مجله اکو هیدرولوژی
سال نهم شماره 4 (زمستان 1401)

Accurate information about the source of suspended sediment in river systems is necessary because supply enhancement of fine-grained sediments to a river system through human activities leads to overloading of suspended sediment, which affects water quality and the ecosystem. In addition, quantifying the relative contribution of different sources is vital to determine the best methods for suspended sediment control. Therefore, reliable information needs about the origin of transported fine-grained sediments by rivers. The purpose of this study is the fingerprint of suspended sediments using geochemical characteristics using the R software Fingerpro package in various land uses/covers of the Vaz watershed in Mazandaran province. In this research, 30 soil samples were collected from different land use, including forest, rangeland, agricultural land, and the streambank as sources of sediment yield, and one sample of suspended sediment at the outlet watershed. Geochemical characteristics of the soil and 59 sediment samples were measured using the ICP-OES GBC Integra device. Then, suitable tracers were identified for the fingerprint of suspended sediments using range tests, Kruskal-Wallis, and discriminant function analysis, in the Fingerpro package of R software including K, Li, P, V, Cr, Fe, Cu, Ga, Ge, Rb, Sb, Ba, Nd, Ta, and W. The separation results of the land use/covers contribution in the yield of suspended sediment with the GoF index showed with the rate of 80.68 that the contribution of agricultural, rangeland, forest, and streambank was with rates of 0.18, 7.90, 5.69, and 86.21 percent, respectively. Finally, the contribution of each source to the yield of suspended sediment per hectare was calculated. Results showed that the streambanks and forests had the highest and lowest participation in the yield of suspended sediment per hectare with rates of 0.513 and 0.0007 percent, respectively. The results also showed that the special contribution of stream bank lands at land uses for agricultural, rangeland, and the forest was the rates of 320.62, 394.61, and 732.85, respectively. The fingerprint results using the geochemical method for managers and planners provide valuable information about the resource contribution of suspended sediment yield to implement management programs for soil and water conservation.

Agriculture has the largest share of total water consumption in the world. Among the cereals, the high consumption and demand of wheat has made it a strategic product. Due to the high level of wheat cultivation in the world, the amount of water used for its production can significantly affect the total water used in the agricultural sector and pose a serious threat to access to water resources. This study was conducted with the aim of evaluating the water shortage in wheat production in Iran, emphasizing the framework of the water footprint in the country during the statistical period of 2007-2018. The results of this study showed that the share of blue, green and gray water footprints is 71.76, 15.87 and 13.11% of the total water footprint in the production of Faryab wheat and 55 and 38.34% of the green water footprint respectively. And it forms gray in dry wheat in Iran. Also, the results showed that the average water stress index of wheat production in the country is 0.6, and the range of spatial changes of this index varies from 0.01 in Guilan to 3.01 in Ardebil at the North. The highest level of water self-sufficiency index (lowest dependency index) is related to North Khorasan, Khuzestan and Fars provinces with an average value of 70% and the lowest level of self-sufficiency index is related to Guilan province (2%), Mazandaran 9% and Tehran 16% (highest dependency index). The present study will be very helpful for making decisions about the sustainable management of water resources for wheat production in Iran.

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.

The habitat suitability index can be applied to predict the distribution of living organisms in the aquatic ecosystem i.e. it can reveal their correlation with environmental factors. By examining the relationship between the habitat suitability index and the ecological niche of a species, important findings can be obtained from the functional aspects of ecological niche theory and intra-species competition. In this study, using traditional morphometric data and k-mean clustering, 103 samples of Squalius namak were grouped based on two groups of small and large fish. Then, to calculate the habitat suitability index, a non-parametric smoothing method was used to draw the relationship between each environmental variable and the number of fish in each station. A polynomial equation was then fitted to the data predicted by the smoothes. The ratio of the common area below the plots to the total area was used as the niche overlap. Finally, using linear regression, the relationship between the habitat suitability of each parameter and the amount of niche overlap obtained from the same parameter was investigated for both size groups. The height and slope of the two linear regressions were analyzed using the analysis of covariance. The results showed that there was no significant difference in the height and slope of the two fitted regression lines, indicating the same changes in the habitat suitability index on the niche overlap of small and large river fish. The average of niche overlap of small and large samples was 52%. Therefore, other parameters are likely to be effective in the competition of two different size of S. namak species.

Hydropower requirement and agricultural development at upstream points of Hirmand River has significantly reduced the water discharge to Sistan region and the has been led to decreasing right of water and drying of Hamoon International Wetland. This, has been considered as the main reason of Hamoons of Sistan water volume reduce and increasing drought periods. Due to the 120-day winds and the location of Sabouri Wetland, one of the three wetlands in this region, some researchers introduced this wetland as the main source of dust in Sistan region. In this study, decreasing the effects of dust propagation due to water cover area using satellite images is investigated. For precise analyzing and estimating water demand for dust propagation decrease, water cover area in Sabouri Wetland and NDWI index in 113 satellite images from 2009 to 2013 are extracted. By calculating this index and water cover area no correlation between the above parameters is observed and specified that Sabouri is not the main source of the dust propagation. Also results indicated that between 2014 and 2018 the lowest water cover area equal to 150 million square meters was available in the region.

Destruction of aquatic ecosystems, reduction of urban water quality and shortage of water caused countries to use unconventional water sources. Currently, the water resources of populated cities like Tehran are under severe pressure. In this research, the Elahieh canal in Tehran 3rd district was selected as a case study. The purpose of this study is to reuse canal water as an important method of sustainable management of water resources. The present research has investigated the supplying, purification and reuse of urban canal water with the aim of irrigating a part of the green areas in the 3rd district of Tehran. The data that is used in this research was collected by field observation method and the analyzes were done in the accredited laboratory. Some of the most important water quality results are as follows: the average amount of coliform bacteria was 1100 MPN/100cc, this value indicates microbial contamination. The presence of sodium reduces the permeability of water in the soil and inhibits the growth of plants. The amount of sodium in the water of this channel is 34 mg/lit, which has exceeded the threshold. The amount of BOD5 and COD was 38 and 72 mg/lit, respectively. Also, the heavy metal test results showed that boron exceeded the threshold with an average of 52 ppb. Finally, the testing of the samples showed that this water will be prepared for reuse by performing various stages of physical and advanced purification and also disinfection. Also, the results showed that using the Elahieh canal water for irrigation, reduces the pressure on the underground water table. Currently, 560 cubic meters per day are being pumped from the Fakhar well, if recycled water is used instead of Fakhar well, 560 cubic meters per day will be saved.

The purpose of the current research is to evaluate the performance of the drainage network and flood control nodes in the base period (1980-2020) and under the influence of climate change for 25 and 50-year return periods in the central part of Tehran's sixth district. The results of calibration and validation of the model showed a good fit between the observational data and the simulation. So that the value of coefficient (NS) in the calibration stage for the first to third event is 0.77, 0.72 and 0.64 respectively and this coefficient was obtained in the validation stage for two events, 0.72 and 0.70, respectively. the drainage network was evaluated for the return period of 25 and 50 years for the base period and under the influence of climate change. The results showed that with the increase of the return period in the base period and in the future, there is overflow and flooding in some flood channels and nodes of the drainage network, so that the number of flood nodes in the base period (1980-2020) and under the influence of climate change scenario RCP2.6 and RCP8.5(2021-2050) for the 25-year return period is 10, 13 and 15 respectively. The number of flood nodes in the base period (1980-2020) and under the influence of climate change scenario RCP2.6 and RCP8.5(2051-2100) for the 50-year return period are 12, 17 and 19, respectively. Increasing the dimensions of channels and implementing methods (LID) is an operational solution to solve the problem of elevation.

Sustainable river management requires the construction and operation of dams that provide environmental flows to support downstream rivers ecosystem. Dam construction in Iran has significantly altered natural flow regimes and caused various environmental issues. The main aim of the present study was to evaluate the hydrologic and environmental alteration of the flow regime in the Jajrud River downstream of the Latian Dam. In this study, a set of long-term flow data (1947-2017) was analyze using the IHA and RVA models. The results show that the degree of alterations for the 24 flow variables is in the range of high to medium, denoting the high hydrological alterations of the Jajrud River. The values of mean, maximum and minimum monthly flows have decreased by 57, 94 and 21 percent, respectively. The overall change is 51%. Magnitude and duration of annual extreme flows have decreased, and in particular, the minimum flows and the base-flow indices have changed the most. The large flood events has been eliminated and small and frequent floods has been damped in the downstream river system. The results indicate that the goals of RVA have not been achieved in the post-construction period of the Latian Dam, and the environmental conditions of the river have been severely damaged. With reference to the eco-hydrological indices, the rehabilitation of the environment status of the Jajrud River requires the dam releases of minimum monthly flows in order of 2.3 to 33.8 m3/s, with an average annual discharge of 6.5 m3/s.

This research was conducted with the aim of investigating the effect of hydrological drought periods on the electrical conductivity of water in selected stations of the southern part of the Karkheh River. Mann-Kendall test was used to assess the trend of the data and Petit test was used to determine the break points in the data. The results of Petit's test for electrical conductivity parameter indicated a failure in the data trend in 1996 and 1997 in different stations. Because of meteorological drought, the electrical conductivity has been increased and at the same time a sharp decrease in discharge is recognizable. Although, the trend of SDI index has not always been accompanied by the trend of increasing EC. In addition, the increase in electrical conductivity in Karkheh Dam’s downstream stations is probably due to the dam regulatory flow decreasing. By observing the break point in the time series of discharge and electrical conductivity in 1997, it was fund that the occurrence of drought and as a result the increase in salinity occurred before the dam impoundment. Also, after that, there is no significant change in electrical conductivity in Abdulkhan and Paypol stations. It seems that the Karkheh dam was not the most effective factor in the increase of EC in the downstream stations after its operation, and reducing the discharge and, as a result, increasing the salinity of the South Karkheh area can be considered as a result of the increase in drought and consumption in the upstream regions.

Land degradation rapidly increased in developing countries. Changes in climate and land use in Fars province in the past few decades have intensified the process of destruction and desertification. In the present research, satellite data was used to investigate the temporal and spatial changes of vegetation and its relationship with climate changes in the climate samples of Fars province in the years 2000 to 2020. The trend of changes of these variables in time with the Mann-Kendall method and in determining the time of change and spatial correlation, Pettit's test and Pearson's correlation test were used, respectively. The trend of NDVI in arid and semi-arid climates is increasing and the point of change is from 2010 onwards. Based on this, it can be expected that in most regions of Fars, we see a decrease in the ratio of precipitation to potential evaporation (increase in evaporation) and the decadence trend is increasing. Precipitation has no trend and the surface temperature is decreasing. The spatial pattern of NDVI and precipitation trend is increasing in more than 70% of the region (south), and AI and LST are decreasing in more than 65% of the region (central). NDVI changes spatial correlation with LST, precipitation and AI variables showed that the type of relationship and the strength of correlation were different in climatic regions. The strongest correlations were seen in the cold ultra-arid climates in the northeast and the temperate Mediterranean located in the northwest of the province.