Mehdi Vafakhah; Mostafa Zabihi Silabi; Sedigheh Modarresi Tabatabaei; Hossein Sarvi Sadrabad; Arezoo Shafiei Bafti; Negin Ghaderi Dehkordi; Mohammadreza Riahi; Seid Saeid Ghiasi
Abstract
Extended abstractIntroductionInvestigating the climatic condition over watersheds has a decisive role in water resource management planning. Meanwhile, changes in temperature and precipitation have a great effect on the discharge of rivers, soil erosion, and fluctuations in the level of ground water, ...
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Extended abstractIntroductionInvestigating the climatic condition over watersheds has a decisive role in water resource management planning. Meanwhile, changes in temperature and precipitation have a great effect on the discharge of rivers, soil erosion, and fluctuations in the level of ground water, and the occurrence of floods. It is very necessary to carry out research related to climate change in order to prepare as much as possible to deal with the harmful costs caused by this change. The review of the studies conducted in Iran also shows that the scale of the study is in most cases at the local level and the study of the mean annual discharge trend and its magnitude has not been studied especially over Iran country. Therefore, the current research was planned with the aim of determining the mean annual discharge trend and magnitude over Iran. Materials and methodsIn the present study, the trend of mean annual discharge in Iran was determined by considering the effect of dams using Mann-Kendall and Sen’s slope methods. First, the statistics of all the hydrometric stations located in the Iran six major drainage watersheds were obtained from Iran Water Resources Management Company. Finally, 139 hydrometric stations with a statistical period of 17 to 65 years were selected in this study. The statistics of these stations were compared with the data available in nearby stations and suspicious values were also controlled. The homogeneity of the data and reconstructing the missing data was carried out using the run test and linear regression through the station with the highest correlation coefficient for each station with incomplete station, respectively. In the next step, non-parametric Mann-Kendall and Sen’s slope estimator tests were carried out within XLSTAT software in order to evaluate the trend and its magnitude analyses. After determining the trend of the study hydrometric stations, the spatial distribution map of the mean annual discharge trend in Iran six major drainage watersheds were prepared within Arc/GIS 10.2 software. Results and discussionThe results showed that 14 hydrometric stations were affected by the dam. However, in the hydrometric stations without dam, 84, six and 35 hydrometric stations have a decreasing trend (60%), an increasing trend (5%), and no trend at the 95% confidence level, respectively. Examining the trend of the time series of mean annual discharge in each of Iran six major drainage watersheds also showed that 80% of the study stations in the Persian Gulf and Oman Sea watershed have a decreasing trend, while no trend were detected in 20%, 10% and 9% of the total study stations in the Caspian Sea, the Central Plateau, and the Persian Gulf and Oman Sea watersheds, respectively as well as all the stations of the eastern watershed (Hammon). In the meantime, all study hydrometric stations in Urmia Lake and Sarakhs watersheds and 68% of the study hydrometric stations in the Caspian Sea watershed have a decreasing trend. ConclusionThe results obtained from this research showed that the decreasing trend was detected in most of the hydrometric stations (84 hydrometric stations). Therefore, the decreasing trend of hydrometric stations in Iran can be related to the decrease in rainfall, increase in temperature and the emergence of excruciating droughts caused by climate changes and also human interference, including the excessive increase in the construction of dams and the change of unprincipled land use. However, one of the limitations of the current research is not taking into account climate changes and land use changes and determining the contribution of each of the mentioned factors in the decreasing and increasing trend of the mentioned stations. The results of the present research can be very useful and important for water planners and politicians in order to manage water resources.
Negin Ghaderi; Karim Soleimani; Ataollah Kavian; Mostafa Rashidpoor
Abstract
Urban watersheds due to their development, have more complex hydrological behavior than natural watersheds, and understanding their hydrological response will help to design appropriate flood control facilities. In this study, SWMM model was used to investigate the potential of urban runoff production ...
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Urban watersheds due to their development, have more complex hydrological behavior than natural watersheds, and understanding their hydrological response will help to design appropriate flood control facilities. In this study, SWMM model was used to investigate the potential of urban runoff production in a part of Babolsar urban area. The purpose of this study was to analyze the water availability of rainwater collected during different return periods for urban use. For this purpose, the SWMM model defined 65.65 ha of study area in the form of six hydrological units (from 5.94 to 16.82 ha), six output nodes and four channels were defined, and the height of runoff from 24-hour rainfall was obtained with different return periods. According to these results, the 24-hour rainfall with a 25-year return period is 70.37 mm, of which 33.73 mm for infiltration and 35.60 mm for runoff. Results showed that about 52.1% of rainfall of Babolsar City plan could have the ability to become runoff. The highest runoff coefficient is in the hydrological unit S3, which has a value of 0.637 at the 100 year return period. However, the lowest runoff coefficient is in hydrological unit S1 which has a value of 0.352 at 2-year return period. The results also showed that the runoff coefficient is directly related to the return period and the larger rainfall has a higher runoff coefficient. Through the collection systems, in addition to reducing the flood hazards of Babolsar City, a water supplement that offsets part of household consumption in the non-urban sector, also water resources management can be done.
