Gokmen Tayfur

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Verified

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• PhD
• Faculty Member at Izmir Institute of Technology

Flood mitigation measures are essential in several aspects of environmental sustainability, such as environmental protection and development, infrastructure resilience, and climate change adaptation strategies. This study investigates several remedial measures such as flood and disaster risk reduction strategies to protect Baledwayne City, Somalia....

The Muskingum model, widely used in flood routing, is the first order differential equation. The accuracy of the routing storage equation of the model depends on correct parameter estimation and a numerical method employed for its solution. In the present study, different explicit numerical methods are used for solving the equation. These methods i...

In this study, time-dependent finite element analyses of the breaching process in two homogenous earth-fill dams were performed using the finite element method. Breaching was initiated at the middle and corner sections of the upper part of the dam bodies. The numerical results were compared with the findings of the experiments realized on dams 60 c...

Piping and overtopping are the most important causes of earth-fill dam failure. Such dams may erode under seepage, causing a reduction in the structural strength. The aim of this study was to investigate the temporal evolution of the breach and flow rate from the breach resulting from the piping in earth-fill dams. The experiments were carried out...

Afghanistan is suffering from periodic events of drought, which has exacerbated in recent years due to extreme climate events in the region. Having an arid to semi-arid climate, the country faces significant challenges of water resources management, especially for irrigation as reliance on agriculture is cumbersome. This study is undertaken to char...

Toprak dolgu baraj yıkılmalarının çoğu üstten aşma ve borulanmadan kaynaklanmakta ve ciddi can ve mal kayıplarıyla sonuçlanabilmektedir. Bu sebeple, baraj yıkılmasıyla oluşan taşkının ilerleyişinin incelenmesi ve riskli alanların tespiti, mansap bölgesinde oluşabilecek zararların önceden belirlenmesi ve önlenmesi açısından önem arz etmektedir. Bu ç...

A significant proportion of Arghandab Catchment in Kandahar Province, Afghanistan has been under potential degradation threat due to soil erosion. This study assessed the extent of soil erosion and estimated the sediment delivery ratio (SDR) in the catchment by employing the Revised Universal Soil Loss Equation (RUSLE), utilizing the Geographic Inf...

This study examines trends in minimum and maximum temperatures at various climate stations located in different regions of Morocco for a period of five decades (1970 to 2019). Mann–Kendall, Sen’s estimator, Innovative Trend Analysis (ITA) and Innovative Polygon Trend Analysis (IPTA) were used in the analysis. The results show significant fluctuatio...

Estimation of peak discharge is a key parameter for risk assessment in case of dam failure, and has attracted great attention from researchers in recent years. Many formulas are available in the literature, but these cannot cover all experimental scenarios. Existing models are typically inadequate to address the complexities of dam breaches. This r...

Baraj yıkılması sonucu oluşan taşkın hareketinin belirlenmesi, mansap bölgesindeki mevcut yerleşim yerlerinde yıkılma sonrası meydana gelebilecek risklerin saptanması ve önlenmesi açısından önemli bir konudur. Sel nedeniyle suyun yayılması ve sediment taşınımının analiz edilmesi, taşkın hareketinin belirlenmesi için toprak dolgu barajlarda incelene...

Water is an invaluable substance that ensures the life cycle and causes hydrologic events worldwide. Water deficit, also known as drought, is a naturally occurring disaster that affects the hydrometeorologic and/or climatic responses in time and space. In this study, the meteorologic and hydrologic droughts in Buyuk Menderes, Kucuk Menderes, and Ge...

Piping is one of the most important causes of earth-fill dam failure. This study investigates the temporal evolution of the breach resulting from the piping in earth-fill dams by means of the image processing technique. The experiments were performed on dams constructed from a mixture of 85 % sand and 15 % clay. A circular tunnel with a diameter of...

Afghanistan, as a landlocked country located within central and southwestern Asia, has an arid to semi-arid climate. Most of the people are involved in agricultural activities, and a major part of the country’s gross domestic product depends on agriculture, but the country has the lowest water storage capacity. Consecutive periods of drought and ra...

Drought assessment and trend analysis of precipitation and temperature time series are essential in the planning and management of water resources. Long-term precipitation and temperature historical records (monthly for 41 years, from 1980 to 2020) are used to investigate annual drought characteristics and trend analysis in Somalia’s northern regio...

Human centric lighting is an umbrella concept which covers human health and well-being in general. As the conventional lighting techniques are based on horizontal workplane illuminance, it drives from the vertical eye level illuminance and its spectral distribution triggering the nonvisual effects on humans. That is named as melanopic illuminance c...

This study investigated surface spreading and underground dam recharge methods to replenish groundwater in Turkey’s Egri Creek Sub-basin of the Kucuk Menderes River Basin. A three-dimensional numerical model was employed for this purpose. Field and lab data are provided to the model for realistic simulations. Pumping test results were used to deter...

Slope length gradient (LS) is one of the crucial factors in the Universal Soil Loss Equations (USLE, RUSLE). This study aimed at estimating the slope-length and slope-steepness (LS) factor for the entire watersheds of Afghanistan by using three different methods, namely; (1) LS-TOOLMFD (Method 1); (2) The Method of Equations (Method 2); and (3) The...

Kabul River Basin is the most populated and an important source of water resources in Afghanistan. The Soil and Water Assessment Tool (SWAT) model, together with the ArcGIS and SWAT-CUP, is employed to predict the runoff in the basin. Nine years of meteorological and hydrological data are employed in the study. The DEM, the soil cover, and the land...

As glass technology has been improved continuously, the daylight passing through the window glasses and its quality remains to be the subject matter in building physics. Combining daylight with the dynamic LED light in offices, people’s wellness in terms of light quality can be inquired to design better built environments. So, this paper is about h...

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,...

Özet: Borulanma toprak dolgu barajların stabilitesini tehdit eden önemli ve karmaşık bir problemdir. Günümüzde borulanmanın karmaşık özellikleri nedeniyle erozyon sürecini tarif edecek genel bir formül mevcut değildir. Bu çalışma kapsamında, toprak baraj gövdesinin üst köşesindeki sızma nedeniyle oluşan borulanmanın gelişimi deneysel olarak araştır...

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...

Barajların mansap bölgesinde yer alan mevcut yerleşim birimlerindeki baraj yıkılması sonucu oluşacak olası risklerin elde edilmesi açısından taşkın hareketlerinin saptanması önemli bir konudur. Toprak dolgu barajlarda taşkın hareketinin belirlenebilmesi için sel nedeniyle suyun yayılması ve buna ek olarak sediment taşınımı faktörleri incelenmektedi...

In 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 revers...

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...

This study evaluates drought at Lashkargah, Farah, Adraskan, and Gardandiwal stations in Helmand River Basin (HRB) in Afghanistan to determine appropriate drought indices for the basin. Thirty seven years of monthly recorded precipitation data from 1979 to 2015 are employed with different drought index (DI) methods which include the Standardized Pr...

— The combination of daylight characteristics and LED lighting quantities determines offices’ visual environment. Lighting conditions can influence office workers’ health and work performance. This study is an experimental one containing lighting measurements in two offices, subjective performance tests, and questionnaires to find out how work perf...

Piping is one of the main causes of the earth-fill dam failures. Most of the researchers realizing numerical analyses make some simplified assumptions concerning the shape of the breach and the discharge of water flowing through the breach. The aim of this study is to realize experiments to provide data needed to perform numerical analyses by makin...

Internal erosion, also known as piping, is one of the most important causes of earth-fill dam breaks. Many researchers dealing with numerical analyses in this area make some simplified assumptions about the shape of the breach and the discharge of water flowing through the breach. This study was conducted in the scope of the project supported finan...

Piping is one of the main problems which threatens stability of earth-fill dams. Realistic approaches are needed for breach mechanism as well as breach geometry and flow. The aim of this study is to realize experiments to provide data needed to perform numerical analyses by making more realistic assumptions. Dam having a height of 0.6 m, a bottom w...

Dynamic LED lighting systems aim to bring the dynamic character of daylight to people's living spaces and to improve the mood, alertness and work performance. The amount and the colour temperature of light correspond to generate such an impact. Thus, the objective of this study is to explore office users’ preferences on dynamic LED lighting systems...

Estimation of withdrawal water and filtered sediment amounts are important to obtain maximum efficiency from an intake structure. The purpose of this study is to develop empirical equations to predict Water Capturing Performance (WCP) and Sediment Release Efficiency (SRE) for Coanda type intakes. These equations were developed using 216 sets of exp...

Estimation of withdrawal water and filtered sediment amounts are important to obtain maximum efficiency from an intake structure. The purpose of this study is to develop empirical equations to predict Water Capturing Performance (WCP) and Sediment Release Efficiency (SRE) for Coanda type intakes. These equations were developed using 216 sets of exp...

The writers thank discussers for their great interest in the reverse flood routing in rivers using linear and nonlinear Muskingum models presented in the original paper. The discussers have suggested several ideas for modifying the structure of the proposed method. Some ideas are useful, and other ideas have adverse implications for model calibrati...

Groundwater (GW) plays a vital role in the socio-economic growth of Kabul River Basin (KRB) in Afghanistan. Since the GW resources in the basin have not been properly managed, there is a need for sound strategies by first identifying the potential GW zones. This study assesses the potential groundwater zones for the KRB using the Geographic Informa...

Baraj yıkılması sonucu oluşacak taşkın hareketinin belirlenmesi, baraj mansabında herhangi bir yerleşim yeri olması durumunda, tehlikenin saptanması açısından önemli ve gerekli bir çalışmadır. Taşkın hareketi sonucu oluşan suyun hareketinin yanında aynı zamanda sediment taşınımı da toprak dolgu barajlar için incelenmesi gereken önemli bir konudur....

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...

This paper reviews the modelling approaches and outstanding issues with regard to non-cohesive sediment transport which has been experimentally and numerically studied for many decades owing to its importance to hydraulic structures, morphology and related areas. About 311 papers are reviewed that included laboratory experiments, field observations...

Widely employed precipitation drought indices, one way or another, impose probability distribution functions to the data when performing the drought analysis. This may be a plausible approach when the data do not have strong discrepancy which can impede the distribution. The precipitation data in semi-arid and especially in arid regions do have a s...

One of the key factors for flood modeling and control is the flood hydrograph, which is not always available due to lack of flood discharge observations. In reverse flow routing, hydraulic or hydrological calculations are performed from the downstream end to the upstream end. In the present study, a reverse flood routing approach is developed based...

zet: Türkiye'nin batısında yer alan Küçük Menderes Havzası, tarımsal faaliyetin yoğun olduğu verimli topraklara ve ürün çeşitliliğine sahiptir. Havzada son otuz yıldır yeraltı suyu seviyesinde ciddi bir düşme gözlemlenmektedir. Bunun sebebi yoğun tarımsal sulama, hayvancılık ve sanayileşmenin getirdiği etkilerdir. Günümüzde Devlet Su İşleri Genel M...

Küçük Menderes River Basin located in the western Turkey has been experiencing groundwater level decrease for the last 30 years. In dry periods, irrigation demand is completely met by the pumping from groundwater system, which reduces water levels significantly. In order to overcome this problem, enough storage can be recharged in the wet seasons w...

Control of the high velosity and kinetic energy of the flow at downstream of the hydraulic structures in order to prevent the erosion of the channel bed is one of the most important concerns of hydraulic engineers. For this reason, energy dissipation structures are used.The sudden symmetrical expanding channel is an energy-dissipation structure tha...

The estimation of groundwater recharge is an essential process for hydrogeological study. Realistic determination approach is crucial for assessing groundwater potential in an aquifer system and estimating of groundwater levels and/or changes in dry periods. Based on these matters, we employ a GIS-integrated groundwater level fluctuation method to...

Prediction of sediment discharge transported within flow is strongly needed in order to provide measures for a well-established erosion control and water quality management practice. Initiated by runoff generation and erosion processes sediment transport is influenced by microtopography over hillslopes of hydrological watersheds. Consideration of m...

Gypsum is widely used in constructions owing to its easy application, zero shrinkage, and excellent fire resistance. Several parameters can affect the properties of gypsum pastes. To study the strength of the gypsum pastes experimentally by trying all these parameters is time-consuming and costly. Therefore, artificial intelligence methods can be v...

Gediz Basin, located in the western part of Turkey constituting 2% land of the country, has an important groundwater potential in the area. Alasehir sub-basin, located in the southeast of the Gediz Basin and subject to the extensive withdrawal for the irrigation, constitutes the study area. Natural recharge to the sub-basin due to precipitation is...

In this paper, seepage of Sattarkhan earthen dam in northwest Iran was simulated using various artificial intelligence (AI) models (e.g., Feed forward neural network, Adaptive neural fuzzy inference system and Support vector regression) and linear ARIMA model based on different input combinations. Both jittering pre-processing and ensembling post-p...

A coupled model is developed to simulate two dimensional water surface profile, suspended sediment load and bed deformation in unsteady open channels. The hydrodynamical component employs the two dimensional shallow water equations to obtain the hydraulic variables. These, in turn, are used in the morphdynamical component to determine the bed defor...

Nowadays, the degree and scale of flood hazards has been massively increasing as a result of the changing climate, and large-scale floods jeopardize lives and properties, causing great economic losses, in the inundation-prone areas of the world. Early flood warning systems are promising countermeasures against flood hazards and losses. A collaborat...

Based on three rainfall run‐off‐induced sediment transport data for bare surface experimental plots, the generalized regression neural network (GRNN) and empirical models were developed to predict sediment load. Rainfall intensity, slope, rainfall duration, soil particle median diameter, clay content of the soil, rill density and soil particle mass...

The Küçük Menderes Basin, located to the west of Turkey, has fertile soil sand product diversity in which agricultural activity is intensive. Groundwater resources have been used intensive for the agricultural facilities therefore a drastic decline in the level of groundwater has been observed in the basin for the last thirty years. The reasons of...

Machine learning (soft) methods have a wide range of applications in many disciplines, including hydrology. The first application of these methods in hydrology started in the 1990s and have since been extensively employed. Flood hydrograph prediction is important in hydrology and is generally done using linear or nonlinear Muskingum (NLM) methods o...

Trend analysis of annual temperature and precipitation time series data collected from three stations (Boutilimit (station 1), Nouakchott (station 2) and Rosso (station 3)) has been used to detect the impacts of climate change on water resources in Trarza region, Mauritania. The Mann–Kendall, the Spearman's rho, and the Şen trend test were used for...

Flow hydrographs are one of the most important key elements for flood modelling. They are recorded as time series; however, they are not available in most developing countries due to lack of gauged stations. This study presents a flood modelling method for rivers having no upstream gauged stations. The modelling procedure involves three steps: (1)...

Izmir is a metropolitan municipality which is the third the most populated city with 4.223.545people in 2016. Fifty-six percent of the drinking water of İzmir city is provided from groundwater resources. The rest comes from Tahtalı and Balçova Dams. The population and water consumption of the city increase each year. Although Gördes dam in Gediz Gr...

This paper investigates meteorological drought in one of Afghanistan’s most important socio-economic river basins called the Kabul River Basin (KRB) using 38 years’ monthly precipitation data. Several drought indices such as Standardized Precipitation Index (SPI), Percent of Normal Precipitation Index (PNPI), Deciles Index (DI), and China-Z Index (...

The Küçük Menderes Basin, located to the west of Turkey, has fertile soil sand product diversity in which agricultural activity is intensive. Groundwater resources have been used intensive for the agricultural facilities therefore a drastic decline in the level of groundwater has been observed in the basin for the last thirty years. The reasons of...

Mathematical (analytical, numerical and optimization) models are employed in many disciplines including the water resources planning, engineering and management. These models can vary from a simple black-box model to a sophisticated distributed physics-based model. Recently, development and employment of modern optimization methods (MOMs) have beco...

This paper investigates meteorological drought in one of Afghanistan's most important socio-economic river basins called Kabul River Basin (KRB) using a 38 years monthly precipitation data. Several drought indices such as Standardized Precipitation Index (SPI), Percent of Normal Precipitation Index (PNPI), Deciles Index (DI), and China-Z Index (CZI...

Drought is a natural phenomenon, usually defined by periods of deficiency of water in a given region. Although many studies have been done on drought worldwide there is no any related scientific research that evaluates the drought conditions in Afganistan due to three decades of conflict and consequently the shortage of meteorological data. Recentl...

Drought is arduous natural disaster causing damages to the world ecosystem. Various drought indexes (DIs) are universally used to investigate the drought conditions such as intensity and duration. This study evaluates the drought appearances in Lashkargah and Gardandiwal stations of Helmand River Basin (HRB) in Afghanistan. Thirty seven years month...

The advection diffusion equation is one of the most popular and convenient equations in calculating the transport of energy and materials in flux areas. In this paper, one-dimensional advection-diffusion equation is solved using the finite difference, fourth order finite difference, finite volume, and differential quadrature methods in explicit con...

This study investigates the appropriateness of four major empirical methods [Lane and Kalinske, Einstein, Brooks, Chang—Simons—Richardson] for predicting suspended sediment loads (SSLs) in three major rivers in the Aegean Region, Turkey. The measured data from 1975 to 2005 were used to test performance of the models. It was found that Brooks method...

The present study aims at assessing the hydrochemistry of the groundwater system of the Maragheh-Bonab Plain located in the East Azarbaijan Province, northwest of Iran. The groundwater is used mainly for drinking, agriculture and industry. The study also discusses the issue of the industrial untreated wastewater discharge to the Plain aquifer that...

Drought Indexes (DIs) are commonly used for assessing the effect of drought such as the duration and severity. In this study, long term precipitation records (monthly recorded for 44 years) in three stations (Boutilimit (station 1), Nouakchott (station 2), and Rosso (station 3)) are employed to investigate the drought characteristics in Trarza regi...

Two variants of the Muskingum flood routing method formulated for accounting nonlinearity of the channel routing process are investigated in this study. These variant methods are: 1) The three-parameter conceptual Nonlinear Muskingum (NLM) method advocated by Gillin 1978, and 2) The Variable Parameter McCarthy-Muskingum (VPMM) method recently propo...

Dams are important structures having many functions such as water supply, flood control, hydroelectric power and recreation. Although dam break failures are very rare events, dams can fail with little warning and the damage at the downstream of the dam due to the flood wave can be catastrophic. During a dam failure, immense volume of water is mobil...

A comprehensive process-based rainfall-runoff model for simulating overland flow generated in rills and on interrill areas of a hillslope is evaluated using a laboratory experimental data set. For laboratory experiments, a rainfall simulator has been constructed together with a 6.50 m × 1.36 m erosion flume that can be given adjustable slopes chang...

Land degradation processes start with accelerated runoff and sediment delivery. In this study, rainfall-runoff induced sediment transport is investigated using data from an indoor laboratory experimental setup consisting of a rainfall simulator and an erosion flume. The data are analysed to develop empirical models using sediment discharge, slope,...