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Showing 2 results for Flood Management

S. Farhadi, M. Galoie, A. Motamedi,
Volume 26, Issue 1 (5-2022)
Abstract

One of the important relationships which are used in the estimation of river discharges and floods is Intensity-Duration-Frequency (IDF). The accuracy of this relation is dependent on the accuracy of its parameters which need to be found based on short-duration rainfall depths (such as 15, 30, 60 minutes, and so on) for a long term (i. e. 30 consecutive years). Unfortunately, only 24-hour rainfall depths are available in many rainfall stations in Iran. Various empirical relations are available to convert 24-hour rainfall depth to sub-daily. One of these methods is IMD and its accuracy in some regions is low. In this research, the IMD method was transformed into a single-parameter equation and then, this parameter is evaluated for some rainfall stations in Iran. To do this, maximum 24, 12, 6, and 3-hour rainfall depths were extracted and their frequencies were calculated using Weibull and Gumbel methods. Regional coefficients in the modified IMD method were estimated using a linear regression method. Although the power of the IMD method is 0.33, results showed that this parameter for the rainfall stations ranged from 0.28 to 0.35. To make more comparison, the IDF relation of Kordan’s watershed was calculated using the short-duration rainfall depth which was estimated using the modified IMD, and then, this IDF was compared to observed data and Ghahraman’s relation which is commonly used in Iran. The comparison showed that the modified IMD relation could estimate the short-duration rainfall data better than Ghahraman’s relation. After calibration of the modified IMD relation for various regions in Iran, the sub-daily rainfall depth can be obtained with high accuracy.

A. Esmali Ouri1, P. Farzi, S. Choubeh,
Volume 26, Issue 3 (12-2022)
Abstract

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.



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