جستجوی مقالات مرتبط با کلیدواژه "flood spreading" در نشریات گروه "جغرافیا"

Groundwater is the single water resource in many regions of Iran. This is considered to be a major limitation in the social and economic development of the country. Destructive floods and water shortage necessitate suitable strategies against flood control. Selecting suitable areas for artificial recharge and directing the floodwater into permeable formations are amongst the most effective strategies in flood spreading projects. Having combined GIS and MCDA approaches, the present study sought to locate the most suitable areas for artificial groundwater recharge operation in the Garabaygan Basin of Iran. To this end, the data layers relating to the eight effective factors were prepared in GIS environment. This stage was followed by elimination of the exclusionary areas for artificial recharge while determining the potentially suitable ones. Having closely examined the potentially suitable areas using the PROMETHEE II-SAW and Fuzzy-AHP methods, the land suitability map for artificial groundwater recharge was produced. The results of the study showed that most suitable areas for the artificial groundwater recharge are located in Quaternary Qg and Qgsc geologic units and in geomorphological units of pediment and Alluvial fans with slopes not exceeding 3 percent. Furthermore, significant correspondence between the produced map and the control areas, where the artificial groundwater recharge projects were successfully performed, provided further evidence for the acceptable efficiency of the integrated PROMETHEE II-SAW method in comparison with Fuzzy-AHP in locating suitable artificial recharge areas.

This study aimed to select favorable site using analytic hierarchy process (AHP) for practices including seeding and seed broadcasting, hoeing and seeding, contour furrowing, pitting and flood spreading to restore degraded rangelands Ghayen Plain, Iran. First, major effective criteria in selecting favorable sites for range restoration measures were adopted from the reputable literatures. Then, 80 questionnaires in the form of pair matrix were designed for each restoration measure with regard to the selected criteria. Questionnaires were distributed among lecturers, experts and authorities in local universities and offices. Final score and relative importance of criteria were calculated on the basis of geometric mean of questionnaires. Hierarchical tree structure with appropriate adaptability was generated in Expert Choice software. Results showed that rainfall and slope played an important roles in selecting favorable site for pitting. Soil infiltration rate and runoff volume had the highest relative importance in selecting suitable site for flood spreading project. Furthermore, for seeding and seed broadcasting practices climate and slope showed high relative importance. Rainfall expressed high relative importance in selecting favorable site for hoeing and seeding projects. Finally, slope and runoff volume were the major criteria in selecting site for contour furrowing project. Based on the generated location maps, 628 ha were suitable for flood spreading. In addition, the suitable area for the contour-furrowing and pitting operations was estimated to be 103 and 199 ha, respectively. The area of suitable sites for direct seeding and hoeing and seeding operations was calculated to be 3623 and 2750 ha, respectively.

  In arid and semi-arid areas, due to the lack of proper management of renewable natural ‎resources, not only the proper utilization of water and soil resources is not done, but also ‎water becomes a natural disaster, and every year, floods cause many human and financial losses. One of the integrated methods of flood control operations is flood spreading. This method improves the status of utilization of water and soil resources, plant cover, and artificial ‎recharge of groundwater. ‎Sediments that are carried with the flood, deposit in flood spreading region and may change the physical and chemical properties of soil over time. The most serious danger which threatens the flood spreading networks and artificial recharge ‎schemes is the reduction of the infiltration of soil due to sedimentation. ‎‎The most important factor affecting the performance of flood spreading systems is the ‎amount of input sediment into the spreading canals, its depositing on the surface and ‎accumulation in the depth of soil, which can change the physical and chemical properties of the soil. In this regard, current research was conducted to investigate the role of input sediments into flood ‎spreading field, determine the penetration depth of sediments and the spatial pattern of ‎physical and chemical changes in soil. ‎ Kashmar flood spreading station is located in 17 km east of Kashmar, in the longitude of 58° 38' to 58° 40' of the east and latitude of 35° 15' to 35° 39' of the north. This research was conducted in the first Phase of Kashmar flood spreading. ‎ In this research, the first five channels of dewatering were divided into three study networks ‎‎(outset, middle, and end), and the upstream of the spreading flood arena was considered as the control sample. In each grid, three points were selected as repeat tests and soil profiles were drilled with a depth ‎of 1 m. In each soil profile, the soil samples from 0-50 and 50-100 cm depths were provided. At the test site, soil infiltration was determined using double rings. After transferring soil samples to the lab, the soil texture (clay, silt and sand percentages) was determined by the hydrometer method. In the laboratory, the value of the chemical parameters of the soil, including soil acidity (PH), electrical conductivity (EC), bicarbonate (HCO3ˉ), sulfate (SO4-2), chlorine (Cl), potassium (K+), and sodium (Na+) were measured. The effects of flood spreading on the physical and chemical ‎properties of soil in spreading filed were investigated with the factorial experiment in a completely randomized ‎block design. ‎ The results of the analysis of variance showed that there was a significant difference between the ‎soil infiltration in channels 1 to 5 and the control arena at the probability level of 1%. However, there was no significant difference (p=%5) in soil infiltration in the start, middle, ‎and end sections of the channels. ‎ In channels 1 to 5 and in the control arena, there was no significant difference (p=%5) in the amount of sand, silt, and clay. Flood spreading increased the amount of the clay in the depths of the channels compared to the control area. The Analysis of the variance showed all chemical properties of the soil. Except potassium, there was a significant difference (p=%1) between the dewatering channel and the control field. ‎The amount of the variables did not change in the second depth compared to the control arena. The interaction ‎effect between the depth and channel was not significant at 5% probability level. ‎ Thus, flood spreading did not change the chemical characteristics of soil in depth.
Discussion and The rate of the soil infiltration in spreading channel reduced 4.3 times of soil infiltration in the control arena. The least infiltration was observed in channels 1 and 2 due to the proximity of these channels to the source of flood and deposition of more suspended load on the surface‎ of the soil. Because the suspended load of floods increased the clay particles and reduced the macro porosity, it decreased the soil infiltration. Flood spreading caused an increase of 1.5% in the soil acidity of the channels compared to the ‎control arena. ‎ A 30% reduction in electrical conductivity was observed in the first two and third channels, compared to the control arena‎. The amount of HCO3-, Cl-, SO4-2, and Na+ reduced in the first, second, and third channels but increased in the fourth and fifth channels. The amount of potassium in all channels decreased compared to the control samples but this decrease ‎was not significant‎. In general, flood spreading in Kashmar site caused the diminution of soil infiltration, which had a negative effect on flood spreading system. Therefore, it is recommended that water spreading channels are plowed every year to increase soil ‎permeability. ‎

Nowadays, one of the main problems that the societies encounter is discharging of the ground waters and the lack of suitable substitution for that. In Bushkan Plain vast use of agricultural lands has caused a drop in groundwater level. One of the suitable solutions to reduce this crisis is artificial feeding of groundwaters. To this end, the most important step in the floodwater spreading plan is suitable zonation for water spreading and forcing the water to penetrate into underground water tables. In this study, a hybrid AHP-Fuzzy method in Geographic Information Systems (GIS) and 8 parameters of the slope, alluvium thickness, electrical conductivity, geology, land use, drainage density, conductivity and altitude are used. First, these layers were converted to Fuzzy and then were evaluated using Analytical Hierarchy Process (AHP) and Expert Choice software. The values achieved in ARC GIS 10/2 on fuzzy layer were multiplied to Fuzzified layers by using Raster calculator and were combined with Fuzzy overlay command and the final maps were then prepared. The results show that gamma value of 0/9 has the best overlapping and eventually, the optimal gamma was found on 5 classes as high improper, improper, average, proper and high proper in the plain. 7/11 percent of the study area was calculated within high improper class, and 11/1 percent of the study area belonged to the high proper class. The southwestern parts of the plain, where pasturage density is low, are the best areas for flood spreading.

Most part of Iran is situated in arid and semi-arid areas. Among features are irregularity in precipitation and improper distribution in terms of time, flood and drought, soil erosion and desertification. Therefore, under such circumstances, the shortage of water along with its effect of farm lands has considerable effect on natural resources. Nowadays in most part of the world, in order to supply water, improve of soil fertility, prevent erosion and flood in additional to watershed artificial flood, flood spreading and aquifer management is utilized and its positive effects are always emphasized. In this study the effects of implemented flood spreading on some physical and chemical properties such as amount of organic mutter, Nitrogen, Phosphor, Potassium, clay, silt, sand, PH and EC comparing with the areas without flood spreading have been studied using T test. Results shows that amount of organic mutter, Nitrogen, Phosphor, Potassium and clay have been increased. The amount of silt, sand, PH and EC have been not changed. Results prove the positive effect of flood spreading on soil properties in this area. Therefore, maintain the implementations of such plans are emphasized.

Flood spreading is among preventing method from damage of deluge, especially perishing of water and soil in latrine basins of arid and semiarid regions. Accumulation of sediments on the flood spreads regions lead to changes in soil fertility, revival and support of plant covering and controlling of desertification and change in physicochemical properties of soil in these regions. In order to measure of soil changes in the station of flood spreading Hashtbandi, Minab, Hormozgan, were dipped 12 cavities in two regions: flooded and control. Sampling was done from 0-30 cm and 30-60 cm depth. Physicochemical properties were evaluated in the samples. The obtained results indicated that the average of organic carbon, total nitrogen, amount of potassium and phosphorous, EC as well as sand percent significantly increased in the flood spreading region than control region and clay percent, pH and saturating percent (SP) decreased in the flood spearing region than control region. Beside, silt amount non-significantly decreased in the flood spreading region than control region. Generally, can be said flood spreading system changes the soil texture during the time and has positive effect on soil fertility. Increasing amount of macro elements such as N, P and k as well as reduction of pH are positive effects for enhancing soil fertility, although increasing EC may be limited planting of some sensitive crops.

The selection of suitable location for implementing of flood spreading project and artificial recharge of aquifers is an important step. To assess this purpose، the Geographic Information System (GIS) conceptual models and decision making systems were used. Regarding different mentioned criteria، it is not possible to use GIS without appropriate Multi-Criteria Decision Making (MCDM) technique. The main aim for this research is to access the suitable location for flood spreading by using the most efficient criteria and classify them into several groups. Consequently، major factors such as slope، geology، geomorphology، hydrology، infiltration rate، cover and environmental impacts of the projects should be considered in the process of selecting appropriate site for artificial recharge through flood spreading. Also evaluating accuracy and application of conceptual models such as Logic Boolean، Multi classmaps، Binary Evidence، the Analytic Hierarchy Process (AHP) have been noticed. In this research، nine physical and environmental efficient variables essential for locating of flood spreading are used. The results indicate GIS-based data combination for ranking suitablelocation of flood spreading by itself، though it is not reliable enough. Also evaluating accuracy of models shows that accuracy of Binary Evidence model for identifying and ranking suitable location of flood spreading is more than that of Boolan model and the Multi class maps model can give better insights to create more realistic output scenarios The most important step in flood spreading process is to define optimal site. The Analytic Hierarchy Process (AHP) is an approach that is suitable for dealing with complex systems related to making a choice from among several alternatives and which provides a comparison of the considered options. In the present research relationship between GIS and Multi-Criteria Decision Making analysis has been investigated in order to find optimal site for flood spreading. The research emphasized the capability of resultant map to be used in site selection for flood spreading.

Flood control and optimal use of it, and artificial recharge of aquifers are among the most important issues, and usage of water spreading in arid and semi-arid regions is considered. The aim of this study is selecting the most appropriate location for water spreading in Kashan, using multi-criteria decision making techniques and hierarchical analysis process. In this plain the parameters such as slope, land use, runoff volume, quaternary units, thickness of Vadose zone, permeability coefficient, storage coefficient and chemical quality of groundwater have been selected in order to determine suitable areas for flood spreading. Then Using GIS, a map prepared has been for each parameter. In next step, by AHP method, the importance of various factors in the location has been evaluated. Results of the weight of evaluation criteria indicated that the factor of runoff volume with a weight equal to 37% was the most important factor; and then in sequence: Quaternary units, slope, Thickness of Vadose of aquifer layer, permeability coefficient, storage coefficient, water quality and landuse, respectively with relative weights of 0.23, 0.16, 0.094, 0.061, 0.039, 0.025 and 0.018. Finally According to zoning map of flood spreading, three priorities for flood spreading area were determined in Kashan plain. The results of the sensitivity analysis showed that using performance and dynamic range between minus 10 to 10 percent of the variation in weight criteria Change significantly in the priorities of the criteria and sub-criteria has not happened and is not a lot of sensitivity. In other words, variability is not so important in this required. These findings indicated that the runoff criterion care now according to the mentioned ranges of others in selecting a suitable location. Furthermore, Quaternary units and slope suitable places are among decisive ones.

Soil properties can influence flood quality and have an important role on them success of flood spreading systems, because developing of flood spreading schemes in the unsuitable area form viewpoint of the soil and flood qualities may lead to desertification of such aria. Acceptance of the fact that flood spreading cause changes in soil characteristics. These changes can contain wide ranges of soil characteristics such as sand, silt, clay, gravel, and saturation percentage, TNV, Ca, Mg, Na, Infiltration, SAR and ESP. Therefore this investigation was conducted for detection of infiltration and influenced soil physical and chemical in flood spreading area of Mousian plain in southern Ilam. Sampling was based on systematic-randomized method from depths of 0-25cm; 25-50cm and 50-75cm in control, first, second and third bonds. Data analysis of variance was done. Mean comparison was based on Duncan’s Multiple Test. Results indicated that silt, clay, Ca, Na, saturation percentage and SAR in flood spreading area compared to control increased and infiltration, sand and gravel decreased. Soil texture in surface depth of control site was loamy sand and in flood spreading site was converted to sandy loam. Also, results indicated that bulk density in flood spreading site compared with control decreased. So, concluded that by entrance of flood, soil physical characteristics were changed.