نشریه مهندسی آب
سال پنجم شماره 2 (پاییز 1396)

The overall objective of this study was to investigate the turbidity and total organic carbon (TOC) of raw water entering the treatment plant and the pre-ozonation unit's efficiency is to remove these compounds. Sampling from raw water and pre-ozonation water was done within 6 months and tested according to the standard method of the method. The results showed that there was a direct correlation between total organic carbon content and turbidity that's more in winter and in February with a high turbidity of 18NTU and TOC above 7mg / l. It was also found that the average pre-ozonation unit efficiency in the removal of total organic carbon with an average ozone dose of 3kg / hr and the contact time 18 minutes, is 20.52%, The highest TOC removal efficiency was in February (35.7%) and the lowest removal efficiency (14.08%) in May. The average turbidity removal efficiency is 61%, the highest and lowest percentages eliminated respectively were in February with 85.2% and 30% in July. Therefore, to increase the efficiency of pre-ozonation unit in removing organic compounds and ... It is necessary to carefully consider the process and design factors To increase the efficiency of removal of compounds.

Drought is a natural hazard with climatic nature. It caused by the precipitation anomalies and irregularities. This paper examines the phenomenon of drought and its spatial and temporal changes in Khuzestan province. In order to determine the severity of the drought, it used Standardized Precipitation Index (SPI) for spatial analysis benefits and temporal communication creation between occurrences of drought. In this study, 48 rain gauges and synoptic stations data from Khuzestan province have been used in years (1982-2014). Zoning maps of Standardized precipitation index (SPI) was drawn using ordinary kriging interpolation method during the study period and the driest and wettest years were identified. The 1999 and 2008 was severe drought years and extreme wet occurred in 1992. According to the results, 1999, 2007 and 2008 were years with the largest percentage of the area of drought and years 1991, 1992, 1997 and 2001 with the highest percentage of wet.

Rainfall trend could be evidence of climate change. There are different ways to review trends in rainfall time series are divided into two categories: statistical parametric and non-parametric. Linear regression method is from statistical and most common non-parametric method is Mann-Kendall. Considering the period of 33 years from 1980-81 until 2013-14, at 47 meteorological stations in Khuzestan province. Results showed that the slope of the regression line can vary from -13 to 0.8. More weather stations are a negative trend in the amount of rainfall and only Abdolkhan and Polezal stations have a significant positive trend. Mann-Kendall test for the existence of trends in rainfall at a confidence level of 5% was found that the negative trends are more stations and rainfall in the province is declining. Only stations of Polezal, Chamnezam, Harmaleh, Abdolkhan and Arabhasan have positive trend and Batvand shoor has Z value equal to zero with rainfall amounts are fixed in the period. Although all stations have a positive or negative trend, but only three stations Sousan, Sepid dasht sezar and Mollasani are significant at a confidence level of 5%. Although it cannot be concluded that climate change has occurred but due to the fact that most stations are reduced rainfall trend is alarming.

Sediments transported by water flow, an important factor in the formation of the geometrical structure and morphology of rivers considered. In this paper, the process of sedimentation Karun river was simulated using the Gstars3 software in the range of Ahvaz hydrometric stations to Farsiat a length of about 50 km. The purpose of this study was to select a suitable mathematical model for estimating the sediment transport rate in a way that is able to simulate accurately in the river. Calibration of sedimentary depositional model shows that for the the range the relationship Ackers- White (1973) and (1990) fitted to existing conditions are Karun River. Also sedimentation volume of hydrometric stations in Ahvaz and Farsiat 18.25 and 16.65 million cubic meters per year respectively was estimated. This indicates that the area is strongly depositing.

Important labyrinth spillway of hydraulic structures to regulate and control the flow of water in canals, rivers and reservoirs dams are considered important. Labyrinth spillway by increasing the length of the spillway crest on the slope in a given headwater they will increase the current carrying capacity. The main objective of this study is the effect of different screen angle and height of directorial on discharge coefficient on trapezoid labyrinth spillway. For this purpose, after doing dimensional analysis by Buckingham method, the relationship resulted in the discharge coefficient (Cd) function of parameters such as the angle of the blades (θ), blades height (hb) and hydraulic load ratio was to spillway height (H0⁄P). The present research experiments have been done on a flume was of 12m, a width of 30cm and a height of 50cm. the results showed that the rise directorial blade angle for a constant and fixed height (7/5, 15, 22/5) led to the discharge coefficient for all the hydraulic load decreases, the reason for this increase confusion and turbulence in the flow lines over spillway and followed by abnormality in bleeding time is different for hydraulic loads ratio the highest spillway discharge coefficient is an spillway with 30 degree angle blades. The results showed that the increasing discharge coefficient of a spillway control to a spillway was a height of 7/5 and 15cm blade respectively. In other words, the ultimate increase of a discharge

Iran has different climatic conditions due to its climatic characteristics. These climatic differences necessitate a suitable hydrological study in each region. Lorestan province, due to its mountainousness, is more humid than other parts. Therefore, this region is more favorable for flood occurrence and requires specific hydrological studies. The purpose of this study is to investigate the Krieger regional coefficient in mountainous areas. Therefore, based on the latest statistics published by the provincial water company, the statistics of the maximum instantaneous flow rates of 24 hydrometric stations were obtained in different parts of the province .The area of ​​the studied watersheds varied from 9550 km2 (Kashkan Poldokhtar) to 35 km2 (small plumber). The results of this study showed that the range of Chigger coefficients in Lorestan province catchment areas is much lower than the cultivars that have been recommended so far. Also, with the increase of the return period, the Krieger coefficient increases in mountainous regions with higher trend than arid regions. This issue should be considered in the planning and management of quantitative water resources.