Paleoclimatic investigation of the Quaternary period reflects fluctuation in climatic conditions during geological periods. Abrupt climatic changes, viewed as problem causing global incidents bring about adverse side effects in sensitive climatic zones such as Iran. Droughts and unpredictable floods that damage natural resources as well as human life become common yearly occurrences. Apart from influences of natural physical factors, human activities, if not properly controlled, add to the destructive power of the floods too. This happened in the Nekaroud basin mainly due to deforestation and damaging changes in landuse during the last century. The huge magnitude flood of summer 1999 which caused irreparable downstream damage and death of citizens is a sad incident of such environmental changes. The present study is an investigation into some characteristics of Nekaroud basin, an analysis of the reasons behind the occurrence of the catastrophic flood, ways to predict and prevent similar disastrous incidents in other catchments basins in Mazandaran as well as in other regions with similar conditions in Iran.

Among the various natural hazards, floods may be considered as the most devastating factor that inflicts great damage on human societies. Therefore, the importance of estimating flood damage and its scope in planning to reduce damages and determine points with high risk is very important. The aim of this study is to determine the extent of flood hazard using OLI satellite data. For this reason, a window of OLI satellite images of Landsat 8 was acquired before and after the Dezful flood of April 25, 2016. First, preprocessing operations include radiometric and atmospheric corrections of images were done, and the principal component analysis was then used to reduce the correlation of the data. Data processing was performed using a Support Vector Machine algorithm with linear and polynomial kernels. In order to train the Support Vector Machine algorithm, training samples for each class (agricultural land, flood extent, water resources, settlement areas, and recreational areas along the river boundary) were harvested at the user level. In order to evaluate the similarity of the classes and the degree of correlation between the samples, the quantitative assessment method of the Jeffries Matusita was performed. The results showed that the flood area was 11593. 26 ha, the highest damage was due to agricultural land with a destruction of 8467. 45 ha and recreational and tourist areas along the riverbank with a destruction of 2659. 14 ha.

Background: Misunderstanding of disaster hinders people from devoting enough attention to disaster preparedness programs. flood is one of the main natural hazards in Iran. Objectives: The present study aimed to determine flood risk perception among residents of a flood-prone area in Iran in 2021. Methods: This cross-sectional study was conducted on 201 inhabitants of three villages along the Hesar-Golestan River in northeast Iran. A researcher-made questionnaire was used to assess their flood risk perception and opinions about the causes of the flood. flood risk perception was assessed using ten questions with a 5-point Likert scale. Risk perception was calculated at three levels: low (scores 10 to 23), medium (scores 24 to 37), and high (scores 38 to 50). Multi-stage sampling technique was used for sampling. Results: The majority of participants (81%) had a moderate risk perception. The mean risk perception score was 30±, 5, which indicates a moderate risk perception. According to the participants, the three main causes of floods were environmental degradation and soil erosion, unplanned development and construction in flood-prone areas, and heavy seasonal rainfall, respectively. There was a significant relationship between gender and age with some opinions about the causes of floods. Conclusion: The risk perception of participants was at a moderate level. Low or moderate flood risk perception can lead to insufficient attention, inaction, or insufficient efforts to reduce the risk and increase preparedness for floods. Taking measures such as educating people about the causes and consequences of floods using appropriate and effective methods can help to manage disasters better.

Global climate change leads to an increasing in the number and severity of weather events such as floods. floods have been reported one-half of all weather-associated disasters with high impacts on countries. Global warming causes a different pat-tern of rainfall in Iran caused long-term drought since 30 years ago and recent heavy raining which lead to a massive flood in this country. It is predicted that health subsequences of Iran 2019 flood such as communicable diseases vary due to the geo-graphical extent and different climates of flooded areas. However, observing long term and short term preventive measures can be effective to reduce the high impact of flood in Iran.

Natural disasters threatening and endangering human communities has resulted in the study and research of such disasters through the related sciences and present methods of forecasting their behavior with time and place and also from a qualification and quantity viewpoint. To this end, numerous methods for the determination of the maximum flood in various return periods has been made available which can be refered to as flood frequency analysis methods. One of these methods is the regional flood frequency analysis in which instead of using the data from a single station, it considers the data and characteristics of a group of similar stations. In the case under the research this method uses L-Moments and Index flood in North, Razavi and South Khorasan water basins and MATLAB software. Maximum annual flood statistics were used from 68 Hydrometric stations with minimum and maximum statistical periods of 6 and 39 years. Using Cluster analysis the region under study was divided to 7 partitions. Discordance test has conducted and only one station in region C was found as discordance station. Because of knowing the homogeneity of the regions, the parameter of Kappa distribution were estimated and with using the simulation method of Monte Carlo with 500 times, the homogeneity measure was tested in 7 regions. Using homogeneity test all regions was found homogen. Using goodness-of-fit measure z and Kolmogrove-Smirnov the Log normal 3 parameters distribution were selected for two regions of A and B, GEV for C, Generalized Pareto for D and E, Generalized logistic for F and Pearson III for G. Besides, GEV distribution was found appropriate for all of the regions, only their parameters are different in any regions. For estimating of index flood a logarithmic model has found for each region with 4 variables of area, height, average slop and form factor. Using of these models, the index flood can be estimated in each region and it can be used for standardize the statistics of maximum flood values.

Background and Objectives: The complex knowledge of local communities on the full cycle of disaster risk management has been proven valuable in various researches. However, the scientific literature still lacks studies that examine how to use Local Knowledge (LK) and the local people capabilities for crowdsourcing in Flash flood Early Warning Systems (FFEWS) studies. Hence the main target of this research is investigation on the capacity of crowdsourcing for FFEWS and identification of Flash flood Hotspots (FFHs) by LK across a flood prone area in northeast of Iran. Materials and Methods: In this study, a questionnaire with three different themes was designed. The first theme was related to the individual characteristics as independent variables, the second theme addressed the residents’ LK in determining the FFHs, the type and the predominant time of the flood occurrence in the region, through asking open ended questions with short-answers. The last theme addressed the assessment of people's capacity in Flash flood Crowdsourcing (FFC), through asking questions with a Likert scale of 0-5. The face-to-face questionnaire administration mode was used for public survey through conducting oral interviews and live discussions.Results: The results showed that there was no significant correlation between the individuals’ characteristics and their willingness and motivation to participate in FFC. Comparing residents’ LK with the 31-year flood report and literature review showed that the residents’ LK about the flood occurrence location, time and type on a local scale was very promising. The research results indicated that the respondents show highest level of willingness for participation in the release of flood warning messages with an average score of 4.23 and the most important motivating factor for their willingness to participate was introduced saving relatives, fellow villagers, and human being from flood hazards with an average score of 4.84.Conclusion: In most of previous studies that have focused on the development of FFEWS, very little attention has been paid to understanding the needs of citizens and promoting their participation. In fact, there is a research gap regarding the method of citizen’s participation and their potential support for FFEWS. Hence in this research, an attempt was made to take a small step towards filling this gap by investigating LK, motivation and willingness of local residents to participate in various aspects and steps of FFEWS. Our findings indicate that involving local people in FFEWS has various unknown aspects that should be explored through more extensive and detailed studies.

Most areas in our country are subject to frequent flood damages and increasing loss of lives and properties. This research present a methodology, based on the use of mathematical hydrologic models simulating mutual interaction of effective factors, to study the spatial distribution of flood producing areas with in watersheds. The watershed of interest, Damavand, was divided into seven subwatersheds which were digitally characterized in a geographic information system (GIS). Subwatersheds flood hydrographs associated with design rainfalls were determined using HMS model and were routed in the stream network to yield the total hydrograph at the outlet. With successively eliminating subwatersheds from the simulation process, in a method titled "successive single subwatershed elimination method", flood hydrograph at the outlet was determined so that the contribution of each subwatershed in the flood peak at the outlet could be quantified. Then, all subwatersheds were ranked with respect to the order of contribution to the outlet flood peak. The routing results show that this contribution is not only a function of subwatershed discharge and size but also a function of other factors. Thus, any flood control measure must consider the flood area prioritization in term of contribution at the outlet.

Using of flood for identification of plant nessassary water for its growthing and decreasing of flood damages is possible in many different methods. By using of water spreading system, seasonal flood in susceptible land will be spreaded and, will have different effects on ground water tables, plant cover and soil on these lands. In order to measurement of physical soil properties variations in Delijan water spreading stations of Markazi province, seven channel water distributions (distribution area) and regions between those (wetness area) were selected and then each channel and wetness area after that were devided to three parts and at center of each parts one compined sample was obtained in two depths of soil (0-25 and 25-50 cm). Also, measuremant of soil infiltration rate in distribution and wetness area was obtained by double ring method. Soil physical properties in two these area and different channel was compared using tstudent and ANOVA method respectively. The results showed that the water Spreading activities has been significant decreasing about sand and infiltration rates at %1 level and about bulk density at %5 level. Also, about the amounts of clay, silt and Sp there have been significant increasing at %1 level.

The frequency and severity of floods has increased globally. However, in many parts of the world, especially in developing countries, there is no accurate data for estimating the probable of flood risk. In this research, flood risk zonation has been done for delineation of flood fringe in Gamasiyab River (south of the Sahneh city, east of the Kermanshah province). The simulation of the flood has been carried out based on the HEC-RAS (one-dimensional hydrodynamic model), and the geometric data has been processed in the GIS by the HEC-GEORAS extension. Also peak discharge in diffrence return periods has been calculated using SMADA software by Type III Pearson distribution. The study area has been divided to four reaches based on river patterns and then manning's roughness coefficient has been calculated for each reach. The results show that 23. 78 km2 and 42. 1 km2 of the river floodplain have been inundated by 25-year and 100-year return periods respectively, so that amount of damage from the 100-year flood was higher than the 25-year flood. Also the width of inundation area in the reaches 2, 3 and 4 indicated that 25-year return period was not good criteria for flood fringe. It is necessary to study the other features of the river, including bed morphology, river depth and river pattern.