Use of Artificial Wetlands in Urban Storm Water Quality Management

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Numerical investigation of free surface flood wave and solitary wave using incompressible SPH method

Simulation of free surface flow and sudden wave profile are recognized as the most challenging problem in computational hydraulics. Several Eulerian/Lagrangian approaches and models can be implemented for simulating such phenomena in which the smoothed particle hydrodynamics method (SPH) is categorized as a proper candidate. The incompressible SPH (ISPH) method hires a precise incompressible hydrodynamic formulation to calculate the pressure of fluid, and the numerical solution is obtained by using a two-step semi-implicit scheme. This study presents an ISPH method to simulate three free surface problems; (1) a problem of sudden dam-break flood wave on a dry bed with and obstacle in the downstream, (2) a test case of the gradual collapse of the water column on a wet bed and (3) a case of solitary wave propagation problem. The model has been confirmed based on the results of experiments for the dam-break problems (in which was set up by the authors) as well as the collapse of the water column test case and analytical calculations for the solitary wave simulation. The computational results with a mean relative error less than 10%/4% for the wave height/wave front position, demonstrated that the applied ISPH flow model is an appropriate modeling tool in free surface hydrodynamic applications

Experimental Study of Hydro-suction Dredging Blockage Depth Under Different Hydraulic Conditions

Hydro-suction is an appropriate and economical method for dredging deposited sediment at reservoirs. In this study, a physical model was made and some experiments were designed to analyze the ranges of blockage depth in different hydraulic conditions. In the model, 80 tests were conducted using three diameters (d), three water heads (H) and different diving depths of pipe inlet (Z) from the sediment level to the blockage depth. In general, the results indicated that the more increase in the diving depth, the higher hydro-suction efficiency. In some of the experiments, a vortex flow was observed under the pipe inlet. The results indicated that the formed vortex flow have a positive effect on the hydro-suction efficiency. The results associated to the blockage depth approved that hydro-suction systems with larger pipe diameter and more water head have a greater blockage depth (Zb). The Froude number (Fr) analysis indicated that an increase in Fr would cause increment efficiency and blockage depth of hydro-suction system. Subject to a constant pipe diameter, the results revealed that increasing the H/d ratio equal to 66.66 and 133.33%, would enhance the Zb/d ratio equal to 58.89 and 112.22%, respectively

Evaluating performance of meta-heuristic algorithms and decision tree models in simulating water level variations of dams’ piezometers

Monitoring the seepage, particularly the piezometric water level in the dams, is of special importance in hydraulic engineering. In the present study, piezometric water levels in three observation piezometers at the left bank of Jiroft Dam structure (located in Kerman province, Iran) were simulated using soft computing techniques and then compared using the measured data. For this purpose, the input data, including inflow, evaporation, reservoir water level, sluice gate outflow, outflow, dam total outflow, and piezometric water level, were used. Modeling was performed using multiple linear regression method as well as soft computing methods including regression decision tree, classification decision tree, and three types of artificial neural networks (with Levenberg-Marquardt, particle swarm optimization, PSO, and harmony search learning algorithms, HS). The results of the present study indicated no absolute superiority for any of the methods over others. For the first piezometer the ANN-PSO indicates better performance (correlation coefficient, R=0.990). For the second piezometer ANN-PSO shows better results with R=0.945. For the third piezometers MLR with R=0.945 and ANN-HS with R=0.949 indicate better performance than other methods. Furthermore, Mann-Whitney statistical analysis at confidence levels of 95% and 99% indicated no significant difference in terms of the performance of the applied models used in this study

Analiza trenda mjesečnih strujanja Şenovom inovativnom metodom trenda

Trend analysis of monthly mean streamflows is essential for better water resources management and planning. In this study, Mann Kendall (MK), Sen’s method and Şen’s innovative trend method (ITM) were employed in order to examine the possible trends of monthly streamflows obtained from nine stations from three basins (Yakabasi and Derecikviran in Western Black Sea Basin; Durucasu, Sütlüce, Kale and Gomeleonu in Yesilirmak Basin; Şimşirli, Tozköy and Topluca in Eastern Black Sea Basin) located in Black Sea Region of Turkey. Based on the MK, streamflow data of Tozköy Station which is located in western part of the Eastern Black Sea Region showed a significantly increasing trend while a significantly decreasing trend was found for the Yakabasi, Derecikviran, Durucasu and Sütlüce stations which are situated in western part of the Black Sea Region. According to the Sen’s trend method, a significantly decreasing trend was seen in Durucasu, Sütlüce, Yakabasi and Derecikviran stations while Tozköy station showed significantly increasing trend. According to the ITM, low-medium values of Tozköy Station indicated slightly increasing trend while low and medium streamflow values of Yakabasi, Derecikviran, Durucasu and Sütlüce stations showed a decreasing trend. High streamflow values of Derecikviran and Sütlüce stations showed a decreasing trend while corresponding values of Yakabasi, Şimşirli and Tozköy stations indicated an increasing trend. It was showed that trends of low, medium, and high data can be easily identified by ITM which has some advantages (having no assumption such as serial relationship, non-normality, and, test number) over the Sen’s method and Mann-Kendall test.Analiza trenda srednjih mjesečnih strujanja je neophodna za bolje upravljanje vodama i planiranje. U ovom su istraživanju korišteni: Mann-Kendallova test (MK), Senova metoda i Şenova inovativna metoda trendova (ITM) kako bi se ispitali mogući trendovi mjesečnih strujanja dobivenih s devet postaja u tri bazena (Yakabasi i Derecikviran u zapadnom slivu Crnog mora, Durucasu, Sütlüce, Kale i Gomeleonu u slivu Yesilirmak, Şimşirli, Tozköy i Topluca u istočnom slivu Crnog mora) koji se nalaze u crnomorskoj regiji Turske. Na temelju MK, podaci strujanja s postaje Tozköy, koja se nalazi na zapadnom dijelu istočne crnomorske regije, pokazali su znatno povećanje trenda, dok su za Yakabasi, Derecikviran, Durucasu i Sütlüce u zapadnom dijelu crnomorske regije uočeni znatno opadajući trendovi. Prema Senovoj metodi trenda, znatno je smanjen trend na postajama Durucasu, Sütlüce, Yakabasi i Derecikviran, dok je postaja Tozköy pokazala znatno povećanje trenda. Prema ITM-u, niske i srednje vrijednosti postaje Tozköy pokazuju neznatno povećanje trenda, dok su niske i srednje vrijednosti strujanja za Yakabasi, Derecikviran, Durucasu i Sutluce pokazale trend smanjenja. Visoke vrijednosti strujanja Derecikviran i Sütlüce postaja pokazale su trend smanjenja, dok su odgovarajuće vrijednosti za Yakabasi, Şimşirli i Tozköy pokazale rastući trend. Pokazalo se da ITM može lako identificirati trendove niskih, srednjih i visokih vrijednosti podataka, što ima neke prednosti u odnosu na Senovu metodu i Mann-Kendallov test (nema pretpostavki poput serijskog odnosa, nenormalnosti i testnog broja)

Spatiotemporal variation of projected drought characteristics in Iran under climate change scenarios using CMIP5-CORDEX product

This study aims to assess the change of drought characteristics (intensity, duration, and frequency) under the effect of climate change in Iran using the modified standardized precipitation index (MSPI) and theory of runs on annual and seasonal scales for three near-future, mid-future (MF), and far-future climates. Hence, regional climate models extracted from South Asia-Coordinated Regional Climate Downscaling Experiments (CORDEX-SA) are applied. Regarding the result, MSPI could assign the standardized precipitation index (SPI) values better than the conventional form of SPI during the historical period (HP). The outcomes revealed that the northeast stations will experience a decrease in intensity (up to 24.57% in MF compared with HP) until 2100 at seasonal timescale, while the duration and frequency of drought will be increased. Although the greatest increase in intensity changes of droughts (up to 91%) until the end of the century will happen in the eastern and southwestern regions of Iran, these regions will face the maximum decrease in the duration (−30.54%) and frequency (−25%) of droughts compared with HP at seasonal timescale. In addition, regarding the outcomes of this study, strategies can be adopted to better manage water resources for various regions of Iran

Experimental study and numerical simulation of dam reservoir sediment release

In this research, experimental and numerical modelling of three-phase air, water, and sediment transport flow, due to the opening of a sluice gate was conducted in two scenarios, i.e., with and without a triangular obstacle. Numerical simulation was conducted using the Navier-Stokes equations with the aid of the volume of fluid method (VOF) to track the free surface of the fluid. For the experimental model, a glass-enclosed flume with 150 × 30 × 50 cm dimensions was used. The experiment was performed for an initial height of the water column at 20 cm and 10 cm sediment column. To evaluate the numerical model's performance, the simulation results were compared with the experimental observations using the average relative error %. The amount of relative error between experimental observations and numerical simulations, for the position and height of the wave flow for the three-phase air, water, and sediment flow, were obtained as 2.64% and 4.51% for the position and height of the water wave, and 2.23% and 2.82% for the position and height of the sediment transport, respectively, for the ‘without obstacle’ scenario, and 3.77% and 5.25% for the position and height of the water wave, and 2% and 7.23% for the position and height of the sediment transport, respectively, for the ‘with obstacle’ scenario. The findings of the study indicate the appropriate performance of the numerical model in the simulation of water and sediment wavefront advance, and also its weakness in the estimation of wave height

Performance of Archimedean copula functions in annual flood estimation, Case study: Qarah-Soo Watershed

Flood is known as one of the most devastating natural hazards which cause great damages to human societies, municipal, industrial and agricultural centers. Flood estimation in confluence points of rivers– for being the location for many infrastructures – due to economic and environmental matters receives a great importance. It is possible to estimate the flooding likelihood by examining the number of floods with specified return period. In this study, according to the statistical data of peak flows between 1358 to 1379 Hijri-Shamsi in the basin of the Qarah-Soo in Kermanshah Province, annual peak flows were estimated using copula in four models of 1) regression 2) summation 3) weight factor and 4) the nearest stations. For this, first, homogeneity and data quality were investigated. The probability distributions were fit to the data series and with regard to marginal distribution functions of upstream stations, joint distribution function at the confluence was obtained by the Archimedean copula functions. Based on the best copula function for upstream stations, Gumbel copula function was selected. Results showed that copula function in the form of regression was superior to the other models with a coefficient of determination equals to 0.711, RMSE equals to 79.387, Kendall's tau correlation coefficient equals to 0.872 and Spearman Rho coefficient equals to 0.677. Eventually, discharge amounts for different return periods were calculated according to the selected model

Management and Nonlinear Analysis of Disinfection System of Water Distribution Networks Using Data Driven Methods

Chlorination unit is widely used to supply safe drinking water and removal of pathogens from water distribution networks. Data-driven approach is one appropriate method for analyzing performance of chlorine in water supply network. In this study, multi-layer perceptron neural network (MLP) with three training algorithms (gradient descent, conjugate gradient and BFGS) and support vector machine (SVM) with RBF kernel function were used to predict the concentration of residual chlorine in water supply networks of Ahmadabad Dafeh and Ahruiyeh villages in Kerman Province. Daily data including discharge (flow), chlorine consumption and residual chlorine were employed from the beginning of 1391 Hijri until the end of 1393 Hijri (for 3 years). To assess the performance of studied models, the criteria such as Nash-Sutcliffe efficiency (NS), root mean square error (RMSE), mean absolute percentage error (MAPE) and correlation coefficient (CORR) were used that in best modeling situation were 0.9484, 0.0255, 1.081, and 0.974 respectively which resulted from BFGS algorithm. The criteria indicated that MLP model with BFGS and conjugate gradient algorithms were better than all other models in 90 and 10 percent of cases respectively; while the MLP model based on gradient descent algorithm and the SVM model were better in none of the cases. According to the results of this study, proper management of chlorine concentration can be implemented by predicted values of residual chlorine in water supply network. Thus, decreased performance of perceptron network and support vector machine in water supply network of Ahruiyeh in comparison to Ahmadabad Dafeh can be inferred from improper management of chlorination