JWSS - Journal of Water and Soil Science

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Consumption of goods and services by households is an important index of their level of economic welfare. State of consumption distribution among households is an important index of equity in economic welfare. In this research, two important dimensions of consumption distribution have been studied: 1) Trend of changes of consumption distribution between Iranian rural and urban households 2) Changes of consumption distribution among households within rural and urban areas in different provinces. Secondary data were used in this research from rural and urban households surveys of expenditure and income for different years.

The results show that the ratio of urban household expenditures over rural household expenditures during 1965-96 has had a decreasing trend, though the gap is still high. To compare consumption expenditure distribution changes within rural and urban areas in different provinces, the data for the two years of 1986 and 1996 have been used. The results show that countrywide the Gini coefficients in 1986 and 1996 in rural areas were higher than those in urban areas in rural areas the coefficients were 0.458 and 0.421 and in urban areas 0.430 and 0.403, respectively, which indicate a decrease of 8.08 and 6.28 percent, respectively. Among the rural areas of 24 provinces, the Gini coefficients of 9 provinces increased and those of 15 provinces decreased from 1986 to 1996. This is while the comparison for the urban areas in the same provinces and for the same period indicates that the Gini coefficient of 6 provinces increased but that of 17 provinces decreased. No change occurred in the case of Tehran Province.

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For the study of field wind erosion and the design and evaluation of wind erosion control techniques, detailed observations of soil particle transport and vertical destribution of eroded soil particles are needed. The objectives of this study were: 1) To describe one device for soil transport particle measurement, i. e. the BSNE sediment catcher and 2) To assess vertical distribution of wind–eroded sediment with height in eastern Isfahan. The BSNE sediment catcher is a wind erosion sampler that traps eroded material at seven heights of 0.24, 0.60, 1.08, 2.00, 3.00, and 4.00 m above the soil surface. Each trap consists of a steel container with an inlet and outlet, mounted on a wind vane that rotates about a central pole. Before using the sampler in the field, it was tested and calibrated in the wind tunnel. The results showed that the average trapping efficiency with speeds ranging from 5.2 to 7.2 m sec^-1 for 4 different wind–eroded sediments was 0.44 to 0.68. However the trapping efficiency depended on wind speed, particle size distribution, particle density and type of sediment. The sampler had the lowest efficiency for particles < 44 μm. A BSNE sediment catcher was installed in Babaii Air Base. After a sampling period, the sediment in each trap was collected and weighed. The trapped materials were a mixture of saltation and suspension particles. Vertical distribution of wind–eroded sediment showed that the amount of soil collected decreased with increased height and the percentage of fine particles (<63μm) increased with height. The amount of trapped materials for each cm2 frontal intake with increased height were 12.00, 3.42, 1.44, 1.56, 0.75, 0.21, and 0.39 g cm-2, respectively, for the one sampling period.

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An intense storm occurred on June 6, 1992 in Mashhad city and its suburb, which caused a flood in the residential areas of Najafi, Chahar-cheshmeh and Nodareh. As a consequence of the abnormally huge flood, 25 people lost their lives and many structures were destroyed. Three recording rain gages located in Mashhad city (airport, College of Agriculture, and Water Authority) and one in the suburbs (Toroq dam) recorded the temporal distribution of the storm. Twenty five other nearby rain gages in the region also recorded the event. The rainfall hyetographs and rainfall amounts were analyzed. The results of this survey showed that: a) maximum rainfall intensity over a 15-minute duration in the College of Agriculture station, one of the centers of the storm, was 112 mm/hr, b) temporal distribution of rainfall for all recording stations were nearly the same, c) these patterns were in close agreement with all historic storms, and d) a return period of 380 years was implied via comparing the maximum rainfall intensity with relevant IDF curves. As a consequence, although an intense storm had happened, it was simply an outlier.

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The purpose of this study is to investigate the income distribution among the farmers of two districts of lowland and upland of Savojbolagh township of Tehran Province, Iran. The data of this study were collected by filling out questionnaires through interviews with 350 farmers who were selected by stratified random sampling. For analysis, such techniques as Gini Ratio, comparing the quintiles, and comparing means of different variables were used. The results showed that the income inequalities in the upland district were larger than in lowland. Income mean in the fifth quintile relative to other quintiles was considerably large and this fact was more serious in upland. As in income distribution, similar inequalities were observed in land distribution. The source of income of the farmers included income from agricultural activities (crops, livestock and fruit production) and from nonagricultural activities (second jobs and other incomes). Inequalities in total income in lowland and upland were mainly generated from agricultural sources of income while non-agricultural sources were less important. Inequalities in income from agricultural sources in lowland were related to livestock, fruits, and crops, and in upland to livestock, crops and fruits, respectively.

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To obtain soil-moisture characteristic curve experimentally is time-consuming and usually subject to considerable errors. So, many investigators have tried to predict soil-moisture characteristic curve by different models. One of these models predicts soil moisture characteristic curve based on soil particle size distribution and bulk density. In this model, soil particle size distribution curve is divided into a number of segments, each with a specific particle radius and cumulative particle mass greater than that of the radius. Using these data, soil-moisture characteristic curve was estimated. In this model, a scale factor, α, is used which may be considered as a constant, or obtained by logistic or linear procedures. The average values of α for clay, silty clay, sandy loam, two loam soils, and two silty clay loam soils were 1.159, 1.229, 1.494, 1.391, 1.393, 1.253 and 1.254, respectively. For most conditions, soil particle size distribution curve is not available, but only the percentages of clay, silt, and sand could be obtained using soil textural data, which is not enough to draw a precise soil particle size distribution curve. In this situation, a precise soil particle size distribution curve must be initially developed on the basis of which the soil moisture characteristic curve can be predicted. In this study, using soil textural data of seven different soils, soil moisture characteristic curve of each was estimated. In these estimations, logistic and linear methods were used to obtain the α value. Then, the results were compared with those of measured soil moisture characteristic curve. For estimation of soil particle size distribution curve, two extreme values for soil particle radius, 125 and 999 m, were used. The results indicated that using particle radius of 999 µm is more appropriate. On the other hand, it was found that for clay, silty clay, and sitly clay loam texture, it is more appropriate to employ a linear equation to determine for estimating soil-moisture characteristic curve while the logistic equation can be more appropriately used for loam and sand loam textures.

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In irrigation scheduling, one question is “how much is the optimal depth?”. In this study the optimal irrigation depth (by assuming the power distribution function and by taking into consideration the distribution function, which governs the data (normal distribution)) by considering the environmental effects was determined for three water management strategies (i. e. unlimited, limited nitrogen leaching and environmental protection) for wheat under center pivot irrigation system. The System layout in 32 hectare field was installed according to the ASAE standard. Four radial lines of catch cans were used at intervals of 6m (two radial lines of catch cans A and B, were installed on the maximum slope with 3˚ between every two rows and two radial lines of catch cans C and D, were installed on the minimum slope with 3˚ between every two rows). The field data were collected by the five different speeds of the center pivot system. The economical ratio (C) for three water management strategies were 31.19, 4.58 and 1.45, respectively. The optimum irrigation water was calculated for the three different management strategies. The results indicated that the lowest value of optimal irrigation depth was observed under the unlimited strategy, and the highest value of optimal irrigation depth was found for the environmental protection strategies (both with assuming power distribution and normal distiribution function).

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Some bioecological aspects of grape leafhopper, Arboridia kermanshah Dlabola, including: the egg distribution under the leaf surface, eggs and nymphs spatial distribution on the vine arms, the adult distribution on three strata of the vine canopy, the adult diel activities and the geographical distribution of this species in Isfahan province were studied. Samplings were done in the 1997. The egg distribution under the leaf surface was determined by repeated sampling during the season and the egg density was estimated on three regions such as the main and secondary vein, the leaf surface margins and others. Eggs and nymphs spatial distribution along the vine arms were studied weekly for six weeks by sampling an arm of five vines during the second generation, the leafhopper population was the highest. The adult spatial distribution on the vine canopy was determined by sampling three strata of the vine canopy using the D-vac apparatus. Diel activities were studied by sweeping nets fifty times per vineyard at the two hour intervals from 8 a.m. to 20 p.m. Temperature and the relative humidity were also measured in the shade once per hour. The presence and the abundance of this species in 87 vineyards in the different climatic conditions were studied by a sweeping net. The leaf margin and around of the secondary vein were preferred for the oviposition of the leafhopper. Adults, nymphs and eggs were more abundant in the middle strata of the vine canopy than others. The mean pattern of the daily activity of the adult indicated one peak at 8 a.m. and the other one at 20 p.m. Maximum temperature thereshold for the adult activities was 28º C. The study of the grape leafhopper distribution in isfahan province indicated that this species was distributed in the most vineyards, but was highly abundant in more humid conditions.

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The soil potassium status and effect of soil physical and chemical properties on it were investigated using 109 surface soils (0-30cm) from four regions in Guilan province. Neutral molar ammonium acetate extractable K (K-NH₄OAc), boiling molar nitric acid extractable K (K-HNO₃) and water soluble K were determined. Results showed that CEC and clay were normally frequency distributed while distribution frequency of other variables such as silt organic carbon and pH were not normal and have significant skew and kurtosis. In addition sand, K-NH₄OAc and K-HNO₃ has logarithmic normal distribution. Water-soluble potassium was affected by sand, pH, O.C and K-NH₄OAc (R²_a=0.73**). Ammonium extractable potassium was affected by soluble potassium, non-exchangeable potassium and CEC (R²_a=0.72**). Boiling nitric acid was affected by exchangeable potassium and silt (R²_a=0.55**). Geographic distribution of K-NH₄OAc data shows amount of it in central parts of Guilan, particularly Sepidrood river watershed is more than other regions. Fomanat region soils have the less clay, CEC, K-NH₄OAc and K-HNO₃. According this study about 68.8 percent of Guilan soils was classified in the range of medium to very low potassium status.

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The purpose of this study was to survey income distribution among the agricultural and non-agricultural rural families in Ghoochan town, Khorasan province. Data was collected by filling out questionnaires, and having interviews with 265 rural families, selected by stratified random sampling. And the obtained data was analysed through Gini ratios, comparison of the quintiles, Lourenz curve and income ratios. The results showed that the income distribution among the non-agricultural families was higher than that among agricultural families. The Gini ratio for agricultural families was 0.57 and for non-agricultural families was 0.45. The lowest Gini ratio was among the families employed for both agricultural and non-agricultural activities (GR=0.38). Therefore, it seems that income inequalities can be improved by making rural families in Ghoochan work in both agricultural and non-agricultural sectors.

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This study was conducted in a sugar beet field at Collage of Agriculture Experimental Station, Ferdowsi University of Mashhad, Iran. In order to describe the pattern of spatial variations and density of Chenopodium album, Solanum nigrum, Amaranthus sp., Portulaca oleracea, Echinochla crus-galli, and Convulvulus arvense as the main prevalent annual and perennial weeds of sugar beet fields, geostatistic methods were used. Samples were taken by systematic method from the corners of (7m × 7m) grids, using (0.5m × 0.5m) quadrates in three stages (before application of herbicides, after herbicide treatment, and before harvesting sugar beets). The integrity of spatial variation of variables was determined by using variogram functions and distribution maps of species. The variograms indicated that variations of all variables did not happen by chance. The maximum and minimum ranges of variation were observed in Solanum nigrum (by 142.7m) and Portulaca oleracea (by 1.5m), respectively. Both maximum and minimum ranges of variations were related to pre herbicide application. The highest and the lowest spatial correlations were related to Amaranthus sp. (in the third sampling treatment) and Solanum nigrum (in the first stage of sampling), respectively. The spatial distribution maps confirmed the patchiness distribution of the weeds. The patch of weed was constructed from a dense point at the center, gradually tapering toward the edges. The patches were skewed across the rows and irrigation channels. The structure of patches altered during the growing season. Any information on the distribution of weeds in the fields can be useful to improve decision makings in relation to applying the herbicides, selecting the herbicide type or applying the amount of herbicide. Also it can be useful to better design of weed control programs.

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  Soil particle size distribution and bulk density are used for estimating soil-moisture characteristic curve. In this model, soil particle size distribution curve is divided into a number of segments, each with a specific particle radius and cumulative percentage of the particles greater than that radius. Using these data, soil-moisture characteristic curve is estimated. In the model a scale factor, a , is used which may be considered as a constant, or obtained by logistic or linear procedures. F or most conditions, soil particle size distribution curve is not available, but only the percentages of clay, silt and sand could be obtained using soil textural data. In this situation, at first a precise soil particle size distribution must be developed, based on which the soil-moisture characteristic curve can be predicted. According to the previous studies, using particle radius of 999 µ m is more appropriate than radius 125 µ m. Also, adjusted coefficients for estimating soil particle size distribution curve for radii 1 to 20  µ m was obtained. In this study, using the soil textural data of 19 different soils from UNSODA database, soil-moisture characteristic curve of each was estimated with logistic and linear methods based on initial and adjusted soil particle size distribution estimation. The estimated values were compared with the measured data. The results indicated that for most soils, using the combination of logistic and adjusted particle size distribution estimation procedures is more appropriate than the previous methods.

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This study was performed in two barley fields, in Experimental Station, Agricultural College of Ferdowsi University of Mashhad in 2003. Sampling was done by systematic method in which samples were taken from the corners of 7m*7m grids using 0.5m 0.5m size quadrates in three stages (pre herbicide, post herbicide and pre harvesting stages). The results indicted that the density of annual weed seedlings in sugar beet- barley rotation was more than fallow- barley rotation, and the density of perennial weed seedlings in fallow-barley rotation was more than sugar beet- barley rotation. Map of species distribution and density confirmed patchiness distribution of the weeds. The shape and size of patches differed based on the field and weed species, but spatial distribution did not change considerably before and after the application of herbicide. Percentage of free weeds area was 11.5% and 1.5% in fallow-barley rotation and 0.6% and 0% in sugar beet- barley rotation in the first and second sampling stages, respectively. These results indicate beside emphasis on weed infestation. The result also indicates inefficacy of sugarbeet-barley rotation compared to follow-barley rotation. Apparently, the evaluation of management and paying special attention to weed dispersal within the field assist in the implementation of appropriate management strategy, which includes high efficacy, and profit for farmers as well as least damage to crops.

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Despite the existence of highly silty soils in southern Mashhad, there is no information about the aeolian and /or in situ formation of these soils. The main objective of this study was to determine the source of silt generation in this area. Granitic hilly lands in southern Mashhad have been covered by silty deposits. Based on the soil origin, four profiles including a residual soil covered by a silty layer, a residual soil with low amount of silt, a highly silty soil and an alluvial soil as well as a deep profile containing a succession of silty and alluvial materials were studied. Cumulative particle size distribution curve (CPSDC), depth distribution curves of silt/sand ratio (Si/S), Folk inclusive graphic standard deviation, Folk inclusive graphic skewness (SKI) and sand grain morphology analyzed by scanning electron microscopy (SEM) were determined and used to identify the source of the silty materials. Based on the results obtained, silty (L), residual-silty (R-L), residual (R), alluvial (A) and alluvial-silty (A-L) horizons were identified. CPSDC of L horizons is sigmoidal in shape and is easily distinguishable from that of the other horizons. In contrast, the CPSDC of alluvial and residual horizons is spherical in shape. CPSDCs for R-L and A-L horizons are neither sigmoidal nor spherical, but something in between. The L horizons have the highest SKI (very skewed to fine particles) and the lowest Folk inclusive graphic standard deviation (very badly sorted). In this regard, alluvial and residual horizons are intermediate. Because of the silt addition to R-L and A-L horizons, these horizons have a nearly zero SKI (symmetrical) and the highest Folk inclusive graphic standard deviation (very badly sorted). Particle size distribution histograms of R-L and A-L horizons are bimodal, a mode for sand and a mode for silt, suggesting two different sources. Depth distribution of Si/S, SKI and Folk inclusive graphic standard deviation of highly silty and other horizonz show a drastic change between L horizons and the other horizons-an indication of lithologic discontinuity and difference in origin. In conclusion, despite the possible contribution of granitic parent rocks to silt generation in the area, loess deposits recognized appear to have mostly been transported by aeolian movement.

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In a study of aphids and their parasitoids in wheat fields of Shiraz region, the species composition, distribution and seasonal dynamics of the dominant species were monitored during 2004-5.Collections were made from 1-3 hectare fields in 10 locations within 50 Km radius around Shiraz city. Species density was estimated by counting individuals present on 40 winter wheat tillers taken at random along 2 transects 5 m apart in the fields. Eight aphid and 3 parasitoid species were identified through this survey. Rhopalosiphum padi (L.) and Metopolophium dirhodum (Wlk.) with relative abundances of 33.94 and 31.33%, Aphidius rhopalosipi De Stefani-Perez and Praon volucre (Hal.) with relative abundances of 55.53 and 39.90%, were the dominant species of aphids and parasitoids, respectively. Seasonal dynamics of the above species were also studied in Badjgah, located 15 Km north of Shiraz city. Peak populations of the dominant aphids occurred between late May and first of June 2004-5, and those of parasitoids were seen 1-3 weeks later. A comparison between seasonal parasitism of the dominant parasitoids showed significant preferences of A. rhopalosiphi on R. padi, and P. volucre on M. dirhodum. Since the total parasitism of both wasps was nearly 30% of the two aphid hosts, attention should be paid to chemical control programs of wheat pests (such as Sunn pest) so that it does not disturb the efficiency of the aphid parasitoids.

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After construction of a dam across a river, sediments settle behind the dam. It is important for dam designers to estimate the rate and distribution of sediments in the reservoir. In this study, the accuracy of area-increment and area-reduction empirical methods to predict the sediment distribution of Dez, Dorudzan and Shahid Abbaspour reservoirs is evaluated. The last measurement of sediment in these reservoirs was in 2003 (Dez), 2005 (Dorudzan) and 2005 (Shahid Abbaspour). The comparison between actual sediment distribution and predicted sediment distribution by using area-increment and area-reduction methods showed the maximum error at the depth of sediment behind the dam. At higher elevations, the error decreased and reached zero when the elevation was maximum. For Dorudzan reservoir, which has the least sediment volume (31 Mm3), the area-reduction method is less accurate, as compared to the area-increment method (81% vs. 37.5%). For Dez and Shahid Abbaspour reservoirs, where their sediment volume is high (608 and 737 Mm3, respectively), the error of the two methods is relatively equal (in Dez, 29% for both methods, and in Shahid Abbaspour, 22% for area-reduction and 25% for area-increment methods). After long-time sedimentation, the shape factor decreased and reservoir type of all three reservoirs changed to 2.

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The application of N fertilizers with surface irrigation stream (surface N fertigation( is a key approach for fertilizer management. The main objective of this study was to investigate furrow fertigation management effects on distribution uniformity and runoff losses of nitrate in field scale. A field corn experiment was carried out with a complete randomized block design having 12 experiments. The field experiments were carried out in free draining furrows having 165 m length and 0.006 m/m slope in Karaj. Required urea fertilizer was applied in four stages: before planting, in seven leaves stage, shooting stage and earring stage. The first stage was accomplished by traditional method and other stages were applied with irrigation water (fertigation). Fertigation timing was respectively 60, 35, and 20 min in the three fertigation stages. Results showed that distribution uniformity of water and fertilizer of low half (DULH) provided high values for all experiments. DULH ranged between 88.0 to 99.0% and 89.7 to 96.0%, respectively for water and fertilizer. Also, distribution uniformity of low quarter (DULQ) ranged between 86.0 to 98.2% and 85.7 to 91.5%, respectively for water and fertilizer. Nitrate losses through surface runoff ranged between 5.7 to 42.0%. Duncan test results for comparison between different experiments showed that there was significant difference (p=0.95) between fertilizer losses at the level of fertilizer injection time of 60 and 35 minutes, but there was no significant difference between levels of 35 and 20 minutes.

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Precision in design of sprinkler irrigation systems and their proper management are very important for both development and also improvement of those systems. Therefore, the main objective of this study was to evaluate the design and management of the solid-set sprinkler systems in Dehgolan plain located in Kurdistan province. For this purpose, 10 solid-set sprinkler systems were selected randomly and a few performance parameters such as: Christiansen’s uniformity coefficient (CU), distribution uniformity (DU), potential application efficiency of low-quarter (PELQ) and application efficiency of low-quarter (AELQ) were estimated. The results of investigation showed the mean values of 66, 50.6, 44.8 and 43. 8%, for the above mentioned parameters, respectively. Also, the results of investigation showed both low PELQ values and water distribution uniformity of those evaluated systems compared to the recommended values by Merriam and Keller (1978). Moreover, due to deficit irrigation, except for one evaluated system, in all other systems, AELQ values were equal to PELQ. The results of our investigation also showed that non-suitable design and implementation of the evaluated systems were among the most important reasons for low values of PELQ, because of non-suitable operating pressure. The most important reasons for low water distribution uniformity were the simultaneous use of many sprinklers and also performance of different sprinklers models in a system. Finally, the results of our investigation showed poor operation for the evaluated systems in many cases.

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Selecting an appropriate particle size distribution (PSD) model for a particular soil may be important for a precise estimation of soil hydraulic properties. Various models have been proposed for describing soil PSDs. The objective of this study was to compare the quality of fitting of eight PSD models (Fredlund, Gompertz, van Genuchten, Jaki, Logarithmic, Exponential, Logarithmic-Exponential and Fractal) in 71 soil samples collected from Lordegan and Saman in Charmahal-va-Bakhtiari province, Iran. Coefficient of determination ( ) and Akaike’s information criterion ( ) were used to compare the goodness-of-fit of the models to the experimental data. Results showed that Fredlund model is best for describing PSD of silt loam, silty clay loam, silty clay and sandy loam soil textures. While Fractal, Exponential and Logarithmic-Exponential models produced the poorest-fit in silt loam, silty clay loam and silty clay, they had the best performance in sandy loam texture. The performance of Fredlund and Gompertz models improved with an increase in clay and silt content from 25 and 40 percentage, respectively. The performance of Fractal, Exponential and Logarithmic-Exponential models improved by increasing the sand content. Reverse correlation was observed between silt content and the performance of the Fractal model.

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Accurate estimation of runoff for a watershed is a very important issue in water resources management. In this study, the monthly runoff was estimated using the rainfall information and conditional probability distribution model based on the principle of maximum entropy. The information of monthly rainfall and runoff data of Kasilian River basin from 1960 to 2006 were used for the development of model. The model parameters were estimated using the prior information of the watershed such as mean of rainfall, runoff and their covariance. Using the developed model, monthly runoff was estimated for different values of runoff coefficient, , return period, , at different probability levels of rainfall for the basin under study. Results showed that the developed model estimates runoff for all return periods satisfactorily if the runoff coefficient value is taken 0.6. Also, it is observed that at a particular probability level and runoff coefficient, the estimated runoff decreases as return period increases. However, the rate of change of runoff decreases slightly as return period increases.

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Free and uncontrolled pasture grazing by animals may decrease soil aggregate stability through reductions in plant cover and subsequent soil organic C, and trampling. This could expose the soil surface layer to degradation and erosion. The objective of this study was to determine the influence of pasture management (free grazing, controlled grazing and long-term non-grazing regimes) on aggregate-size distribution and aggregation parameters by wet and dry sieving methods in two native pastures, protected areas in Chaharmahal va Bakhtiari province. The studied pastures were 1) SabzKouh pastures protected from grazing for 20 years, and 2) Boroujen pastures protected from grazing for 25 years. Soil samples were collected from 0-15 cm depth during the grazing season in summer 2008. Samples (finer than 2 mm) were analyzed for aggregate-size distribution and aggregation parameters by wet and dry sieving methods. Results showed that pasture management had a significant influence on aggregate-size distribution and aggregation parameters in the two areas. The two methods indicated that macro-aggregates in non-grazing and controlled grazing regimes were higher than those in free grazing regime, whereas in free grazing management micro-aggregates showed an opposite trend, and were greater compared with the other grazing regimes. Similarly, soil aggregate stability indices (i.e. mean weight diameter, aggregate geometric and ratio mean diameter) were all improved by non-grazing regimes, suggesting that animal grazing and trampling break down large soil aggregates due largely to compaction and reduced plant coverage. However, the extent to which grazing affects soil aggregation depends in large part on grazing intensity and duration, and the area involved.