JWSS - Journal of Water and Soil Science

Due to the limited freshwater, farmers have to use exotic waters such as seawater. One of the management methods is the conjunction use of fresh and seawater. The goal of this study was to investigate the effect of conjunctive irrigation with seawater and fresh water on the yield and yield components of Dill (Anethum graveolens L.) in greenhouse conditions. The research was done based on a completely randomized design including 3 replications as pot planting in Gorgan University of Agricultural Sciences and Natural Resources during 2016. In this study, there were five irrigation regimes (Irrigation with one-third of the sea water with tsp water, Irrigation with half seawater and then one more half with fresh water, Alternate irrigation with seawater and tap water, and Conjunction irrigation). The results inducted that the effect of different irrigation regimes on Umbrellas per plant, umbels per umbrellas and thousand kernel weights was highly significant (P<0.01), but the number of leaves per plant, branches number, the number of seeds per plant, and the seed number in umbrellas were significant at 5 percent level (P<0.05). In this study, all parameters were decreased significantly with the increase at all levels of water salinity. The results showed that one-third seawater and tap water irrigation regime, as compared to other regimes after control regimes, had the highest Umbrellas per plant, umbels per umbrellas, the number of leaves per plant, branches number, the number of seeds per plant, and the seed number in umbrellas. One-third, half alternate, alternate and the mixture of sea water and tap water resulted in the decrease of thousand kernel weights, reaching ti 13.6, 19.0, 30.1 and 65.1 percent, respectively.

Shortage of water resources and renewable per capita in last 30 years is put Iran on crisis threshold. Wastewater reuse is one of the battle solutions for water shortage and prevents wastewater depletion and environmental pollution. Thus, a pilot scale experiment was carried out to evaluate an integrated anaerobic/aerobic treatment for removal of BOD₅ and COD, also to reduction of hydraulic retention time by considering optimum removal efficiency. The pilot was an anaerobic/aerobic bioreactor type under continuous-feeding regime based on a central composite design. The pilot was studied in different retention time and aeration was carried out between 5-15 hours. According to different retention times for COD removal efficiency, 24 hours was selected as optimum hydraulic retention time, that it is comparable to those obtained for 48 hours and over in plant roughly and could remove COD and BOD in acceptable ranges, results showed that average removal efficiency for BOD₅ were 63.86 and 83.99 percent in aerobic and anaerobic phases, respectively. The average removal efficiency for COD was 76.5 and 74.35 percent for anaerobic and aerobic sections, respectively. The average removal efficiency for BOD₅ and COD in this integrated aerobic-anaerobic pilot 95.24 and 94.8 percent, respectively.

Today, the preparation of flood zoning maps is one of the basic and important issues in the study of development projects in the world; it is considered before any investment by the related organizations. In this paper, flood zoning was performed using the two-dimensional model HEC-RAS and GIS in order to assess the risk of the construction of a railway station near the bank of the Iranshahr River, in a range of 2500 meters. Two-dimensional hydraulic application could create a more accurate flow pattern in comparison to the one-dimensional model used in the previous studies, especially in the flood plain areas. In this paper, due to the important role of the topography of the area in ensuring the accuracy of the calculation, a Digital Elevation Model (DEM) was used with very high precision (about 2 meters), as obtained from aerial photos. The results of this study indicated the onrush of flood, depth and flow velocity in different return periods. Based on the comparison of water surface profiles in the floodplains with the return period of 100 and 25 years, the maximum difference between the water levels was 0.5 m, which seemed to be reasonable by considering the low slope of the studied area. The results of this paper, therefore, showed that the location of the railway station was in medium risk and the outskirt of floodplain.

Expert aquatic designers face many problems; among these, in hydrology, defective occurrences in time-series can cause errors in the ultimate results of the study. This more often happens in the regions where the number of hydrometric and rain gauge stations is limited. In addition, assessing, developing and maintaining the use of water resources require accessible long-term and high-quality quality hydrological time-series. Thus, this necessitates correcting the statistical flaws and magnifies the importance of how to deal with the problems in the hydrological analyses. Statistical methods are, currently, used to infill data and statistical gaps. In this study, in order to introduce a multivariate method for estimating the missing data on rainfall and runoff, in a hydrologic homogeneous region in the Mazandaran province, self-organizing map methods were examined under two scenarios and some reliable estimates were obtained. In this regard, the correlation coefficients between the observational data and the model output were calculated for the precipitation data up to 0.92 and up to 0.95 for the runoff data. Therefore, to avoid the reduction of uncertainty caused by the inadequate data in water resource management, this method could be used.

Surge tanks and air chambers are the most useful solution to deal with water hammer in water transmission systems (WTS). The optimal design of these protective devices can be effective in reducing the costs of constructing and operating a water transmission system. In this article, some software with the capability of simulating and optimizing these protective equipment is presented. To simulate the behavior of the system in the transient condition, the characteristic method was used. To optimize the number, dimensions and location of the surge tanks and air chambers, the genetic algorithm was employed. Constraints of the problem included the control of negative and positive pressures within the permissible range to prevent the cavitation and water hammer. To test the performance of simulation and optimization models, a well-known water transmission system in the previous research was selected as a case study. The results indicated that the critical heads were damped to a safer and allowable range; also, the total cost of the surge tanks and air chambers was reduced by 17% by the proposed method.

Water resources are limited in many areas of the world; sometimes, even these limited resources are negligently contaminated. One of the polluting factors of water is oil and its derivatives. Oil absorption using textiles is one of the common ways to separate oil from water. In this study, we used three types of textiles with different properties in order to make the filter. The experiments were performed using three different concentrations of 10, 20 and 30% oil. In this study, three types of BC, PET and PP textiles in the presence of horizontal and vertical drainages were investigated. The PET and PP textiles were made of nonwoven polyester and polypropylene fibers, respectively, and the BC textile was a two-component nonwoven textile of both polyester and polypropylene fibers that was used for the first time. Flow through the textiles was turbulent. Coefficients of flow were calculated using non-Darcy flow relations and the optimization method. The results showed that at low oil concentrations, the oil absorption had an inverse relation with the porosity and turbulent flow coefficients, but at higher concentrations, the effect of these agents was less; instead, the effect of the concentration and the intrinsic ability of the non-woven fibers was greater.  The best performance was related to PP and PET with the horizontal drainage that had 95 and 91 absorption rates, respectively.

The goal of this study was to investigate the effects of treated urban wastewater and different harvesting times on the yield and yield components of Sorghum (cv. Speed feed) in the greenhouse condition. The research was done based on a completely randomized design including 3 replications as pot planting in Ferdowsi university of Mashhad in 2016. In this study, the effects of four mixtures consisting of the moderations use of the treated urban wastewater and freshwater (0, 25, 75 and 100 percent mixture of treated urban wastewater and freshwater) and three harvesting times level (pre-flowering, after 50 percent of the plant to flowering, and grain filling stage) on the yield and yield components of Sorghum were evaluated. The results inducted that the effect of different moderations of irrigation regimes on all of them parameter was highly significant (P<0.01), but plant height was non-significant; it was also revealed that the effect of harvesting times on all of the parameters was highly significant (P<0.01), but leaf width was non-significant. The results also exhibited that the interaction effects of irrigated regimes and harvesting times on the leaf number, panicle length and width, leaf, panicle, and stem was highly significant (P<0.01), but plant height, stem diameter, branches number, and leaf length and width were significant at the  5 percent level (P<0.05). Also, the use of 25, 75, and 100 percent mixture of wastewater resulted in the  forage yield of  37.5, -29.3, and 12.9 percent (pre-flowering); -31, -15.3, and -47.4 percent (after 50 percent of the plant to flowering),  and -11.8, -35.7 and -28.4 percent (grain filling stage), respectively. The highest forage weights (46.2 g per plant) showed, in the study, irrigated by a mixture of 75 treated wastewater and 25 freshwater, and harvesting the plant after 50 percent in flowering stage; on the other hand, the best treatment in this study irrigation by the mixture of 75 treated wastewater and 25 freshwater and harvesting the plant after 50 percent in the flowering stage, Thus, using the treatment in farm experiment required the field research.