Instantaneous Unit Sediment Graph Research Articles

Soil Moisture Accounting (SMA) based sediment graph models for small watersheds

The sediment graph models are useful for computation of sediment yield as well as total sediment out flow from watershed. In this study, the analytical development of proposed sediment graph models is based on Soil Moisture Accounting (SMA) procedure coupled Soil Conservation Service-Curve Number (SCS-CN) method, Nash’s Instantaneous Unit Sediment Graph (IUSG)model and Power law. This coupling has led to the development of four sediment graph models (SGMs), i.e., SMA-SGM1, SMA-SGM2, SMA-SGM-3 and SMA-SGM4 depending on the four different hydrologic conditions as: (i) initial soil moisture (V0) = 0 and initial abstraction (Ia) = 0, (ii) initial soil moisture (V0)≠0andinitialabstractionIa=0, (iii) initial soil moisture (V0)=0and(Ia)≠0, and (iv) initial soil moisture (V0)≠0andinitialabstration(Ia)≠0, respectively. These models are applied on six natural watersheds with nineteen storm events having different land use/land cover, climatic condition (arid, semi-arid, humid and sub-tropical), rainfall and land slope conditions. The goodness-of-fit statistics is evaluated in terms of Nash Sutcliffe efficiency (NSE) and relative error (RE) between observed and simulated (calibrated and validated) sediment graphs. Further, the performance of these models is also compared with the sediment graph model of Bhunya et al. (2010) (BSGM) on all the six study watersheds. It is found that the proposed models perform very well in simulating sediment yield generation process for all the watersheds and show significant improvement over the BSGM model.

Special Issue on Soil Erosion and Sediment Yield Modeling

Soil erosion is one of the most serious environmental problems because it removes fertile soil that is rich in nutrients and, in turn, increases the natural level of sedimentation in rivers and reservoirs, reducing their storage capacity and life span. Land degradation stems from a combination of factors related to land use, agricultural intensification, and intense rainstorms. For maintaining and improving soil productivity, soil resources need to be conserved for optimal land use. In other words, to restore the productivity of soil and prevent further damage, planning for conservation and management of watersheds become vital. For assessing soil erosion and sediment yield from watersheds, several empirical models on the basis of geomorphological parameters have been developed and are available in the literature. Among several methods, the sediment yield index (SYI) method and universal soil loss equation (USLE) are extensively used for the estimation of soil erosion and prioritization of watersheds for their treatment. Research in hydrological modeling and related watershed planning issues form a significant component of the prevailing environmental activities. During the last three decades, a number of empirical and conceptual hydrological models have been developed for the prediction of soil erosion and sediment yield modeling. Thus, there is a need to have another look at different aspects of soil erosion and sediment yield modeling and enhance their understanding for improved practical applications. The present special issue of the Journal of Hydrologic Engineering focuses on soil erosion and sediment yield modeling, including the effects of land use/cover changes, extended applications using empirical and physically based soil erosion and sediment yield models, and watershed management coupling remote sensing and the geographic information system (GIS). Within this framework, the papers of this special issue have been grouped into the following: studies on the basis of physically based, conceptual, and empirical models; advancement and review; watershed management; and experimental work. Papers titled “Identification of Critical Erosion Watersheds for Control Management in Data Scarce Condition Using the SWAT Model,” “Use of Caesium-137 Measurements and Long-Term Records of Sediment Load to Calibrate the Sediment Delivery Component of the SEDD Model and Explore Scale Effect: Examples from Southern Italy,” “Application of SWAT Model and Geospatial Techniques for Sediment-Yield Modeling in Ungauged Watersheds,” “Soil Erosion and Sediment-Yield Prediction at Basin Scale in Upstream Watershed of Miyun Reservoir,” “Improved Hillslope Erosion Module for the Digital Yellow-River Model,” and “Evaluation of GIS-Based Watershed Model for Streamflow and Sediment-Yield Simulation in the Upper Baitarani River Basin of Eastern India” fall in the category of physically based soil erosion and sediment yield modeling. Papers titled “Inductive Group Method of Data Handling Neural Network Approach to Model Basin Sediment Yield,” “Modeling Suspended Sediment Using Artificial Neural Networks and TRMM-3B42 Version 7 Rainfall Dataset,” and “Accounting for Conceptual Soil Erosion and Sediment Yield Modeling Uncertainty in the APEX Model Using Bayesian Model Averaging” deal with conceptual modeling for soil erosion and sediment yield. Papers titled “Application of GISCoupled Modified MMF Model to Estimate Sediment Yield on a Watershed Scale,” “Impact of Climate Change on Future Soil Erosion in Different Slope, Land Use, and Soil-Type Conditions in a Part of the Narmada River Basin, India,” and “Spatially Distributed Sheet, Rill, and Ephemeral Gully Erosion” employ empirical models for the estimation of sediment yield. The paper “Sediment Graphs Based on Entropy Theory,” which derives an instantaneous unit sediment graph (IUSG or USG) to determine sediment discharge and establishes a relation between sediment yield and runoff volume, exhibits an advancement in the field of sediment yield modeling. Conversely, the paper “Geographic Variation of USLE/RUSLE Erosivity and Erodibility Factors” provides a comprehensive review on the subject. The papers “Integrated Modeling Approach to the Response of Soil Erosion and Sediment Export to Land-Use Change at the Basin Scale,” “Evaluating the Impact of the Spatial Distribution of Land Management Practices on Water Erosion: Case Study of a Mediterranean Catchment,” and “Sediment Fingerprinting for Calibrating a Soil Erosion and Sediment-Yield Model in Mixed Land-Use Watersheds” deal with watershed management. The papers “Establishing a Soil Loss Threshold for Limiting Rilling,” “Transport Capacity of Overland Flow with High Sediment Concentration,” “Modeling Rainfall Erosivity by Measured Drop-Size Distributions,” “Modeling Rill Erosion at the Sparacia Experimental Area,” “Rapid Weathering and Erosion of Mudstone Induced by Saltwater Migration near a Slope Surface,” and “Rain Microstructure and Erosivity Relationships under Pressurized Rainfall Simulator” are on the basis of experimental work. The aim of this issue is to present high-quality technical articles representing the most recent developments in the field of soil erosion and sediment yield modeling, including practical applications. This special issue is expected to become the first in a sequence of future issues on this topic.

Sediment Graphs Based on Entropy Theory

AbstractUsing the entropy theory, this paper derives an instantaneous unit sediment graph (IUSG or USG) to determine sediment discharge and the relation between sediment yield and runoff volume. The derivation of IUSG requires an expression of the effective sediment erosion intensity whose relation with rainfall is revisited. The entropy theory provides an efficient way to estimate the parameters involved in the derivations. Sediment discharge is also computed using the instantaneous unit hydrograph (IUH), which can also be derived using the entropy theory. This method works as well as the IUSG method, especially when the peak sediment discharge and peak runoff occur at the same time. The entropy theory yields the probability distribution of sediment yield and of sediment discharge, which can then be used to estimate uncertainty in sediment yield prediction.

Recorded lag times of snowmelt events in a small catchment

Recorded lag times of snowmelt events in a small catchment The hydrological and meteorological data collected in small, lowland catchment during snowmelt floods have been used to calculate lag time of runoff (Lag) and lag time of sediment yield (Lags). Both, Lag and Lags are important characteristics of the instantaneous unit hydrograph (IUH) and instantaneous unit sedimentgraph (IUSG). Field data from Zagożdżonka River catchment have been used to demonstrate the relationship between lag times. The results of investigation show that: a) there is a strong relationship between Lag and Lags; b) in most cases the value of a = Lags/Lag is smaller than 1; c) in case of snowmelt floods there was only poor correlation between parameter a and the total runoff depth (water supply).

Estimation of sediment yield during storms based on soil and watershed geomorphology characteristics

Concentrated rainfall usually results in serious soil erosion on steep hillslopes. Since the itinerary of the eroded sediment is complicated, estimating watershed erosion during storms is practically difficult. A physically-based approach for sediment yield estimation during storms was proposed in this study. By using soil and watershed geomorphologic information, analytical solutions for sediment travel time in different orders of overland areas and channels were derived to develop a geomorphologic instantaneous unit sedimentgraph (GIUS) which showed the temporal distribution of sediment discharge resulting from an instantaneous rainfall excess input. The resultant GIUS was a function of the rainfall excess intensity and sediment delivery ratio. The linearity restriction of the unit hydrograph theory was relaxed. Sediment yields during storm events were calculated by convoluting rainfall intensities with the proposed GIUS, which had been verified by using data from the Goodwin Creek Experimental Watershed in Mississippi, the United States. The simulated and the measured sediment yields were in good agreement for the test storms. Sensitivity of the sedimentgraph to the model parameters was also investigated. The proposed model was considered a promising application for sediment yield estimation in the field of water resources design.

A Simple Conceptual Model of Sediment Yield

The sediment graphs (time distribution of sediment yield) are very essential if the sediment transports the pollutants that are toxic at high concentrations, requiring determination of peak, rather than average sediment flow rate. In this paper, an effort has been made to develop a simple conceptual model of sediment yield based on Soil Conservation Service Curve Number (SCS-CN) method, instantaneous unit sediment graph (IUSG) method, and Power law and the performance is tested using real field data of Chaukhutia watershed of Ramganga river catchment (area = 452.25 km2). The proposed model is found to provide realistic estimates of temporal variation of sediment yield as well as total sediment yield during a storm event. The model is found to be most sensitive to parameter β followed by k, $\upalpha$ , A, and ns. A comparison is made with the existing IUSG based models of Kumar and Rastogi (J Hydrol 95:155–163, 1987) and Raghuwanshi et al. (J Hydraul Eng ASCE 120(4):495–503, 1994) for developing sediment graphs.

Conceptual model of sedimentgraph from flood events in a small agricultural watershed

Conceptual model of sedimentgraph from flood events in a small agricultural watershed A procedure for predicting the sediment graph (i.e. the suspended sediment flux), from a small river catchment by heavy rainfall, has been developed using the concept of an instantaneous unit hydrograph (IUH) and dimensionless sediment concentration distribution (DSCD). A formula for instantaneous unit sedimentgraph (IUSG) is presented, and a procedure for estimating the sediment routing coefficient, which is a key parameter of the IUSG, based on measured data of rainfall-runoff-suspended sediment is applied. Field data from a small, field sized agricultural basin, lacated in center of Illinois has been used for analizing lag times for runoff (LAG) and sediment yield (LAGs). Assumptions about sediment generated during rainfall events are discussed.

A sediment graph model based on SCS-CN method

This paper proposes new conceptual sediment graph models based on coupling of popular and extensively used methods, viz., Nash model based instantaneous unit sediment graph (IUSG), soil conservation service curve number (SCS-CN) method, and Power law. These models vary in their complexity and this paper tests their performance using data of the Nagwan watershed (area = 92.46 km 2 ) (India). The sensitivity of total sediment yield and peak sediment flow rate computations to model parameterisation is analysed. The exponent of the Power law, β , is more sensitive than other model parameters. The models are found to have substantial potential for computing sediment graphs (temporal sediment flow rate distribution) as well as total sediment yield.

Tank Model for Sediment Yield

A tank model consisting of three tanks was developed for prediction of runoff and sediment yield. The sediment yield of each tank was computed by multiplying the total sediment yield by the sediment yield coefficients; the yield was obtained by the product of the runoff of each tank and the sediment concentration in the tank. The sediment concentration of the first tank was computed from its storage and the sediment concentration distribution (SCD); the sediment concentration of the next lower tank was obtained by its storage and the sediment infiltration of the upper tank; and so on. The SCD, caused by the incremental source runoff (or the effective rainfall), was obtained by the theory of the instantaneous unit sediment graph (IUSG) and a sediment routing function. Using the SCD, the sediment yield was computed from the tank model as well as by the IUSG model. The sediment yield obtained from the tank model was then compared with that from the IUSG model. Finally, the tank model was verified on an upland watershed in northwestern Mississippi.

Prediction of sediment yield by coupling Kalman filter with instantaneous unit sediment graph

An instantaneous unit sediment graph (IUSG) model in conjunction with Kalman filter was investigated for prediction of sediment yield from an upland watershed in Northwestern Mississippi. The state vector of the watershed sediment yield system was constituted by the IUSG and then the sediment yield was estimated by the IUSG model using Kalman filter. The initial values of the state vector were assumed as the average of the IUSG values and the initial sediment yield estimated from the average IUSG. The IUSG model using Kalman filter with a recursive algorithm accurately predicted sediment yield from watershed W-5, Mississippi. The filter allowed the IUSG to vary in time, increased the accuracy of the IUSG model, and reduced physical uncertainty of the sediment yield process in the watershed. Copyright © 1999 John Wiley & Sons, Ltd.

Prediction of sediment yield by coupling Kalman filter with instantaneous unit sediment graph

Prediction of sediment yield by coupling Kalman filter with instantaneous unit sediment graph

Predicting Sedimentgraphs for a Small Agricultural Catchment

The key components of a sedimentgraph prediction procedure for small agricultural catchments are outlined in the paper. An instantaneous unit sedimentgraph (IUSG) based on the IUH and on a dimensionless sediment concentration distribution is developed, and used for transforming the sediment produced during a specified rainfall duration into a sedimentgraph. Rainfall-runoff-suspended sediment transport data from the River Dart basin, in Devon, UK, are used to evaluate several relationships for sediment yield estimation. The relationship between the lag time of the direct runoff hydrograph and the sedimentgraph is analysed, and the use of these lag times for estimating an IUSG (sediment routing) parameter is examined. The effectiveness of the proposed sedimentgraph prediction procedure is demonstrated by the successful regeneration of a measured sedimentgraph.

Modelling sediment transport in stream channels in the arid zone of India

AbstractEphemeral channels in arid regions convey larger amounts of sediment than perennial channels in humid regions. Sediment graphs at the outlet of channels have been derived by the standard sediment rating curve technique and by a lumped model based on the instantaneous unit sediment graph (IUSG) concept. The IUSG gives estimates of sediment transport that are better than those derived with the sediment rating curve as it takes into account the availability of erodible material within the channel bed.

Instantaneous‐Unit Sediment Graph

A model for an instantaneous‐unit sediment graph (IUSG), based on attenuation and translation functions of mobilized sediment has been developed and applied to a Chaukhutia watershed (452.25 km2) of the Ramganga reservoir catchment in Northern India. An IUSG is a sediment graph resulting from one cm of mobilized sediment generated uniformly over the basin area during the effective rainfall of infinitesimally small duration. The catchment representative IUSG was converted into a unit sediment graph and convolved with mobilized sediment for generation and prediction of sediment graphs. The predicted sediment graphs showed good agreement with their observed counterparts except for lower peak sediment‐flow rates. The changes in hydrologic regime of catchment due to adoption of conservation measures are mainly reflected by the attenuation of crest segments and peak sediment flow rates of IUSGs for the successive years 1976–77 through 1983–84.

Modelling suspended sediment flow in arid upland basins

Abstract A conceptual basin model of the instantaneous unit sediment graph was developed for sediment graph prediction from arid upland basins by routing mobilized sediments through a series of linear reservoirs. The sediment graphs generated by convolution of the instantaneous unit sediment graph compared reasonably well with the observed ones for four representative arid upland sub-basins in the Luni basin, India. The mobilized sediment during a storm was related to effective precipitation and the parameters of the model were estimated from observed events. The model can be applied to ungauged flow events through parameterization.

DEVELOPMENT OF A CONCEPTUAL SEDIMENT GRAPH MODEL

ABSTRACT A conceptual model of an instantaneous unit sediment graph for the prediction of suspended sediment has been developed by using the concepts of time area diagram. For the model development, the required parameter of sediment storage constant is determined through a method of trial and error. Empirical relationships based on the watershed parameters have also been generated to determine sediment storage constant. The developed model has been used to study changes in basin characteristics of the watershed due to various soil conservation measures practiced in it, and to predict sediment graphs with rainfall data as input.

A conceptual catchment model for estimating suspended sediment flow

A conceptual catchment model of the instantaneous unit sediment graph was developed for sediment graph prediction and to determine the effect of soil conservation measures on sediment flow for a mountainous watershed by routing mobilized sediment through a series of linear reservoirs. The sediment graphs generated by convolution of the instantaneous unit sediment graph with mobilized sediment were compared with the natural observed ones on the Chaukhutia watershed comprising an area of 452km 2 of the Ramganga reservoir catchment. The mobilized sediment during a storm was related to rainfall excess and the parameters of the model were estimated utilizing fourteen sediment events observed during the years 1976–84.

A sediment graph model based on an instantaneous unit sediment graph

A model was developed for predicting sediment graphs from agricultural watersheds. Storm sediment graphs are predicted by convolving source runoff with an instantaneous unit sediment graph (IUSG). The IUSG is the distribution of sediment from an instantaneous burst of rainfall producing one unit of runoff. The IUSG is the product of an instantaneous unit hydrograph and the sediment concentration distribution. Initial sediment concentration of the IUSG is assumed to vary linearly with source runoff volume. A sediment‐routing function, based on travel time and sediment particle size, is used to predict the sediment concentration distribution. Tests with 50 storms from five watersheds showed that the model is applicable to agricultural watersheds in the Texas blacklands. It should be useful in designing reservoirs or in waterquality‐modeling problems.