A comparative study on daily evapotranspiration estimation by using various artificial intelligence techniques and traditional regression calculations.

Evapotranspiration is an important parameter to be considered in hydrology. In the design of water structures, accurate estimation of the amount of evapotranspiration allows for safer designs. Thus, maximum efficiency can be obtained from the structure. In order to accurately estimate evapotranspiration, the parameters affecting evapotranspiration should be well known. There are many factors that affect evapotranspiration. Some of these can be listed as temperature, humidity in the atmosphere, wind speed, pressure and water depth. In this study, models were created for the estimation of the daily evapotranspiration amount by using the simple membership functions and fuzzy rules generation technique (fuzzy-SMRGT), multivariate regression (MR), artificial neural networks (ANNs), adaptive neuro-fuzzy inference system (ANFIS) and support vector regression (SMOReg) methods. Model results were compared with each other and traditional regression calculations. The ET amount was calculated empirically using the Penman-Monteith (PM) method which was taken as a reference equation. In the created models, daily air temperature (T), wind speed (WS), solar radiation (SR), relative humidity (H) and evapotranspiration (ET) data were obtained from the station near Lake Lewisville (Texas, USA). The coefficient of determination (R2), root mean square error (RMSE) and average percentage error (APE) were used to compare the model results. According to the performance criteria, the best model was obtained by Q-MR (quadratic-MR), ANFIS and ANN methods. The R2, RMSE, APE values of the best models were 0,991, 0,213, 18,881% for Q-MR; 0,996; 0,103; 4,340% for ANFIS and 0,998; 0,075; 3,361% for ANN, respectively. The Q-MR, ANFIS and ANN models had slightly better performance than the MLR, P-MR and SMOReg models.

Laboratory and numerical investigation of the 2-array submerged vanes in meandering open channel.

In the case of flooding in rivers, river regulation structures are important since scours occur on the outer meander due to high flow velocities. In this study, 2-array submerged vane structures were investigated which is a new method in the meandering part of open channels, both laboratory and numerically with an open channel flow discharge of 20 L/s. Open channel flow experiments were carried out by using a submerged vane and without a vane. The flow velocity results of the computational fluid dynamics (CFD) models were compared to the experimental results and the results were found compatible. The flow velocities were investigated along with depth using the CFD and found that the maximum velocity was reduced by 22-27% along the depth. In the outer meander, the 2-array submerged vane with a 6-vane structure was found to affect the flow velocity by 26-29% in the region behind the vane.