IRANIAN WATER RESEARCH JOURNAL
Year:2010 | Volume:3 | Issue:5|Papers Count:11

In order to evaluate the adaptability of Poterum sanguisorba in Shahrekord region, a field experiment was conducted fewer than two regimes of, deficit (once per two weeks) and full irrigation (once per week). Plant parameters which were measured include height, shoot dry weight, leaf number per plant, leaflet number per leaf, crude protein of shoot, number of seeds produced per plant and weight of 1000 seeds at three stages (1, 2 and 3 months after planting). These parameters were statistically analyzed by GLM method. The results showed that plant height, shoot dry weight, leaf number per plant, leaflet number per leaf and seed number per plant, weight of 1000 seeds and crude protein under full irrigation were significantly different (p<0.01) compared to deficit irrigation regime. The tallest plant heights of 15.3, 26.3 and 59.7 cm and greatest shoot dry weights of 1.4, 4.8 and 11.2 ton/ha were measured in the first, second and third stages respectively. Maximum leaf number per plant at first, second and third stages were approximately 15, 28 and 90 respectively. Under full irrigation regime the highest leaflet number per compound leaf were 11.6, 16.5 and 20 respectively at first, second and third stages respectively. Maximum seeds per plant of 271 and greater weight of 1000 seeds of 9.4 gram were produced under full irrigation regime. The highest level of crude protein extracted from shoot plant in full irrigation regime was 21.5% in the first stage, 23.5% in the second stage and 11.3% in third stage.

Wetted front position is important in optimal drip irrigation system design. Wetted pattern depends on parameters such as emitter discharge, applied water volume, soil texture and structure and land slope. This field study was conducted in four slopes (0, 5, 15 and 25%) and 3 discharge rates (2, 4, and 8 lit /hr.) in three application times (1, 2 and 4 hours). Soil texture was silt clay loam. Wetted pattern dimensions were measured by excavation sections parallel to the surface; moisture was measured in these sections 24 hours after finishing irrigation. It is recommended that if to consider changing wetted pattern position in sloping lands and moisture distribution, emitter position toward plant has to be improved. This can be determined by the demonstrated equations.

Wheat yield and water productivity are affected by water and nitrogen fertilizer management and climatic data. The aim of the present study was to assess the efficiency of artificial neural networks (ANNs) models in predicting winter wheat yields and water productivity using climatic data and seasonal water-nitrogen variables. The calibration and verification of the proposed models were accomplished using data from field experiments carried out in three years. The models were evaluated using several statistical error and goodness-of-fit measures, including the coefficient of determination, root mean square error (RMSE), mean bias error (MBA), and standard error (STE). The applied ANNs models had desirable accuracy in estimating crop yields and water productivity. ANN models consistently produced more accurate predictions than multiple linear regression models. The sensitivity analysis indicated that the productivity of wheat water has the highest level of sensitivity to the seasonal water use. The data generated here suggested that maximum and minimum wheat water productivity would be achieved with about 272 and 490 mm seasonal water use, which were determined 1.55 and 0.81 kg m-3, respectively. The applied ANNs can provide the background for promoting the water productivity for this strategic crop in different weather condition, and give us the possibility of the logical and economical use of water sources and nitrogen and also programming the combined usage of both resources in the study area.

Applications of geographic information systems (GIS) and remote sensing to estimate runoff of watersheds have increased in recent years. In this research, runoff curve number map of Birjand Mansourabad watershed was prepared by GIS data and Landsat ETM+ satellite images based on factors such as hydrologic for soil group, land use and land cover. The land cover map was determined using Normalized Difference Vegetation Index (NDVI) and VI Index and was classified as three groups: good, fair and poor. The watershed land use map was produced by Landsat satellite data and hydrologic soil group map was produced using field survey, watershed soil, and slope, geology and land use maps. The combination of these maps in GIS and using SCS table, runoff curve number and soil surface store Coefficient maps was obtained. Several rainfall-run off events were used to evaluate the accuracy of the result. It was found that predicted peak discharge using HEC-HMS model is similar to the observed peak discharge which indicates that the predicted result is reasonably accurate. On the other hand curve number obtained of observed flood data was compared with curve number computed by the model with error analysis of RMSE=3.57 and MRE=0.05 showing that the obtained results are accurate.

Determination of soil water content using Time Domain Reflectometery (TDR) method is recently considered modern and widely used. For practical applications, TDR needs to be calibrated based on relationship of dielectric constant and volumetric moisture content of soil. There are many empirical correlations between dielectric constant and volumetric moisture content that these equations don’t spot all of soil characteristic. The paper presents investigation of models accuracy for soil organic matter. This study was carried out in laboratory conditions based on complete randomized design separately for three soil textures including light, medium and heavy. The treatments in each experiment were different contents of soil organic matter (0.5, 2, 3.5, 5, 6.5 %) with three repetitions. In this study investigated the accuracy of Topp et al (1980), Mixing (1990), Malicki et al. (1996), Roth et al. (1992) and Oleszczuk et al. models (2004). The estimation potency of moisture content of these models survey with scales (RMSE) and (RE). The results showed that the models of Topp et al. (1980), Malicki et al. (1996) and Oleszczuk et al. (2004) with correlated coefficient 0.85, 0.84 and 0.84, least different and Roth et al. (1990) and mixing models, were most different in estimation of soil water content. Also in these models in high percent of soil organic matter and Clay, increased the amount of error in estimation of soil water content.

Chemical clogging can reduce geotextile permeability and obstruct drainage system. Calcium carbonate is a substance of low solubility which precipitates rapidly and forms the hard pan layer which results in clogging the drain envelope. The study was done on drain envelope in Abadan palm grove showed calcium carbonate was the main precipitated chemical in drain envelops. Laboratory column filter tests were conducted to simulate calcium carbonate precipitation on geotextile. Experiments performed with three types of geotextile including woven and nonwoven types. The result shows that carbonate calcium precipitation decrease the ability to percolate water through the geotextile. Calcium carbonate precipitation was collected at an aerated/non-aerated interface in the filters and surrounded the fibers as a layer. Chemical precipitation in geotextile cover surrounds the fibers and increase thickness with time. Hydraulic conductivity was decreased about 30 percent by chemical precipitation. Results also show that according to laboratory conditions, clogging time for two kind of nonwoven geotextile is 4 and 6 years.

The use of treated municipal wastewater for irrigation in arid and semi-arid regions like Iran was considered in recent decades. Wastewater irrigation could cause excessive accumulation of heavy metals in agricultural soils. Soil contamination with these elements lead to high metals uptake by crops and thus affect food chain. In this research the distribution of heavy metals in pepper tissues after irrigation with wastewater was investigated. For this reason a pot experiment was carried out and a completely randomized design was used. Different percents of treated wastewater were applied for irrigation. Increasing the percent of wastewater had no significant effect on lead and nickel soil and tissues concentrations. Lead and nickel in the available soil were still less than allowable. Before planting lead and nickel soil concentrations were almost the same but at the end of the growing season lead tissue concentrations were about 2 times more than nickel concentrations. The highest lead and nickel tissue concentrations were in pepper roots and the lowest concentrations were in pepper fruits.

Drought stress, as one of the most important environmental stress, plays a vitalrole in reducing crop yield all around the world. Super absorbent hydro gels which absorbs high amount of water are known as compounds which can reduce detrimental impacts of drought stress. In order to investigate the effects of super absorbent hydro gels on soil condition, an experiment was conducted at the institute of higher agricultural education of natural rources, Jiroft City. Three replications were used in the experiment. Drought stress condition was applied to the main plots at three levels, irrigation of 100% of crops water requirement (no stress), 75% (mild stress) and 50% (severe stress) and super absorbent levels were applied to the sup-plots at three levels (0, 200 and 300 kg/ha). Drought stress reduced grain yield, yield components and biological yield. Yield reduction was higher at 50% crop water requirement. On the contrary, super absorbent hydro gels particularly at 300 kg/ha diminished the detrimental effects of water stress on yield. Application of super absorbents caused higher number of rows per ear only under drought stress condition. Meanwhile, grain yield, biological yield, grain weight and number of grains per row were under both stress and non-stress conditions. It was concluded that application of super absorbent hydro gels can increase yield and yield components through increasing soil water holding capability for a long time.

In this study, drinking water quality of Bandar Abbas was investigated. There were collected 180 water samples from 15 stations and analyzed during 6 months in 2007. The clustering and factor analysis were used for classification of stations and pollutants. The analyzed water quality parameters were: pH, turbidity, total hardness, total alkalinity, TDS, EC, NO3, NO2, SO42-, Cl, Ca, F, Mg, HCO3-, and coliform bacteria. The results show that the main pollutants were: Hco3 and total alkalinity in June, EC and TDS in July, HCO3, total alkalinity and total hardness in August, HCO3-, EC, and TDS in September, HCO3- and total alkalinity in October and November. The maximum similarity between sampling stations were: 11 and 12 in June, 3 and 6 in July, 11, 3 and 14 in August, 11 and 14 in September, 12 and 14 in October, and 9, 4 and 14 in November. Therefore, HCO3- and total alkalinity are the main pollutants and station 12 has minimum similarity with other stations. The parameters were in the standard ranges. The EC, TDS, Turbidity, total alkalinity and total hardness in old regions of the city were higher than new regions. The trend of water quality parameters are ascending from September to November due to the decrease in water level of Minab dam and the use of groundwater resources.