مجله سامانه های سطوح آبگیر باران
سال نهم شماره 3 (پیاپی 30، پاییز 1400)

Dams control most of the sediment entering the reservoir by creating static environments. However, sediment leaving the dam depends on various factors such as dam management method, inlet sediment, water height in the reservoir, the shape of the reservoir, and discharge flow. In this research, the amount of suspended sediment of Doroodzan Dam based on a statistical period of 25 years has been investigated using three learning methods based on the data-driven algorithm, namely the K nearest neighbors, regression, and neural network. The results show that among different structures of the K nearest neighbors, the selection of 6 neighborhoods has more precise outcomes than other structures. Also, among different structures of neural networks, a structure with two hidden layers and 4 and 7 nodes in each hidden layer respectively, predicted suspended sediment more accurately than other neural network structures.  Comparison of different algorisms was indicated that neural networks have more accurate results than other mentioned methods.

In arid and semi-arid countries such as Iran, which are always faced water supply problems in various sectors due to climate stress, the importance of surface runoff management in watersheds is becoming increasingly apparent. One of the components of water resources management in each region is the initiatives of people living in and around watersheds based on their indigenous and empirical knowledge. The purpose of this study is to investigate the effect of native water-spreading weirs in the Riab watershed on the reduction of floods resulting from maximum 24-hour rainfall with different return periods. The results show that the volume of floods generated from maximum 24-hour rainfall according to Lacey’s formula in the return period of 2 and 5 years are 5.35 and 7.17 million cubic meters, respectively, and in the return period of 10, 25, 50, 100, 200, 500 years, the flood volumes are 8.44, 10.09, 11.39, 12.73, 14.17, 16.21 million cubic meters, respectively. The water-spreading weirs created in the region with a flood volume of 8.36 million cubic meters have a great impact on the control of the floods created so that the floods created by the maximum 24-hour rainfall in the 2 and 5 year return periods are completely controlled and runoff does not leave the basin.

Indigenous flood harvesting method for irrigation in Khorasan, which are called water-spreading weir are constructed and operated by farmers without any cost to the government. Although, the benefits of water-spreading weirs are clear for many experts and the authorities as well, this method receives a little attention by governmental soil and water conservation services. This problem and a few suggestions for the purpose of extension of this method among stakeholders were presented in this article based on the documentary method. After a short review on the historical background of water-spreading weirs, some technical and legal issues associated with water-spreading weirs and barriers to its development were discussed. First, the legal status of water-spreading weirs ownership was explained followed by the maximum total area of water-spreading weirs for an upstream watershed, developing water-spreading weirs in dry farming fields, land use change of natural resources into water-spreading weirs, and the need to adapt the watershed management and soil and water resources management programs in the upstream basin with downstream water-spreading weirs. Based on the authors' experiences, a ratio between 1:10 and 1:20 between the water-spreading weirs area to upstream basin was proposed for arid and hyper-arid climates, respectively. Also, the ability of Article 3 of the Law on Revising the Law on Protection and Utilization of Forests and Rangelands was explained in order to assigning permission to exploit national lands to construct new water-spreading weirs. Finally, some suggestions for better maintaining of existing water-spreading weirs as well as encouraging the farmers and facilitating the process of constructing new water-spreading weirs on national lands and drylands were presented.

Nowadays, considering the urban facilities and infrastructure development, utilization and maintenance are very important for many reasons. In this regard, the management, collection, and disposal of sewage and rainwater are very noticeable. The lack of surface water collection networks-being one of the most crucial urban facilities and infrastructure-along with the old swage network caused many health problems for citizens in some cities in the country. This study has been conducted to investigate the effects of lack of surface water collection and disposal networks in Ahwaz City. In the present research, the occurrence of floods and rainfall effects on the sewage accidents and drainage was examined using data in 2018 and 2019. The results show that the amount of swage drainage increased with increasing rainfall and it depends on rain intensity and duration. Due to the design of Ahvaz sewerage network separately, rainwater entering the network has caused damage and dissatisfaction of citizens and the design and implementation of surface water collection network is necessary to increase efficiency and reduce maintenance costs of sewerage network.

Today, water quality reduction and water pollution are some of the challenges in different countries around the world. One way to meet these challenges is to harvest and store rainwater using rainwater catchment systems. By collecting rainwater using rainwater catchment systems, water does not flow on the ground. Therefore, using the rainwater catchment system helps to prevent rainwater from mixing and contaminating with various pollutants. Since the value of rainwater and preventing its contamination in Islamic teachings is important, 63 verses of the Holy Quran are about the importance of water, including rainwater. One of the most important verses is in verse 205 of Surah Al-Baqarah. Also, in several hadith sources such as vasael al_shia, the issue of non-pollution of rainwater has been explicitly mentioned. Although the use of rainwater catchment systems has not been explicitly mentioned in the Qur'an and hadiths, in this article, we attempt to find Qur'an and hadith principles in collecting and storing rainwater with these systems.

Flow rate measurement is important in estimating other hydraulic flow parameters such as discharge and sedimentation. In recent decades, estimating flow velocity in open channels has attracted the attention of many researchers. Since flow velocity measurement methods in open channels are practically expensive and rarely used, in this study, by designing inexpensive GPS vessels with different sizes in cylindrical shapes and Spherical, velocity flow in open channels was investigated. GPS, stopwatch, and tape measure were used to measure the velocity, and comparing the results of these tools with each other showed a slight difference between the devices in estimating the velocity value. These vessels were used for open channels with several minutes to several hours intervals. The results of two field measurements of GPS vessels were analyzed, one in the water channel located in Agha Seyed Sharif Shaft and the other in a natural stream located in Fouman. The cost of construction of these vessels was much cheaper than other flow velocity measuring instruments and they had good accuracy.