hadi modaberi

The effects of natural and human factors on changes in hydrological cycles in watersheds have threatened the safety and health of aquatic ecosystems and reduced biodiversity in rivers and wetlands. In recent years, in order to preserve natural ecosystems, functions and services related to them, increasing attention has been paid to the evaluation of environmental flows in these ecosystems. The present paper was carried out with the purpose of estimating the environmental water demand of Palangver river using simple ecohydrological methods that take into account the ecological characteristics of the river in addition to the hydrological characteristics.
Research

In this research, due to the existence of different ecological conditions and different habitat diversity in the upstream and downstream of Palangver river, the data of 2 hydrometric stations of Masjedpish in the upstream and Kolesar in the downstream were used at first. Then the effective meteorological parameters such as precipitation and the periods of wet and drought year were analyzed and by calculating the hydraulic regime of the flow, the flow rates in the river were analyzed in different months of the year. In the next step, the environmental flow of the river was calculated on a monthly basis using the variability curve method in minimum and maximum conditions and compared with the results of other hydrological methods such as Tennant, Texas, modified Texas and transfer of flow continuity curve methods.

The environmental flow values estimated by the RVA method in the Palangver River at two hydrometric stations of Masjedpish in the upstream and Kolesar in the downstream, in the conditions of minimum environmental flow were obtained 0.84 and 5.01 cubic meters per second, and in the conditions of maximum environmental flow were obtained 1.4 and 9.69 cubic meters per second, respectively. The estimated values of the environmental flow in minimum conditions at Masjidpish station show that the RVA method can completely maintain the ecological conditions of the river in a part of the year, because in the months of September to May, it covers a number between 60 and 80% of the monthly average. But in the months of June, July and August, when water withdrawal from the river is increased due to the agricultural uses, the RVA method has considered about 20-40% of the average flow; although this amount is far from the ideal conditions, it can be an acceptable amount to maintain minimum ecological conditions in the river considering the environmental conditions and water resource allocation management.
Also, the results of the estimated values of the environmental flow in the minimum conditions at Kolesar station in the downstream of the river showed that the RVA method can maintain the ecological conditions of the river because in the whole year, it has been able to include a number between 55 and 80% of the monthly average even in hot and critical months.

In the condition of lack of data, using the values estimated from the flow variability range method in minimum average conditions can maintain the ecological conditions of the river to a large extent by providing reasonable values. Since the main spawning time of fishes in the Palangver ecosystem is in the months of March, April and May, therefore the results of the RVA method have been able to maintain the suitable conditions for this important ecological function in the minimum conditions in both upstream and downstream stations and the full scientific guarantee for this ecological value is to maintain fish spawning operations in this area. It is also recommended to use RVA methods in the maximum conditions and FDC-shifting method in the cold months of the year, i.e. from October to May, due to providing values close to the average or even higher. But in the critical months of the year, it is recommended to use RVA methods in the minimum conditions, modified Texas method, Texas method and FDC-shifting method respectively.

Technical limitations in classifying heterogeneous wetland environments, characterized by diverse vegetation cover, land use, and species diversity, often lead to interference in classification results and reduced accuracy in differentiating vegetation classes within wetland ecosystems. There is limited research available to improve classification methods in wetland environments. The main objective of this study is to investigate the combination of multi-spectral and radar data in improving the classification methods of wetland environments and to provide a method for fine separation of different plant covers in these biodiversity environments. In order to better examine the changes of the spectral index during a year, the open-source system of Google Earth Engine is used so that the spectral behavior of the phenomena during the year can be accurately studied.

In this study, a combination of Sentinel-1 and Sentinel-2 data was used as the first data series, and a combination of Sentinel-2 data with spectral indices such as NDVI, SAVI, and mNDWI was used as the second data series. The best image for each season (summer, autumn, winter, and spring) from 2016 to 2022 was selected to create classification maps and examine detailed changes in the wetland. For image classification, training areas were selected based on field sampling, combining satellite imagery and Google Earth images. Classification was performed using three supervised algorithms: Support Vector Machine, Artificial Neural Network, and Maximum Likelihood. Also, the index map was prepared in the Google Earth Engine system and the indices were calculated using the ready-made products available in this system and were reviewed monthly for one year. To ensure the classification and to evaluate the classification accuracy, the most common accuracy estimation parameters, overall accuracy, producer accuracy, user accuracy and Kappa coefficient were used.

The results indicated that the combination of Sentinel-1 and Sentinel-2 data yielded better results compared to the combination of Sentinel-2 data with spectral indices. The overall accuracy and Kappa coefficient for the four periods were 92.99%, 87.43%, 83.80%, and 97.90% (in 2016, 2017, January 2022, and July 2022, respectively) when using the combination of Sentinel-1 and Sentinel-2 data, which were significantly higher than the results obtained with the combination of Sentinel-2 data and spectral indices. Furthermore, the combination of Sentinel-1 and Sentinel-2 data resulted in better detection of water bodies and lotus habitats within the wetland. NDVI, SAVI and mNDWI have a high correlation in examining the changes, so that an increasing trend was observed in the first six months of the year and a decreasing trend in the second six months, and the trend of vegetation and water changes is the same.

Due to the complexity of wetland spatial structures and existing threats, identifying land cover types is challenging. This study demonstrates the use of multi-temporal Sentinel-1 and Sentinel-2 data to comprehensively assess wetland characteristics. The accuracy assessment for the four study periods from 2016 to 2022 using three classification algorithms, Support Vector Machine, Maximum Likelihood, and Artificial Neural Network, showed that the combination of Sentinel-2 and Sentinel-1 data outperformed the combination of Sentinel-2 data with spectral indices in terms of overall accuracy and Kappa coefficient. Among the three algorithms used, the Maximum Likelihood algorithm consistently achieved the highest overall accuracy and Kappa coefficient compared to the other two algorithms.

Lakes, vital for human survival, are highly productive ecosystems providing services such as water supply and nutrient regulation. However, escalating water scarcity, fueled by global population growth and climate change, necessitates a comprehensive, long-term approach. The research method used in the study is an integrated framework of hydrology and ecological response components to determine environmental water requirements for Ovan Lake, Iran. The research delves into Ovan Lake's hydrological components, exploring precipitation, evaporation, surface water, and groundwater exchange. Identifying the great reed warbler breeding operation on the lake's margin reed lands as a key ecological relationship, the study highlights its role in reflecting the favorable status of other species and providing conservation benefits. Maintaining a water depth between 50 and 70 cm near the reeds, along with a reed cover width of approximately 20 m in March, as the breeding month, is recommended to ensure optimal breeding conditions for great reed warbler. Correlations between hydrological conditions (water depth, area, and volume) and ecological water depth are established, estimating environmental water requirements at 241 and 207 thousand m3 during drought and wet periods, respectively. The analysis computes water shortfalls needed to meet environmental water needs under different scenarios and ecological conditions. It matches minimum and optimum water levels to drought and wet periods based on available conditions. Results indicate challenges in maintaining ecological conditions in late spring and summer due to reduced rainfall and increased evaporation, emphasizing the need for proactive management strategies to sustain Ovan Lake's environmental health and restoration.

Forests are regarded as an economically viable solution to reduce greenhouse gas emissions and mitigate climate change. Carbon sequestration in forests is accomplished through surface and underground biomass as well as soil, which are interconnected and important sources of carbon storage. using direct calculations based on stem analysis and plant biomass. Four poplar plantations were selected, and a one-hectare plot was sampled in each plantation. DBH and the total height of all trees were measured in each plot, and two poplar trees were randomly selected and cut for analysis. Stem analysis, wood biomass determination, and carbon measurement were conducted. In each plot, soil profiles were dug, and samples were taken to measure the physicochemical properties. The results showed that Shaft had the highest density (N/ha) (326), followed by Siahkal (216), Langrud (129), and Talesh (190), respectively. Stand tree stem carbon content (tons per hectare) was the highest in Talesh with 52 tons per hectare, followed by Shaft (38.7), Siahkal (28.3), and Langrood (24.16). Allometric equations were established based on the highest correlation coefficient (r2) and the lowest standard error value (SE) between age as the independent variable and carbon as the dependent variable. Calculation of carbon sequestration in plantation stand stock and soil can provide insights into species function and their responses. Furthermore, comparing carbon sequestration in different sites can aid in the restoration of degraded lands and the conversion of such lands into high-yield plantations, which can be an effective measure in managing carbon sequestration using fast-growing species.

An examination of the trend of climate data recorded in the past decades, as well as the output results of all climate models predicting the future climate, indicate the occurrence of negligible changes in the global climate. Therefore, long-term forecasting of climate variables has received much attention. In order to predict the climatic parameters in Evan Lake, downscaling of general circulation models (GCMs) was used by using the LARS-WG model. The General Circulation Model (GCM) is the most current method by using in climate change studies. They are a key to understanding changes in climate; Although GCMs are imperfect and uncertain. The LARS-WG model was implemented to predict climatic parameters and the necessary analyzes were performed on its results. After selecting the general circulation model and the scenario more in line with the climatic conditions of the region, the outputs of the selected model were compared with the base period to determine the trend of their changes. The results show a decrease in average rainfall (39.9 mm), an increase in minimum and maximum temperatures (0.4 ° C) and an increase in the number of wet days (7 days) and the number of frost days (5 days). Also, the number of dry days (7 days) and the number of hot days (5 days) will decrease in the climate period 2030-2020.

Rising demand for water consumption has exacerbated complex conflicts between the agricultural, drinking, and industrial sectors. The main purpose of this study is to investigate the effect of reducing the discharge of rivers entering the wetland based on environmental guidelines on the water balance of the wetland. Due to the location of Anzali Wetland in the downstream of a catchment, it is necessary to determine the minimum flow of incoming rivers in such a way as to ensure the survival and dynamism of the downstream ecosystem.

In this study, the regulatory flow of the river is estimated based on environmental scenarios in Tenant, Texas, and transfer continuity curves, then the effect of discharge allocation in each scenario on the water balance of the wetland, and finally, the volume of the wetland is investigated. To calculate the water balance of the Anzali wetland, changes in the volume of the wetland per month are identified. To calculate the changes in the volume of the wetland in each month, it is necessary to calculate the volume of the wetland in two consecutive months. According to the discharge of environmental flow, the level of the Caspian Sea, and net evaporation in March and based on the balanced equation, the volume of the wetland in March is calculated as the initial conditions. Then, for the environmental flow on a monthly scale, the difference in elevation between the water level of the wetland and the sea is obtained. In the next step, according to the sea level values, the wetland water level is also calculated. Afterward, based on the surface-volume-height relationships of the wetland reservoir, the volume of the wetland is additionally obtained.

The results showed that the highest discharge of environmental flow and consequently the highest volume of the wetland is obtained by applying the flow continuity curve transfer method and the lowest is obtained by applying the conservative scenario of the tenant method. Evaluation of wetland volume in flow allocation scenarios based on environmental guidelines defined for rivers demonstrates that the release of flow in the range of environmental discharges is not able to provide suitable ecological conditions as well as appropriate status for tourism. Therefore, deciding on any water withdrawal from the upstream requires a comprehensive analysis of the swamp water balance. By applying the correct management of input and output components in the water balance equation of the wetland, it is possible to increase the volume of water in the Anzali wetland to the extent that the maximum economic benefit of the functions and services in the wetland can be done by considering all stakeholders.

The present study gives the important conclusion that it is not possible to exploit any of the rivers entering Anzali Wetland, even if environmental considerations are observed, and before deciding on any operation and construction of dams such as Shafarood Dam, it is essential to analyze the response of the swamp, accurately. To make the results of this study practical, it should be acknowledged that recognizing the balance components and observing the ecological water content of the rivers entering the Anzali Wetland are doubly important, especially in cases where the wetland is subject to special regulations and competition of multiple users.

In this study, the estimation of the environmental water requirement of the Amirkelayeh wetland has been investigated to achieve the desired and acceptable conditions in at least three scenarios of wet, normal, and drought conditions. To aim this purpose, first, the determination of drought classes in different years was calculated based on the SPI index. In the next step, the water shortage values of the wetland to meet the water needs of the Amirkelayeh wetland are obtained using the simulation results of the long-term statistical period of the balance equation, available water resources, and its adaptation to the targeted ecological conditions in different scenarios. The results show that in the first half of the wet year and in drought conditions, the water requirement at the minimum ecological conditions will be met by supplying around 0.62 million cubic meters of water, while in normal and wet conditions, there will be no water shortage, while in the second half of the water year and in normal and wet drought conditions, water demand will reach 3.65, 3.54, and 2.68 million cubic meters, respectively. It is considered that the most critical condition of water shortage in the wetland will happen in July. Furthermore, the volume of water that could be extracted from Seyed Ali Akbari creek was estimated at 4.7 million cubic meters. Regarding the flow of this creek, it was concluded that only in the first half of the water year can this source be used to supply the wetland’s water required. In addition, by increasing the storage capacity of the wetland reservoir in normal and wet conditions, 1.5 million cubic meters of water can be stored and if the efficiency rises, around 0.55 million cubic meters of water consumption can be saved.

In this study, the effects of the exploitation of the Sefidrood drainage irrigation network on Anzali International Wetland in the framework of IWRM are investigated. For this purpose, first, the values of hydrological indicators including water level, area, and volume of Anzali wetland were determined by considering economic, social and ecological conditions at the desired and minimum levels. After examining the current condition of the wetland, the relationship between the inflow to the wetland and the upstream exploitation system was simulated using the WEAP model and the model was calibrated for the baseline scenario with R2 and RMSE of 0.99 and 0.47, respectively. The results of scenario analysis in different conditions showed that currently the volume and level of the wetland are more dependent on the sea level and the inflow to the wetland only in flood conditions can show its effect on the volume and level of the wetland. Based on the results, it can be said that the ecological life of Anzali wetland is more affected by the discharge of the wetland to the Caspian Sea than by the quantitative management of water resources upstream of the wetland and water abstraction from Sefidrood irrigation and drainage network for agriculture, animal husbandry and aquaculture.

Wetlands as the most important aquatic ecosystems, in addition to include many ecological values, have provided many goods and services to local communities. Determining the amount of water required to simultaneously preserve the environmental and socio-economic values ​​of wetland stakeholders, is essential given the key role of water in functions dependent on aquatic ecosystems. Normally, socio-economic issues are less considered in calculating the water needs of wetland ecosystems, but in comprehensive approaches within the IWRM framework, in addition to hydrological and ecological issues, socio-economic issues related to the livelihood of human communities are also considered. In the present study, Anzali International Wetland was selected as a case study, and the required depth and volume of the wetland for tourism purposes was determined using a combined method that uses hydrological, ecological, and socio-economic methods. In this method, at first, all the services that the wetland provides to local stakeholders were identified through face-to-face interviews, observation, and review of resources, and it was shown that in socio-economic issues, boating tourism is one of the most important factors in determining the required water of the wetland. In the next step, the locations of cooperatives and boating docks were identified, and by selecting ecological-tourism indicators, the optimal routes for moving motorboats to these places were identified.  By estimating the depth of water required for the movement of boats, the volume of water required for the tourism water needs in Anzali Wetland was estimated to be 130 million cubic meters, which is 50 million cubic meters more than the current volume of the wetland and also less than the minimum ecological needs of the wetland.

Wetlands, because of their direct and indirect services to the human community, are of vital importance and attracted a growing consideration for rehabilitation and maintenance. To preserve the wetlands’ environmental values and henceforth guaranteeing the welfare of the stakeholders, it is essential to provide them with their required water necessary for presenting proper ecological services to the related aqua creatures and stakeholders. In the present research, the international Anzali wetland was selected as the case study and a conceptual model, developed based on IWRM principals, was employed to evaluate the economic loss due to its ecological condition deterioration. Defining the favorable and minium acceptable ecological conditions in Anzali wetland, the economic values of its services in an IWRM framework were calculated. To quantify the ecological condition of Anzali wetland, the economic values of direct and indirect use-values and the non-use values of the wetland was calculated as much as 10222220 million Rials. Then, through using the lost benefit method, the reduced values of the present condition of the wetland’s ecological services compared with the suitable and minimum conditions were determined. In this paper, by introducing some indices for the main careers of the stakeholders, the impacts of unbalanced hydrological conditions on the wetland’s tangible ecological services and through which on the system’s integrated water resources management were revealed.

Wetlands are one of the important natural habitat across the world and have a lot of benefits especially for energy circulation in the environment. In this aqua habitat, animals and plants are dependent to each other and because of their ecological role the life can be continued at this ecosystem. To conserve environmental and socio-economic values of wetlands, determining their ecological water requirement is of vital importance. The international Anzali wetland, which has been enrolled at the Ramsar convention, was selected as the case study in this research and its environmental water requirement was determined through using a combined hydrologic- ecological method. In this method, historical hydrologic condition of rivers entering the wetland and the Caspian Sea surface level as the prominent and influential factors on the hydrologic condition of the wetland were analyzed and considering the most important ecological functions for the wetland the key index was selected. The relationship between the wetland’s depth-water surface level and the ecological condition of the selected index across the different parts of the wetland and during the past years were investigated. Based on the achieved results, the ecological level and the pertinent volume of the wetland at the two minimum and optimum conditions were determined.

In this paper, using variance based methods, the sensitivity analysis of the two well recognized water quality indices, namely NSFWQI and IRWQISC, is presented in a comparative approach. The research was conducted by employing monthly sampling at thirteen stations on Pasikhan River during 2015. Sensitivity analysis of the two models’ parametres could lead to recognize the most important ones for their better measurement and also to evaluatie the correctness of the parametrs’ weights used in the Iranianian model. In the seasonal analysis, BOD was determined as the most sensitive parameter for both indices. In spatial analysis, NSFWQI classified the river water quality as “Good” and “Bad” in upstream and downstream Pasikhan River, respectively. Using Factor prioritization approach, it was found that DO was the most effective parameter in NSFWQI, for which applying the approach minimized the uncertainty of the model output. In IRWQISC, Do at U/S stations and BOD at D/S stations were the most influencing parameters on the model output variance, which emphasized the importance of the frequency and precision of sampling of these two factors against the other nine employed factors . Another important achievement of the present research was revealing the inconsistency of the weights used in IRWQISC, with respect to the parameters’ sensitivity and their influence on the model output in Pasikhan River.