Mir Jafar Sadegh Safari

Yasar University · Civil Engineering

Self-cleansing is a design criterion for drainage systems which mitigates the continuous deposition of sediments at the channel bottom. In recent decades, in order to improve the knowledge for determination of self-cleansing conditions applicable for drainage system design, laboratory experimental studies on sediment transport in rigid boundary cha...

In this study, Regression in the Reproducing Kernel Hilbert Space (RRKHS) technique which is a non-linear regression approach formulated in the reproducing kernel Hilbert space (RRKHS) is applied for rainfall-runoff (R-R) modeling for the first time. The RRKHS approach is commonly applied when the data to be modeled is highly non-linear, and conseq...

It has been known that the channel cross-section shape impacts on flow velocity at sediment deposition condition; however, existing models only apply to specific cross-section shapes and there has been a lack of a general incipient deposition model applicable for all types of cross-section shapes. To this end, this study is designed to generalize i...

Self-cleansing is a hydraulic design concept for drainage systems for mitigation of sediment deposition. Experimental studies in the literature have mostly been performed in circular channels. In this study, experiments were conducted in five cross-section channels: trapezoidal, rectangular, circular , U-shape and V-bottom to investigate the non-de...

Multiple kernel fusion (MKF) refers to the task of combining multiple sources of information in the Hilbert space for improved performance. Very often the combined kernel is formed as a linear composition of multiple base kernels where the combination weights are learned from the data. As the first application of an MKF approach in hydrological mod...

A joint determination of horizontal and vertical movement of water through porous medium is addressed in this study through fast multi-output relevance vector regression (FMRVR). To do this, an experimental data set conducted in a sand box with 300 × 300 × 150 mm dimensions made of Plexiglas is used. A random mixture of sand having size of 0.5-1 mm...

Sediment transport modeling is an important problem to minimize sedimentation in open channels that could lead to unexpected operation expenses. From an engineering perspective, the development of accurate models based on effective variables involved for flow velocity computation could provide a reliable solution in channel design. Furthermore, val...

Kıyı alanları toplumlar için ekonomik, tarımsal ve kültürel anlamda yerleşim alanı olarak her zaman tercih edilmiş yerlerdir. Bu nedenlerle kıyı bölgeleri doğal ya da beşerî faktörler sebebiyle sıklıkla tahribata uğrayan bölgelerdir. Kıyı alanlarının ekosisteminin bozulması pek çok hayvan ve bitkinin doğal yaşam alanlarının yok olmasına, çeşitliliğ...

Sediment transport is a noteworthy task in the design and operation of sewer pipes. Decreasing sewer pipe hydraulic capacity and transport of pollution are the main consequences of continuous sedimentation. Among different design approaches, the non-deposition with deposited bed (NDB) method can be used for the design of large sewer pipes; however,...

For various reasons, it is not always possible to obtain adequate and reliable long-term streamflow records in a river basin. It is known that streamflow records are even shorter when the stations located on tributary channels are of the interest. Hence, it is necessary to develop dependable streamflow estimation models for the tributary streams th...

The trend analysis of annual temperature (daily average) and total precipitation has been conducted for 14 stations located in the Aegean Region, Turkey. The Sen, Spearman's rho, and Mann-Kendall test methods are used in the detection of the historical trends in the region. The Pettitt test is also implemented to find the significance of the trend,...

Suspended sediment load modeling through advanced computational algorithms is of major importance and a challenging topic for developing highly accurate hydrological models. To model the suspended sediment load in the Rampur watershed station in the Mahanadi River Basin, Chhattisgarh State, India, unique integrated computational intelligence regres...

The effects of climate change on the water resources of the Aegean Region in Turkey are investigated through trend analysis of yearly temperature (daily average) and total precipitation time series data gathered from 3 stations (Izmir, Seferihisar, Cesme) in the research region. The techniques of Sen, Mann-Kendall, and Spearman's rho test are emplo...

As a complex hydrological problem, rainfall-runoff (RR) modeling is of importance in runoff studies, water supply, irrigation issues, and environmental management. Among the variety of approaches for RR modeling, conceptual approaches use physical concepts and are appropriate methods for representation of the physics of the problem while may fail i...

Drought indices are commonly used to monitor the duration and severity of droughts. In this regard, the continuously changing climate regardless of its cause or effect pushes the limit of the water deficit through time and space. Izmir is a raising city in Turkey, which owns various water resources including but not limited to seashores, lakes, riv...

Abrupt changes in the Lake Urmia water level have been addressed in many studies, and yet the link between the water level decline and hydro-meteorological variables in the basin is a major topic for debate between researchers. In this study, a set of data-driven techniques are used to investigate the components of the water budget in Lake Urmia. T...

This study addresses the link between suspended sediment concentration, precipitation, streamflow, and direct runoff components. This is important since suspended sediment concentration in the streamflow has invaluable importance in the management of the river basin. For this, the daily streamflow time series in five consecutive stations at Upper R...

Sediment incipient motion is one of the main aspects of the sediment transport hydraulics. Determination of the flow condition where sediment particles start to move from the channel bottom is of importance for channel design practice to prevent continues deposition of the sediment in drainage channels. Sediment incipient motion relationships exist...

Fast multi-output relevance vector regression (FMRVR) algorithm is developed for simultaneous estimation of groundwater and lake water depth for the first time in this study. The FMRVR is a multi-output regression analysis technique which can simultaneously predict multiple outputs for a multi-dimensional input. The data used in this study is colle...

Labyrinth weirs are utilized to transport a greater discharge during floods in contrast to conventional weirs due to their increased weir crest length. Nevertheless, due to the increased geometric complexity of labyrinth weirs, determination of accurate discharge coefficients and accordingly, head-discharge ratings are quite essential issues in pra...

Soil moisture (SM) is of paramount importance in irrigation scheduling, infiltration, runoff, and agricultural drought monitoring. This work aimed at evaluating the performance of the classical ANFIS (Adaptive Neuro-Fuzzy Inference System) model as well as ANFIS coupled with three bio-inspired metaheuristic optimization methods including whale opti...

State-of-the-art random forest (RF) models have been documented as versatile tools to solve regression and classification problems in hydrology. They can model stochastic time series by bagging different decision trees. This article introduces a new hybrid RF model that increases the forecasting accuracy of RF-based models. The new model, called GA...

This paper analyses experimental data on sediment incipient motion with varying sediment bed thickness (of d50, 5, 10 and 24 mm). Sediment particles (with sizes ranging from 0.5 mm to 4.78 mm) were used to evaluate the effect of deposited bed. Variation of shear velocity estimation was investigated where the critical Shields parameter was expressed...

The world's water resources are decreasing day by day due to factors such as climate change, drought, inefficient pricing policies implemented by the government, population growth, uncontrolled water consumption, technological developments, and industrialization. A decrease in water resources causes water scarcity in the long-term period. This stud...

Water is an invaluable substance of which ensures the life cycle and hydrological events across the world. In this respect, water deficit also known as drought is a natural disaster related to water scarcity in time and space. Although there is no solid definition for the phenomenon, the outcome of repeated wet and dry spells cause in economic, soc...

Droughts are one of the major concerns associated with agro-food and socio-economical security in the World. The continuously changing climate regardless of its cause and effect pushes the limit of the water deficit to the limits. Izmir is a raising city of Turkey that owns various water resources including but not limited to seashores, lakes, rive...

Water is an invaluable substance of which ensures the life cycle and hydrological events across the world. In this respect, water deficit also known as drought is a natural disaster-related to water scarcity in time and space. Although there is no solid definition for the phenomenon, the outcome of repeated wet and dry spells cause economic, social...

Owing to the nonlinear and non-stationary nature of the suspended sediment transport in rivers, suspended sediment concentration (SSC) modeling is a challenging task in environmental engineering. Investigation of SSC is of paramount importance in river morphology and hydraulic structures operation. To this end, for SSC modeling, first random forest...

The investigation of sediment transport in tropical rivers is essential for planning effective integrated river basin management to predict the changes in rivers. The characteristics of rivers and sediment in the tropical region are different compared to the those of the rivers in Europe and the United States, where the median sediment size tends t...

Lake water level changes are relatively sensitive to the climate-born events that rely on numerous phenomena, e.g., surface soil type, adjacent groundwater discharge, and hydrogeological situations. By incorporating the streamflow, groundwater, evaporation, and precipitation parameters into the models, Urmia lake water depth is simulated in the cur...

To reduce the problem of sedimentation in open channels, calculating flow velocity is critical. Undesirable operating costs arise due to sedimentation problems. To overcome these problems , the development of machine learning based models may provide reliable results. Recently, numerous studies have been conducted to model sediment transport in non...

Sediment transport modeling is of primary importance for the determination of channel design velocity in lined channels. This study proposes to model sediment transport in open channel flow using kernel ridge regression (KRR), a nonlinear regression technique formulated in the reproducing kernel Hilbert space. While the naïve kernel regression appr...

Scour depth prediction and its prevention is one of the most important issues in channel and waterway design. However the potential for machine learning algorithms to provide models of scour depth has yet to be explored. This study provides the first quantification of the predictive power of a range of standalone and hybrid machine learning models....

Drought is one of the most important phenomena related to the agriculture-food and socioeconomic problems all over the world. The Aegean region has a variety of water resources, including but not limited to seacoasts, lakes, streams, and groundwater aquifers. For this reason, the evaluation of historical and future drought events and their effects...

Labyrinth weirs are utilized to increase the weir crest length to transport a greater discharge during floods in contrast to conventional weirs. Nevertheless, due to the increased geometric complexity of labyrinth weirs, determination of accurate discharge coefficients and accordingly, head-discharge ratings are quite essential issues in practical...

This study presents developing procedures and verification of a new hybrid model, namely wavelet packet-genetic programming (WPGP) for short-term meteorological drought forecast. To this end, the multi-temporal standardized precipitation evapotranspiration index (SPEI) has been used as the drought quantifying parameter at two meteorological station...

A novel method is suggested for the determination of flow discharge in vertical sluice gates with considerably small bias. First, in order to derive an equation for the discharge coefficient, energy-momentum equations are implemented to define the physical realization of the phenomenon. Afterward, the discharge coefficient is presented in terms of...

Sediment transport modeling has been known as an essential issue and challenging task in water resources and environmental engineering. In order to minimize the adverse impacts of the continues sediment deposition that is known as a main source of pollution in the urban area, the self-cleansing method is widely utilized for designing the sewer pipe...

This study addresses the application of signal processing in the evaluation of meteorological drought associated with monthly precipitation time series. Several drought indices and a Haar wavelet decomposition (WD) with ten components are implemented in the evaluation of the monthly precipitation of a mountainous region called Mount Uludag in Turke...

In this closure, we respond to the comments of Ebtehaj et al. (2020), and show why our approach and models are suitable for our study. We also provide additional details regarding several features of our study.

Suspended sediment load is a substantial portion of the total sediment load in rivers and plays a vital role in determination of the service life of the downstream dam. To this end, estimation models are needed to compute suspended sediment load in rivers. The application of artificial intelligence (AI) techniques has become popular in water resour...

River suspended sediment load (SSL) estimation is of importance in water resources engineering and hydrological modeling. In this study, a novel hybrid approach is recommended for SSL estimation in which multi-layer perceptron (MLP) is hybridized with particle swarm optimization (PSO) and then, integrated with differential evolution algorithm (DE)...

Excavation on the inclined surfaces on the dam reservoir and rising water level may also affect the slope stability of the inclined surfaces in the dam reservoir under static and dynamic conditions. In this study, it is aimed to present a three-dimensional (3D) model to analyze slope stability of access road to the dam’s crest and calculates the va...

The application of a robust learning technique is inevitable in the development of a self-cleansing sediment transport model. This study addresses this problem and advocates the use of sparse kernel regression (SKR) technique to design a self-cleaning model. The SKR approach is a regression technique operating in the kernel space which also benefit...

The state-of-the-art genetic programming (GP) has received a great deal of attention over the past few decades and has been applied to many research areas of water resources engineering, including prediction of hydrometeorological variables, design of hydraulic structures, and recognition of hidden patterns in hydrological phenomena such as rainfal...

Inasmuch as channels are designed to mitigate continues sedimentation, sediment transport models have been developed to calculate flow velocity to keep sediment particles in motion. In order to promote the computation capability of sediment transport models, recently machine learning algorithms have attracted interests, extensively. However, accura...

Wind speed data are of particular importance in the design and management of wind power projects. In the current study, three types of linear time series models including autoregressive (AR), moving average (MA), and autoregressive moving average (ARMA) were employed to estimate short-term (i.e., daily) and long-term (i.e., monthly) wind speeds. Th...

Sedimentation in sewer networks is a major problem in urban hydrology. In comparison to the well-known classic sediment transport models, this study investigates the capabilities of soft computing methods, including multigene genetic programming (MGGP), gene expression programming, and multilayer perceptron to derive accurate sewer design models. A...

Assimilating unique features of genetic programming (GP) and gene expression programming (GEP), this study introduces a hybrid algorithm which results in promising incipient non-cohesive sediment motion models. The new models use the dimensionless input parameters including relative particle size, relative deposited bed thickness, channel friction...

Recently, as an alternative method for monitoring of drainage systems, Internet of Things (IoT) technology is initiated in smart cities. IoT is used for detection of the location of the sediment deposition within the drainage pipe system to alert for repairing before complete blocking. However, from the hydraulic point of view, it is reasonable to...

Mitigation of sediment deposition in lined open channels is an essential issue in hydraulic engineering practice. Hence, the limiting velocity to keep the channel bottom clean from sediment deposits should be determined and expressed equation in all form. Recently, sediment transport modeling using various artificial intelligence (AI) techniques ha...

The standardized precipitation evapotranspiration index (SPEI) at three different time scales (i.e., SPEI-3, SPEI-6, and SPEI-12) from six meteorology stations located in Turkey are modeled in this study. To this end, two types of classic time series models, namely linear autoregressive (AR) and non-linear bi-linear (BL) are used. Furthermore, the...

Estimation of soil temperature (ST) as one of the vital parameters of soil, which has an impact on many chemical and physical characteristics of soil, is of great importance in soil science. This study applies a time series-based model, namely fractionally autoregressive integrated moving average (FARIMA), as well as two machine learning-based mode...

Highlights • Design of GP model for electricity demand prediction. • Design of DT model for electricity demand prediction. • GP is slightly superior to DT. • GP provides explicit model. • GP and DT can be used for 1-day ahead forecast of electricity in Nicosia. Article Info Abstract Several recent studies have used various data mining techniques to...

This paper presents the results of a comparison between multivariate adaptive regression splines (MARS) and random forest (RF) techniques in pipe failure prediction in two water distribution networks. In this regard, pipe diameter, pipe length, pipe installation depth, pipe age and average hydraulic pressure are considered as input variables. Resul...

It is well documented that standalone machine learning methods are not suitable for rainfall forecasting in long lead-time horizons. The task is more difficult in arid and semiarid regions. Addressing these issues, the present paper introduces a hybrid machine learning model, namely multiple genetic programming (MGP), that improves the predictive a...

River flow rates are important for water resources projects. Given this, the current study explored the use of autoregressive (AR) and moving average (MA) techniques as individual time series models and compared them to the same models hybridized with an autoregressive conditional heteroscedasticity (ARCH) model to estimate monthly streamflow. In a...

This paper investigates a meteorological drought analysis at two meteorology stations near metropolitan city of Ankara, Turkey. The standardized precipitation evapotranspiration index (SPEI) were estimated at the reference period 1971–2000 and compared with those of the near future climate period (2016–2040) under RCP4.5 and RCP8.5 greenhouse gas s...

Precipitation is an essential parameter of the hydrological cycle that known as the most important climatic variable in water resources management. In this study, monthly rainfall data obtained from Iranian Meteorological Organization at the period 1951 to 2017 were used to model monthly rainfall in Urmia city. To this end, we used two different me...

Bursa is the 4th major city of the Turkey and an important hub for agree-food security in the region. Several studies have reported a potential ongoing drought in the Uludag region at Bursa. Hence, a monthly precipitation time series between February 1980 to October 2018 in Uludag station is used. Wavelet decomposition (WD) analysis together with s...

Prediction of river flow as a fundamental source of hydrological information plays a crucial role in various fields of water projects. In this study, at first, the capabilities of two time series analysis approaches, namely self-exciting threshold autoregressive (SETAR) and generalized autoregressive conditional heteroscedasticity (GARCH) models, t...

Sediment deposits may influence the performance of the sewer systems. Sediments are the main store of pollutants which causes sewer systems overflows. In order to prevent the deposition of sediment in sewer systems, self‐cleansing design criteria are used. Among various criteria; “self‐cleansing with deposited bed” criterion is found appropriate fo...

Sediment deposition in sewers and urban drainage systems has great effect on the hydraulic capacity of the channel. In this respect, the self-cleansing concept has been widely used for sewers and urban drainage systems design. This study investigates the bed load sediment transport in sewer pipes with particular reference to the non-deposition cond...

Precipitation estimation has an important role in water resources management. modelling this hydrological variable and estimating its amount in every scale for every area, as one of the important atmospheric parameters, is a necessary for better planning in agriculture and water resources. In the present study, for predicting monthly precipitation...

Remaining long-term deposited materials in sewage systems cause depositional changes, especially when rainfalls are not present, permanent deposition on the bottom of the pipe changes in cross-section of flow due to the shear rate and shear stress. It therefore impacts on the sediment transport capacity and hydraulic resistance of the flow in sewer...

Self-cleansing is a design criterion for drainage systems which mitigates the continuous deposition of sediments at the channel bottom. In recent decades, in order to improve the knowledge for determination of self-cleansing conditions applicable for drainage system design, laboratory experimental studies on sediment transport in rigid boundary cha...

It is known that construction of large sewers based on consideration of flow with non-deposition without a bed deposit is not economical. Sewer design based on consideration of flow with non-deposition with a bed deposit reduces channel bed slope and construction cost in which the presence of a small depth of sediment deposition on the bed increase...

Incipient motion of sediment is one of the main aspects of the sedimentation process. Determination of the minimum shear stress or velocity required to initiate the motion of sediment particles is a crucial task in the rigid boundary drainage system design. This study investigates incipient motion through laboratory experiments conducted in trapezo...

Drainage systems must be designed in a way to minimize undesired problems such as decrease in hydraulic capacity of the channel, blockage and transport of pollutant due to deposition of sediment. Channel design considering self-cleansing criteria are used to solve sedimentation problem. Incipient deposition is one of the non-deposition self-cleansi...