No abstract

The objective of the present study is to make a database that describes the leaching-permeability behavior of collapsible gypseous soil. The data will be implemented to develop ANN prediction models for predicting the saturated coefficient of permeability and percentage of solubility by weight. The complex soil behavior and tedious and time consume in soil testing have driven researchers to use Artificial Neural Network (ANN) as tool for prediction. The objectives of the study were to investigate leaching-permeability behavior of collapsible gypseous soils and to develop ANN models for estimating the saturated coefficient of permeability and solubility of the soils. The MATLAB R2015a software was used to predict the saturated coefficient of permeability and the solubility percentage by weight of gypseous soils. The dataset used in this work included (513) records of experimental measurements extracted from leaching-permeability tests conducted on gypseous soil samples taken from Baher Al-Najaf in Iraq. Four input variables were investigated to have the most important influence on the permeability and solubility percentage by weight. According to the achieved statistical analysis, the ANNs model have a reliable capability to find out the predictions with a high-level of accuracy. The gypseous soils exhibited a high rate of dissolution of soluble minerals content, which caused increase in the coefficient of permeability as the soil samples reach the state of long-term full saturation.

The problems caused by suspended sediment overloading in open channels are of great importance to the hydraulic engineers. One of the important problems caused by the sediment overloading during flood seasons is the change in bed level and corresponding water level of rivers due to its deposition on the river bed. At the upstream reaches, the bed slope is high, velocity is high and hence the rivers carry large amount of sediment during flood seasons. In this paper, eighty-one experiments on a laboratory open-channel of cross-section dimensions (20*50) cm and (10) m long. The experiments include using sharp crested weir in the last third part of the channel. Three heights of weir are used; namely half width of channel (B), equal to the width, and 1.5 times the width of channel). Also, three bed slopes of the channel are used; namely 0.015, 0.0225, and 0.03). In all experiments, the values of discharge are limited between 100 and 300 l/min. The concentration of suspended sediment is measured upstream and downstream the weir through each experiment to calculate the sediment reduction ratio (SRR%). The results of the laboratory experiments showed that the sediment reduction ratio increases with the increase of weir height and reaches about (63%) at a channel bed slope of (0.015) and a weir height 1.5B. When the discharge is more than (100 l/min), the highest values of sediment reduction ratio are obtained for the three slopes used and at weir height of 1.5B.

Assistant Professor (Graduate-Ph.D. Student), Department of Civil Engineering, College of Engineering, University of Babylon, Hillah, Iraq.

The drip irrigation method is the best method that has been used in the world among the other irrigation methods because of its good and high uniformity. To achieve the goals of using a drip irrigation system, it must be designed and operated properly so that rates and location of delivery of water in the root zone is matched to crop requirements. Generally, the criteria for a drip irrigation system operation are based on soil texture classes. Soil wetting is one of the most important parameters to determine the deep percolation rate and efficiency of the system. Knowledge of soil wetting pattern and its movement plays a large role in deciding depth and space of pipes, the design of irrigation scheduling and improving the efficiency of the drip irrigation system.The objective of this study is to develop an approach to operating the drip irrigation system in sandy and clay soils by improving the preparation of a computerized method of operating of high workability regarding the type of crops, its consumptive use, type of soil, frequency of irrigation and water distribution in the network .The study adopts two approaches as follows: field work approach and theoretical approach. In field work approach, soil analysis to physical conditions and chemical properties that affect a soil quality as well as suitability for growing plants. To observe the performance of this system, a study was conducted in an engineering laboratory of soil tests. For the theoretical approach a well known piece of software called CROPWAT was used for the calculation of crop water requirements and irrigation requirements based on soil, climate and crop data. Measurements of the conceptive use, discharge, velocity, wetted soil width, wetted soil depth, frequency of irrigation for the two types of soil with silt content were calculated.