Estimating river sediment delivery is one of the important issues for researchers in hydrological studies because of its complexity. In a river that has sediment data in a few days per month, estimating of river sediment delivery is carried out by using sediment rating curve method. In this study in order to exactly estimation for such rivers, a new approach has been developed which it can be called as "Discharge-Sediment Relative Approach (DSRA) ". It is developed based on expanding sediment concentration continuity curve based on individual sediment concentration data in a few days of each month. In this method, the fluctuation of sediment concentration between two continuous measurements is reconstructed based on the ratio of the measured sediment concentration and water discharge. In this paper the DSRA method has been applied to estimate of Dez river sediment delivery as a case study. Also the amount of sediment inflow to Dez reservoir were calculated by using the USBR rating curve method. Comparison of calculated results with measured data obtained from Dez reservoir bathymetry showed that errors of the DSRA method to estimate of the annual sediment inflow to Dez reservoir was obtained as 8.5% while this value for USBR rating curve method was about 27%. This means that the DSRA Method could be considered as a good approach to estimate of river sediment delivery for gauged basins.

Extended AbstractBackground and ObjectivesFlood is a natural disaster that causes a lot of damage in different parts of the world every year, because it has caused a lot of financial and human losses in many countries. One of the main problems of floods is soil erosion and the production of sediments that are transported along the river during the flood and destroy the buildings on the banks of the river, reduce the capacity of canals and reservoirs of dams, and damage agricultural lands. Since the amount of sediment in a river is a random variable that is a function of several correlated random characteristics such as flow rate, suspended load and bed. Therefore, estimation of sediment load based on univariate probabilistic analysis is not a reliable criterion. For this reason, multivariate analyzes are of special importance. The bivariate behavior of the flood discharge and the resulting sediment load depends on their joint cumulative distribution function, which can be implemented with the help of copula functions. Since hydrological variables are multidimensional and copula functions allow multidimensional analysis of variables and give us more information about hydrological processes. Therefore, the use of copula functions can be an important step in promoting hydrological research. Based on this, the aim of the current research is to investigate the two-variable behavior of flood discharge and sediment load using copula functions and to analyze the frequency of both variables in the Minab watershed.MethodologyIn this study, Archimedean and elliptical copula functions were used as a tool for bivariate analysis of flood (Qw) and sediment discharge (Qs). First, marginal distribution functions were fitted on flood (Qw) and sediment discharge (Qs) variables. Then, using conventional correlation methods such as spearman, Pearson and Kendal tau, the correlation between the variables was checked. In the next step, elliptic copula (T-Student and Gaussian) and Archimedean (Frank, Joy, Clayton, Gamble) functions were fitted to the variables based on the maximum likelihood method, and the best fitted function was the two variables of flood discharge and sediment. The copula was normal. After the coupling of the variables, the single and double return period of 2 to 1000 years in "AND" and "OR" mode and in conditional modes with scenarios T(Qf/Qs<=qs) and T(Qf/Qs>=qs) It was calculated and finally two-variable return period analysis was done based on return period tables and graphs.FindingsThe results of the correlation test showed that there is a positive and significant relationship between the investigated variables in the study area. Based on the results of Chi-plot and Kendall-plot, there is an acceptable correlation between the two investigated variables. The results of the copula fit showed that the normal copula has an acceptable performance on the investigated variables. Examining the return period of flood discharge and sediment discharge showed that the changes in sediment discharge are far greater than the changes in flood discharge in higher return periods, so that with the increase in the return period, the amount of flood discharge increases exponentially. The AND scenario gives much higher values than the return period of OR and is a suitable tool for risk analysis of hydrological events. Also, among the conditional scenarios, the scenario T(Qf/Qs>=qs) showed greater values of the return period than T(Qf/Qs<=qs). Finally, the risk analysis in the studied area showed that the risk of flooding and sedimentation in the two-year return period with the AND and OR scenarios is without risk, but for the two conditional cases, it has a low risk. Or in the 20-year return period, the risk of the 50-year project for all scenarios except the OR scenario and the rest of the scenarios have predicted critical conditions.ConclusionThe results of the return period analysis showed that in the case of "AND" return period, the return period values are much larger than the "OR" values. In the same way, it has a higher risk. Also, considering the conditional scenarios were also significantly different. Therefore, ignoring the correlation between flood discharge and sediment may significantly overestimate or underestimate the actual amount of sediment, as a result of which the probability of the corresponding occurrence increases or decreases. Therefore, depending on the purpose and needs in the region, the following scenarios can be used.

In this research it is attempted to optimize relations between flow discharge and suspended sediment discharge in selected hydrometric stations located on the main branch of Gorganroud River. Homogeneity of data was initially tested using Smirnov-Kolmogrov technique. Then, using daily discharge data and employing "Technical Hydrology" software, monthly hydrographs of the discharge were drawn for all selected stations. Considering hydro-climatic factors that affect the suspended sediment discharge, such as hydrograph condition, classified discharge, and time, some models were tested on the basis of the sediment transport equation. Some regression models were obtained between flow and suspended sediment discharge, and values of “a” and “b” parameters were then resulted for each parts of the model. To select the optimum model, mean squares of errors were used as an index according to which models with low values of mean squares of errors were selected as optimum ones for each station. Results indicated that general regression model which uses only one equation as sediment rating curve equation bears the highest error among all tested models for estimating suspended sediment. So, it is recommended to employ the models with low errors for estimating sediment discharge in the study area.

Extended Abstract Background: Large-scale and regional planning requires observed data on environmental variables, such as runoff and suspended sediment load from watersheds. Data is fundamental for generating information and knowledge, and scientific management of a system is impossible without a monitoring and measurement plan. Management of watershed systems and water resources is no exception to this axiom. With ongoing trends in socioeconomic development, climate change, increasing pressure on natural resources and watersheds, and, consequently, an increase in floods and sediment yield, there will be a greater need for more accurate information about sediment and runoff processes in the near future. Many tools and instruments for measuring runoff and sediment components have been produced and marketed by a number of foreign companies. However, their cost is very high in Iran, on the one hand, and a device that measures both components at once is very rare, on the other hand. To carry out simulations that are both accurate and efficient, it is essential to have access to sufficient and reliable data and information for verification and validation purposes. In the field of water resources and watershed management, data and information are considered to be crucial tools. By providing important insights into the management of water resources, the availability of data and information can help enhance the efficiency and optimization of water usage, prevent natural hazards (such as floods and droughts), manage water quality, and improve the management of water supply and demand. Therefore, this study aimed to design and construct an automated flood and sediment load-monitoring device with the ability to record the runoff height of watersheds and a planned sampling of runoff for measuring suspended sediment using cheap sensors and tools. Methods: This study presents an innovative device designed to monitor runoff discharge and suspended sediment sampling. The device has been constructed and installed at the outlet of the sub-basin under study. A regular cross-section was constructed at the outlet to facilitate the installation of the device, which enabled the monitoring of the runoff hydrograph of the sub-basin outlet and suspended sediment load sampling. In this research, analog hygrometer sensors were used to measure the height of runoff with 3 cm intervals (measurement accuracy of 3 cm). DC pumps with valves were used to collect the sediment sample, which created a vacuum in the sampling container and caused the runoff sample to be transferred into the container. To evaluate the device's capabilities in real and natural conditions, it was installed at the outlet of a sub-watershed in the eastern loess lands of Golestan province, located upstream of Qapan Oliya village in the Kalaleh district for two years to record the hydrograph of likely flood events and take runoff samples at the user-defined depths of flood (two samples at depths of 20 and 60 cm in rising limb and one sample at a depth of 20 cm in recession limb of hydrographs). The samples were stored in 0.5 liter containers, and the user was informed by sending an SMS to replace the filled containers with empty ones. It is noteworthy that the device under consideration facilitates the collection of runoff samples at any frequency and at any height for research requirements. The device boasts a remarkable advantage in the form of its SMS notification feature, which keeps the user informed about the monitoring site and equipment status, including runoff sampling, power outages, and battery status. The device incorporates a built-in battery that remains active during power outages in the electricity network to record flood events. Additionally, the user can communicate with the device via a mobile phone at any time and receive SMS updates on the device's operating status, such as power, battery, memory level, and event registration. Furthermore, to ensure accurate rainfall data recording, a WatchDog tipping bucket rain gauge has been installed within the studied sub-basin. Results: During these two years, only three rainfall events leading to runoff and flooding occurred in this sub-watershed, and the designed device successfully recorded the hydrograph of all three events and informed the user. In each of these recorded flood events, at least two runoff samples (one sample in the rising limb and one sample in the recession limb of the hydrograph) were collected and stored by the device to be transferred to the laboratory to determine the suspended load. The present study has demonstrated that the automated runoff and sediment monitoring device, which has been specifically designed to measure a range of parameters such as flow rate, water level, and suspended sediment load, represents a valuable and practical tool for those seeking to monitor runoff and sediment at the outlet of watersheds. Conclusion: Data and information play a vital role in water resources and watershed management. The availability of such data and information in the management of watersheds and water resources helps enhance water use optimization and efficiency, prevent natural disasters such as floods and droughts, manage water quality, and improve water supply and demand management. Therefore, the prototype of the designed device shows that this device has a good capability for the industrial production of an inexpensive runoff and sediment monitoring tool to scientifically manage small-scale watersheds.

The transport of sediment in rivers is a crucial aspect of hydraulic engineering and environmental management. This study focuses on suspended sediment transport in the Balaroud River, a significant tributary of the Dez River in northern Khuzestan Province, Iran. We evaluated various sediment transport equations, including those by Rouse (1937), Lane & Kalinske (1941), Brooks (1958), Bagnold (1966), and Yang (1996), to determine the most accurate model for estimating suspended sediment load in this river. Data spanning from 2007 to 2020, collected from the Khuzestan Water and Power Authority (KWPA), were analyzed to compare these models against measured sediment loads. The Rouse method proved to be the most reliable, achieving approximately 80% accuracy in estimating suspended sediment load. The modified Yang equation followed with about 60% accuracy, while accuracy for Brooks' method was around 49%. Conversely, the Bagnold (1966) and Lane & Kalinske (1941) models demonstrated significantly lower accuracies of 21% and 12%, respectively. The study reveals that Rouse and Yang equations align better with the Balaroud River's conditions, marked by its sandy substrate and the influence of the Balaroud dam on flow dynamics. The findings underscore critical discrepancies among the evaluated equations and the necessity for case-specific assessments to enhance sediment transport predictions. This research highlights the importance of selecting models tailored to the unique characteristics of each river system for effective sediment management and environmental conservation. Recommendations include prioritizing the Rouse equation for similar rivers and pursuing further research to develop models suited to diverse sediment transport dynamics.

The correct prediction of effective factors in water resource projects is one of the most important problems of water recourse engineers. Suspended sediment volume carried by rivers is one of these important factors due to its negative issues in water quality, reservoirs capacity and river morphology. In fact deriving a proper method for sediment volume estimation can be one of the most important problems in erosion and sedimentation process. Although During recent decades, some black box models based on artificial neural networks (ANN), have been developed to overcome this problem and those accuracy privilege to empirical relations such as sediment rating curves have been shown, But these type of models are implicit that can not be simply used by other investigators. Therefore it is still necessary to develop an explicit model for the discharge–sediment relationship. It is aimed in this study, to develop an explicit model based on genetic programming (GP). Explicit models obtained using the GP are compared with artificial neural network technique in suspended sediment load estimation. The daily stream flow and suspended sediment data from one station on Lighvan River in Orumieh lake basin are used as a case study. The results indicate that the proposed GP method performs quite well compared to artificial neural network models and is quite practical for use.

Suspended sediment transport by rivers is important in water quality of cities and villages fed by certain drainage basins. Therefore determination of effective discharge and its characteristics, which carries the highest amount of sediment in long term, is very important. To determine characteristics of effective discharge, probability density function for water discharge is calculated based on daily discharge data and by multiplying coefficients of sediment rating curves by probability density function, sediment density function is drawn. Then, its return period is calculated by statistical analysis of maximum instantaneous discharge. In this research, the above-mentioned method was employed for six headwater streams of Gorgan Drainage basin, using statistical data of suspended sediment records in the past 13 to 16 years in regions with areas between 13 and 165.5 km2. The results have shown that suspended sediment of effective discharge of the stations is between 0.11 to 75.4 (m3s-1), their average frequencies between 0.07 to 16.5 days per year and their return period ranges from 0.96 to 2.07 with of average 1.45 years. The amount of sediment transported by effective discharge is higher than the amount of sediment transported by other discharges, and varies by 3.7 to 15 percent as compared to yearly-suspended sediment. Furthermore, comparing different stations in terms of specific suspended sediment of effective discharge, it has been shown that Nomal and Pasposhte hydrometric stations have the lowest and largest amounts, respectively. Generally, effective discharge for suspended sediment occurs every year or every two years and carries the highest amount of sediment in subcatchments as compared to other discharges.

Concentrations of eight metals namely, Cr, Mn, Fe, Co, Ni, Cu, Zn and Pb were examined in the surface sediments of discharge channels of six industries in Lagos using x-ray fluorescence spectrometry. These channels drain into the Isolo Canal which empties into the Lagos Lagoon and eventually into the Atlantic Ocean. This study was conducted to detect any contamination levels within the sediments and possibly determine their sources. Sediment samples were collected over a period of six months. The results provided evidence of large differences in total metal concentrations in the sediment samples from the six industrial sites. Box plots of the average absolute deviation from median emphasized that metal concentrations were not homogeneously distributed similarly, calculation of the F ratio confirmed location effect on the concentration of the various metals investigated. The trace metals Cr, Mn, Co, Ni and Cu might be entirely from crustal materials or natural weathering processes whilea significant amount of Zn and Pb are from anthropogenic sources.