Nosrat Aghazadeh; Manochehr Chitsazan; Yahya Mirzaee; Hamed Ebrahimi
Abstract
Due to various sources of contamination in the urban aquifers, the potential for pollution of groundwater resources is high. Thus, the vulnerability of groundwater resources can be very effective in identifying vulnerabilities and sensitive groundwater aquifers. The aim of this study was to present a ...
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Due to various sources of contamination in the urban aquifers, the potential for pollution of groundwater resources is high. Thus, the vulnerability of groundwater resources can be very effective in identifying vulnerabilities and sensitive groundwater aquifers. The aim of this study was to present a modified DRASTIC Model to determine groundwater vulnerability in Urmia urban aquifer. To this end, parameters with low impact such as slope and aquifer media were ignored from the DRASTIC Model. Instead, land use, urbanization index, water value and pollution sources were added to the model. Also, the impact of unsaturated zone media and recharge layers were corrected. Results of the modified DRAST-VUL Model in the study area demonstrate that in most areas, the risk of pollution is low to moderate and the vulnerability in 29% of study area is high due to agricultural and industrial activities and low groundwater depth. Considering the results, the vulnerability index is the most sensitive measure to the parameter of pollutant sources, land use and the unsaturated zone. The sensitivity of the model to recharge, transmissivity and water value parameters were low due to the increase of impermeable surface in urban area. Based on positive results obtained from model validation through nitrate, the proposed model can be considered as an effective tool for the protection, revention and optimal utilization of groundwater resources in the study area. Also, this vulnerability model can be used for other urban aquifers.
Mehdi Teimouri; Omid Asadi Nalivan
Abstract
With the increase in population, the importance of groundwater resources as one of the most important sources of drinking water in the arid regions becomes apparent. In this research, in order to determine the areas with groundwater potential in the city of Torbate Jam and prioritizing the effective ...
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With the increase in population, the importance of groundwater resources as one of the most important sources of drinking water in the arid regions becomes apparent. In this research, in order to determine the areas with groundwater potential in the city of Torbate Jam and prioritizing the effective factors, hierarchical analysis methods and maximum entropy method using MaxEnt model and the factors of distance from fault and fault density, lithology, slope, slope direction, distance from the waterway and drainage density, elevation, land use, slope curvature, topographic humidity index and topographic position indicator was used. Also, for assessing these two methods, the Receiver Operating Characteristic (ROC) was used. From 220 sources, 30% were randomly assigned as validation data and 70% were categorized as test data in maximum entropy method. Results showed that 29.6% of the watershed had high groundwater potential according to the maximum entropy method. Based on Jack-Knife Diagram, DEM, slope, distance from fault and lithology were the most important factors affecting groundwater potential, respectively. The Area Under the Curve (AUC) in the maximum entropy method indicated a precision of 91% (excellent) at the training period and 80% (very good) in the validation period to determine areas with potential for groundwater. Based on AHP method, 34.4% of the area has groundwater potential, and the slope layers, lithology, elevation and distance from the faults were the most important factors, respectively and accuracy of this method was 73%. The results showed that applying AHP and maximum entropy methods, while saving time and cost, have a good ability to predict the potential of groundwater and the maximum entropy method has more superiority than the hierarchical analysis method.
ehsan bazrafshan; Elhame Naghipour; Mina Dehghani; Omid Nazri Zade Sisakht; mehdi sepehri; ali reza ildoromi
Abstract
Flooding is one of the most important environmental hazards that can cause severe damage to life and financial damage. In many cases land use changes cause flooding. In this study in Gonbad Chi warershed to assess the impact of proposed and the built watershed mechanical operations (check dams) on flood ...
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Flooding is one of the most important environmental hazards that can cause severe damage to life and financial damage. In many cases land use changes cause flooding. In this study in Gonbad Chi warershed to assess the impact of proposed and the built watershed mechanical operations (check dams) on flood mapping, firstly the fuzzy logic and AHP were used to prepare base map based on combination of layers i.e. slope, land use, Permeability and flow accumulation. In next step by determining the location of check dams and separation of the operation according to dam height and determine the extent of the effect of the check dams using elevation contour lines, the mapping of impact of watershed management operations was prepared. In the end with composition of base mapping with impact of check dams, a new map that called flood mapping is created. Although the results have a positive impact 9% and less than it on reducing the risks of flood but these results in built check dams is very low than proposed check dams but in total the impact of built and proposed dams is low that it’s result is from low number and distribution of check dams.
Saeed Arab; Yasamin Segar; Mehdi Naderi khorasgani; Mohammad Asadi; Parvin Kia
Abstract
In a watershed, we can investigate the relationship between geomorphometric factors and sediment index. Digital Terrain Model (DTM) derived from DEM, has a high ability to receive, process, store, manage and monitor information for a catchment area. With the help of DTM in a watershed we can calculate ...
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In a watershed, we can investigate the relationship between geomorphometric factors and sediment index. Digital Terrain Model (DTM) derived from DEM, has a high ability to receive, process, store, manage and monitor information for a catchment area. With the help of DTM in a watershed we can calculate the sediment index (power stream, sediment transport and wetness) and some geomorphometric factors such as total length and slope along drainage, length and slope of straight drainage, drop coefficient, sinuosity and downstream elevation and its mapping. Bahadorbeyg Basin with an area of 216.69 km2 on northern pediment slopes of Alvand in Hamedan Province was selected for this study. First, the drainage rating was managed in DTM and the sediment index map along with the map of some geomorphometric factors (interpolation method) with four ranks and 30 focus points. Runoff and sediment discharge factors were proposed as a point estimator from the combination of sediment index with mean runoff and sediment discharge of the hydrometric station. In a complete regression model between sediment index (dependent variable) and some geomorphometric factors along with partial runoff and sediment discharge (independent variables), statistical relationships were significant at the level of 0.01 and 0.025. Results showed that the partial runoff and sediment discharge, the slope along drainage (total and direct), the drainage straight length, the downstream elevation and sinuosity are the most important factors affecting the sediment index, respectively. Finally, according to a time-series function (23 and 24 years old), the variation trend of runoff discharge had downward pattern in the basin and did not match with sediment discharge.
Elham Afrough; Masoud Masoudi; Seyed Yousef Erfanifard
Abstract
Destroying natural resources and environment is one of the most important problems in different regions around the world, especially in arid zones. So that extent areas of these zones are being destroyed in extensive spectrum of these destruction processes. For this reason, evaluating and providing vulnerability ...
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Destroying natural resources and environment is one of the most important problems in different regions around the world, especially in arid zones. So that extent areas of these zones are being destroyed in extensive spectrum of these destruction processes. For this reason, evaluating and providing vulnerability map of vegetation degradation in our country can considerably help the management and executive planning. In the present research, the criteria used in a new model called NIDLTS are proposed for evaluating the vegetation degradation. These criteria are natural index(N), human indirect index (I), human direct index (D), livestock pressure (L), trend of degradation (T) and state indicators (S). In order to estimate each criterion, a number of risk index were used. Natural indices studied in this research were climate change, draught, climate and suitability of lands. Human indices which were studied are population density, population growth, governmental expenses from executive works and researches, changing natural resources land to agricultural lands, percentage of unemployment, percentage of illiteracy. The indices of studied status are percentage of crown cover, production of the present biomass and production of the present biomass to the potential. Hazard index related to each destruction group were classified in to five classes of hazard intensity with numerical values in order to be analyzed in GIS. Then, the weight of each index and each main group of NIDLTS framework were calculated by Hierarchy Analysis Process (AHP); so that giving priority was done through investigating their share and effects in the vegetation decline. Finally, the vulnerability map of vegetation risk was generated through overlaying all the layers for each criterion in GIS. Results showed that among the human factors, the changing land use from natural resources to agriculture is the most important factor, whereas among the natural factors, drought is the most important factor in the study area. Also, among all the criteria, natural index has the highest effect and the trend of degradation of natural resources lands has the lowest effect in the vegetation degradation during the time. The final hazard map showed that the most widespread hazard class is moderate, followed by no-hazard in the region. It seems logical that the proposed model of NIDLTS for assessing the hazard of vegetation degradation can provide a more accurate estimation of vegetation degradation in a region with taking into consideration of the ecological, anthropogenic and hazard trend in comparison with some other evaluations that only consider the current state of vegetation degradation.
Hassan Vagharfard; Hassan Moghim
Abstract
Flood spreading is an effective way to increase the groundwater level, rectify the critical conditions of groundwater, and prevent flooding at Naeim-Abad, Fars Province. The most important step in the successful implementation of artificial recharge is the selection of recharge areas in the studied region. ...
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Flood spreading is an effective way to increase the groundwater level, rectify the critical conditions of groundwater, and prevent flooding at Naeim-Abad, Fars Province. The most important step in the successful implementation of artificial recharge is the selection of recharge areas in the studied region. In this research, the GIS technique and Analytical Hierarchical Process (AHP) method have been used. We considered nine factors–land, slope, and distance from the road, altitude, thickness of the alluvium, distance from the stream, surface permeability, land use, and fault for analysis in this research. Each layer was prioritized using the AHP method and the different layers were integrated. Expert Choice software was used to prioritize nine considered factors. The results showed that 3.6% of the Naeim-Abad area was suitable for flood spreading based on the AHP method and GIS technique. In this research, hydrologic factors with a weight of 0.687 had the most impact among the main criteria for locating areas prone to flood spreading. Among the sub-criteria of this criterion, surface permeability with a weight of 0.558 had the greatest influence. In addition, the sub criterion of land use was weighted equal to 0.701, which had the highest weight among the sub criteria. The lowest weight among the sub criteria was attributed to the distance from the road with a weight of 0.106, which indicated the least influence on locating suitable areas for flood spreading.
