Irrigation
A. Vaezihir; M. Khalkhali; M. Tabarmayeh
Abstract
Introduction Groundwater is an important resource for domestic, agricultural, and industrial purposes (Andualem and Demeke, 2019). However, the growing population and advanced irrigation technologies have significantly led to increased groundwater exploitation resulting in aquifer depletion. Exploitation ...
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Introduction Groundwater is an important resource for domestic, agricultural, and industrial purposes (Andualem and Demeke, 2019). However, the growing population and advanced irrigation technologies have significantly led to increased groundwater exploitation resulting in aquifer depletion. Exploitation of groundwater from fractured rock aquifers using wells to supply drinking water is more sustainable than the utilization of springs with low and variable discharge. In the case of drought and periods of critical condition of water usage, springs of fractured rock aquifers may dry up or decrease making them unreliable water resources to supply drinking water. Over recent decades, the use of fractured rock and karstic units as a remarkable water resource is known as a valuable source of freshwater worldwide. However, these aquifers are extremely vulnerable to contamination due to their unique hydrogeological characteristics and require more protection (Zarvash & Vaezi, 2014). These resources contribute to providing more than 70% of the rural population and around 50% of the urban population with drinking and household demand needs. Since the degree of development of karst landforms varies substantially from region to region, exploring groundwater potential zones in karstic or fractured rock domains across the world is important, which is mostly achieved using evaluating affecting factors in creating the groundwater occurrence. This evaluation is done by incorporating weighted factors such as Weighted Overlay, Weighted Sum, and Fuzzy Overlay and utilizing geographic information systems (GIS) or other remote sensing techniques, which is addressed frequently in literature summarized by Vaezihir and Tabarmayeh (2016); Seif and Kargar (2011); and Amiri et al. (2021). Considering the importance of such issue, this research aims to investigate the potential of karstic or fractured rock resources in West Azerbaijan to gain more insight into this valuable resource of groundwater. Materials and MethodsWest Azerbaijan province, with an area of 43,660 km² including Lake Urmia, is equivalent to 2.65% of the total area of Iran and located in the Alborz-Azerbaijan structural zone with a mean annual precipitation of about 370 mm. The maximum temperature of this province, dominated by a semi-arid and Mediterranean climate, is recorded in Shahin Dezh and Miandoab, and the minimum is measured in Chaldoran, and Tekab Metrological Stations, respectively. About 78% of the total area of West Azerbaijan province is formed by karstic units with more spatial distribution in the southern area. This karstic area encompasses 71% of the total province springs with 59% of the total discharge. In the current research, lithology unit types, fracture density, elevation, slope, aspect, drainage density, and vegetation coverage, along with the precipitation, area, and humidity index as the main factors were regarded as governing factors in the development of karst aquifers, have been considered to evaluate the potential groundwater resources. After the preparation of all affected layers using various data resources including available geological maps digital elevation map of West Azerbaijan Province obtained from the Geological Survey and Mineral Exploration of Iran, Landsat satellite data, the Fuzzy logistic and SUM and Weighted overlay technique has been used to prepared groundwater potential zone. Results and DiscussionThe groundwater potential zone were determined through combining 9 affected layers in developing the groundwater resource. The results obtained based on employing both weighted overlay and SUM were classified into 5 classes including low, very low, medium, high and very high potential zones. The index value in SUM methods estimated to be 16.24, 26.24, 24.24, 20.95, 12.13%, while it changes to 22.82, 24.13, 22.14, 16.23, and 14.67 respectively. Overlaying the location of springs as an indicators of groundwater resource on hardrock and karstic domain on generated maps showed that 30.9 and 33.08 percentage of springs fall in area with the high and very high potential zone, respectively. A significant differences on maps generated based on two mentioned technique, particularly in area classified as low potential zone with 24.13 and 16.24 percent in weighted overlay and SUM. ConclusionInvestigation of the groundwater potential zone by integrating the layer provided by Fuzzy logic technique through two SUM and weighted overlay methods indicated the province of Azerbaijan Arabi has a moderate level of classification. However, in some areas, there were significantly higher or lower potentials.
A. Vaezihir; mehri tabarmayeh
Abstract
Introduction: Ground water as a dynamic and recyclable natural resource in fractured rock terrains are characterized by single and double fracture porosity models. Due to the heterogeneous nature of the medium hydraulic properties of these rocks are mainly controlled by fracturing and influenced by multivariate ...
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Introduction: Ground water as a dynamic and recyclable natural resource in fractured rock terrains are characterized by single and double fracture porosity models. Due to the heterogeneous nature of the medium hydraulic properties of these rocks are mainly controlled by fracturing and influenced by multivariate parameters. This heterogeneity is due to various compactions , density of fractures and degree of weathering. Therefore, regarding the importance of ground water resources in social and economic development, the study of fractured rock aquifers especially in arid and semi-arid regions is of interest. In this paper zoning of aquifers has been carried out according to their potential using concept of overlaying of drastic parameters on groundwater development.
Materials and Methods: The study area is located in the southwest of Marivan city, Iran. Due to the existence of sandstone and igneous formations and tectonic activities, fractured aquifers, was probably developed. In this paper, Simple Additive Weighted (SAW) and Analytic Hierarchy Process (AHP) using eigenvectors were used to find ground water resources. In order to evaluate the groundwater potential sources, lithology, fracture density, elevation, slope, aspect, drainage density and land use parameters were considered. For this purpose, layers of these information were provided in the IDRISI and GIS medium and then sorted and weighted using the weighted cumulative integrate AHP and SAW methods. The index of ground water potential sources was determined by multiplying each raster layer by its corresponding weighting factor assigned by the AHP and SAW methods. Finally the potential groundwater zoning map was generated by cumulating the seven individual rating and weighting maps.
Results and Discussion: According to the output map of AHP model, 56.8 percent of the total study area had a very high water potential and this includes 94.26 percent with high potential and areas with moderate, low and very low water potential included 22.96, 24.96 and 17.07%, respectively. Regarding to the paired comparison AHP model, despite of direct determination of the weight of the SAW model, weight classes of each criterion were achieved according to the preferred class of all classes to the criteria. It is normal that the results from these two models will be different, so that according to SAW method, 0.73,13.07,30.16,18.65,7.37% of study area included area with very high, high, moderate, low and very low groundwater potential resources, respectively. For validation of two mentioned models (AHP and SAW models), The map of springs location were overlaid on the map of potential sources of groundwater of these two methods and the results showed a good agreement with the model of the position of the spring.
Conclusion: In This study the AHP and SAW models were used to finding underground water sources. The results showed that in both methods, highly potential water resources areas were mainly located in the northwest of the study area and the west and southwest area had higher potential water resources relative to the east part of the study area. This could be due to low slope and elevation or may be related to the alluvial deposits which covered upper parts of the hard rock with low thickness and this plays a main role in recharging of hard rock.
However, comparing the results of the two methods showed that AHP method has better results than the SAW. The result of AHP map showed that the east and center part of the study area had moderate to high groundwater potential which consist of about 50% of area.
M. Tabarmayeh; A. Vaezi Hir
Abstract
It is more expensive to remove pollution from groundwater than to prevent it. Delineation areas that arevulnerable to surface pollutants is one of methods to prevent pollution of groundwater resources. Focusing on this issue, DRASTIC model was used for evaluation of vulnerability of Tabriz-plain aquifer ...
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It is more expensive to remove pollution from groundwater than to prevent it. Delineation areas that arevulnerable to surface pollutants is one of methods to prevent pollution of groundwater resources. Focusing on this issue, DRASTIC model was used for evaluation of vulnerability of Tabriz-plain aquifer to pollution and the aquifer vulnerability map was prepared. The study shows that main zone of the aquifer’s groundwater is low to modrate vulnerability to pollution (DRASTIC Index of 120-40) that consist of about 55.84% and areas with low, moderate to high, and high risk zones comprise 21.81,22.08.% and 0.26% of the studied area, respectively Two tests of sensitivity analyses were carried out: the map removal and the single-parameter sensitivity analyses. Based on the characteristics of the studied area, the results from both map removal and single-parameter sensitivity analyses showed that the depth to water table has the most significant impact on the vulnerability risk zone. By overlaying of the vulnerability and landuse maps the areas where are subjected to potential release of pollutants from the agricultural activities were determined .Nitrate ion concentration and SINTACS model confirms the results of the vulnerability assessment.