Meanders, as a interesting water flow patterns in nature, is giving dynamic to courses of rivers. Creation of curvature on courses of rivers is give enough energy for migrate active channel on floodplain.This migration is main reason for many geomorphology in events is floodplains and at final is changing the floodplain pattern. These changing is created many problems for man-made structures that is constructed at bank or on courses of rivers. Aji-Chay River, as a typical meander is migrate on floodplain by creation curvature on its course (is situated at 37° 58’ to 38° 07’ N and from 46° 15’ to 47 °45’ W). In this article is analyzed and estimated migration rate, migration potential and time of migration, by use of experimental methods, by satellite and areal images In this study rely on parameters of meanders, as bind and width of river corridor is estimated by use of W methods and  Dt, R/W calculation, in order to investigation on capability of rivers for movement. In this study also is estimated time of active channel migration on floodplain by use of valid methods .The results of this study show that active channel of Aji-Chay repeatedly movement on floodplain in during time and because these movement and changing and bank erosion, is flatten the floodplain. In part of Aji-Chay course time period for completed a cycle of migration is from 1 to over 5 years. This period is vary in many parts of river course. The results of this study also suggested that sinuosity rate at length of Aji-Chay course is changed in during time and old race of water flow is evidence these changes.

Research on flood predicting models is one of the first steps in reducing flood damage and managing future floods in catchments. The aim of this study was to evaluate flood susceptibility in Birjand plain catchment through four machine learning models including support vector machine (SVM), J48 decision tree, random forest (RF) and Adaptive neuro fuzzy inference system (ANFIS). Therefore, in order to implement and validate the mentioned models, a list of flood-prone areas in the study area was prepared (42 flood-prone locations). In addition, 19 hydrogeological, topographical, geological and environmental criteria affecting flood occurrence in the study area were extracted to be used to predict flood susceptibility map. The results showed that the highest accuracy was related to the RF model (0.845) and the lowest accuracy was related to the SVM model (0.791). In addition, the validation of the results using the ROC curve showed that the most accurate values of flood susceptibility belong to the RF model (AUC = 0.958). The results of this study can be used to manage vulnerable areas and reduce flood damage.

An investigation was carried out to assess the subsurface suitability of the River Nzoia floodplain in Budalangi Division of western Kenya for supporting shallow foundation structures. An analysis of the conditions in the area during flood seasons was conducted using soil mass characterisation, geotechnical testing, slope stability analyses, terrain evaluation and analysis of ground conditions in buildings in the area. The analyses reveal that significant slope failure occurs when the percentage of water exceeds 50% in slopes cut at angles greater that 24°. The suitability of the ground for supporting shallow foundation structures has been established from the results of fieldwork and from laboratory studies.

Flood is one of the complex and destructive natural phenomena led to human and financial losses around the country and world every year. Generally methods of flood controlling are classified in two parts consist of structural and non structural methods. Construction of dam is one of the structural methods plays an important role in flood control. A dam by storing a part of flood volume causes to dropping in flood peak and reduces the flood damage in down lands. In this study, by using of river analysis systems (HEC-Ras) and geographic information system (GIS) and utilizing of Google-Earth software, the floodplain with frequency of 50, 100, 500 and 1000 years investigated at Narmaab River of Golestan. Then effect of construction of Narmaab Dam on reducing the flood plain at down lands has been studied. Therefore several scenarios were defined for dam flood storage volume and in any case the flood plain and flood damage at down lands was estimated. The results show that construction of Narmaab Dam with a flood storage volume equal to 6 million cubic meters can reduce damage of flood with frequency of 50 and 1000 years by %75.1 and %40.7 respectively.

Planning and providing appropriate tools to reduce the adverse effects of natural hazards including floods is inevitable. Achieving the above goal depends on having sufficient and accurate knowledge and information about the vulnerability of different ecosystems (watersheds) to various destructive factors. Vulnerability assessment by identifying potential stresses and disturbances (natural and man-made) as well as estimating the sensitivity of watersheds allows for predicting the effects and selecting appropriate solutions for the sustainable management of these ecosystems. Therefore, this study has been designed to identify and rank vulnerable sub-watersheds to floods in the Ardabil plain, taking into account social, economic, infrastructural, and ecological dimensions. First, the indicators and criteria of each dimension were identified taking into account the conditions prevailing in Ardabil plain. Then, information and data on climatic, hydrological, demographic, economic, infrastructure, and land use were obtained from relevant authorities. Then, the mentioned criteria were standardized and the weight according to their importance was calculated based on the BWM method the data obtained from this stage were performed using the TOPSIS technique to rank flood vulnerability for different sub-watersheds in Ardabil plain for the period 2007-2017. Finally, a map of Ardabil's plain vulnerability to floods was prepared and presented. According to the results, the criteria of building density, rainfall, population density, and the unemployment rate were the most important criteria of vulnerability and among the studied dimensions, the infrastructure dimension is too significant in flood vulnerability in Ardabil plain. Based on the comprehensive vulnerability map, sub-watershed 7 in Ardabil plain was identified as the most vulnerable sub-watershed in the study area.

Nowadays, around the world, environmental impacts, as one of the most important dimensions of sustainable development, play a significant role in strategic decision makings. Water resources management is one of the most sensitive measures due to its bi-directional relationship with sustainable development and also as a facilitator of this path, especially in arid and semi-arid regions. One of the main purpose of the LCA approach is to assess the environmental impact of emissions. In this study, environmental compatibility of mechanical watershed management measures to manage water resources is investigated by using this approach. Therefore, material flow, energy and environmental impacts of all stages of the life cycle of one unit of flood spreading system (located in Daefeh watershed in Rafsanjan plain) were analyzed based on IMPACT 2002+ method available in the Simapro software. The results showed that the earthen structure of the flood spreading system with 8. 37 kPt environmental impact is the hot spot of this system (Mostly due to the earthworks), including 91. 34% of environmental burdens in the construction phase and 55. 2% of the total emission effects. The findings of this research showed that the environmental consequences of emissions during the life cycle of this system were 15. 2 kPt. Construction process stage (with the highest amount of environmental burdens in each impact category except for resource depletion) 39. 2%, use stage 31. 3%, extraction and productivity of materials 23. 3% and transportation stage 0. 93% of Environmental burdens were allocated in this study. The environmental consequences of emissions in the categories of adverse effects on human health, climate change, resource depletion and ecosystem depletion of the flood spreading system are 6. 63, 3. 54, 3. 06 and 1. 94 kPt, respectively. Also the results of this study will be useful for evaluating the environmental effects of different structures. Finally, it is suggested that in the integrated watershed management, which is responsible for protecting our nation's natural resources, life cycle assessment approach be developed and the green building approach could be implemented, such as selecting the design discharge with environmental considerations, selecting quantities and types of environmentally friendly materials.

In this research for evaluating the natural and artificial recharge of Moosian aquifer (located in Ilam provience, Iran) and for predicting its water table flactuations in the future years, a three dimensional groundwater numerical model (MODFLOW) were used. Based on the measured water level in 1989, the water table in 8 piezometric wells was assumed to represent a stable state of the aquifer and the model was calibrated on the basis of this information as the stable condition. In the next stage of the calibration, based on the output of the first stage, the unsteady state of the calibration was carried out for 7.5 years in 15 periods (1989-1997). To investigate the effects of flood spreading on the water table in the next 48 priods(24 years), the forecasting outputs of a stochastic-deterministic rainfall-runoff model was used as input to the numerical model, and the response of the aquifer in the unsteady state was predicted. The results showed that in spite of recharging the aquifers, because of high rate of exploitation, the aquifer will not come to a steady state and the water table in many piezometric wells continue to fall. Sensitivity analysis of the model showed that recharge is the most sensitive factor on the fluctuation of water table.

Flood is one of the most terrible natural disasters in the world, flood damages leave long-term damages in various sectors, especially agriculture. Hazard analysis and vulnerability assessment is one of the primary steps in flood disaster management. Although such studies less done in irrigation networks. In this research, hazard analysis and vulnerability assessment has been done for the irrigation network in the east of Shuaibieh plain. It is an important irrigation project of Khuzestan province, and its flood will cause irreparable damages to the farmers and residents. For this purpose, hydraulic simulation has been done in Hec-Ras-2D and for 25, 50, 100 and 200 years return periods. The extent, inundation depth and flood velocity were extracted from the model. Using the model outputs and with the aim of existing standards, flood hazard maps have been drawn. According to these maps, for each flood with a return period greater than 50 years, more than 50 percent of the Shuaibieh plain is at unsafe level for all people and structures. By using the prepared questionnaires from 42 local farmers and irrigation network operators, various vulnerability indexes (economic, social, environmental, resilience, and flood magnitude) were estimated and by Analytic Hierarchy Process of them, the vulnerability was assessed. Finally, with superposition of each vulnerability index map, the total vulnerability map of the plain against floods was drawn. The highest and lowest levels of vulnerability are related to coping capacity index with 33.7 percent and social index with 9.6 percent, respectively.

Most rivers have flood plains that extend laterally away from the main channel at a gentle gradient or in a series of terraces. Multistage channels are deliberately formed in certain cases in order to increase conveyance capacity in large floods, and to have recreational expanses available at other times of the year. Two-stage channels, thus consist typically of a main river channel in which there is some discharge all of the time and flood plains, which are dry for most of the time, yet perform a vital function in times of flood. Since flood alleviation schemes are the focus of much of engineering work, the prediction of the conveyance capacity, velocity distribution and boundary shear stress distribution in such channels is clearly important. The boundary shear stress distribution is a prerequisite for studies on bank protection and sediment transport. Prediction of these parameters in two stage or compound channels is complicated by the lateral exchange of momentum that takes place in the shear layer that forms between the generally faster moving water in the main river channel and the slower moving water on the flood plain. Superposition of high lateral shear on bed-generated turbulence and longitudinal secondary flow structures is a convoluted problem in fluid mechanics. In the context of the river channels with flood plains, the problem is usually further complicated even for moderately straight channels by the complex geometry of the cross-section and the heterogeneous nature of the boundary roughness.

In general, the protection and utilization of surface water in arid regions, done by different methods such as Flood water spreading that undoubtedly will affect on sustainable development of groundwater resources. In order to provide, suitable, executive and manageable solution, Continuous monitoring is essential for such projects. For this reason the effect of Dehender Flood spreading on downstream unconfined aquifer was evaluated. For this purpose, the location of flood spreading and hydrogeological conditions of downstream aquifer determined by data and information that are Gathered from Hormozgan regional water authority along with field observations. Then 7 Observation wells were chosen. Finally, the effect of flood water spreading on water table surface groundwater changes was investigated by using underground water balance equation and unit hydrograph befor and after the construction of flood spreading system. The results of this evaluation showed that the average level of the water from sea level at the central of the plain(are not affected by flood water spreading) and near flood spreading (are affected by flood water spreading respectively) befor and after the construction of flood spreading system are: 213. 4, 209. 5 and 254, 251 meter of the sea level. As a result we can state that flood water spreading play an important role in sustainable development of ground water resources.