Harran Üniversitesi mühendislik dergisi, Jun 1, 2017
Barajların elektrik üretimi ve sulama gibi alanlarda elde edilecek faydaları ile ülke ekonomileri... more Barajların elektrik üretimi ve sulama gibi alanlarda elde edilecek faydaları ile ülke ekonomilerine katkılarının yanı sıra çevre düzenlemesi, ulaşım ve taşkın koruma gibi alanlarda da faydaları bulunmaktadır. Ancak oluşabilecek aksaklıklar baraj yapılarının yükseklikleri ve aktif depolama hacimlerinin büyüklüğüne göre farklı seviyelerde tehlikeler meydana getirmektedir. Özellikle baraj alanlarına yakın yerleşim bölgeleri için barajlarda oluşabilecek yıkılmanın önceden minimum hata ile tahmin edilebilmesi hayati önem taşımaktadır. Bu çalışma baraj yıkılma modellerinde kullanılan debi tahmin yöntemlerinin temel amaçları, hesap yöntemleri ve uygulama alanları ile elde dilecek sonuçların karşılaştırılmasını içermektedir. Literatürde bulunan ve bu araştırmada incelenen yöntemler tarihi baraj yıkılma verilerine istatistiksel regresyonlar uygulanarak elde edildiği için bazı durumlarda yetersiz kalmaktadır; özellikle bu verilerin elde edildiği baraj türlerinin (baraj yüksekliklerinin) tüm barajları içermemesi sebebiyle önerilen regresyon denklemlerinin yüksek belirsizlikleri olduğu görülmektedir.
Bu çalışmada, Gaziantep ili merkez meteorolojik gözlem istasyonundan elde edilen 2000-2010 yıllar... more Bu çalışmada, Gaziantep ili merkez meteorolojik gözlem istasyonundan elde edilen 2000-2010 yılları arasındaki kısıtlı periyoda ait 11 yıllık güneş radyasyonu ve meteorolojik değişkenler (ortalama sıcaklık, bağıl nem, güneşli gün sayısı, rüzgar hızı, buhar basıncı) arasındaki ilişki genetik programlama tekniği ile formüle edilerek tahmin edilmeye çalışılmıştır. Elde edilen sonuçlar ölçülmüş veriler ile istatistiksel olarak ve trend karakteristiklerine göre karşılaştırılmıştır. Yapılan model karşılaştırmaları sonucunda mevcut veriler ile en iyi tahmin sonuçlarını lineer genetik programlama tekniğinin verdiği tespit edilmiştir. Elde edilen genetik programlama denklemleri kullanılarak türetilen sentetik verilerin güneş enerjisi santralleri projelerinin fizibilite ve tasarımında faydalı veri olarak kullanılabileceği düşünülmektedir.
In this study, the geomorphologic parameters of Damlıca basin are determined by using Geographic ... more In this study, the geomorphologic parameters of Damlıca basin are determined by using Geographic Information Systems (GIS). The digital elevation model (DEM) of the basin is downloaded from Aster-GDEM web page and this digital map is used in the GIS computer program to obtain the geomorphologic parameters of the Damlıca basin, such as the area of the basin, its perimeter, river length, slope, etc. The extracted parameters are compared with the parameters obtained by conventional methods. This study shows that the geomorphologic parameters of the Damlıca basin obtained using GIS are much more precise than those produced by conventional methods.
In this study, synthetic unit hydrograph parameters which are qp, tp, t b are calculated by using... more In this study, synthetic unit hydrograph parameters which are qp, tp, t b are calculated by using Synder, Mockus, SCS (Soil Conservation Service) and DSI (State Hydraulic Works) methods. First according to observed data, calculations were done. Then the mentioned above methods, which are based on both topographic map and geographic information systems values, were applied. Three catchments, Damlıca, Vize, Kumdere were studied. Synder, Mockus, SCS and DSI methods were applied for each catchment.
During the last two decades, researchers have noticed that the use of soft computing techniques a... more During the last two decades, researchers have noticed that the use of soft computing techniques as an alternative to conventional statistical methods based on controlled laboratory or field data, gave significantly better results. Gene-expression programming (GEP), which is an extension to genetic programming (GP), has nowadays attracted the attention of researchers in prediction of hydraulic data. This study presents GEP as an alternative tool in the prediction of scour downstream of a flip-bucket spillway. Actual field measurements were used to develop GEP models. The proposed GEP models are compared with the earlier conventional GP results of others (Azamathulla et al. 2008b; RMSE ¼ 2.347, δ ¼ 0.377, R ¼ 0.842) and those of commonly used regression-based formulae. The predictions of GEP models were observed to be in strictly good agreement with measured ones, and quite a bit better than conventional GP and the regression-based formulae. The results are tabulated in terms of statistical error measures (GEP1; RMSE ¼ 1.596, δ ¼ 0.109, R ¼ 0.917) and illustrated via scatter plots.
Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of... more Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of hydraulic data. This study presents linear genetic programming (LGP), which is an extension to GP, as an alternative tool in the prediction of scour depth around a circular pile due to waves in medium dense silt and sand bed. Field measurements were used to develop LGP models. The proposed LGP models were compared with adaptive neuro-fuzzy inference system (ANFIS) model results. The predictions of LGP models were observed to be in good agreement with measured data, and quite better than ANFIS and regression-based equation of scour depth at circular piles. The results were tabulated in terms of statistical error measures and illustrated via scatter plots.
Risk assessment process of dams can be time-consuming and may require high investments. If risk v... more Risk assessment process of dams can be time-consuming and may require high investments. If risk value of every dam is defined, then the resources could be shared more efficiently. Descriptions of evaluation procedures for various failure modes such as piping, flood, earthquake and stability are described in this chapter. Consequence assessment procedures are presented in detail, together with the steps of the risk evaluation process, thus helping to identify the appropriate failure mode for examined dam. Moreover, the evaluation of dam safety failure modes with the appropriate life loss potential procedures is described in this chapter. Estimated loss of life and damage in downstream from a dam failure are used to create three classes in dam safety regulation studies that are: • High Hazard if probable loss of life is expected; • Significant Hazard if possible, loss of life and major damage is expected; • Low Hazard if no loss of life, minor image is expected.
Peak breach discharge occurring upon dam failure is an essential parameter for dam safety studies... more Peak breach discharge occurring upon dam failure is an essential parameter for dam safety studies. In literature there are many methods for predicting peak breach discharge. The methods, together with the most widely used dam breach parameters, are described in this chapter, together with the relevant formulations and definitions.
International Journal of Environmental Science and Technology, May 21, 2018
Wise prediction of discharge is vital for effective utilization of water resources and hydropower... more Wise prediction of discharge is vital for effective utilization of water resources and hydropower generation. There is no doubt that the future climate change will substantially affect precipitation amount, discharge and hydro-meteorology which are considered as major sources for hydropower energy. In this study, we present an application of downscaling technique on prediction of discharge of a local gage station in Turkey. Variable input set of the Third Generation Coupled Global Climate Model variables are statistically downscaled and coupled with variable forms of local discharge (Q, LnQ, MavQ, StdQ, and Q/Qmax) by using five different models as Gene-expression programming, Group Method of Data Handling, K-nearest neighbour, logistic regression and linear regression. Different sub-models are developed and calibrated based on the training period, and the best model is selected based on the testing period. Future projecting of discharge is done based on the Third Generation Coupled Global Climate Model A2 scenario, and the financial analysis is carried out by using this forecasted Q values. Editorial responsibiility: iskender AKKURT.
Several researchers have attempted to estimate the maximum depth and location of local scour, par... more Several researchers have attempted to estimate the maximum depth and location of local scour, particularly, based on conventional regression analysis. Many of these equations in the literature failed to estimate the scour depths satisfactorily. This study presents explicit formulation extracted from a multi-output descriptive neural network (DNN), which estimates both the depth and location of maximum scour. The DNN method extracts rules (information) conveyed from input layer to output layer of a NN consisting two outputs. The present DNN results are compared to non-linear and linear regression equations derived by the author and selected other empirical equations available in the literature. The results show that the proposed DNN estimates the maximum-scour depth and its location in strict agreement with the measured ones (R 2 = 0.819 and 0.907, respectively), and dominantly better than the other equations (R 2 = 0.687 and 0.706 being the highest results for d m and for x m , respectively). This study shows that the explicit formulation extracted from DNN can replace the conventional regression equations with much more accuracy.
Water Science & Technology: Water Supply, Oct 23, 2020
Spillways are constructed to evacuate flood discharge safely so that a flood wave does not overto... more Spillways are constructed to evacuate flood discharge safely so that a flood wave does not overtop the dam body. There are different types of spillways, with the ogee type being the conventional one. A stepped spillway is an example of a nonconventional spillway. The turbulent flow over a stepped spillway was studied numerically by using the Flow-3D package. Different fluid flow characteristics such as longitudinal flow velocity, temperature distribution, density and chemical concentration can be well simulated by Flow-3D. In this study, the influence of slope changes on flow characteristics such as air entrainment, velocity distribution and dynamic pressures distribution over a stepped spillway was modelled by Flow-3D. The results from the numerical model were compared with an experimental study done by others in the literature. Two models of a stepped spillway with different discharge for each model were simulated. The turbulent flow in the experimental model was simulated by the Renormalized Group (RNG) turbulence scheme in the numerical model. A good agreement was achieved between the numerical results and the observed ones, which are exhibited in terms of graphics and statistical tables.
Water Science & Technology: Water Supply, Nov 5, 2021
The use of a statistical downscaling technique is needed to investigate the hydrological conseque... more The use of a statistical downscaling technique is needed to investigate the hydrological consequences of climate change on the local hydropower capacity. Global Circulation Models (GCMs) are crucial tools used in various simulations for potential climate change effects, including precipitation and temperature. Statistical downscaling methods comprise the improvement of relations between the large-scale climatic parameters and the local variables. This study presents the trend analysis of the observed variables compared to the statistically downscaled emission scenarios that are adopted from the Canadian Second Generation Earth Systems Model (CanESM2) in the basin of Göksu River which is located in Turkey. The key purpose of the research is to evaluate both the predicted monthly precipitation and the projections of GCMs within the three simulated scenarios of RCP2.6, RCP4.5, and RCP8.5 by Gene Expression Programming (GEP). In addition, the findings of statistical downscaling of monthly mean precipitation will be compared to the Linear Regression model (LR). The R-value is 0.827 and 0.755 for precipitation of the GEP model for the periods of calibrating and validation. In comparison with the LR model for the validation and calibration periods , the results of the GEP model prove its applicability in projecting the data of the monthly mean rainfall. Generally, in the simulated periods of 2021-2100, the mentioned scenarios forecast a decline in the monthly mean precipitation in the basin. Moreover, the scenario of RCP8.5 projects more suitably for the case study than expected under the scenarios of the RCP4.5 and RCP2.6. The mean statistically downscaled CanESM2 model was compared with the trend analysis of the areal mean precipitation (PM) over the case study area, and the trend was shown decreasing. However, the RCP 8.5 scenario has the more quasi-asymptotic for trend.
Water Science & Technology: Water Supply, Oct 27, 2021
Changes in extreme precipitation are expected to be one of the most important impacts of climate ... more Changes in extreme precipitation are expected to be one of the most important impacts of climate change in cities. Urban floods are mainly caused by short duration extreme events. Hence, robust information on changes in extreme precipitation at high-temporal resolution is required for the design of climate change adaptation measures. However, the quantification of these changes is challenging and subject to numerous uncertainties. This study assesses the changes and uncertainties in extreme precipitation at hourly scale over Denmark. It explores three statistical downscaling approaches: a delta change method for extreme events, a weather generator combined with a disaggregation method and a climate analogue method. All three methods rely on different assumptions and use different outputs from the regional climate models (RCMs). The results of the three methods point towards an increase in extreme precipitation but the magnitude of the change varies depending on the RCM used and the spatial location. In general, a similar mean change is obtained for the three methods. This adds confidence in the results as each method uses different information from the RCMs. The results of this study highlight the need of using a range of statistical downscaling methods as well as RCMs to assess changes in extreme precipitation.
In this paper the effects of the aspect ratio (width to depth ratio, b/d) on the cost of a trapez... more In this paper the effects of the aspect ratio (width to depth ratio, b/d) on the cost of a trapezoidal concrete-lined channel (either power channel or irrigation channel) are analysed. The recommended b/d ratios given in the literature and their limitations are also discussed. Efforts are made to derive an equation for determining the optimal depth of the water from known parameters such as discharge, velocity and bed slope for concrete-lined channels. An equation for finding the minimum possible discharge within a specific velocity and bed slope is developed based on a semi-theoretical approach. The same approach is followed to obtain another formula for finding the maximum possible velocity for a specific discharge and bed slope. The obtained equations eliminate the iteration process commonly involved in finding the dimensions of a trapezoidal channel. A relation is developed for finding the aspect ratio in response to a given discharge and bed slope by using linear genetic programming techniques. The results show that the proposed model can be successfully applied in the design of lined channels as an alternative to existing methods.
Insignificant changes in the future system might be assumed due to the impacts of climate changes... more Insignificant changes in the future system might be assumed due to the impacts of climate changes. Temperature changes and anticipated precipitation suggest possible changes in floods. Extreme events will have bigger impacts on sectors with direct connections to climate, such as water sector; there is great belief that climate changes have the potential to critically affect water management systems. This study investigated how future climate change might affect the Inflow Design Flood (IDF) of Darbandikhan Dam. The study uses the projected downscaled daily inflow from Global Climate Models (GCMs) in comparative to the historical peak inflows. Flood frequency analysis based on historical data, both observed and statistically downscaled, was used to obtain the new design flood values. Analysis of the future projections of flood frequency analysis (FFA) reveals a general tendency toward changes in the magnitude of IDF.
ABSTRACT The global warming and the climate change have caused an observed change in the hydrolog... more ABSTRACT The global warming and the climate change have caused an observed change in the hydrological data; therefore, forecasters need re-calculated scenarios in many situations. Downscaling, which is reduction of time and space dimensions in climate models, will most probably be the future of climate change research. However, it may not be possible to redesign an existing dam but at least precaution parameters can be taken for the worse scenarios of flood in the downstream of the dam location. The purpose of this study is to develop a new approach for predicting the peak monthly discharges from statistical downscaling using linear genetic programming (LGP). Attempts were made to evaluate the impacts of the global warming and climate change on determining of the flood discharge by considering different scenarios of General Circulation Models. Reasonable results were achieved in downscaling the peak monthly discharges directly from daily surface weather variables (NCEP and CGCM3) without involving any rainfall-runoff models.
Harran Üniversitesi mühendislik dergisi, Jun 1, 2017
Barajların elektrik üretimi ve sulama gibi alanlarda elde edilecek faydaları ile ülke ekonomileri... more Barajların elektrik üretimi ve sulama gibi alanlarda elde edilecek faydaları ile ülke ekonomilerine katkılarının yanı sıra çevre düzenlemesi, ulaşım ve taşkın koruma gibi alanlarda da faydaları bulunmaktadır. Ancak oluşabilecek aksaklıklar baraj yapılarının yükseklikleri ve aktif depolama hacimlerinin büyüklüğüne göre farklı seviyelerde tehlikeler meydana getirmektedir. Özellikle baraj alanlarına yakın yerleşim bölgeleri için barajlarda oluşabilecek yıkılmanın önceden minimum hata ile tahmin edilebilmesi hayati önem taşımaktadır. Bu çalışma baraj yıkılma modellerinde kullanılan debi tahmin yöntemlerinin temel amaçları, hesap yöntemleri ve uygulama alanları ile elde dilecek sonuçların karşılaştırılmasını içermektedir. Literatürde bulunan ve bu araştırmada incelenen yöntemler tarihi baraj yıkılma verilerine istatistiksel regresyonlar uygulanarak elde edildiği için bazı durumlarda yetersiz kalmaktadır; özellikle bu verilerin elde edildiği baraj türlerinin (baraj yüksekliklerinin) tüm barajları içermemesi sebebiyle önerilen regresyon denklemlerinin yüksek belirsizlikleri olduğu görülmektedir.
Bu çalışmada, Gaziantep ili merkez meteorolojik gözlem istasyonundan elde edilen 2000-2010 yıllar... more Bu çalışmada, Gaziantep ili merkez meteorolojik gözlem istasyonundan elde edilen 2000-2010 yılları arasındaki kısıtlı periyoda ait 11 yıllık güneş radyasyonu ve meteorolojik değişkenler (ortalama sıcaklık, bağıl nem, güneşli gün sayısı, rüzgar hızı, buhar basıncı) arasındaki ilişki genetik programlama tekniği ile formüle edilerek tahmin edilmeye çalışılmıştır. Elde edilen sonuçlar ölçülmüş veriler ile istatistiksel olarak ve trend karakteristiklerine göre karşılaştırılmıştır. Yapılan model karşılaştırmaları sonucunda mevcut veriler ile en iyi tahmin sonuçlarını lineer genetik programlama tekniğinin verdiği tespit edilmiştir. Elde edilen genetik programlama denklemleri kullanılarak türetilen sentetik verilerin güneş enerjisi santralleri projelerinin fizibilite ve tasarımında faydalı veri olarak kullanılabileceği düşünülmektedir.
In this study, the geomorphologic parameters of Damlıca basin are determined by using Geographic ... more In this study, the geomorphologic parameters of Damlıca basin are determined by using Geographic Information Systems (GIS). The digital elevation model (DEM) of the basin is downloaded from Aster-GDEM web page and this digital map is used in the GIS computer program to obtain the geomorphologic parameters of the Damlıca basin, such as the area of the basin, its perimeter, river length, slope, etc. The extracted parameters are compared with the parameters obtained by conventional methods. This study shows that the geomorphologic parameters of the Damlıca basin obtained using GIS are much more precise than those produced by conventional methods.
In this study, synthetic unit hydrograph parameters which are qp, tp, t b are calculated by using... more In this study, synthetic unit hydrograph parameters which are qp, tp, t b are calculated by using Synder, Mockus, SCS (Soil Conservation Service) and DSI (State Hydraulic Works) methods. First according to observed data, calculations were done. Then the mentioned above methods, which are based on both topographic map and geographic information systems values, were applied. Three catchments, Damlıca, Vize, Kumdere were studied. Synder, Mockus, SCS and DSI methods were applied for each catchment.
During the last two decades, researchers have noticed that the use of soft computing techniques a... more During the last two decades, researchers have noticed that the use of soft computing techniques as an alternative to conventional statistical methods based on controlled laboratory or field data, gave significantly better results. Gene-expression programming (GEP), which is an extension to genetic programming (GP), has nowadays attracted the attention of researchers in prediction of hydraulic data. This study presents GEP as an alternative tool in the prediction of scour downstream of a flip-bucket spillway. Actual field measurements were used to develop GEP models. The proposed GEP models are compared with the earlier conventional GP results of others (Azamathulla et al. 2008b; RMSE ¼ 2.347, δ ¼ 0.377, R ¼ 0.842) and those of commonly used regression-based formulae. The predictions of GEP models were observed to be in strictly good agreement with measured ones, and quite a bit better than conventional GP and the regression-based formulae. The results are tabulated in terms of statistical error measures (GEP1; RMSE ¼ 1.596, δ ¼ 0.109, R ¼ 0.917) and illustrated via scatter plots.
Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of... more Genetic programming (GP) has nowadays attracted the attention of researchers in the prediction of hydraulic data. This study presents linear genetic programming (LGP), which is an extension to GP, as an alternative tool in the prediction of scour depth around a circular pile due to waves in medium dense silt and sand bed. Field measurements were used to develop LGP models. The proposed LGP models were compared with adaptive neuro-fuzzy inference system (ANFIS) model results. The predictions of LGP models were observed to be in good agreement with measured data, and quite better than ANFIS and regression-based equation of scour depth at circular piles. The results were tabulated in terms of statistical error measures and illustrated via scatter plots.
Risk assessment process of dams can be time-consuming and may require high investments. If risk v... more Risk assessment process of dams can be time-consuming and may require high investments. If risk value of every dam is defined, then the resources could be shared more efficiently. Descriptions of evaluation procedures for various failure modes such as piping, flood, earthquake and stability are described in this chapter. Consequence assessment procedures are presented in detail, together with the steps of the risk evaluation process, thus helping to identify the appropriate failure mode for examined dam. Moreover, the evaluation of dam safety failure modes with the appropriate life loss potential procedures is described in this chapter. Estimated loss of life and damage in downstream from a dam failure are used to create three classes in dam safety regulation studies that are: • High Hazard if probable loss of life is expected; • Significant Hazard if possible, loss of life and major damage is expected; • Low Hazard if no loss of life, minor image is expected.
Peak breach discharge occurring upon dam failure is an essential parameter for dam safety studies... more Peak breach discharge occurring upon dam failure is an essential parameter for dam safety studies. In literature there are many methods for predicting peak breach discharge. The methods, together with the most widely used dam breach parameters, are described in this chapter, together with the relevant formulations and definitions.
International Journal of Environmental Science and Technology, May 21, 2018
Wise prediction of discharge is vital for effective utilization of water resources and hydropower... more Wise prediction of discharge is vital for effective utilization of water resources and hydropower generation. There is no doubt that the future climate change will substantially affect precipitation amount, discharge and hydro-meteorology which are considered as major sources for hydropower energy. In this study, we present an application of downscaling technique on prediction of discharge of a local gage station in Turkey. Variable input set of the Third Generation Coupled Global Climate Model variables are statistically downscaled and coupled with variable forms of local discharge (Q, LnQ, MavQ, StdQ, and Q/Qmax) by using five different models as Gene-expression programming, Group Method of Data Handling, K-nearest neighbour, logistic regression and linear regression. Different sub-models are developed and calibrated based on the training period, and the best model is selected based on the testing period. Future projecting of discharge is done based on the Third Generation Coupled Global Climate Model A2 scenario, and the financial analysis is carried out by using this forecasted Q values. Editorial responsibiility: iskender AKKURT.
Several researchers have attempted to estimate the maximum depth and location of local scour, par... more Several researchers have attempted to estimate the maximum depth and location of local scour, particularly, based on conventional regression analysis. Many of these equations in the literature failed to estimate the scour depths satisfactorily. This study presents explicit formulation extracted from a multi-output descriptive neural network (DNN), which estimates both the depth and location of maximum scour. The DNN method extracts rules (information) conveyed from input layer to output layer of a NN consisting two outputs. The present DNN results are compared to non-linear and linear regression equations derived by the author and selected other empirical equations available in the literature. The results show that the proposed DNN estimates the maximum-scour depth and its location in strict agreement with the measured ones (R 2 = 0.819 and 0.907, respectively), and dominantly better than the other equations (R 2 = 0.687 and 0.706 being the highest results for d m and for x m , respectively). This study shows that the explicit formulation extracted from DNN can replace the conventional regression equations with much more accuracy.
Water Science & Technology: Water Supply, Oct 23, 2020
Spillways are constructed to evacuate flood discharge safely so that a flood wave does not overto... more Spillways are constructed to evacuate flood discharge safely so that a flood wave does not overtop the dam body. There are different types of spillways, with the ogee type being the conventional one. A stepped spillway is an example of a nonconventional spillway. The turbulent flow over a stepped spillway was studied numerically by using the Flow-3D package. Different fluid flow characteristics such as longitudinal flow velocity, temperature distribution, density and chemical concentration can be well simulated by Flow-3D. In this study, the influence of slope changes on flow characteristics such as air entrainment, velocity distribution and dynamic pressures distribution over a stepped spillway was modelled by Flow-3D. The results from the numerical model were compared with an experimental study done by others in the literature. Two models of a stepped spillway with different discharge for each model were simulated. The turbulent flow in the experimental model was simulated by the Renormalized Group (RNG) turbulence scheme in the numerical model. A good agreement was achieved between the numerical results and the observed ones, which are exhibited in terms of graphics and statistical tables.
Water Science & Technology: Water Supply, Nov 5, 2021
The use of a statistical downscaling technique is needed to investigate the hydrological conseque... more The use of a statistical downscaling technique is needed to investigate the hydrological consequences of climate change on the local hydropower capacity. Global Circulation Models (GCMs) are crucial tools used in various simulations for potential climate change effects, including precipitation and temperature. Statistical downscaling methods comprise the improvement of relations between the large-scale climatic parameters and the local variables. This study presents the trend analysis of the observed variables compared to the statistically downscaled emission scenarios that are adopted from the Canadian Second Generation Earth Systems Model (CanESM2) in the basin of Göksu River which is located in Turkey. The key purpose of the research is to evaluate both the predicted monthly precipitation and the projections of GCMs within the three simulated scenarios of RCP2.6, RCP4.5, and RCP8.5 by Gene Expression Programming (GEP). In addition, the findings of statistical downscaling of monthly mean precipitation will be compared to the Linear Regression model (LR). The R-value is 0.827 and 0.755 for precipitation of the GEP model for the periods of calibrating and validation. In comparison with the LR model for the validation and calibration periods , the results of the GEP model prove its applicability in projecting the data of the monthly mean rainfall. Generally, in the simulated periods of 2021-2100, the mentioned scenarios forecast a decline in the monthly mean precipitation in the basin. Moreover, the scenario of RCP8.5 projects more suitably for the case study than expected under the scenarios of the RCP4.5 and RCP2.6. The mean statistically downscaled CanESM2 model was compared with the trend analysis of the areal mean precipitation (PM) over the case study area, and the trend was shown decreasing. However, the RCP 8.5 scenario has the more quasi-asymptotic for trend.
Water Science & Technology: Water Supply, Oct 27, 2021
Changes in extreme precipitation are expected to be one of the most important impacts of climate ... more Changes in extreme precipitation are expected to be one of the most important impacts of climate change in cities. Urban floods are mainly caused by short duration extreme events. Hence, robust information on changes in extreme precipitation at high-temporal resolution is required for the design of climate change adaptation measures. However, the quantification of these changes is challenging and subject to numerous uncertainties. This study assesses the changes and uncertainties in extreme precipitation at hourly scale over Denmark. It explores three statistical downscaling approaches: a delta change method for extreme events, a weather generator combined with a disaggregation method and a climate analogue method. All three methods rely on different assumptions and use different outputs from the regional climate models (RCMs). The results of the three methods point towards an increase in extreme precipitation but the magnitude of the change varies depending on the RCM used and the spatial location. In general, a similar mean change is obtained for the three methods. This adds confidence in the results as each method uses different information from the RCMs. The results of this study highlight the need of using a range of statistical downscaling methods as well as RCMs to assess changes in extreme precipitation.
In this paper the effects of the aspect ratio (width to depth ratio, b/d) on the cost of a trapez... more In this paper the effects of the aspect ratio (width to depth ratio, b/d) on the cost of a trapezoidal concrete-lined channel (either power channel or irrigation channel) are analysed. The recommended b/d ratios given in the literature and their limitations are also discussed. Efforts are made to derive an equation for determining the optimal depth of the water from known parameters such as discharge, velocity and bed slope for concrete-lined channels. An equation for finding the minimum possible discharge within a specific velocity and bed slope is developed based on a semi-theoretical approach. The same approach is followed to obtain another formula for finding the maximum possible velocity for a specific discharge and bed slope. The obtained equations eliminate the iteration process commonly involved in finding the dimensions of a trapezoidal channel. A relation is developed for finding the aspect ratio in response to a given discharge and bed slope by using linear genetic programming techniques. The results show that the proposed model can be successfully applied in the design of lined channels as an alternative to existing methods.
Insignificant changes in the future system might be assumed due to the impacts of climate changes... more Insignificant changes in the future system might be assumed due to the impacts of climate changes. Temperature changes and anticipated precipitation suggest possible changes in floods. Extreme events will have bigger impacts on sectors with direct connections to climate, such as water sector; there is great belief that climate changes have the potential to critically affect water management systems. This study investigated how future climate change might affect the Inflow Design Flood (IDF) of Darbandikhan Dam. The study uses the projected downscaled daily inflow from Global Climate Models (GCMs) in comparative to the historical peak inflows. Flood frequency analysis based on historical data, both observed and statistically downscaled, was used to obtain the new design flood values. Analysis of the future projections of flood frequency analysis (FFA) reveals a general tendency toward changes in the magnitude of IDF.
ABSTRACT The global warming and the climate change have caused an observed change in the hydrolog... more ABSTRACT The global warming and the climate change have caused an observed change in the hydrological data; therefore, forecasters need re-calculated scenarios in many situations. Downscaling, which is reduction of time and space dimensions in climate models, will most probably be the future of climate change research. However, it may not be possible to redesign an existing dam but at least precaution parameters can be taken for the worse scenarios of flood in the downstream of the dam location. The purpose of this study is to develop a new approach for predicting the peak monthly discharges from statistical downscaling using linear genetic programming (LGP). Attempts were made to evaluate the impacts of the global warming and climate change on determining of the flood discharge by considering different scenarios of General Circulation Models. Reasonable results were achieved in downscaling the peak monthly discharges directly from daily surface weather variables (NCEP and CGCM3) without involving any rainfall-runoff models.
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