The presence of water resources, particularly rivers, significantly influences site selection. Throughout history, settling near rivers has brought numerous advantages, but it has also posed certain risks. This study focuses on the sub-basins southeast of the CASPIAN SEA. Initially, we explore the connection between the layout of ancient settlements and the drainage networks. Additionally, we analyze the relationship between flood risk and the settlement patterns of these ancient sites by estimating the flooding risk based on linear, areal, and relief aspects. This reSEArch marks the first time such an analysis has been conducted. The findings underscore the importance of proximity to rivers in site selection, with areas close to rivers with lower stream orders being the most favorable for settlements. The study reveals a decrease in the frequency of sites near higher stream orders in relation to flooding risk. Conversely, there is an increase in the frequency and density of ancient sites near the first stream orders and at greater distances from the rivers, coinciding with an elevated flooding risk in the sub-basins. These results indicate that the inhabitants of the southeastern areas of the CASPIAN SEA sub-basins were cognizant of the flooding danger and factored it into their decision-making when selecting settlement sites

Nowadays, climate change and SEA level rise are serious threats to the social, economical and environmental vulnerability of the ocean coasts all around the world, and the CASPIAN SEA rapid fluctuations during the third millennium have set different conditions on the environmental structure of coastal areas. The main target of this study is to evaluate the coastline morphology behavior and the deformation of habitats and ecological condition of Boujagh National Park (BNP) due to CASPIAN SEA level changing during the progression and regression phases between 1978-2019. Initially, based on the available scientific documents, familiarity with the study area was carried out and the axes of measurements were defined. In field operations, sedimentation and erosion units of coastal zones and also different habitats were identified and geographically determined. In the next step, the rate of deformation of coastal habitats was calculated and classified using satellite images and GIS, and ultimately, validity of the results was verified with field evidence. The comparison of regression amount in BNP indicated that maximum negative shoreline displacement (892 m) has occurred in the east part of Sefid-rud River mouth during 1978-1995. So that, the shoreline negative changing has reached to 850 m in the north- western of central part of study area, while 738 m in north- eastern of central part in the period of 1995- 2019. The inundation zone extent has declined 104 ha between 1995 and 2019. Also the SEA regression amount of area was 111 ha in the period of 1978- 1995, while changed to 380 ha during 1995-2019. During the last 24 years, there have been widespread environmental alterations in the studied area and a large part of the coastal wetlands has been dried up. The most important habitats affected by the CASPIAN SEA fluctuations include coastal lagoons, dry and wet sandy beach, fluvial meadow and river estuary.

In this study 16 groups of zooplankton belong protozoa, arthropoda, rotifer and cyliophora were investigated. The number of these zooplanktons were accounted in m3 and also their biomass (mg/m3) was measured. The average biomass of zooplankton was measured 531. 74, 30. 77, 225. 07 and 96. 26 mg/m3 respectively and the total was attained 883. 83 mg/m3. The maximum and minimum biomass of all zooplanktons was estimated in November and July, 3446. 23 and 6 mg/m3 respectively. Furthermore, the maximum and minimum numbers of zooplanktons were found in September and July which were 48. 4 and 0. 002 millions respectively and the average number was 8. 4 ind/m3.

CASPIAN SEA is the largest enclosed body of water on the earth. Since the collapse of Soviet Union in 1991 and discovering large oil and gas fields, some issues such as political, economic and environmental events, made the CASPIAN SEA important. The ecology of the SEA are being endangered due to several issues such as petroleum extraction, river and SEA pollutions, water level rise, biological damages, decline of CASPIAN SEAls and lack of legal regime among the neighbors. Tremendous infrastructures have had serious impacts on the ecosystems around the CASPIAN SEA and have often imposed long term damages to the SEA. Activities around the CASPIAN SEA endangered the balance of this very sensitive and fragile ecosystem. Large oil stains on the SEA level and thousands of acres of soil contaminated by oil leaking from abandoned wells are some parts of the pollutions. Some people must endure to the CASPIAN borders. In addition, there are various pollution-related industries, especially chemical and mineral industries, large non-irrigated agricultural and also domestic wastes. on human welfare and wildlife of the area. Ecological balance of the CASPIAN SEA is nearly going to be ruined (Efendieva & M. Dzhafarov 1993). The increase of pollutions in the area has made many problems. The negative effects of shipping activities, oil and gas extraction and oil transport through the SEA, have always been problematic. Destruction of flora and fauna are of the consequences of pollution. Finally, exploitation of CASPIAN SEA oil and gas provide the new challenges about the ecosystem of the environment. The natural resources of environment are the source of potential wealth. So they can easily increase the conflict for example legal aspects between neighbors as well as the risk of security in the region.