M.R. Ansari; F. Soleimani; A. Ahmadi
Abstract
Introduction: Soil erosion is the most widespread form of soil degradation jeopardizing food security worldwide. In Iran, gully erosion is important because about 90% of the country has arid and semi-arid climates and rainfall is not adequately distributed. In such conditions, the absence or lack of ...
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Introduction: Soil erosion is the most widespread form of soil degradation jeopardizing food security worldwide. In Iran, gully erosion is important because about 90% of the country has arid and semi-arid climates and rainfall is not adequately distributed. In such conditions, the absence or lack of vegetation cover with increasing runoff causes more than 2 billion tons of soil losses annually. Therefore, conducting basic and applied researches on soil erosion via different methods for comprehensive management of natural resources is emphasized. The prerequisite for all kinds of erosion, such as gully erosion, is the prediction of the risk of gully formation in different areas susceptible to erosion. Materials and Methods: The study area is located in Ghaleh Gorg watershed which sub-basin of Shahid Modarres that large part of these farmlands has been destroyed by gully erosion. The purpose of this study was to apply fuzzy logic operators for gully erosion zoning. In this research, six effective parameters on soil erosion including mean weight diameter of aggregate, sodium adsorption ratio, salinity, percent of fine sand, silt and clay were determined according to standard laboratory methods. After re-classification, standardization of prepared layers was carried out by the Fuzzy method. Hence, Fuzzy-based layers were integrated using operators of Fuzzy algebraic sum, Fuzzy algebraic production and Fuzzy gamma with 0.2, 0.5, 0.8, 0.9 values and the obtained results were evaluated. The validation of prepared maps was done based on two methods of map matching percentage of areas with very high and high sensitivity with gullies map of the study area and quality sum index (Qs). Results and Discussion: The Fuzzy results of raster layers showed the relative accumulation of silt, clay and fine sand grains in the middle to western parts of the region due to leaching and soil aggregation of Aghajari formation with a high slope of >20%. The deposition of this sediments was with 0-5% slope in the middle and western part of the basin. Results of layer integration indicated the fact that the fuzzy summation and multiplication method are not suitable approaches for final mapping because of their high increasing and decreasing effects, respectively. About Fuzzy Gamma operator 0.2, the results revealed that about 17.07% of the area was in the high and very high-risk zone and 67.07% of the area was in the low risk zone. In Fuzzy Gamma 0.5, about 31.16% of the area was in high risk and 55.38% in low risk zone. And only 60.38 percent of the gullies was in the high-risk area. Thus, these both operators 0.2 and 0.5 cannot be an acceptable method for preparing the final fuzzy map. The results of gamma operator 0.8 showed that about 43.21% of the area was in high and very high risk classes and 42.45% of the area was in low and very low risk classes. In the gamma operator 0.9, about 60.92% of the area was in high and very high risk zone and 17.1% of the area was in low and very low-risk zone. Also, regarding the distribution range of gullies, 94.93% of gullies was in high and very high risk classes, which is more acceptable and better than gamma 0.8. According to the obtained results, Fuzzy gamma 0.9 with 94.93 matching percentage of areas containing very high and high sensitivity and maximum quality sum index (0.73) among different operators was selected as the best method for preparing Fuzzy map in the study area. Conclusion: According to the results of this study and its comparison with field observations, effective factors contributing to the initiation and development of gully erosion were sensitivity of the geological formations, soil texture type, salinity and alkalinity and non-implementation of biological and biomechanical operations to the soil and vegetation cover restoration. Around 3855 hectares (60.38%) out of 6327.5 hectares of the total studied area were at high and very high erosion risk. Furthermore, 2056 hectares (94.93%) out of the 2166 hectares of the gullies area were at high and very high risk of erosion, denoting the high accuracy of the final map. Among the available methods, Fuzzy Gamma 0.9 with the highest overlap between the area of high and very high-risk classes of the gully map (94.93%), and the highest qualitative sum index (0.73), was selected as the best fuzzy method for zoning in the study area.
Naser Arya Azar; Abolfazl Majnooni Heris; Reza delearhasannia
Abstract
Introduction: Water as the most limiting factor in agricultural production plays an important role in providing food for population of the country. Therefore, it is necessary to use optimal water resources of the country and increased its productivity. So to improve irrigation efficiency, as ...
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Introduction: Water as the most limiting factor in agricultural production plays an important role in providing food for population of the country. Therefore, it is necessary to use optimal water resources of the country and increased its productivity. So to improve irrigation efficiency, as well as the proper use of land and available water resources the best irrigation system should be used to supply plant water requirement. This selection is influenced by various factors such as cultivar type, available water content, water quality, soil characteristics, climatic conditions, selective cultivar pattern, labor force skill, and etc. The mentioned effective parameters depending on the region may change. Therefore, it is necessary to identify the homogenies areas for application of irrigation system.
Materials and Methods: The study area is the Ajichay River Basin in East Azarbaijan Province. This basin is located between 37° 30' to 38 ° '30 northern and 45° 24 ' 47° 53' eastern. In this study AHP method and GIS were used for identifying homogeneous zones of irrigated and rainfed areas. Analysis Hierarchical Process method is one of the most comprehensive systems designed for decision making with multiple criteria. This method was first proposed by Thomas El Saaty in 1980, which is based on paired comparisons. This gives managers the opportunity to study different scenarios. In the AHP model, we construct a matrix for comparing two factors. It has two important features, 1- Considering multiple quantitative and qualitative factors in problem solving and 2- The ability to analysis complex issues through hierarchical factors. In this study, to determine the homogeneous irrigation regions, first, the criteria was determined. In AHP method questionnaires were prepared, to score, these questionnaires were provided to the experts of this field. Then using the AHP method the criteria was compared with together. Finally, for each of the criteria, the interpolation maps in the GIS using geostatistical methods were obtained. These maps were divided into different zones using available tables and resources. The maps were combined in their scores in GIS and homogeneous irrigation areas (sprinkler, drip and surface irrigation systems) were selected.
Results and Discussion: In this study, the agricultural lands, including under irrigation lands, dry farming and gardens, were distinguished from non-cultivated lands. In agricultural land of Tabriz plain, applying sprinkler irrigation system has moderate restrictions and some areas face severe restrictions. In the southern parts of Bostanabad plain, the implementation of the sprinkler irrigation system is suitable. The possibility of sprinkler irrigation in dry farming lands was also investigated. Lands that located in the Bostanabad, Heris and Sarab plains will be relatively suitable for sprinkler irrigation. But for the Tabriz plain, the underground water and soil quality are low, applying sprinkler irrigation system has moderate restrictions. However, in Sarab plain, the appropriate area is visible. Implementation of drip irrigation system in the study area, in a large part of the Sarab plain and the southern parts of the plain of Bostanabad were appropriately determined. But in Tabriz plain and lands near the Urmia Lake, the implementation of this system has severe restriction. Like sprinkler irrigation, agricultural land of Tabriz plain has a moderate restrictions. Most areas of Heris, Bostanabad and Sarab plains, for applying this system will be relatively suitable. According to expert, water SAR and land gradients have more effect on the implementation of surface irrigation systems. If we can correct these two parameters with management and planning tasks, the implementation of this system will be appropriate in many areas of the basin. Most agricultural land has a moderate restriction on the implementation of this system.
Conclusion: The AjiChay Basin with an equivalent area of 12600 km2 is one of the largest sub basins in Lake Urmia basin. Since agriculture is important in this basin and also the quality of irrigation water in some parts of this basin is low, therefore, it is essential to pay attention to the type of irrigation method. Considering the parameters of water, climate and soil, suitable and unsuitable areas for surface irrigation, sprinkler and drip irrigation systems were determined. Thus, implementing irrigation system in agricultural lands in the margins of Lake Urmia and in some areas, will be severe restrictions. Getting away from Lake Urmia the groundwater quality, which is mainly used for agriculture, using irrigation systems is relatively appropriate.
Sona Azarneshan; farhad khormali; fereydoon sarmadian; farshad kiani; kamran Eftekhari
Abstract
Introduction: Assessing the soil quality of agricultural land is essential for the economic success and sustainability of the environment in developing countries. Recently, there are many types of methods for assessing soil quality, each of them uses different criteria. Considering that Qazvin plain ...
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Introduction: Assessing the soil quality of agricultural land is essential for the economic success and sustainability of the environment in developing countries. Recently, there are many types of methods for assessing soil quality, each of them uses different criteria. Considering that Qazvin plain is one of the most important regions of agricultural products in Iran as well as Middle East, so the assessment of the soil status using quantitative models of soil quality can be used as an indicator of the status of soils in relation to sustainable agriculture, optimal utilization of resources Natural and better land management. Among the quantitative models of soil quality index, cumulative model integrated quality index (IQI) and Nomero (NQI) index can be mentioned. Therefore, this study intends to evaluate the best quantitative and quality index model by examining and comparing two methods of selecting the appropriate criteria, Total data set (TDS) and Minimum (MDS) and the second order soil quality index, integrated quality index(IQI) and Nomero (NQI) index in Qazvin plain lands.
Material and Methods: The study area with 25220 hectares is located in east of Qazvin Province. The average annual precipitation is 275 mm and the soil moisture and temperature regimes are Thermic, Dry xeric and Weak Aridic, respectively. A total of 76 samples from the depth of 0-20 cm of the soil surface were studied and based on uniformity, soil type and land use. In this study, four types of criteria that affect the quality of soil in terms of their performance, including: upper limit, lower limit, optimal limit and descriptive function were selected. To qualify (normalize), the upper limit, lower limit and peak limit were selected. In the following, the Total Data Set (TDS) and the Minimum Data Set (MDS) set of data were used. In the TDS method, all of the measured characteristics (a total of 19 physicals, chemical and biological properties of the soil) were considered. Then, the degree of soil quality indices was determined based on the combination of TDS and MDS criteria and the final NQI and IQI quality indices.
Result and Dissection: Comparison of soil types in the region showed that the Aridisols had good, moderate and poor quality (19.35% of soil with good quality, 67.76% with moderate quality and 12.94% with poor quality), Entisols have good and medium quality (53.21% of the soil with good quality and 46.79% with moderate quality) and Inceptisols have very good, good, moderate and poor quality (96.9% Soils with very good quality, 66.73% with good quality, 15.85% with moderate quality and 13.44% with poor quality).
According to the TDS standard and the NQI model, the soils with qualities I, II and III were 30.67%, 66.86%, 47.2% of the total soils of the area (lands with poor quality soil quality were not observed in TDSNQI method). Therefore, according to this method, Aridisols has a very good, good and medium quality (13.26% of the soil with a very good quality rating, 73.88% with a good quality and 12.84% with a moderate quality grade), Entisols with The good quality (100% of the soil with good quality degree) and Inceptisols have a very good and good quality (28.11% of the soil with a very good quality grade, 71.88% with a good quality grade). The results of quantitative soil quality by using the MDS standard method and IQI model were showed, soils with very good, good, moderate and poor degree are 2.45, 16.45, 48.93 and 46.3 percent of total land area respectively.
The results of the combination of the MDS and the NQI model also showed that the soils with a very good, good and average grade are 30.67%, 66.86% and 47.2% of the total land, respectively. Also, the results of the combination of the MDS and NQI model showed that the soils with very good, good and average quality are 30.67%, 66.86% and 47.2% of the total land area respectively. The results of the evaluation based on 4 indicators showed that good quality (II) was prevalent in the studied soils and accounted for about 47% of the total area studied in Qazvin plain lands. The map of distribution of soil quality degrees, the distribution of soil degrees is relatively similar to all of four combination methods, the choice of criteria and model. By examining the linear relationship between the indices obtained from TDS and MDS criteria and the IQI and NQI indexes, it is observed that the correlation coefficient is more and more reliable than the NQI model when used in the IQI model (R2 = 0.77). So the highest correlation coefficient we observed two methods for selecting the TDS and MDS criteria when using the IQI model. In general, the results of this study indicate a better performance of the MDS criteria than TDS.
Conclusions: Therefore, the main results of this study suggest using the IQI model with the MDS selection method as the starting point in the global standard path for future studies. Special attention should be paid to the criteria chosen by the MDS. In addition, conducting a series of research into the future in order to modify the MDSIQI model can make it more relevant to international standards.
s. nazaryan; Ali Najafi nejad; N. Nura
Abstract
Introduction : Given its low and sparse precipitation both in spatial and temporal scales, Iran is nestled in an arid and semiarid part of the world. On the other hand, because of population growth, urbanization and the development of agriculture and industry sector is frequently encountered with increasing ...
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Introduction : Given its low and sparse precipitation both in spatial and temporal scales, Iran is nestled in an arid and semiarid part of the world. On the other hand, because of population growth, urbanization and the development of agriculture and industry sector is frequently encountered with increasing water demand. The increasing trend of water demand will widen the gap between water supply and demand in the future. This, in turn, necessitates urgent attention to the fundamentals of economic planning and allocation of water resources. Considering the limited resources and the declining water table and salinization of groundwater, especially in semi-arid areas forces us to exploit surface waters. When we evaluate the various methods of collecting rainwater, surface water that is the outcome of rainfall-runoff responses in a basin, is found to be a potential source of water and it can be useful to meet some of our water demand if managed properly. Water shortages in arid areas are critical, serious and persistent. Thus, water harvesting is an effective and economic goal. The most important step in the implementation of rain water harvesting systems is proper site selection that could cause significant savings in time and cost. In this study the potential of surface waters in the Aq Emam catchment in the east Golestan province was evaluated. The purpose of this study is to provide a framework for locating areas with water harvesting potential.
Materials and Methods: For spatial evaluation of potential runoff, first, the amount of runoff is calculated using curve number and runoff potential maps were prepared with three classes: namely, the potential for low, medium and high levels. Finally, to identify suitable areas for rain water harvesting, rainfall maps, soil texture, slope and land use were weighted and multiplied based on their importance in order to determine the appropriate areas to collect runoff
Results and Discussion : The results of runoff production potential indicated that May and June accounted for the highest runoff and it can be inferred from these results that both of these months are characterized with storms which was confirmed by interviewing local residents and as range-land covers the largest land use in the basin as well as low vegetation density in the spring and summer due to overgrazing, much more runoff has been produced which is in line with the studies conducted by the Department of Natural Resources of the Golestan province in Aq Emam watershed (2003) as well as findings of Eftekhari et al. The results showed that the highest areas of the sub watershed 8, and 3 were suitable for rain water harvesting. Thus, the appropriate areas for rain water harvesting in the sub watersheds do not have a uniform spatial distribution according to the results. It can be argued that these sub basins are characterized by 4 criteria to be appropriate for rain water harvesting, which is in confirmation with Miliniai et al. Also according to the results, the areas suitable for rainwater harvesting in each sub-basin have heterogeneous spatial distribution as confirmed by the results of Eftekhari and Jin et al. Given the final map from integrating data layers, it was found that the central part of the study area has a good potential for rainwater harvesting and as results show, suitable area for water harvesting in the watershed coincides with range-lands that have a moderate crown cover as confirmed by the results reported by Tabatabaii et al.
Conclusion: Finally it can be said that spatial evaluation and identification of proper areas for rain water harvesting is an important and necessary step in the application of rain water harvesting systems.
Keywords: Surface water harvesting, Spatial evaluation, Sub watersheds priority, GIS, SCS
habib beigi
Abstract
Boroujen–Fradonbeh plain is one of the nine main agricultural hubs of Charmahal Provine. The aim of this study was to define and map a deficiency index of soil micronutrients and the effect of wastewater application on it. For this, 200 surface soil (0-30 cm) samples were randomly collected and plant ...
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Boroujen–Fradonbeh plain is one of the nine main agricultural hubs of Charmahal Provine. The aim of this study was to define and map a deficiency index of soil micronutrients and the effect of wastewater application on it. For this, 200 surface soil (0-30 cm) samples were randomly collected and plant available concentrations of copper, zinc, iron, and manganese were determined. After variography and determining the most suitable spatial estimation method, maps of each micronutrient was drawn, normalized, and ranked. An integrated deficiency map was then constructed using the weights from rank maps. According to the maps of copper, zinc and iron, the available concentrations increased from west to east of the plain. This increase was attributed to the wastewater irrigation. The mean value of the integrated map, namely 85.5, indicated the seroius soil deficiency of micronutrients in this plain where 34% of the area was showing severe deficiency. Wastewater application has increased the overall availability of micronutrients by 4%. Sensivity analysis indicated that the map was most sensitive to zinc. Therefore, zinc concentration must be monitored with more precision and frequency across the plain.
Mohammad Taleai
Abstract
According to predictions, due to population increase and income growth, demand for food will continue to rise by over 3% annually. Wheat with providing over 33% of global world foods is one of the main sources for food security and meeting the needs of increased population. Land suitability assessment ...
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According to predictions, due to population increase and income growth, demand for food will continue to rise by over 3% annually. Wheat with providing over 33% of global world foods is one of the main sources for food security and meeting the needs of increased population. Land suitability assessment (LSA) is one of the basic approaches for obtaining maximum profit while protecting environmental resources for future. In this context, the suitability of arable lands of Miyaneh County is assessed for rain-fed wheat based on the FAO model and Fuzzy-AHP-OWA technique in GIS environment. In this study, with considering regional conditions and previous scientific researches, 8 environmental parameters (depth and texture of soil, erosion, slope, elevation, rainfall, temperature and degree days), 3 economic parameters (cooperatives, distance to markets and communication lines) and a social parameter (force labor) are used for land evaluation. These parameters were aggregated in two-stage using OWA model. Resulted suitability maps based on environmental criteria and fuzzy linguistic quantifier (LQ) includes: at least one, few, some, half, many, most and all, illustrate an overall accuracy, 26.7, 61, 84.3, 57, 44 , 8, 38.5 and 22% respectively, in compared with ground truth map.The final suitability maps based on social and economical criteria present 21.5, 61.8, 88.2, 53.7, 39.6, 38 and 19.3% overall accuracy. Based on this research finding,the proposed approach based on Fuzzy-AHP-OWA has great potential to model land use suitability evaluation problem. In addition, from the used criteria climate, soil, slope, number of co-operatives, distance to markets and communication lines are most important in evaluating land suitability for rain-fed wheat
