Leila Kashi Zenouzi; Mohammadreza Yazdani; Mohammad Khosroshahi; Mohammad Rahimi
Abstract
Introduction: Groundwater is the only major source of water for drinking, agricultural and industrial purposes in the Marand city, and its vital importance makes sure that its quality is seriously considered. With qualitative zoning, the process of underground water quality changes is determined at any ...
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Introduction: Groundwater is the only major source of water for drinking, agricultural and industrial purposes in the Marand city, and its vital importance makes sure that its quality is seriously considered. With qualitative zoning, the process of underground water quality changes is determined at any time, place, and condition. It is possible to save time and cost by removing the stations with similar quality status and install new stations at times that are different or critical. In this paper, using the observational data of wells in Marand watershed, the spatial distribution of some groundwater quality parameters has been studied and analyzed using land-based methods. Geostatistical methods for estimating the unknown are remarkably effective.
Materials and Methods: In order to predict the spatial distribution of groundwater quality, data was collected from 48 water wells, semi-deep wells, springs, and others from the Water Resources Management Company. In this research, the spatial variation process of five qualitative parameters of water include EC, electrical conductivity, chlorine and sulfate (SO42-) anions, and Sodium Rate Absorption (SAR) and soluble solids (TDS): Total Dissolved Salts) were studied. After reviewing, some of them were omitted due to statistical deficiencies. Common time base was selected for studying the Blue Years 2003-2005, and the years 1388-88 and 1391-1391. Data homogeneity was evaluated for the statistical period between 1384-1384 by the sequencing test method. According to the mentioned method, there was no heterogeneity in the data. Statistical deficits were determined according to the correlation coefficient of a variable. Data were normalized using SPSS 18.0 software using logarithmic transformation method and their elongation and bending values were obtained in the range -2 and 2. In this study, for estimation of groundwater quality parameters including EC, TDS, Cl-, SAR and SO42-, piezometric wells data were used during the years 84, 88 and 91. Statistical analysis methods consisted of conventional Kriging method in Spherical, Gaussian and exponential modes and Weighted Inverse Distance (IDW) methods with power from 1 to 3 were studied. Cross-validation, G statistics (GetisOrd General G) and Morans Index were used to select the best and most suitable interpolation method. The values of all three evaluation methods were calculated and analyzed using Arc / GIS 10.3 software.
Results and Discussion: Based on the cross-evaluation method, the Kriging method is less effective than RMSE and ME in comparison with the Inverse Distance Weighting method. The zonation map of anion SO42- in year 2012 with G statistics and Moran index was 21.41 and 0.99 %, had the highest interaction in spatial structure and EC zonation map in year 2005 with Moran index and G statistic was 0.16 and 45 respectively has the least interaction of spatial structure. Charts of Changes in Quality Parameters showed that, water quality in latitude and longitude, values which were Cl, EC, SAR, and TDS and SO42 anions between the years 2005-2009 in the western-eastern part have been intangible and have been steeply sloping in the year 91. But in the North-South direction of 84 to 91 increased and then decreased in the middle of basin. Finally, by disconnecting the map of land use and geology of the watershed with the zoning maps of each of the parameters, it is concluded that due to the distribution of villages, residential areas and agricultural lands around them in the center and east of the watershed, the trend of groundwater quality parameters had been changed. The underground waters of Marand country watershed were influenced by human activities. Also, some geological formations and gypsum and dolomite minerals in the area in groundwater quality have led to an increase in TDS values and sulfidation of water resources in the eastern parts of the basin.
Conclusion: Groundwater quality is always influenced by various factors such as flow direction, groundwater level, climatic factors (precipitation, evapotranspiration, etc.), type and composition of geological formations of the region and human factors (land use, extraction of groundwater resources, Entry of household wastewater and agriculture into groundwater resources, etc.). Therefore, due to the importance of the use of groundwater resources and the limitations of its use, it is suggested that continuous monitoring of groundwater quality changes should be carried out using ground-based methods and in order to evaluate the effective factors of water quality parameters spatial distribution maps was prepared and analyzed. In the present study, based on the previous studies, two geology formation and land use types were selected to prepare map of water quality parameters and it turned out that both of these factors are the most important factors affecting the groundwater quality in the Marand country watershed.
Leila Bakhshandehmehr; Mohammad Reza Yazdani; Ali-Asghar Zolfaghari
Abstract
Introduction: In recent years, due to the reduction in surface water, utilization of groundwater has been increased to meet the growing demand of irrigation water. The quality of these water resources is continually changing, due to the geological formations, the amount of utilization, and climatic parameters. ...
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Introduction: In recent years, due to the reduction in surface water, utilization of groundwater has been increased to meet the growing demand of irrigation water. The quality of these water resources is continually changing, due to the geological formations, the amount of utilization, and climatic parameters. In many developing countries, the irrigation water is obtained from poor quality groundwater resources, which in turn, creates unfavorable circumstances for plant growth and reduces the agricultural yield. Providing adequate water resources for agricultural utilization is one of the most important steps needed to achieve the developmental targets of sustainable agriculture. Thus, this necessitates the assessment and evaluation of the quality of irrigation water. There are many proposed methods to determine the suitability of water for different applications, such as Piper, Wilcox, and Schoeller diagrams. Zoning of quality and suitability of irrigation water could represent the prone and critical areas to groundwater exploitation. Garmsar alluvial fan is one of the most sensitive areas in the country where traditional agriculture practices had turned into modern techniques and excessive exploitation of groundwater has caused an intensepressure on aquifers and increased water salinity. The aim of this study is to evaluate the suitability of groundwater for irrigation in a 10-year period (2002-2012) and its changes in this basin.
Materials and Methods: Garmsar alluvial fan is located in the North-West of Semnan Province. Semnan is situated in the Southern hillside of the Alborz Mountains, in North of Iran. The study area includes the agricultural land on this alluvial fan and covers over 3750 hectares of this basin. In order to evaluate the quality of groundwater in this area, the electrical conductivity and sodium absorption ratio of 42 sample wells were calculated. The raster maps of these indicators were obtained using Geo-statistical techniques. The suitability of irrigation water was determined by Wilcox diagram. Upon evaluating the data distribution and testing the data from Klomogrov-Smirnov normality test, normalization of the data was performed in SPSS software. Spatial correlation and spatial structure of variables were analyzed by drawing their semi-variograms in GS+ software. The most accurate variogram model was selected according to the lowest Residual Sums of Squares (RSS) and the highest correlation coefficient (R2). Interpolation and zoning of the indicators were performed in ArcGIS software and the Quality classes were determined.
Results and Discussion: According to the results of Kolmogorov-Smirnov test, none of the data series had normal distribution. Therefore, they were normalized through calculating the logarithm of variables. Fitting and the selection of variograms were performed in GS+ software and after the calculation of errors, kriging method with Guassian model was determined as the best fitting model. The correlation coefficient was 0.896 for electrical conductivity and 0.99 for sodium absorption ratio. Interpolation of indicators in ArcGIS implied fewer measurements of these indicators in north of the study area (Hableh-Rood inlet). The maximum measurement of indicators was observed on the western edge of the alluvial fan. In total, the values of both electrical conductivity and a sodium absorption ratio indicators in the western half of the area, in the vicinity of the third period domes, were more than the eastern half. The result of the water classification using Wilcox diagram represented the unsuitability of groundwater for irrigation in all of the study area. The area with unusable groundwater for irrigation has increased over the 2005 – 2009 period.
Conclusion: In this study, relying on the use of GIS and Geo-statistical methods, the quality of Garmsar basin groundwater has been evaluated. The electrical conductivity was applied to monitor water salinity, and Sodium absorption ratio was used to monitor alkalinity. The interpolation of these indicators was performed by Kriging method and Guassian fitting model. Likewise, in other studies, the Kriging method was introduced as an appropriate method for the interpolation of chemical parameters of the groundwater. The accuracy of various fitting models in the prediction of interpolated values differed according to the number and the distribution of sample points. In the current study, the Guassian fitting model was determined as the best model to interpolate both of the indicators. According to the maps, it seems that the third period domes in the western margin of the study area have a great influence on the quality of Garmsar’s surface water and groundwater. In total, the groundwater of Garmsar basin didn’t poss high suitability for irrigation, and was classified into two unsuitable and unusable classes. Moreover, according to the maps, the maximum area of unusable groundwater for irrigation in the area was observed in 2008.
S. Yousofi Moghadam; S.F. Mousavi; B. Mostafazadeh fard; M.R. Yazdani; A. Hemmat
Abstract
Abstract
Puddling is the most common method of land preparation of paddy fields in lowland rice cultivation. Puddling affects the physical, chemical and biological properties of soil and these changes are effective on rice growth. The soil that is more susceptible to changes in structure is easier ...
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Abstract
Puddling is the most common method of land preparation of paddy fields in lowland rice cultivation. Puddling affects the physical, chemical and biological properties of soil and these changes are effective on rice growth. The soil that is more susceptible to changes in structure is easier to puddle. This research was aimed to investigate the effects of different puddling levels on moisture content and bulk density of three dominant soil textures of paddy fields in Guilan province. The experiment was designed as factorial with completely randomized blocks having three replications. Undisturbed soil samples were taken from 3 different soils (silty clay, clay loam and loam) with cylindrical samplers with diameter and height of 50 cm. The soil samples were puddled by a laboratory apparatus. The puddling treatments were: P0 (no puddling), P1 (low puddling), P2 (medium puddling) and P3 (high puddling). Soil moisture content and bulk density of all soil samples was measured every 24 hrs for six days. Analysis of variance showed that puddling had significant effect (p < 0.05) on soil moisture content and bulk density. The water content of the puddled layers decreased with an increase in settling time. During drying period, P0 dried faster than P1, P2 and P3. In P0 to P3 treatments of the loamy soil, the moisture content decreased about 22.6, 16.3, 14.8 and 9.6% after 144 hrs past puddling, respectively. The trend was similar for other two soils. Measurement of bulk density in 0-15 cm depth showed that P1 caused bulk density of silty clay and clay loam soils to decrease 23.8 and 22.8%, respectively; however, it caused the bulk density of loamy soil to increase 4.1%. Bulk density increased with time in all the three soils. Bulk density increased with depth and this increase was higher for lower puddling levels. It seems that higher puddling levels are more suitable for paddy fields preparation because they loose water more slowly. To determine what puddling level is appropriate for different soil textures, parameters such as water infiltration, water retention and amount of water used should be investigated.
Key words: Puddling, Paddy fields, Soil bulk density, Soil moisture content, land preparation, Rice
