Background: Heavy metal pollutants in rivers are one of the serious environmental concerns in aquatic Ecosystems. Sediments, as an environmental indicator, have an acceptable ability to express the degree of environmental pollution with heavy metals. Therefore, with the aim of evaluating the health of the Water Ecosystem of Zayandeh Rood, we investigated pollution using sediment indicators. Methods: In this study, the sediments of Zayandeh Rood River were sampled at 17 stations. Metals lead, zinc, iron, cadmium, cobalt, nickel, copper and chromium were measured by acid digestion method with atomic absorption device. Also, land accumulation indices, Nemerow pollution index and ecological risk potential were calculated. Results: The average concentration of metals in sediments is 1762. 92 iron, 201. 52 nickel, 44. 07 zinc, 23. 36 cobalt, 28. 67 copper, 11. 51 lead, 10. 09 chromium, and 0. 87 cadmium mg/kg. According to the Igeo index, the average concentration of chromium, iron, copper, zinc and lead elements in all stations was lower than the average of the earth's crust, and the concentration of nickel and cadmium in all stations was higher than the background value. In all stations, the ecological risk potential index of cadmium was higher than other elements. Conclusion: Considering the condition of river sediments in terms of cadmium and nickel pollution and their very high ecological risk, it is necessary to comprehensively monitor the river and its living organisms. Also, in order to evaluate its health and ecological risk with the approach of examining the trend of spatial and temporal changes, heavy metal pollution in Water and river sediments should be taken into consideration.

Modeling Water resource systems is an essential part of the Water resource planning and evaluation process. An assessment of how changes in Water production and performance are important in the past and in the future. The InVEST model features Ecosystem services in the form of maps with low input data levels, but high volume output data, and simplifies complex issues, thereby increasing the ability to solve problems. In the present study, the modeling of Ecosystem production services (Water production) in the middle of Taleghan Watershed was investigated using InVEST Water Inventory. At first, the maps of the limiting root layer, the average annual rainfall, available Water availability, land use and the boundary of the basin and sub basins were entered as inputs of the model and maps of the amount of Water produced in each sub-area Cubic meter/year), the approximate value of actual evapotranspiration with the fraction of rainfall per pixel, the actual evapotranspiration map in terms of (mm) per pixel is estimated, the estimated Water production map per pixel (in millimeters per year) Was obtained. Based on the calculations done by the model in total in the Taleghan Middel Watershed, annual production of 200. 9 million cubic meters of Water is generated. Which has the highest amount of Water production under the Hasanjun area with 59. 3 million cubic meters of Water produced below the Donbalid, Zidast 1 and Zidasht 2 regions.

Water is the most precious treasure available to mankind very much felt in arid areas covering a wide area of Iran. The main aim of the present study was to estimate the economic value of Zayandrood Water for use and non-use services as well as estimating Water value in agriculture for wheat and barley products in eastern Isfahan using contingent and residual valuation methods. In addition, in the present study, the value of Water in the industrial sector was estimated for the steel and Mobarakeh industries in Isfahan using the residual method and gross margin. The results showed that the average willingness to pay of each household in 2016 for the monthly use was 29, 943 Rials and for monthly non-use was 41216 Rials. Also, the value of each cubic meter of Water in the agricultural sector in 2015 was 1191 Rials for wheat production in the Abshar network and 2033 Rials for Ruddasht network. Regarding barley production in the Abshar network, it was 308 Rials and for Ruddasht network it was 210 Rials. In addition, the value obtained for each cubic meter of Water for the Steel and Mobarakeh industries of Isfahan was estimated at 764, 000 Rials. Finally, it is suggested that the gradual correction of the price of Water over time will help to better allocate it between different products, which will improve the productivity of Water in agricultural production and save Water consumption.

Abstract Zayandehroud is the Water source for life in Central Iran, but it has become has turned into one of the most vulnerable Ecosystem due to human disturbances. In this study, Water quality and Ecosystem health of Zayandehroud was evaluated in a segment of the river with permanent flow, from the Zayandehrud Regulating Dam to Pol-Kalleh. Water and benthic macroinvertebrate samples were collected from 11 stations during the summer of 2022. The Iranian Water Quality Index for Surface Water (IRWQISC), along with richness and diversity indices, as well as biological indices (BMWP and ASPT), were calculated. The findings revealed that the IRWQISC index categorizes Water quality as moderate in most stations, with relatively good quality observed in only three stations. In contrast, the BMWP index denoted poor conditions, the ASPT index reflected severe to moderate pollution levels, and the Shannon diversity index also indicates severe to moderate pollution. The IRWQISC index was unable to accurately capture the effects of Water flow interruption downstream of the Cham-Aseman diversion dam and its impact on the deterioration of Water quality and overall river Ecosystem health. However, the substantial decline in the richness index and biological indices at the Pol-Kalleh station highlights a significant ecological imbalance in the river Ecosystem.

Mangrove Ecosystems have many functions for coastal areas, including ecological, social, and economic services. These functions have a systemic impact on the environment of other coastal Ecosystems and human life. The mangrove Ecosystem covering an area of 197.92 ha in Bedono, Demak Regency, Central Java was threatened due to the wave abrasion and high tides. Some parts of Bedono Village had become inundated and flooded permanently, zink as part of the ocean. This research was conducted to quantify Water pollution in the mangrove Ecosystem of Bedono Village using the Storage and Retrieval (STORET) method and the pollution index (PI). The fieldwork was conducted June 2022, by collecting Water samples for laboratory analysis tests and in-situ Water quality measurement. The parameter of the Water quality that exceeded threshold of the Government Regulation of the Republic of Indonesia Number 22 of 2021 are the dissolved oxygen (DO) ranges between 4.39-8.78 mg L-1, BOD ranges between 30-32.4 mg L-1, phosphate ranges between 0.063-0.074 mg L-1, ammonia ranges between 0.148-0.48 mg L-1, Cr ranges between 0.071-0.21 mg L-1, and Pb ranges between 0.071-0.21 mg L-1. Based on the STORET method, the Water quality in the mangrove Ecosystem was found to be in the category of moderately (-16, for harbor function) – heavily polluted (-80, for tourism and -90, marine biota), whereas based on the PI index it was lightly polluted (1.77-4.12, for harbor function) – moderately polluted (11.06-13.83for tourism, and 9.96-11.85, marine biota).

Introduction Iran has limited Water resources, and more than 90% of its Water is used in the agriculture sector. Virtual Water exchange plan is a suitable method to optimize Water consumption in the agricultural sector. Attention to Water resources, economic factors, technology and transportation, society, and the environment is necessary to examine the suitability of virtual Water exchange plans between regions. In the present study, using the principal components analysis method and also considering the indicators of resources, technology and transportation, economy, society and environment, an index to evaluate the appropriateness of the virtual Water exchange plan for wheat, barley and rice products was defined for each province. The innovation of the present study is the study of 3 different crops and considering all the important indicators for prioritizing the provinces of the country in their cultivation. Also, the innovation of the present study compared to other studies is the study of all provinces of the country. Materials and Methods The purpose of this study is to create a Water-Ecosystem-economy index according to the conditions of Iran and to use it to investigate the suitability of the virtual Water exchange plan for three wheat, barley and rice crops in different provinces. In this regard, in order to determine the appropriateness of the virtual Water exchange strategy, at the beginning, the provinces that have a comparative advantage in these three products are determined based on the Aggregated Advantage Index, and then, for the provinces with comparative advantage, Virtual Water exchange strategy has been studied through integrated Water index. The integrated Water-Ecosystem-economy index is based on the study of Cui et al. (2018), which has been adjusted according to the conditions in Iran. Principal component analysis (PCA) method was used for indexing. After creating integrated index for each province in each product, the provinces of the country are ranked based on the integrated index in the virtual Water exchange of each product, and each province that has more points is suitable for implementing the virtual Water exchange strategy for the products. If the integrated index is between 8 and 10, the conditions of the province are very good, between 6 and 8, the conditions of the province are good, between 4 to 6, the conditions of the province are average and below 4, the conditions of the province for crop cultivation are poor. Results and discussion The results show that Kermanshah, Ilam, and Fars are good and North Khorasan and Golestan are weak for the exchange of virtual Water of wheat. In the barley, Chaharmahal Bakhtiari has a good condition, and Khorasan Razavi has a weak condition. For paddy, Mazandaran has a good, and Gilan and Golestan have a weak condition. Suggestion 1-The use of the results can help managers and policymakers to solve the problems of Water in the country. 2-It is suggested that in future studies, horticultural and industry products should be considered.

Extended Abstract IntroductionLake Urmia is one of the largest saltWater lakes in the world, located in the northwest of Iran, and is recognized as a sensitive and unique Ecosystem. Unfortunately, this lake has faced serious environmental crises in recent decades. One of the main challenges is the significant decrease in the Water level of the lake due to climate change, human activities, and the construction of numerous dams in its Watershed. According to recent reports, the Water level of Lake Urmia has significantly decreased since the mid-1990s, leading to very adverse effects on biodiversity and marine life. This crisis, in addition to threatening the environment, has also had profound economic and social impacts on local communities. In this context, the main objective of this research is to examine the role of NDVI and analyze its relationship with the health of the Lake Urmia basin Ecosystem. By utilizing satellite data, we aim to record changes in NDVI over time and assess its effects on Ecosystem health. With the help of this data, it will be possible to identify areas under pressure and formulate policies for the proper management of Water resources and the protection of related Ecosystems. MethodologyThe importance of assessing Ecosystem health, especially in areas with specific environmental conditions, has become one of the key topics in environmental sciences today. In this study, Sentinel satellite images were obtained from the Copernicus Open Access Hub platform. The selected dates included various time periods from 2017 to 2023 to examine changes in land use and vegetation cover over time. Sentinel images were downloaded in different bands, including red (B4), green (B3), blue (B2), and near-infrared (NIR; B8). These bands were essential for calculating NDVI and analysing land use. To ensure high data quality, pre-processing steps included atmospheric corrections and cloud removal. QGIS software and the ENVI remote sensing tool were used for atmospheric corrections and cloud removal. Additionally, geometric corrections were performed in later stages to align the images. One of the effective tools in this regard is the use of the Normalized Difference Vegetation Index (NDVI). NDVI, as a remote sensing index, has significant capabilities in assessing and monitoring vegetation conditions. Results and DiscussionThrough necessary investigations and analyses of land use change maps, it was found that the area of construction land, which was approximately 133,796 hectares in 2017, increased to 188,779 hectares by the end of the period. Additionally, the area of orchards rose from 5,696 hectares in 2017 to 6,744 hectares in 2023. The agricultural land also increased from 979,333 hectares in 2017 to 1,380,279 hectares in 2023. Furthermore, the area of Water bodies decreased from 134,726 hectares in 2017 to 49,401 hectares in 2023. The increase in agricultural land in the Urmia Lake basin is one of the most significant changes that has occurred in recent decades and has had multiple impacts on the region's Ecosystem. Various factors such as population growth, rising demand for food products, and the desire for diversity in crop cultivation have led agriculture to become one of the main activities of the local population. This change has directly affected Water resources, soil quality, and biodiversity in the basin.ConclusionThe conducted studies indicate that the increase in vegetation cover and the construction of dams in the Watershed of this lake are among the effective factors in this trend. The first point to consider is the direct relationship between vegetation cover and ater absorption. The increase in vegetation cover, especially in the Watershed of the lake, helps in moisture retention in the soil and reduces evaporation. Although this issue can help conserve Water resources in the short term, in the long run, the increased vegetation will require more Water, and local factors may seek to allocate more Water for this purpose. Secondly, the construction of dams for managing Water resources and storing Water during critical times also affects the natural flow of Water to the lake. These dams can be significant in optimizing Water consumption, but at the same time, they create natural barriers in the river's path and disrupt the Water flow to the lake. As a result, with the reduction of Water entering the lake, the Water level gradually decreases.

ABSTRACT Today, climate change and its obvious negative effects on Ecosystems have caused concern. This research seeks to test whether vegetation changes are sensitive to climate shocks and also how the Ecosystem recovery process is through this index. In this regard, by using the GEE platform, Java coding, GIS and statistical analysis, vegetation and Palmer indices were calculated and based on time series climate data, vegetation and climate changes were presented. The results of Palmer's drought index show that during the statistical period (1985-2020) the study area is facing drought or is moving towards drought. Also, the results indicate the longest period of drought in the region from 2013 to 2020. Totaly from 420 evaluated months, the NDVI index is below the change threshold in 70 months. Among these, 31 months of the study period is below the acceptable threshold in green and non-reservoir seasons, which is ecologically worrying. The distribution of the vegetation index based on hexagons in 1985 and 2005 had a normal and almost normal distribution; But in 2020, the graph deviated from the normal state and skewed towards the vegetation cover index under stress or even thin covers. According to the analysis of the indicators, it is predicted that the Gorgan region is on the border of such ecological developments and the historical Ecosystem of the region is moving towards new Ecosystems or being in a new equilibrium state with climatic conditions and human disturbances Extended Abstract Introduction Today, climate change and its obvious negative effects on terrestrial Ecosystems have caused great concern to humans. These changes are effective on vegetation performance, plant distribution patterns, and have economic and environmental consequences. Therefore, it is important to know the behavioral pattern of vegetation changes against climate changes. Reviewing the studies of scientists in the world shows many researchers have used the NDVI index to study temporal and spatial changes in vegetation and its relationship with the climatic index of precipitation in different parts of the world. Studies have shown that NDVI follows precipitation with different time scales. Surveys showed that there are very few studies on determining the threshold of changes in the vegetation cover index in the face of climate shocks. Determining these thresholds can provide a suitable solution for evaluating the state of the Ecosystem, the consequences of climate shocks and the reversibility or disturbance in the Ecosystem. This study was conducted with the aim of improving our understanding of the dynamics of vegetation in the forest city of Gorgan during 1985-2020 against climatic stresses.   Methodology The current research is a comparative and monitoring research and seeks to test whether changes in vegetation cover are sensitive to climate shocks and also how the Ecosystem recovery process is through this index. To achieve the gole, first, NDVI index was selected among the optimal vegetation indices and its calculation process was done as a time series in the GEE system. In parallel with those climate shocks, the main elements including temperature, precipitation and storm were calculated during the historical process of 35 years and the average and standard deviation statistical indicators were calculated for them and the trend of changes in the thresholds was determined. The results of climate plots and climate changes show that in the years before 1985, 2005 and 2020, drastic changes have occurred in climatic elements and climatic factors. Therefore, these years can be considered as the periods when the climate shock happened.. Next, the region was divided into 436 hexagons and the NDVI index for each of the hexagons was calculated and modeled for the years 1985, 2005 and 2020 as selected years affected by climate shocks. In conclusion, to analyze the trend of changes in the time series of the vegetation index and compare the behavior of its changes with climatic indices, the Palmer index was calculated.   Results and discussion The results of climate change monitoring based on the Palmer index showed that during the statistical period the study area is facing drought in most years. The most severe climatic fluctuations and drought in the region were recorded in 2018 and in the months of October to December. The longest period of drought has also prevailed in the region from 2013 to 2020. During this period, rainfall, temperature and storm fluctuations have the most changes. The results of drought monitoring show that in 270 months, the region is facing climatic drought stress, 57 months of the study period, the region is facing severe and very severe drought stress. The results of the time series of the NDVI vegetation index showed that, out of the 420 evaluated months, 70 months of the year the NDVI index is below the change threshold, 31 of which are in the green and non-accumulating seasons, the seasons when the vegetation is expected to be at its maximum. Placing below the acceptable range means crossing the ecological thresholds and challenges the recovery and restoration of the Ecosystem, also the ecological performance will be affected at this point. Based on the assessment of the Palmer index, from 2014 to 2019, the situation of the Palmer index is in the extreme drought range. Also, since 2015, i.e. with a one-year time delay, NDVI index has experienced the lower limit of the equilibrium threshold of vegetation cover. These conditions are also valid for the years 2008, 2009, 2002 and 1997. In general, it can be said that the vegetation cover index is dependent on climatic changes and fluctuations and shows high sensitivity to changes. The important point in this section is that in the years when the NDVI index changes are at the lower limit of the threshold, we witness the most climate shocks and temperature changes, the occurrence of severe storms and precipitation fluctuations. The distribution of the vegetation index based on hexagons in 1985 and 2005 have a normal distribution; but in 2020, the graph has deviated from the normal state and skewed towards the vegetation cover index under stress or even thin covers. The visual interpretation done on the vegetation cover index in 1985 confirms the condition of the vegetation cover in the southern and western limits of the region in a state with suitable dense and pasture vegetation and forest cover on the edges. However, in 2005 and 2020, this cover has been changed and mainly turned into agricultural land and poor rangeland. In such a way that in 2020, the situation of the region has revealed the critical state of vegetation. The vegetation cover index in the central areas of the city has also reached from a relatively favorable situation in 1985 to a critical situation with almost no dense and stress-free vegetation cover in 2020. The results of the present studies are consistent with the studies of Visentr Serrano et al. in 2013 and confirm the relationship between NDVI vegetation and climate change. In addition, the results of the studies are consistent with the studies of Alwesabi 2012, Xiai & Moody, 2005 and Yan et al. 2001. In such a way that the present study and the aforementioned studies all confirm the influence of the vegetation index on climate fluctuations and precipitation with a one-year time difference.       Conclusion In general, the threshold is defined as a border with different conditions. After crossing the thresholds, the stability and positioning of the NDVI in the equilibrium range is often difficult, and the Ecosystem is constantly spending energy to restore itself or to position itself in a new stability state. The result of the mentioned disorders is the reduction of resilience and resistance in the region, which leads the Ecosystem to alternative states or crossing the threshold or being in a new equilibrium state. The results showed that the areas where green vegetation is concentrated and denser are less affected by climatic stresses and show more resilience. However, the areas that have become spots and islands due to destruction in the urban areas are more affected by climatic stress and destruction and show less tolerance against the destruction factors. The results help managers to focus their management plans for the preservation and maintenance of urban green spaces as well as forest and pasture ecotones on the edge of the city by knowing the thresholds.   Funding There is no funding support.   Authors’ Contribution Authors contributed equally to the conceptualization and writing of the article. All of the authors approved thecontent of the manuscript and agreed on all aspects of the work declaration of competing interest none.   Conflict of Interest Authors declared no conflict of interest.   Acknowledgments  We are grateful to all the scientific consultants of this paper.