نشریه سد و نیروگاه برق آبی ایران
پیاپی 34 (پاییز 1401)

This paper aims to estimate flood damage on land use areas through a three-step process: identification of flood areas using Sentinel-1 images, mapping of land use using Sentinel-2 images, and estimation of damages in each land use class. The case study is located in the north of Ahvaz City in Khuzestan Province. To generate the flood extent map, the water index from Sentinel-1 images before and after the flood is obtained by fusing VV and VH polarizations using the discrete wavelet transform method. Then, the water index image of each time is segmented into superpixels using Simple Linear Iterative Clustering (SLIC). Afterward, the obtained superpixels are classified using K-means clustering into water bodies and backgrounds. The results obtained by classifying Sentinel-2 images indicate that agricultural lands are the most prone to damage. In total, 27% of the areas were destroyed, and 26% of these damages belong to agricultural lands. Moreover, more than 50% of agricultural lands are covered by type 2 and 3 agricultural fields.

In this research, the flow of the river leading to the Karun 4 Dam was developed using the NAM simulation model and the precipitation, temperature and evaporation parameters were modeled. To predict the flow, meteorological maps of the COLA were used to predict precipitation and temperature. According to the results more than 70% of the predictions in the flood period were observations, the use of this system for the management of Karun 4 dam hydropower plant has resulted in significant economic benefits and financial incomes. The results of the research showed that by relying on the flood warning system, even in flood seasons, the volume of the reservoir can be kept at a high level to increase the efficiency and electricity production, and in case of warning, if necessary, the volume of the reservoir can be increased to trigger the flood. Lower levels decreased. Also, due to the accurate functioning of six-day forecasts in low water years such as the water year 2015-2016, early water extraction was put on the agenda, so water extraction was done this year in March. Early water withdrawal in this water year saved 400 million cubic meters of water.

The number of hazards and related damages is one of the main concerns of nankind in the last century. A review of international statistics shows that the largest number of catastrophic events are related to the Asian continent. The country of Iran is also facing this issue and also the climate change causes the aggravation of these damages. The current research seeks to explain the dimentions of international studies in this field. The methodology considered for conducting this research is based on the qualitative research method and was designed with a review approach of written documents related to the topics, indentification, classification, and a three-level analytical framework. The results showed that from the point of view of the level of exposure, floods and from the point of view of the number of casualties, earthquakes have the highest statistics at the international level, and it is very important pay attention to non-structural strategies to face risks, especially the insursnce strategy.

In this research, the location of the temporary flood storage sites and the design of the river flood diversion system have been carried out using one-dimensional and two-dimensional hydraulic modeling of the flood and considering the structural and hydraulic design criteria of diversion dams. An important portion of the Gorganrood River, which includes the downstream reach of the Golestan Dam to the connection to the Caspian Sea, has been selected as a case study, and the effect of flood diversion on the peak discharge and flood level of the most vulnerable flood prone areas including the cities of Aqqala and Gomishan, has been studied. Locating the diversion and storage locations has been done using Flo-2D, HEC-RAS and SWMM models, and then, according to the criteria of cost and efficiency, suitable locations of flood storage sites have been determined.  Finally, the separate and combined performance of these dams on the flood features of the river at the damage points during 4 important rainfall events have been estimated. The results showed that if flood diversion systems are used, the peak flow of the flood at the entrance to Aqqala and Gomishan city will decrease by 16.35 and 22.15% on average.

Unexpected events such as floods, and development interventions such as dams, and civil structures have effects and risks that cause damages. They bring irreparable harm. The development interventions that are built in the riverbeds and flood-prone areas simultaneously suffer from the effects and damages of the flood and intensify the social effects. Social impact assessment (SIA) and social risk assessment (SRA) and evaluating the effects of such events and interventions creates a better insight in project management, and the combination provides the basis for the development of the application of social assessments. makes Using theoretical literature, interviews with experts and qualitative method of data analysis, this research makes the common denominator of evaluating the effects and social risks of flood as the basis of the research and identifies its social effects and possibilities. pay The results of the research show that the effects and probabilities that are classified in demographic indicators are from the highest intensity and the longest duration of the negative social effect/possibility, and on the other hand, the indicators of social protection, risk management and activation. Formal and informal groups and institutions have the highest intensity and the longest duration of positive social effect/probability caused by floods.