نشریه مهندسی آب
سال هفتم شماره 4 (زمستان 1398)

Water systems have vital importance for human and provide vast domain of benefits for society in a format of resources and water services. Iran always suffering from water crisis since positing in the arid and semi-arid area, however, this tension has rising trend in recent years because of population growth, climate change, agricultural low efficiency, inaccurate land use pattern, economics condition and etc, which have dealt this matter with severe challenges. Most of the experts believe that Iran’s water crisis returns to lack of good governance instead of water scarcity which put Iran in crisis condition of supply and demand. In this paper firstly the effective challenges of efficient governance factors have been detected then, approaches to the compatibility of this factors will be forward.

The erosion of the substrate and the carrying of the material is called scouring. Due to the fact that one of the most important reasons for the destruction of the bridges, especially in flood situations, is the local scouring around the bridge, the determination of the local scour depth near the bridges is very important. An important role in designing bridges is in the face of this destructive phenomenon. For this reason, it is important to provide methods to control and reduce this phenomenon. Using SSIIM software, which is a time-consuming three-dimensional software, scour and scrubbing are checked using collar and splitter. It was found that simultaneous use of collar and gap has a significant effect on reducing the scour depth and the results of numerical modeling show a difference of 20-25% with the results of the experimental model.

Finding a suitable sanitation landfill is a complex process that depends on various factors and criteria. The purpose of this research is to select suitable location for sanitary landfill of municipal solid waste in Shushtar city based on environmental, health and economic criteria. In this research, the capabilities and methods based on the GIS and the process of fuzzy hierarchy analysis have been used. In the first stage, the parameters affecting the landfill location include geology, groundwater maps, distance from wells, land use, faults, slope of land, river, flood areas, protected areas, distance maps from main roads, layers The distance was from rural urban centers and were selected. After the standard maps were prepared, standardization of the layers was performed. Then, using the fuzzy hierarchy process analysis, the weight of the criteria was calculated and after applying the weights in the corresponding layers, the overlaying of the layers was performed with the help of fuzzy functions. The result of the combination of layers indicates the proper places for burial, waste. The final landfill map was classified as waste landfill. The results showed that the areas around the villages of Abbagni, Baneh Kazem, Shirkishan and Abdol Amir are suitable as suitable areas for urban waste disposal.

Hydraulic structures such as stilling basins, mainly are used for the purpose of energy dissipation in the lower zone of overflows, chute and diversion dams, in order to control hydraulic jump. In this research, the rate and effect of the jump is determined by laboratory tests. In these experiments, the sharp roughness of the bed of basin and also the change in the slope of the basin( structure ) from 0 to 0.3 percent were tested and parameters such as flow rate, initial depth, secondary depth, jump length of water surface profile, water head on overflow crown and water head prior to overflow were accurately measured. The analysis of data showed that the sharp roughness can effectively reduce the length of jump to to 35.5%. For sharp shape roughness, with an increase in the landing rate, the ratio y2 / y1 increases by an average of 6.5%. For a Froude number with a sharp roughness setting, the Lj / y2 ratio decreases by an average of 1.2%.

Crop residue burning has been proved to have negative impacts on regional atmospheric environment, soil organic material, reduce soil fertility for long term and soil and water pollution. Therefore, the aim of this study is to investigate the effect of Burning the wheat residue and sawdust on the water repellency of soil. For this purpose, sampling was done of soil surface (0-15 cm) in the east of Ahvaz city in four treatments: sawdust, burned sawdust, wheat residue and burned wheat residue, with 3 replications in ratio of 5, 10 and 25 presents by weight. for measure soil water repellency, was used water drop penetration time (WDPT) method. Analysis of obtained data and mean comparisons were done with using SPSS software and drawing charts with Excel. The results showed that the average water drop penetration time into the soil was 116.33 seconds, the soil was placed in the strongly water repellent class. With the addition sawdust and wheat residues to the soil, were decreased the amount of water penetration into the soil. So that the (WDPT) time from 116.33 in blank treatment decreased to 62.67 and 47.67 second (respectively) in the 25% treatment. The water repellency class was changed from strongly to slightly water repellent. But burned sawdust and burned wheat residues were increased the amount of water penetration into the soil, so that the (WDPT) from 116.33 in blank treatment increased to 923 and 1008.33 second (respectively) in the 25% treatment.

The atmospheric currents in the watershed are covered with snow and rain and return to the atmosphere in the form of evaporation, runoff. The present study was conducted in Koohrang watershed with the aim of determining the potential of rainwater harvesting using ANP and GIS techniques. After preparing basin maps such as land use, slope, etc., the amount of soil infiltration and initial maintenance was determined. Initial results showed that the Koohrang watershed has relatively good maintenance and the highest percentage of curve area is 0.8. The results of ANP method for determining the potential of rainwater harvesting showed that the hydrology criterion is better than the physical and topographic criteria, respectively. In the sub-criteria (land use, soil hydrological group and soil texture), land use performs better than the soil hydrology and soil texture groups in rainwater extraction, and the soil hydrological groups are 2.5 times higher than soil texture. The inconsistency coefficient obtained for comparing the metrics and sub-metrics is 0.8 and 1.2, respectively. By calculating all the effective parameters in calculating runoff potential, a potential map for this watershed was prepared in five floors. The map of rainwater harvesting potential in the Koohrang watershed is relatively good. The overall results showed that the network analysis methods considering different field parameters can be a suitable method for estimating the potential of rainwater harvesting and proper mediation for loss.

Investigation and prediction of climatic extreme values especially temperature is necessary for identifying climatic bottlenecks and opportunities in an area. The increase in greenhouse gas concentrations due to human activities has resulted in global warming and consequently changes in climate extreme indices. For conducting this research, the daily meteorological data of the Iranian Meteorological Organization, including mean temperature, minimum temperature, maximum temperature data for the Khuzestan synoptic stations, for a period of 30 years (1987-2016) were used. Calculation of temperature indices as defined by 1ETCCDMI Expert Group was estimated using RClimdex software. Mann-Kendall nonparametric test was also used to investigate the trend of climate change. Regular and simple kriging method with different models was used to estimate the spatial statistics of temperature data. According to the obtained results, the conventional kriging method with Logical Quadratic Model 2 with the least error rate was selected. The effect of changing the fit indices on the mean monthly temperature ranges from 250 to 314 km. The results of temperature analysis showed that warm indices had an increasing trend which was significant for indices such as summer days, tropical nights, warm days and nights at 5% level. Cold indices have a decreasing trend over the period under study. The results of temperature analysis correspond to the warming of the area and show the decrease in intensity and frequency of cold days and nights.