Ownership of Natural waterways, including rivers, Natural streams and canals, is one of the most important issues of the water law of the country; therefore, in this article, the evolution of the ownership of the mentioned waterways from the beginning of the legislation until now has been studied. For this purpose the fallowing articles were studied: the Civil Code (as the main law on ownership), paragraph 6 of Article 96 of the Municipal Law (as the first law governing the ownership of urban waterways), Article 2 of the Water Law and its nationalization, as well as Article 2 of the Law on Fair Water Distribution (as Specific laws in the water sector). In this research, the legal criteria for determining the waterway bed have been criticized and the legal effects of these criteria on the ownership of lands adjacent to Natural waterways have been explained. Also, in the current article, an attempt has been made to mention the evolutionary stages of the ownership of waterways' bed. Therefore, taking into account the various divisions for property, ownership of waterways with the term "Natural" or "public use" should be included in the category of public property. Reviewing the legal status of this type of property in the relevant laws from the beginning of the legislation until now, it was found that the legislator does not have the same approach to the ownership of waterways. The evolution of the relevant laws indicates that the legislator had three different approaches on the ownership of this category of property. Therefore in accordance with the circumstances of the time, the adoption of the law can be classified and reviewed in three historical important periods: 1-private property of waterways, 2-government ownership, 3-Water governance that considers waterways' property as public wealth and commonalities, at the disposal of the Islamic government. Study of the historical course of legislation showed that the Iranian legal system formed its first approach which was the protection of private property; and then gradually moved toward the governmentalization of these properties; and finally included them in the category of public property and Natural resources, which are in the possession of the government. During the period of privet property of waterways (1906-1968), the waterways' bed was occupied by adjacent land owners and exploited according to the existing conditions. The article 23 of the Civil Code (1924) related the exploitation of ownerless property (including public properties) to relevant laws which had not been well developed until that time. Moreover, the article 25 of the Civil Code has forbidden the occupation of public properties. Paragraph 6 of Article 96 of the Municipal Law indicated that the waterways' beds within the cities are considered as public property that is owned by the municipality. Besides, any civil operations within the beds of waterways in cites is subjected to the permission of the Ministry of Power. The second period started in 1968 with the Water Law and its nationalization which introduced water ways as public properties. The Coastal Land Law described the conditions of construction, inside the bed or nearby the water bodies, with technical details. The third period of water governance started in 1983 with the Law on Fair Water Distribution. The results of this study showed that according to the current legal system of the country, the bed of Natural waterways is not privately owned, and in addition the government does not own them; but the bed of waterways are among the public property and national Natural resources. Although the bed of Natural waterways is under the control of the government, it should be noted that this control is only to manage the use of water and protect national resources and the environment. This possession does not mean that the government owns them. Therefore, for example, the government does not have the right to sell or transfer them. Hence, the actions of the Ministry of Energy are purely administrative. The special emphasis of this article is on how to apply legal rules and standards in recognizing the bed of Natural waterways and its final limit, as well as its stabilization in nature in order to protect public rights and prevent damage to adjacent landowners or limitation of their ownership.

The Muskingum-Cunge method is still frequently used for flood routing. During the last decade different modifications were proposed for this method to increase its accuracy. However, difficulties arise in the selection of an appropriate ‘‘reference’’ discharge for evaluating the routing parameters and in the small volume loss that can occur. In this research in order to study the applicability of the different schemes of the Muskingum-Cunge method in field conditions, some observed flood events of Karoon River, Western Iran, have been routed by these schemes and the results were compared with that of the observed values of the downstream end of the reach as well as outputs obtained by the dynamic wave model. The results indicated that the studied schemes generally provided reasonable output in comparison with the observed hydrographs. Also the discrepancy among the results of these schemes was not significant. In addition, the computed results reasonably concurred with that of dynamic wave model. Finally, the sensitivity analysis of computational grid size is performed. The results showed that the effect of changing the time step rather than the space step is bigger on the output of models.

Introduction Physiography is a part of earth science studies in which the physical characteristics of the drainage basin such as area, perimeter and relief, slope, direction, etc. are studied. The studies that examine the physical characteristics and shape of a basin are called Physiography. Knowledge of the physiographic characteristics of a basin along with information about the climatic conditions of the region can provide us with a relatively accurate image of the quantitative and qualitative function of the hydrological system of that basin (Pitlick, 1994). The increase in the rank of waterways in a drainage basin is under the influence of various geomorphological, geological, and climatological ecosystems and contexts. In dealing with open systems, the researchers’ assumption is usually on the effectiveness of specific and accessible vectors and the evaluation of the system's behavior in relation to those vectors. The area of study in this research includes Iran. Iran with an area of about 1648195 square kilometers is approximately located between 25-40 degrees north latitude and 44-64 degrees east longitude. Materials and Methods In this study, the accuracy of physiographic relationships in the basins was discussed. The existing relationships and the connection between them represent the relation of physiographic characteristics of the basin. In dealing with open systems, the researchers’ assumption is usually on the effectiveness of specific and accessible vectors and the evaluation of the system's behavior in relation to those vectors. Accordingly, in this study, the increase in the rank of the waterways drainage basin of Iran in the form of 984 sub-basins was investigated in terms of the bifurcation ratio, total length of waterways, the total average of waterways, and basin area. The relation between the equal rank of waterway and drainage basin area and also the relation between specific retention constant and slope and drainage density are among the physiographic characteristics of the drainage basin that were evaluated in this study. For this purpose, first, the layer of main rivers and waterways was prepared from DEM 30*30 extracted from the SRTM satellite. After extraction of the waterway in Arc GIS 10. 3 software, Iran's rivers were ranked based on the Horton-Strahler theory. The relation between the equal rank of waterway and drainage basin area and also the relation between specific retention constant and slope and drainage density are among the physiographic characteristics of the drainage basin that were evaluated in this essay. Discussion In the drainage basin of Iran, a regression equation was established between the ‘area’ as an independent variable and the sum of flow ranks as a dependent variable, and the obtained equation responded positively to this hypothesis with a favorable level of significance. The amount of the explanation coefficient of most sub-basins is more than 0. 99, which indicates the great effectiveness of the expanse of the basins on the sum of the ranks of rivers flow. The lowest explanation coefficient is in the Abarkooh-Sirjan basin (0. 89) and then in Dar-Anjir Desert sub-basins (0. 92) (probably due to the basins being dry and playa), Aras (due to having just one bank) And Haraz-Qarah Su (0. 96), and Sefidrud-Haraz (0. 97) (due to the different climate of the basins), respectively. The bifurcation ratio has an inverse relationship with the ranks so that as the waterway rank increases, the bifurcation ratio coefficient decreases. The highest percentage belongs to the Sefidrud-Haraz (82%), Gavkhouni 72%), and Namak Lake (62%) basins. The common feature of the three basins is that their final drain is located in a corner of the basin and not in the center. Siahkuh Desert sub-basins (35%), Bandar Abbas-Sadich (36%), Karkheh and Abarkooh-Sirjan (37%) have the lowest frequency percentage of high ranks. In the drainage basin, a regression equation was established between the area and equal ranks according to their frequency. In this equation, the area was the independent variable and the bifurcation ratio was the dependent variable and according to the level of significance obtained from the equation, the drainage basin responded positively to the hypothesis. Basins with smaller areas also had smaller bifurcation ratios. The highest explanation coefficients belong to Qarah-Su-Gorganrood (99%) and Dur-Anjir Desert (98%) sub-basins, and the lowest explanation coefficients belong to Sefidrud and Hamun-e Jaz-Murian (50%), Hamun-e Mashekl (54%), Urmia (59), and Helleh (62%) sub-basins. The flow length of each rank is measured and categorized in all basins. The prevailing result is the existence of a negative relationship between total flow length and rank. A regression equation was established between retention constant and slope, and regression equations were estimated with a positive procedure. In this examination, the slope was considered the independent variable and the retention constant was considered the dependent variable. Some basins were excluded from the examination, most likely due to the topographic and lithological effects of the basins that have changed the specific retention constant. Basins may be more expanded in the mound area, reducing drainage density in these areas. Even among the basins where acceptable regression equations have been obtained, the explanations coefficient varied between 50% (Hamun-Helmand, Abarkooh-Sirjan, Sefidrud) up to a maximum of 79% (Gavkhouni) and most of them had been between 50% and 60%. Conclusion There is a direct relationship between the two parameters that is, the sum of the rank of waterways in a drainage basin and the area of the drainage basin of Iran so that in most drainage basins the explanation coefficient of these two parameters is estimated to be 99%. In the drainage basin of Iran, the amount of the explanation coefficient of the bifurcation ratio and increasing the rank of rivers varies from 35% in the Siahkuh Desert basin to 82% in the Sefidrud drainage basin. The area of the basin with a 99% explanation coefficient may affect the bifurcation ratio. In some basins of Iran that have active tectonics or rivers are captured or diverted, sometimes the flow length is fewer in the lower ranks than in the higher ranks. Provided that the topography of the basin is balanced over time, by increasing the rank of waterways, the flow length average increases in the same rank. The assumption that as much as the retention constant of the basin increases then the drainage density of the basin decreases, can be generalized in most of the drainage basins of Iran with an explanation coefficient higher than 90%.

The wake wash from passing ships can cause environmental damage. The wake wash is an important issue for naval architects and shipbuilders in concentrating on more environmentally friendly designs. This paper presents results of a parametric study of catamaran hull form to obtain low wake wash hull form configurations or low speed inland waterway boats. The study uses a Computational Fluid Dynamics (CFD) simulation, and model experiments were carried out for validation of the CFD software set-up. The study concentrates on the asymmetric catamaran hull form. The investigation is conducted on two configurations of hull form, Flat Side Inward (FSI) and Flat Side Outward (FSO) configurations. The investigation is conducted on a hull form with a Length to Beam (L/B) ratio of 12.2, 15.2 and 18.3 and a Separation to Length (S/L) ratio of 0.2, 0.3 and 0.4. The results based on wave height criteria at various longitudinal cuts have shown that the FSO configuration has a lower wake wash compared with the FSI configuration. Considering L/B and S/L ratios, hull forms with a larger separation or higher L/B ratios produce lower wave heights.

IntroductionAfghanistan is a  country that shares four waterways (Hirmand, Kabul, Harirud, Amu) with neighboring countries. These watercourses are an important source of water supply in Afghanistan and its neighboring countries. Except for the Hirmand River which has the 1973 treaty as its governing source of legal regulation, the other three water basins of Afghanistan do not have a treaty exploitation system and are considered subject to the customary rules. Therefore, any use of these waterways is only possible within the framework of the customary rules of international law of the sea. Due to various historical reasons, Afghanistan has not had the opportunity to avail itself of these watercourses. In the last few years, this country has designed and implemented programs to manage and use its water resources. Many of these actions were faced with protests from Afghanistan's neighboring countries. These countries have considered the actions taken by Afghanistan to be in conflict with international law, especially the customary law governing international waterways. According to the practice of states, and the opinions of international judicial and non-judicial institutions, currently, there are rules such as reasonable and equitable utilization, the prohibition of incurring serious harm to other countries, and the responsibility to cooperate, which underly the basic and customary rules of international law of the sea. The customary characteristic makes states legally obliged to comply with these rules regardless of their membership in international treaties. States’ violation of customary obligations will result in international liability. Without a doubt, Afghanistan, as a member of the international community, will not be exempt from this rule. Research Questions The present research examines the status of the customary obligations regarding the non-navigational use of international waterways in the legal system and the practical practice of the Afghan government. The research seeks to answer these questions: What is the approach of Afghanistan's legal system towards the international customary rules of the sea and do the domestic laws require the government to comply with these obligations or not? What is the practical practice of the government in this case and to what extent are Afghanistan's actions consistent with the international customary rules? Research Background As an important source of life and livelihood, the subject of waterways has been of interest to humans forever. The greatest human civilizations are built next to water sources. With the formation of nation-states, the discussion of international waterways and their exploitation by countries was raised. In this regard, many researches have been conducted and published by scholars on how to regulate the use of international watercourses around the world.Although such research was initially centered around the use of navigation, with the increase in population, the climate changes, and the pollution of water resources, non-navigational exploitation and their related topics also attracted the attention of scholars. Regarding the international watercourses of Afghanistan, many researches have been published by different authors both inside and outside of Afghanistan, in different languages.The common denominator of all of these efforts is the focus on contractual obligations, management, and the protection of water resources. Therefore, an important i.e., international customary obligations of Afghanistan and its practice and performance in this area has been neglected. However, some authors have mentioned some of these obligations in their research. For example, we can refer to works such as the research  of Mr. Jamshid Momtaz titled “The legal system of the middle East watercourses”, “Ali Raghanabi: The legal principles governing the international rivers, with an emphasis on the Hirmand River”, “Nusratullah Afzali: The principles governing the international watercourses with an emphasis on the Harirud river”, and “Mrs. Sara Naqshband: International Practices in the Settlement of International River Disputes”. Within Afghanistan, in the last few years, research has been carried out in the field of Transboundary Rivers. The major parts of these research papers have been carried out by the Doran Institute, which is a private research institute. This research center has so far published two articles in this area (Amu and Kabul) and besides these, publishes a journal about the waters of Afghanistan, the first issue of which was published in 2015. This research focuses on the capacities of the mentioned areas, the capabilities and challenges of their use, and the climate risks that threaten these waters; it briefly refers to the legal aspects of using these waters. however, it has not been specifically and comprehensively addressed. DiscussionArticle 7 of Afghanistan’s Constitution recognizes the government’s responsibility to comply with the United Nations Charter, the Universal Declaration of Human Rights, and other treaties that Afghanistan has accepted, but it does not make any reference to international customary obligations. Of course, this does not mean that Afghanistan does not accept customary international obligations. the obligation to comply with the UN Charter (based on Articles 1 and 2 and other principles of the Charter) is not limited to treaties, and includes obeying all binding sources of international law. The constitution, especially its seventh article, has stated the obligations that need to be approved by the parliament (National Council) and approved by the president. Customary international obligations are usually entered into national systems through automatically and informally and do not require a special process for ratification andapproval. The study of Afghanistan's legal practice, including the study of the past constitutions (1980 and 1987), in which, in addition to treaties, Afghanistan's obligations to other accepted principles and rules of international law are set out, supports this claim.This is why the Afghanistan transboundary water policy, which was approved by the Council of Ministers in 2015, mentions Afghanistan's responsibility to comply with the international rules and regulations in the operation of transboundary waters in its sixth chapter. International rules and regulations include contractual and customary rules.The practice of the Afghan government in the exploitation of common waterways is in line with its responsibility to act by these rules. The signing of a treaty with Iran (in 1973) and an agreement with the Soviet Union in the field of utilization of the Amu River (in 1958 and 1964) indicates that this country considers itself bound to international obligations in this field. Conclusion The Afghan constitution is silent on its international customary obligations. nevertheless, the emphasis on compliance with the United Nations Charter in its seventh chapter also includes complying with the customary rules. The legal and practical practice of the Afghan government shows that this country considers itself obliged to comply with these obligations not only as a  member of the international community; but also according to its domestic laws. However, examining the degree of compliance of this country's actions in the use of international waterways with its international obligations requires examining all the related factors. Without access to the relevant information, it would be very difficult to consider these actions in violation of these obligations. However, the principle of responsibility to cooperate obliges the Afghan government to take appropriate measures to deal with these protests within the framework of international law.

BACKGROUND AND OBJECTIVES: The Coronavirus 2019 pandemic has revealed significant shortcomings in the Philippines’ solid waste management system, particularly in addressing the surge of pandemic-related waste. Unreliable waste collection, insufficient public knowledge, and improper waste disposal practices have exacerbated risks to the environment and public health. Despite these concerns, the specific impacts of Coronavirus 2019 pandemic related waste on human health and the environment in the Philippines’ context remain underexplored. This study aims to quantify Coronavirus 2019 related waste generated from both household sources and non-household establishments, assess disposal practices, characterize waste composition, determine generation rates, and classify waste types. Moreover, a comprehensive waste flow analysis will be carried out to monitor the movement of both appropriately and inappropriately managed Coronavirus 2019 waste, examining its implications on terrestrial and aquatic environments, as well as public health. Insights from the Philippines can significantly contribute to the formulation of resilient and adaptive waste management approaches in response to future public health emergencies worldwide.METHODS: Coronavirus 2019 pandemic related waste generation from both household sources and non-household establishments was quantified through a 5-day at-source waste analysis and characterization study conducted in twenty-six urban and rural barangays of General Santos City. The determination of sample sizes was conducted using conventional statistical techniques, informed by the most up-to-date census data and business establishment profiles. Structured questionnaires and checklists were used to gather information from household respondents regarding Coronavirus 2019 related waste sources, generation rates, and disposal behaviors. To determine the degree of environmental contamination related to pandemic waste, further waste characterization was carried out in the Silway and Makar Rivers, two key urban waterways that pass through populated and commercial districts prior to their discharge into Sarangani Bay.FINDINGS: According to the Waste Analysis and Characterization Study, waste linked to the Coronavirus 2019 pandemic totals about 52,877.7 kilograms per day, which is equivalent to 1.57 percent of the city’s total daily waste. This equates to an estimated 4,654,720 discarded face masks from household sources and 633,050 from non-household establishments daily. Coronavirus 2019 pandemic related waste density in the Makar and Silway Rivers-tributaries of the Sarangani Bay Protected Seascape was recorded at 0.238 gram per square meters and 0.706 gram per square meters, respectively. Mainly consisting of plastic face masks, this waste poses environmental threats as possible microplastic sources, jeopardizing both marine environments and human well-being. Waste flow analysis illustrated the management pathways of Coronavirus 2019 pandemic-related waste, underscoring its significant environmental and social repercussions.CONCLUSION: The Coronavirus 2019 pandemic has highlighted critical gaps in waste management systems and the environmental and health hazards associated with emerging waste streams such as Coronavirus 2019. Mismanagement of this waste stream results in environmental damage and considerable threats to public health. The study emphasizes the pressing requirement for better waste governance, infrastructure enhancements, and public education to reduce the enduring effects of waste associated with the pandemic.

The riverbed and margin vegetation causes to increase in roughness against flow, decrease in average flow velocity, reduce water-energy, and alterations in layer velocity distribution (the flow velocity profile) across the river. In current experimental research, the effect of branching vegetation on the stream flow and bed formation is analyzed. The flow conditions are examined in experimental channel with 7 meter length, 25 cm width and height through different flow rates (3, 5, 7 lit/s) and slopes under different(0. 001, 0. 003, 0. 005) and densities of vegetation (50, 25 and 12 percent). According to the processed data, it can be implicated that the difference between flow level, substrate, and rate is affected by the types of vegetation density; thereby existence of vegetation causes resistance to flow and depth increment. In all experiments, through the vegetation density increment, the bed erosion increases compared with the primary condition in which the most and least alterations are observed in 50 and 12-percent density, respectively. In the condition of equal flow rate with density increment, the flow depth is increased. The bed particle displacement in the section covered by vegetation is increased through density increment in which flow level in 50 is more than 25 and 12-percent density, as well as, flow substrate erosion and alteration whereas sediment (particles accumulation) is appeared frequently under less density at the end of section covered by vegetation.

Nature has aesthetics of its own, what can provoke the human mind into better recognizing the concept of beauty via mental perception. As such, human mind can interact with the nonverbal expressions of nature only to better his/her primitive aesthetic knowledge and reach a more novel recognition of aestheticism via the practice of interpretative deduction. This article has been the result of a series of discussions and dialogues between the authors on the nature of aesthetic geotouring and exploring the Natural phenomena based on the Dialectical Method of Socrates and modelled after the Platonic dialogues. The outcome of this dialectic study brings to light the fact that touring in nature through providing the due opportunity for mental perception of aesthetic phenomena can provide a clearer definition of ‘beauty’ in its rich variety. Aesthetic search as such will culminate in forming a more illuminated mental concept of beauty in mind, what can influence human rationale for aesthetic judgment and enrich even more the texture of human aesthetic creation. Such aesthetico-interpretative endeavor might lead to a higher potential for creating more original works of literature and art and culminate in a better judgment about such aesthetic creations.

Common international waterways have special importance and status in terms of international law and relations. Undoubtedly, one of the most important challenges of the last century of international institutions is to try for more coordination between States with common water resources and fair allocation of these resources among them. Familiarity of the States with international customs and laws on how to exploit shared water resources will lead to optimal management and reduce tensions in this area. In this regard, several international treaties and agreements have been prepared with the efforts of international organizations and institutions. In addition, many customary laws have been appeared in this regard at the international level.Despite the great importance of the issue, the challenge of using international waterways  has not yet been managed and planned by an international binding agreement or law, although with the passage of time, public understanding for international participation to solve resource problems Common blue has increased; But the world community has not yet reached a suitable conclusion on an international document that can be agreed upon for the management and protection of common water resources.Until now, various laws, treaties and resolutions have been approved regarding the joint exploitation of common water resources, but due to the existence of problems and ambiguities in some of the articles of these laws, none of these laws are used as a reference law. One of the important reasons for that is the existence of different doctrines and attitudes towards environmental law and its philosophy.According to the Helsinki Laws of 1996, all countries located along the river have equal rights to use water resources, and no country has the right to use river water if it causes damage to other countries along the river. In the 1997 Convention on the Rights of Non-Navigational Uses of International waterways, many legal principles raised in international environmental law, such as "the principle of rational and fair exploitation and use of water and the principle of prohibiting damage to the territory of the state Other" and the principle of "international cooperation" have been formulated and presented.In terms of research, the articles written in this field are mostly in English. One of the most important works done in Persian language in this field is an article written by Mr. Shuli, Watan Feda and Mrs. Sarkar Khanum Arideh entitled "Examination of the theories and legal provisions of water sharing in the laws of international treaties on border waters" The article examines international treaties on border waters, which is very valuableConsidering the important differences and problems of the Islamic Republic of Iran with its neighbors regarding common waterways and considering the severe water shortage, the most important achievement of this article is the pathology and finding ways to optimally use international regulations, laws and obligations to prevent It is a violation of the right of our country and also to refrain from any tension with the neighbors in this regard. The most important hypothesis of the article is about this axis: "customary obligations of countries and approved international conventions on the issue of international waterways are the only way to resolve the disputes of neighboring countries in this area. The purpose of this article is to analyze the existing international laws, customs and treaties on how countries use common water resources. Based on the findings of this study, compliance with regulations and treaties by countries will lead to optimal management and reduce tensions in this area.