جستجوی مقالات مرتبط با کلیدواژه « Water loss » در نشریات گروه « آب و خاک »

Improving soil physical properties and increasing water retention in the soil are management strategies in soil and water conservation and enhancing crop yield in rainfed lands. This study was conducted to investigate the role of tillage direction and wheat stubble mulch level in improving soil physical properties in rainfed land in Zanjan province. A field experiment was done at two tillage directions: up to the downslope and contour line, and five stubble mulch levels: zero, 25, 50, 75, and 100% of land cover equal to 6 tons per hectare. A total of 30 plots (2 m×5 m) were created. The results indicated that water infiltration and water content were considerably affected by tillage direction, whereas its effect on water holding capacity was not significant. This physical property of the soil was influenced by the inherent properties of the soil, including particle size distribution. The change of up to down tillage direction to the contour line increased soil infiltration to 11% and water content to 6%. The physical soil properties were wholly influenced by mulch consumption. Soil water content increased in mulch treatments along with water holding capacity and infiltration rate. The highest volumetric water content was at 100% mulch level (10.62%) which was 11% more than the control treatment. However, there was no significant difference between 100% and 75% mulch treatment. This revealed that the application of 75% stubble mulch in contouring tillage is a substantial strategy for improving soil physical properties and controlling water loss in rainfed lands of semi-arid regions.

The lack of water resources in arid and semi-arid regions like our country and the high volume of water losses through evaporation have made the importance of appropriate and practical methods to reduce evaporation from water reservoirs to be more and more clear day by day. Water is one of the most essential human needs. Evaporation is one of the climatic phenomenon in lakes and open space water loss. Different types of decreasing evaporation varied according to regional and economic conditions and environmental issues. On the other hand, in Iran the research conducted regarding reducing and controlling evaporation from water reservoirs is limited. Therefore, the current research is carried out with the aim of using new, economic, and appropriate to climatic conditions and accessible methods to reduce evaporation from water reservoirs, especially agricultural water reservoirs, in the Semnan region.

The efficiency of 6 physical covers (white plastic balls, empty bottles, bottles filled with straw and stubble, green canopy net with 50% density, green canopy net with 80% density, and white canopy net with 50% density), after preparation on the sunken Colorado evaporation pans, is evaluated in four periods of about 30 days in fall 2018 and winter of 2019 and spring and summer of 2021. Measuring the amount of evaporation from pans during 4 periods of approximately 30 days in different seasons of the year are done daily at 10:30 in autumn and winter and at 9:30 in spring and summer. It should be noted that the water temperature is also measured using an alcohol thermometer at the same time as the water level reading.

Based on the results of measurements, the rate of evaporation from the treatments of white plastic balls, empty bottles, bottles containing straw and stubble, green canopy net with 50% density, green canopy net with 80% density, canopy net White with a density of 50% and the control is equal to 259, 320, 213, 277, 369, 283 and 754 mm, respectively in four periods, which clearly shows a significant reduction in the evaporation of the applying six covers to the amount of 66, 58, 72, 63, 52 and 61 percent compared to the control treatment.

In general, according to the efficiency of all the treatments in this research and the application of these covers, taking into account the economic, social conditions and the feasibility of implementation, in order to reduce evaporation from open water reservoirs, especially agricultural water storage pools, it is evaluated as efficient and suitable. Generally, among the methods used, the most efficient related to the bottle filled with straw and stubble, followed by plastic ball treatments and green canopy netting with a density of 80 are evaluated as the most appropriate methods.

Loss of more than 30% of the incoming water to the country's drinking water distribution networks due to leakage from the network, has caused serious concern to the officials of the country's water and sewage companies and finding the location of leakage in distribution networks is one of the important issues and concerns of users and related organizations. Reducing the amount of leakage in water supply networks is one of the main methods of managing the water distribution network in different countries. Currently, several methods have been proposed to detect leaks in water supply networks. In this paper, hydraulic modeling of a real network flow by WaterGEMS hydraulic software and inverse solution of flow equations, having measured values of pressure in a number of network nodes, location prediction and leakage rate in the network Water distribution works were carried out in Mohiabad city located in Kerman province. First, the hydraulic model of the studied network was prepared and calibrated in the hydraulic analysis software and the amount of existing leaks was collected, and then by analyzing the network for different states and number of hypothetical leaks, the pressure values in different network nodes were calculated. In the second stage, using artificial neural networks, after network training, by presenting the measured pressures in some network nodes as input data to the neural network, the position and amount of possible leaks were predicted. Investigation and comparison of the results of hydraulic analysis of the network and artificial neural network showed a very high accuracy of artificial neural networks in estimating the amount and position of leaks.

Water resources management is one of the most important issues that are considered by experts in this field due to the reduction of rainfall and the reduction of groundwater levels. In this study, to reduce pipe fractures and water loss in Salehabad city (Comparison of water production and customer consumption data showed that there is more than 60 percent water loss in this network) field studies, pressure gauges, leak detection, and hydraulic analysis were performed by combining AutoCAD, WaterGEMS and GIS software. Points of the water distribution network that had more than 50 mH2o pressure were identified and then by field studies and using the method of closing the gate valves as a step by step, 6 points were identified as high-risk points of leakage. Therefore, with the check of the areas by the leak detector, 3 cases of pipe fractures were found and the remeasurement showed that the repair of these pipe fractures had reduced water loss by 20 percent. Depending on the urban texture and topography of the area, it was suggested to reduce the network pressure to 16 to 30 mH2o by installing a pressure relief valve in critical points of the network.

Sloping farmlands are the major sources of soil, water and nutrient losses in arid and semi-arid regions. Information about the impacts of different tillage practices on soil erosion, nutrient loss and crop nutrient uptake on the sloping farmland of semi- arid soil is, however, limited. This study was carried out to investigate the effects of tillage direction on soil, water, nitrogen and phosphorous losses and their uptake by plant in a rainfed wheat land. Field experiments were conducted in two tillage directions: downslope tillage and contour line tillage with four fertilization treatments: control, urea, triple superphosphate, and urea + triple superphosphate at the field plots with 1.75 m ´ 8 m in dimensions by using the randomized completely block design at three replications in Zanjan Township during 2014-2015. According to the results, Significant differences were found between the two tillage practices in soil loss (P < 0.001), water loss (P < 0.001), nitrogen loss soil loss (P < 0.001), and nitrogen uptake by wheat grain (P < 0.001), while phosphorous loss and its uptake did not show any statistically significant difference. Soil and water loss in the downslope tilled plots was 1.65 and 2.50 times higher than the contour line tillage, respectively. Nitrogen loss in the downslope tilled plots was 1.29 times more than that in the contour line tilled plots. Nitrogen loss in the plots was attributed to soil and water loss, so significant relationships were observed between nitrogen loss and soil loss (R2 = 0.59) and water loss (R2 = 0.55). This study, therefore, revealed that the tillage direction is an important factor controlling runoff, soil loss, and nitrogen loss and its uptake by wheat in the rainfed lands of semi-arid regions. Application of the contour tillage is, therefore, the first step to conserve soil and water and to improve soil productivity in these regions.

Today, the problems of water scarcity, limited water resources, high volume of evaporation, and water losses have highlighted the importance of ways to reduce the rate of evaporation from small and large reservoirs. In order to increase water supplies, reducing losses through evaporation have been investigated both in theoretical aspects and in practical applications in a number of countries (Ali et al., 2011; Barnes, 2008; Coleman, 2000). One of the most important methods for water conservation is the application of chemical films for reducing evaporation from open water resources such as reservoirs, lakes, and the like (Craig et al., 2007). These applications are especially important in arid and semiarid areas for the purpose of reducing evaporation rates from water surfaces. Most materials suggested by researchers for reduced evaporation have been the fatty alcohols containing 14 to 22 carbon atoms, such as Tetradecanol (C14), Pentadecanol (C15), Xadecanol (C16), Heptadecanol (C17), Octadecanol (C18), Nonadecanol (C19), Eicosanol (C20), Heneicosanol (C21), and Docosanol (C22).The two most favoured compounds used for evaporation control are Hexadecanol (C16H33OH) and Octadecanol (C18H35OH) although more complex variants are currently in development since they offer high resistance to water evaporation. In fact, small flakes of the solid alcohol spread spontaneously to form monolayers with a high molecular packing density (Manges and Crow, 1966). In this study, a new chemical method has been used to reduce the rate of evaporation. A new combination is made from polyvinyl butyral resin and Hexadecanol and Octadecanol as two fatty alcohols to reduce of evaporation from surface water sources and wastewater tailings dam of Sarcheshmeh Copper Complex.

Water deficit in arid and semi-arid regions is the major yield-limiting factor of crop plants in arid and semi-arid regions. So, prevention of water loss is the first major step to obtain proper crop yield in rainfed lands of these regions. This study was conducted to investigate the effect of mulch application on soil water retention under rainfed conditions in a semi-arid region. Toward this, five wheat straw mulch levels (0, 25%, 50%, 75%, and 100% of land surface cover) were used according to the randomized complete block designat three replications in a rainfed land with 10% steepness in Zanjan. About 6 ton straw mulch was used in 100% treatment. Fifteen plots with 2m×5m in dimensions were installed in the land and S was measured using the volumetric method in each mulched plot at 7-day interval during wheat growth period (from October 2015 to July 2016). Results indicated that SWR temporally varied during the growth period, so that the highest value of SWR in the mulched plots was observed in March, when the heavy rainfalls were occurred in the area. SWR was significantly related to straw mulch level (R2= 0.95, p< 0.001). Increasing SWR in the mulched plots was attributed with increasing soil water holding capacity. Application of straw mulch positively affected on the soil water holding capacity. The highest SWR was observed in 100% mulch (10.62%), about 11% more than that one in the contour plot. There was no significant difference between 75% mulch and 100% mulch in SWR as well as soil water holding capacity, so the application of 75% straw mulch can be considered as the optimum level for increasing soil water holding capacity as well as SWR in the rainfed lands of semi-arid regions.

Water use efficiency or the amount of dry matter production per unit of consumed water is one of the most important indices in irrigation scheduling. Accurate determination of water use efficiency¡ with taking into account various factors to better irrigation management requires the use of scientific methods and tools such as simulation model of irrigation. The aim of this study was to evaluate the effect of irrigation frequency¡ inflow rate and deficit irrigation on water use efficiency by using a seasonal simulation model to determine the best conditions to maximize water use efficiency. In order to determine the appropriate combination of design parameters such as inflow rate¡ cutoff time and irrigation frequency during the maize growing season¡ calibrated model for two different fields located in Karaj was run for different conditions and water use efficiency for each case was determined. The results showed that the highest water use efficiency for the college farm was happened in 3-day irrigation frequency and 50 percent deficit irrigation and for the Institute farm¡ the best condition was in 5-day irrigation frequency and 25 percent deficit irrigation. Using seasonal simulation models for furrow irrigation scheduling to increase water use efficiency and reduce water loss is recommended.

Performance evaluation of current status of irrigation systems and introducing practical approaches can help to use water more efficiently in field. This study was conducted to evaluate the furrow irrigation systems in corn farms of Moghan agro-industry and husbandry, Parsabad, Ardebil, in 2015. Evaluation of these systems was conducted in seven corn farms. The results indicated that the average water application efficiency, storage efficiency, infiltration efficiency, distribution efficiency, application efficiency of low quarter, distribution uniformity of low quarter and potential efficiency of low quarter are 41.90%, 92.48%, 75.28%, 91.44%, 36.85%, 85.01% and 59.72%, respectively. The reason for the low value of irrigation application efficiency is the difference between application efficiency of low quarter and potential efficiency of low quarter. Therefore, the poor management of surface irrigation was concluded. Proper furrow run and cutoff time and utilizing siphon can improve the current status drastically and will result in irrigation efficiency improvement.

Investigation of trend of underground water level changes in Lavar plain in Hormozgan province. The purpose of this study is to investigate the quantity of groundwater in the Lavar plain of Fin section in Bandar Abbas region, and identify and assess the consequences of additional extraction of groundwater and provide useful strategies for progressive problems. In order to do this research, 6 observation wells were studied in the period of 20 years (1964-1394). For this purpose all the meteorological, hydrological, hydrogeological, geological and geological data of the area have been collected and analyzed. After that, overdrawing, drainage and drainage losses in the plain groundwater area were calculated. Based on the calculations, the groundwater level of the plain has fallen 28.4 m in the 20-year period, which is an average of 21 centimeters a year on average. Therefore, if no serious and effective action is taken in this area, this plain will face not only environmental degradation but also economic and social problems in the future. To prevent the destruction of the aquifer, which is a vital issue, precise control over the removal of groundwater resources, preventing the development of agricultural landslides, artificial nutrition of groundwater table, promoting culture of conservation and greening of crops is recommended.

Design of a minimum cost canal section involves minimization of the sum of costs per unit length of the canal, subject to uniform flow condition. These costs are included with costs related to covering every meter of channel length, the cost per cubic meter earthworks and costs associated with water loss (including seepage and evaporation losses) as the objective function is considered in this study. Seepage and evaporation are forms of water loss in an irrigation canal, while the seepage loss depends on the canal geometry and evaporation loss is proportional to the area of free surface. In this study, the main constraint equation is Manning’s Formula. In addition, the minimum permissible velocity and Froud’s number are used for optimizing design canal as subsidiary constraints. In this study the Optimization algorithm based on directly search is used and a computer program in MATLAB was developed to solve the above mentioned equations. Feasibility simplex and optimal design to minimize costs of per unit of length of canal is improving with obtained non-dimension carves from results. Studies comparing results with other researchers, can be seen the effect of further constraints and earthworks and cover costs related to the final dimensions of the channel.

In more irrigation systems in our country، pumping stations equipped with fixed speed pump are implemented. These pumps in addition to waste water، consume excessive energy. Providing a method for adjusting the pumps functioning with obligations of operation can improve efficiency of water distribution and also productivity of energy. One of the choice toward this aim، is employing the variable speed pumps which consistent themselves with variable demand of system. In this study، by coding in MATLAB software، design of pumping stations equipped with variable- speed pumps was done for a drip irrigation system. Then regarding to variable demand of discharge and pressure during irrigation season، the designed system was evaluated and compared with some ordinary operation methods based on constant speed pumps. The results show that the utility of variable- speed pumps to supply the pressure head and discharge is definitely acceptable; while the water losses in ordinary pumping stations، depending on the type of station، is 16 to 36 percent.

In this research, a part of the distribution network in Lar city was selected for the calculation of real loss volume and leakage indicators in the network. Magnetic flow meter, data logger, and digital Dickson pressure gauge were installed at the input of the network. The pressure and flow rate were recorded in 15 minutes time intervals. Then, on various stages of research real water loss and leakage performance indicators, including ILI, UBRL and TIRL were calculated. Based on the results, the real water loss was between 12.1-18.7% with an average of 15.5%. The Technical indicator for real losses (TIRL) during measured periods were in the range of 97.2-188.5 lit.d-1.con-1 with the mean of 147.5 lit.d-1.con-1. Unavoidable background real losses (UBRL) were between 34.2-44.6 with the mean of 40.0 lit.d-1.con-1 and infrastructure leakage index (ILI) was between 2.8-4.2 with the mean of 3.6, which indicate that the network condition is undesirable. The mean recyclable leakage for each connection is 107.5 lit. d-1. con-1, which considering the number of service connections (18100), the total recyclable leakage in water distribution network in Lar city is 710199 m3.year-1.

Proper and organized use of natural resources can help preserve this valuable asset. Land use optimization science can be especially useful in this regard. The main purpose of the present study is to present an appropriate model for optimized allocation of lands with the purpose of gaining the minimizing surface runoff and sedimentation in Jajrood watershed. This watershed is located in the south of Tehran province, Iran. To determine the best land use combination, first the runoff amount in every land use was calculated, and then sedimentation was determined in every land use. Finally, the multi-objective linear programming model was used to solve the optimization problem based on Simplex Method. Results showed that the present land uses area was not optimized and require changes in existence land uses. The optimization results emphasize that the area of irrigated farming lands and rangelands should be reduced and orchards should be increased. The results also indicate that after optimization was employed, surface runoff decreased 73.03 percent and sedimentation decreased about 36.93 percent. The results of sensitivity analysis showed that total surface area of orchards and irrigated farming was the most sensitive factor to changes in runoff and sedimentation. In addition results showed that the most sensitive coefficient in runoff minimizing function is rangeland coefficient and in minimizing sediment function is irrigated farming coefficient, which is due to the high runoff and sedimentation rate of these two kinds of land uses.