriving the unit hydrograph." Hydrology Research 39, no. 3 (June 1, 2008): 201–8. http://dx.doi.org/10.2166/nh.2008.038.

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In the past, to derive the unit hydrograph (UH) various distribution functions have been utilized so far, though they had their own limitations. In this study, the applicability of two-parameter beta distribution has been explored for the derivation of UH. The parameters of the distribution function were estimated using the Genetic Algorithm which facilitates the minimization of global error. The suitability of the derived UH resulting from the two-parameter beta distribution was verified by comparing the UH derived by the two-parameter gamma distribution. The results obtained from both the distributions were almost similar and close to the observed UHs, which confirmed the applicability of the two-parameter beta distribution as an alternate approach for the derivation of the UH.

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Pereira, A. G. C., F. A. S. Sousa, B. B. Andrade, and Viviane Simioli Medeiros Campos. "Higher order Markov Chain Model for Synthetic Generation of Daily Streamflows." TEMA (São Carlos) 19, no. 3 (December 17, 2018): 449. http://dx.doi.org/10.5540/tema.2018.019.03.449.

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The aim of this study is to get further into the two-state Markov chain model for synthetic generation daily streamflows. The model proposed in Aksoy and Bayazit (2000) and Aksoy (2003) is based on a two Markov chains for determining the state of the stream. The ascension curve of the hydrograph is modeled by a two-parameter Gamma probability distribution function and is assumed that a recession curve of the hydrograph follows an exponentially function. In this work, instead of assuming a pre-defined order for the Markov chains involved in the modelling of streamflows, a BIC test is performed to establish the Markov chain order that best fit on the data. The methodology was applied to data from seven Brazilian sites. The model proposed here was better than that one proposed by Aksoy but for two sites which have the lowest time series and are located in the driest regions.

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Balbastre-Soldevila, García-Bartual, and Andrés-Doménech. "A Comparison of Design Storms for Urban Drainage System Applications." Water 11, no. 4 (April 11, 2019): 757. http://dx.doi.org/10.3390/w11040757.

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The present research develops a systematic application of a selected family of 11 well-known design storms, all of them obtained from the same rainfall data sample. Some of them are fully consistent with the intensity–duration–frequency (IDF) curves, while others are built according to typical observed patterns in the historical rainfall series. The employed data series consists on a high-resolution rainfall time series in Valencia (Spain), covering the period from 1990 to 2012. The goal of the research is the systematic comparison of these design storms, paying special attention to some relevant quantitative properties, as the maximum rainfall intensity, the total cumulative rainfall depth or the temporal pattern characterising the synthetic storm. For comparison purposes, storm duration was set to 1 hour and return period equal to 25 years in all cases. The comparison is enhanced by using each of the design storms as rainfall input to a calibrated urban hydrology rainfall–runoff model, yielding to a family of hydrographs for a given neighbourhood of the city of Valencia (Spain). The discussion and conclusions derived from the present research refer to both, the comparison between design storms and the comparison of resulting hydrographs after the application of the mentioned rainfall–runoff model. Seven of the tested design storms yielded to similar overall performance, showing negligible differences in practice. Among them, only Average Variability Method (AVM) and Two Parameter Gamma function (G2P) incorporate in their definition a temporal pattern inferred from empirical patterns identified in the historical rainfall data used herein. The remaining four design storms lead to more significant discrepancies attending both to the rainfall itself and to the resulting hydrograph. Such differences are ~8% concerning estimated discharges.

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Mizukami, N., M. P. Clark, K. Sampson, B. Nijssen, Y. Mao, H. McMillan, R. J. Viger, et al. "mizuRoute version 1: a river network routing tool for a continental domain water resources applications." Geoscientific Model Development Discussions 8, no. 11 (November 2, 2015): 9415–49. http://dx.doi.org/10.5194/gmdd-8-9415-2015.

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Abstract. This paper describes the first version of a stand-alone runoff routing tool, mizuRoute, which post-processes runoff outputs from any distributed hydrologic model or land surface model to produce spatially distributed streamflow at various spatial scales from headwater basins to continental-wide river systems. The tool can utilize both traditional grid-based river network and vector-based river network data, which includes river segment lines and the associated drainage basin polygons. Streamflow estimates at any desired location in the river network can be easily extracted from the output of mizuRoute. The routing process is simulated as two separate steps. The first is hillslope routing, which uses a gamma distribution to construct a unit-hydrograph that represents the transport of runoff from a hillslope to a catchment outlet. The second step is river channel routing, which is performed with one of two routing scheme options: (1) a kinematic wave tracking (KWT) routing procedure; and (2) an impulse response function–unit hydrograph (IRF-UH) routing procedure. The mizuRoute system also includes tools to pre-process spatial river network data. This paper demonstrates mizuRoute's capabilities with spatially distributed streamflow simulations based on river networks from the United States Geological Survey (USGS) Geospatial Fabric (GF) dataset, which contains over 54 000 river segments across the contiguous United States (CONUS). A brief analysis of model parameter sensitivity is also provided. The mizuRoute tool can assist model-based water resources assessments including studies of the impacts of climate change on streamflow.

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Singh, Sushil K. "Errata for “Discussion of Simplified Two-Parameter Gamma Distribution for Derivation of Synthetic Unit Hydrograph” by Sushil K. Singh." Journal of Hydrologic Engineering 11, no. 5 (September 2006): 513. http://dx.doi.org/10.1061/(asce)1084-0699(2006)11:5(513).

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Bahrami, Erfan, Omolbani Mohammadrezapour, Meysam Salarijazi, and Parviz Haghighat Jou. "Effect of Base Flow and Rainfall Excess Separation on Runoff Hydrograph Estimation using Gamma Model (Case Study: Jong Catchment)." KSCE Journal of Civil Engineering 23, no. 3 (January 14, 2019): 1420–26. http://dx.doi.org/10.1007/s12205-019-0591-3.

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Long, A. J. "RRAWFLOW: Rainfall-Response Aquifer and Watershed Flow Model (v1.11)." Geoscientific Model Development Discussions 7, no. 5 (September 9, 2014): 5919–63. http://dx.doi.org/10.5194/gmdd-7-5919-2014.

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Abstract. The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, springflow, groundwater level, solute transport, or cave drip for a measurement point in response to a system input of precipitation, recharge, or solute injection. The RRAWFLOW open-source code is written in the R language and is included in the Supplement to this article along with an example model of springflow. RRAWFLOW includes a time-series process to estimate recharge from precipitation and simulates the response to recharge by convolution; i.e., the unit hydrograph approach. Gamma functions are used for estimation of parametric impulse-response functions (IRFs); a combination of two gamma functions results in a double-peaked IRF. A spline fit to a set of control points is introduced as a new method for estimation of nonparametric IRFs. Other options include the use of user-defined IRFs and different methods to simulate time-variant systems. For many applications, lumped models simulate the system response with equal accuracy to that of distributed models, but moreover, the ease of model construction and calibration of lumped models makes them a good choice for many applications. RRAWFLOW provides professional hydrologists and students with an accessible and versatile tool for lumped-parameter modeling.

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Mizukami, Naoki, Martyn P. Clark, Kevin Sampson, Bart Nijssen, Yixin Mao, Hilary McMillan, Roland J. Viger, et al. "mizuRoute version 1: a river network routing tool for a continental domain water resources applications." Geoscientific Model Development 9, no. 6 (June 23, 2016): 2223–38. http://dx.doi.org/10.5194/gmd-9-2223-2016.

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Abstract. This paper describes the first version of a stand-alone runoff routing tool, mizuRoute. The mizuRoute tool post-processes runoff outputs from any distributed hydrologic model or land surface model to produce spatially distributed streamflow at various spatial scales from headwater basins to continental-wide river systems. The tool can utilize both traditional grid-based river network and vector-based river network data. Both types of river network include river segment lines and the associated drainage basin polygons, but the vector-based river network can represent finer-scale river lines than the grid-based network. Streamflow estimates at any desired location in the river network can be easily extracted from the output of mizuRoute. The routing process is simulated as two separate steps. First, hillslope routing is performed with a gamma-distribution-based unit-hydrograph to transport runoff from a hillslope to a catchment outlet. The second step is river channel routing, which is performed with one of two routing scheme options: (1) a kinematic wave tracking (KWT) routing procedure; and (2) an impulse response function – unit-hydrograph (IRF-UH) routing procedure. The mizuRoute tool also includes scripts (python, NetCDF operators) to pre-process spatial river network data. This paper demonstrates mizuRoute's capabilities to produce spatially distributed streamflow simulations based on river networks from the United States Geological Survey (USGS) Geospatial Fabric (GF) data set in which over 54 000 river segments and their contributing areas are mapped across the contiguous United States (CONUS). A brief analysis of model parameter sensitivity is also provided. The mizuRoute tool can assist model-based water resources assessments including studies of the impacts of climate change on streamflow.

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Long, A. J. "RRAWFLOW: Rainfall-Response Aquifer and Watershed Flow Model (v1.15)." Geoscientific Model Development 8, no. 3 (March 30, 2015): 865–80. http://dx.doi.org/10.5194/gmd-8-865-2015.

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Abstract. The Rainfall-Response Aquifer and Watershed Flow Model (RRAWFLOW) is a lumped-parameter model that simulates streamflow, spring flow, groundwater level, or solute transport for a measurement point in response to a system input of precipitation, recharge, or solute injection. I introduce the first version of RRAWFLOW available for download and public use and describe additional options. The open-source code is written in the R language and is available at http://sd.water.usgs.gov/projects/RRAWFLOW/RRAWFLOW.html along with an example model of streamflow. RRAWFLOW includes a time-series process to estimate recharge from precipitation and simulates the response to recharge by convolution, i.e., the unit-hydrograph approach. Gamma functions are used for estimation of parametric impulse-response functions (IRFs); a combination of two gamma functions results in a double-peaked IRF. A spline fit to a set of control points is introduced as a new method for estimation of nonparametric IRFs. Several options are included to simulate time-variant systems. For many applications, lumped models simulate the system response with equal accuracy to that of distributed models, but moreover, the ease of model construction and calibration of lumped models makes them a good choice for many applications (e.g., estimating missing periods in a hydrologic record). RRAWFLOW provides professional hydrologists and students with an accessible and versatile tool for lumped-parameter modeling.

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Michel, Claude. "Discussion of “Simplified Two-Parameter Gamma Distribution for Derivation of Synthetic Unit Hydrograph” by P. K. Bhunya, S. K. Mishra, and Ronny Berndtsson." Journal of Hydrologic Engineering 10, no. 6 (November 2005): 519–20. http://dx.doi.org/10.1061/(asce)1084-0699(2005)10:6(519).

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Singh, Sushil K. "Discussion of “Simplified Two-Parameter Gamma Distribution for Derivation of Synthetic Unit Hydrograph” by P. K. Bhunya, S. K. Mishra, and Ronny Berndtsson." Journal of Hydrologic Engineering 10, no. 6 (November 2005): 520–21. http://dx.doi.org/10.1061/(asce)1084-0699(2005)10:6(520).

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Bhunya, P. K., S. K. Mishra, and Ronny Berndtsson. "Closure to “Simplified Two-Parameter Gamma Distribution for Derivation of Synthetic Unit Hydrograph” by P. K. Bhunya, S. K. Mishra, and Ronny Berndtsson." Journal of Hydrologic Engineering 10, no. 6 (November 2005): 521–22. http://dx.doi.org/10.1061/(asce)1084-0699(2005)10:6(521).

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Fadila, Shofwatul, and Sentot Purboseno. "Upaya Pengendalian Banjir Kawasan Sub-Das Celeng Pra Pembangunan Embung Imogiri." ETNIK: Jurnal Ekonomi dan Teknik 1, no. 10 (August 20, 2022): 670–81. http://dx.doi.org/10.54543/etnik.v1i10.110.

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Flood on March 17 in the Celeng River, Wukirsari Village, D.I. Yogyakarta became the biggest flood that ever happened on the Bog River. Floods are caused by heavy flow of water from the hills in the Imogiri and Dlingo areas. The Celeng River overflowed and submerged four hamlets in Wukirsari Village, Imogiri District. This study aims to determine flood control efforts in the Celeng sub-watershed area. The research location is in the Kali Celeng sub-watershed, Wukirsari, Imogiri, D.I. Yogyakarta with the control point located in the lower reaches of the Celeng River right at the confluence of the Celeng River and the Oyo River. The hydrological analysis was calculated using the Gamma 1 unit hydrograph method with a return period of 10 years. The maximum flood discharges for each of the Celeng sub-watersheds are 75.73 m3/s, 38.22 m3/s, 37.20 m3/s, 18.54 m3/s, and 21.57 m3/s, and 26.29 m3/s, while the 10-year return flood discharges for the Oyo watershed is 959.60 m3/s. The hydraulic analysis was carried out by modeling the 13.35 km long Celeng River channel with HEC-RAS 4.1 software. The flow simulation is carried out steadily. The simulation results show that during the simulation of the existing state there are several points of the section of the Celeng River that overflow. The overflowing sections are then normalized with certain groove dimensions that are adjusted to the location of the flood point. The results of the flow simulation after normalization show that most of the Celeng River channel can accommodate the flood discharge that occurred. The sections that still overflow after normalization are then given embankments with an average height of 0.75 m.

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Singh, Sushil K. "Transmuting Synthetic Unit Hydrographs into Gamma Distribution." Journal of Hydrologic Engineering 5, no. 4 (October 2000): 380–85. http://dx.doi.org/10.1061/(asce)1084-0699(2000)5:4(380).

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Singh, V. P., and P. K. Chowdhury. "On Fitting Gamma Distrubution to Synthetic Runoff Hydrographs." Hydrology Research 16, no. 3 (June 1, 1985): 177–92. http://dx.doi.org/10.2166/nh.1985.0014.

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Twelve methods of fitting the two-parameter gamma distribution to unit hydrographs are evaluated using experimental data. Five of them are the methods of moments (MOM), cumulants (MOC), maximum likelihood estimation (MLE), least squares (MOLS), and principle of maximum entropy (POME). The remaining seven are based on specification of different point and planar boundary conditions. It is found that of the later seven methods, only one is satisfactory; the other six are inaccurate and should be abandoned for purposes of achieving a mathematical fit. The first five methods are reliable, easier and efficient, and should be preferred.

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Bhunya, P. K., R. Berndtsson, C. S. P. Ojha, and S. K. Mishra. "Suitability of Gamma, Chi-square, Weibull, and Beta distributions as synthetic unit hydrographs." Journal of Hydrology 334, no. 1-2 (February 2007): 28–38. http://dx.doi.org/10.1016/j.jhydrol.2006.09.022.

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HAKTANIR, TEFARUK, and NURULLAH SEZEN. "Suitability of two-parameter gamma and three-parameter beta distributions as synthetic unit hydrographs in Anatolia." Hydrological Sciences Journal 35, no. 2 (April 1990): 167–84. http://dx.doi.org/10.1080/02626669009492416.

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Ciupak, Maurycy, Bogdan Ozga-Zielinski, Jan Adamowski, Ravinesh C. Deo, and Krzysztof Kochanek. "Correcting Satellite Precipitation Data and Assimilating Satellite-Derived Soil Moisture Data to Generate Ensemble Hydrological Forecasts within the HBV Rainfall-Runoff Model." Water 11, no. 10 (October 15, 2019): 2138. http://dx.doi.org/10.3390/w11102138.

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An implementation of bias correction and data assimilation using the ensemble Kalman filter (EnKF) as a procedure, dynamically coupled with the conceptual rainfall-runoff Hydrologiska Byråns Vattenbalansavdelning (HBV) model, was assessed for the hydrological modeling of seasonal hydrographs. The enhanced HBV model generated ensemble hydrographs and an average stream-flow simulation. The proposed approach was developed to examine the possibility of using data (e.g., precipitation and soil moisture) from the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Satellite Application Facility for Support to Operational Hydrology and Water Management (H-SAF), and to explore its usefulness in improving model updating and forecasting. Data from the Sola mountain catchment in southern Poland between 1 January 2008 and 31 July 2014 were used to calibrate the HBV model, while data from 1 August 2014 to 30 April 2015 were used for validation. A bias correction algorithm for a distribution-derived transformation method was developed by exploring generalized exponential (GE) theoretical distributions, along with gamma (GA) and Weibull (WE) distributions for the different data used in this study. When using the ensemble Kalman filter, the stochastically-generated ensemble of the model states generally induced bias in the estimation of non-linear hydrologic processes, thus influencing the accuracy of the Kalman analysis. In order to reduce the bias produced by the assimilation procedure, a post-processing bias correction (BC) procedure was coupled with the ensemble Kalman filter (EnKF), resulting in an ensemble Kalman filter with bias correction (EnKF-BC). The EnKF-BC, dynamically coupled with the HBV model for the assimilation of the satellite soil moisture observations, improved the accuracy of the simulated hydrographs significantly in the summer season, whereas, a positive effect from bias corrected (BC) satellite precipitation, as forcing data, was observed in the winter. Ensemble forecasts generated from the assimilation procedure are shown to be less uncertain. In future studies, the EnKF-BC algorithm proposed in the current study could be applied to a diverse array of practical forecasting problems (e.g., an operational assimilation of snowpack and snow water equivalent in forecasting models).

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Yanmaz, A. Melih, and M. Engin Gunindi. "Assessment of overtopping reliability and benefits of a flood detention dam." Canadian Journal of Civil Engineering 35, no. 10 (October 2008): 1177–82. http://dx.doi.org/10.1139/l08-052.

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There is a growing tendency to assess safety levels of existing dams and to design new dams using probabilistic approaches according to project characteristics and site-specific conditions. This study is a probabilistic assessment of the overtopping reliability of a dam, which will be designed for flood detention purpose, and will compute the benefits that can be gained as a result of the implementation of this dam. In a case study, a bivariate flood frequency analysis was carried out using a five-parameter bivariate gamma distribution. A family of joint return period curves relating the runoff peak discharges to the runoff volumes at the dam site was derived. A number of hydrographs were also obtained under a joint return period of 100 years to observe the variation of overtopping tendency. The maximum reservoir elevation and overtopping reliability were determined by performing a probabilistic reservoir routing based on Monte Carlo simulations.

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Maino, Andrea, Matteo Alberi, Emiliano Anceschi, Enrico Chiarelli, Luca Cicala, Tommaso Colonna, Mario De Cesare, et al. "Airborne Radiometric Surveys and Machine Learning Algorithms for Revealing Soil Texture." Remote Sensing 14, no. 15 (August 8, 2022): 3814. http://dx.doi.org/10.3390/rs14153814.

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Soil texture is key information in agriculture for improving soil knowledge and crop performance, so the accurate mapping of this crucial feature is imperative for rationally planning cultivations and for targeting interventions. We studied the relationship between radioelements and soil texture in the Mezzano Lowland (Italy), a 189 km2 agricultural plain investigated through a dedicated airborne gamma-ray spectroscopy survey. The K and Th abundances were used to retrieve the clay and sand content by means of a multi-approach method. Linear (simple and multiple) and non-linear (machine learning algorithms with deep neural networks) predictive models were trained and tested adopting a 1:50,000 scale soil texture map. The comparison of these approaches highlighted that the non-linear model introduces significant improvements in the prediction of soil texture fractions. The predicted maps of the clay and of the sand content were compared with the regional soil maps. Although the macro-structures were equally present, the airborne gamma-ray data permits us shedding light on finer features. Map areas with higher clay content were coincident with paleo-channels crossing the Mezzano Lowland in Etruscan and Roman periods, confirmed by the hydrographic setting of historical maps and by the geo-morphological features of the study area.

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Saidi, Mohamed El Mehdi, Tarik Saouabe, Abdelhafid El Alaoui El Fels, El Mahdi El Khalki, and Abdessamad Hadri. "Hydro-meteorological characteristics and occurrence probability of extreme flood events in Moroccan High Atlas." Journal of Water and Climate Change 11, S1 (July 23, 2020): 310–21. http://dx.doi.org/10.2166/wcc.2020.069.

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Abstract Flood frequency analysis could be a tool to help decision-makers to size hydraulic structures. To this end, this article aims to compare two analysis methods to see how rare an extreme hydrometeorological event is, and what could be its return period. This event caused many deadly floods in southwestern Morocco. It was the result of unusual atmospheric conditions, characterized by a very low atmospheric pressure off the Moroccan coast and the passage of the jet stream further south. Assessment of frequency and return period of this extreme event is performed in a High Atlas watershed (the Ghdat Wadi) using historical floods. We took into account, on the one hand, flood peak flows and, on the other hand, flood water volumes. Statistically, both parameters are better adjusted respectively to Gamma and Log Normal distributions. However, the peak flow approach underestimates the return period of long-duration hydrographs that do not have a high peak flow, like the 2014 event. The latter is indeed better evaluated, as a rare event, by taking into account the flood water volumes. Therefore, this parameter should not be omitted in the calculation of flood probabilities for watershed management and the sizing of flood protection infrastructure.

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Acanal, Nese. "Snyder-gamma synthetic unit hydrograph." Arabian Journal of Geosciences 14, no. 4 (February 2021). http://dx.doi.org/10.1007/s12517-021-06531-7.

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Sutariya, Prerna. "A Comparative Study on the Derivation of Unit Hydrograph for Dhadhar River Basin." International Journal of Scientific Research in Science, Engineering and Technology, June 20, 2019, 36–43. http://dx.doi.org/10.32628/ijsrset196378.

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Several techniques are available for the development of the unit hydrograph. But most of these traditional methods require manual fitting of the unit hydrograph through few points, which does not guarantee the area under the unit hydrograph to be unity. More over most of the stations are ungauged, due to which it becomes difficult to develop the unit hydrograph. So in order to overcome these problems, two methods have been considered in this study for the development of the unit hydrograph for Dhadhar river basin. They are the “two parameter Gamma distribution” and “three parameter Beta distribution”, both of which are based on Probability Distribution Functions (pdfs). The unit hydrograph developed by the two parameter Gamma distribution match well with the one developed by CWC method, but the unit hydrograph developed by the three parameter Beta distribution does not match well with the one developed by the CWC method. From the unit hydrograph, runoff hydrograph is convoluted for the year 2018. For this the hourly rainfall are generated from daily rainfall values by disaggregation. But on plotting, the simulated discharge hydrograph is found to be greater than the observed discharge. This may be due to non-incorporation of the inflow outflow processes of many hydraulic structures such as dams, irrigation schemes etc., existing in the basin in the model study.

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Tayfur, Gokmen, and Tommaso Moramarco. "Kinematic reverse flood routing in natural rivers using stage data." Applied Water Science 12, no. 8 (June 18, 2022). http://dx.doi.org/10.1007/s13201-022-01707-2.

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AbstractIn many developing countries, due to economic constraints, a single station on a river reach is often equipped to record flow variables. On the other hand, hydrographs at the upstream sections may also be needed for especially assessing flooded areas. The upstream flow hydrograph prediction is called the reverse flood routing. There are some reverse flood routing pocedures requiring sophisticated methods together with substantial data requirements. This study proposes a new reverse flood routing procedure, based upon the simple kinematic wave (KW) equation, requiring only easily measurable downstream stage data. The KW equation is first averaged along a channel length at a fixed time, t, assuming that channel width is spatially constant, and then the spatially averaged equation is averaged in time, Δt. The temporally averaged terms are approximated as the arithmetical mean of the corresponding terms evaluated at time t and t + Δt. The Chezy roughness equation is employed for flow velocity, and the upstream flow stage hydrograph is assumed be described by a two parameter gamma distribution (Pearson Type III). The spatially averaged mean flow depth and lateral flow are related to the downstream flow stage. The resulting routing equation is thus obtained as a function of only downstream flow stage, meaning that the method mainly requires measurements of downstream flow stage data besides the mean values of channel length, channel width, roughness coefficient and bed slope. The optimal values of the parameters of reverse flood routing are obtained using the genetic algorithm. The calibration of the model is accomplished by using the measured downstream hydrographs. The validation is performed by comparing the model-generated upstream hydrographs against the measured upstream hydrographs. The proposed model is applied to generate upstream hydrographs at four different river reaches of Tiber River, located in central Italy. The length of river reaches varied from 20 to 65 km. Several upstream hydrographs at different stations on this river are generated using the developed method and compared with the observed hydrographs. The method predicts the time to peak with less than 5% error and peak rates with less than 10% error in the short river reaches of 20 km and 31 km. It also predicts the time to peak and peak rate in other two brances of 45 km and 65 km with less than 15% error. The method satisfactorily generates upstream hydrographs, with an overall mean absolute error (MAE) of 42 m3/s.

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Bhunya, P. K., R. Berndtsson, P. K. Singh, and P. Hubert. "Comparison between Weibull and gamma distributions to derive synthetic unit hydrograph using Horton ratios." Water Resources Research 44, no. 4 (April 2008). http://dx.doi.org/10.1029/2007wr006031.

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Singh, Sushil K. "Clark's and Espey's unit hydrographsvsthe gamma unit hydrograph / Les hydrogrammes unitaires de Clark et de Espeyvsl'hydrogramme unitaire de forme loi gamma." Hydrological Sciences Journal 50, no. 6 (December 2005). http://dx.doi.org/10.1623/hysj.2005.50.6.1053.

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Filander, Zoleka, Adam N. H. Smith, Hayley C. Cawthra, and Tarron Lamont. "Benthic species patterns in and around the Cape Canyon: A large submarine canyon off the western passive margin of South Africa." Frontiers in Marine Science 9 (November 18, 2022). http://dx.doi.org/10.3389/fmars.2022.1025113.

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Although submarine canyons are internationally recognized as sensitive ecosystems and reported to be biological hotspots, regional studies are required to validate this consensus. To this end, hydrographic and benthic biodiversity data were collected during three cruises (2016-2017) to provide insights on the benthic patterns within South African canyon and non-canyon offshore areas. A total of 25 stations, sampled at 200-1000 m depth range, form the basis of the multivariate analysis. Diversity gradients were calculated and then differences were compared across substrate types and depth zones represented within 12 canyon and 13 non-canyon stations. Significant differences in both substrate and depth were evident, despite measures being highly variable. This observation of varying diversity in different substrates is in line with previous studies. No clear pattern was observed for species diversity (delta+). However, non-canyon stations overall showed a higher diversity in comparison to canyon stations. A notable peak in diversity is observed in canyon areas in the 401-500 m depth zone. Species richness followed an opposing pattern, as it decreased with depth and was consistently higher in canyon areas. These results align with the well-defined influence of depth-related variables on the distribution of taxonomic groups and the substrate available, at various scales. The eutrophic characteristic of the Benguela region may have attributed to the insignificant diversity differences between canyon and non-canyon stations. To assess the benthic species structure in canyon and non-canyon areas, we converted the 108 benthic species into a gamma+ matrix. We then modelled the biological response to predictor variables (substrate and depth). Although the canyon and non-canyon areas have an overlapping species composition, the main effects (canyon vs. non-canyon, depth, and substrate) showed significant differences. Thirteen species were characteristic of canyon areas, whilst only three distinguished non-canyon areas. The region has a long history of anthropogenic activities, so the observed benthic profiles may already be altered. The current study therefore provides the first detailed taxonomic description and analysis of benthic species profiles in the Cape Canyon, and advances important baseline information necessary for understanding the ecological importance of the Cape Canyon.

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Journal articles on the topic 'GAMMA HYDROGRAPH'

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