Zohreh Talebi; Seyyed Ali Ayyoubzadeh; Hossein Mostafavi; Mohammad Mehdi Hoseinzadeh; Hossein Shafizadeh
Abstract
ABSTRACTBackground and Purpose: Change is an integral part of all river systems. Most rivers now operate under fundamentally different conditions to those that existed prior to human disturbance. Human interventions indirectly change geomorphic processes such as sediment transport, erosion and sedimentation ...
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ABSTRACTBackground and Purpose: Change is an integral part of all river systems. Most rivers now operate under fundamentally different conditions to those that existed prior to human disturbance. Human interventions indirectly change geomorphic processes such as sediment transport, erosion and sedimentation along the rivers, and the spatial distribution and rate of these processes often including profound changes to river morphology. Therefore, it is important to evaluate the morphological quality, especially for the rivers of Iran, which are characterized by a very high level of human pressure. For this reason, In this research, a morphological evaluation from the upstream to the middle of the Talar River (Northern Iran - Mazandaran) using the Morphological Quality Index (MQI) and with the aim of determining changes in its morphological quality has been considered.Materials and Methods: Talar River was divided into two landscape units, three segments and 23 reaches based on the hierarchical approach and according to the physiographic condition. The evaluation of Talar river has been done after drawing and analyzing the spatial units using Morphological Quality Index (MQI).Results and Discussion: The results obtained from 28 MQI parameters in 23 reaches show that about 15% of the reaches have a "good" condition, almost 35% of the reaches have a "moderate" condition, and more than 50% have a "poor" and "very poor" condition, which means significant damage to the river corridor in the reaches. The subject of investigation and the need to pay attention to the corrective solutions and restoration of the river and its banks. Along the Talar River, due to the large amount of agriculture, urban development and road crossing, the reaches that are in the urban area have poor and very poor morphological quality class, and the reaches that are in the forest area, virgin and untouched, have The morphological quality has been evaluated as good. Also, the results of the evaluation indicate that the average quality class of the investigated reaches is in "moderate" conditions.Conclusion: Considering that the urban and agricultural development and sediment collection takes place in the boundary of the river bed and the vegetation cover and the river corridor have been destroyed in most of the reaches, measures such as observing the boundary of the river bed and boundary as well as planting plants On the river bank and removing sediment based on annual yield will help to restore the river in many reaches. In addition, the results of this evaluation have shown that the MQI morphological quality index method can be a suitable and effective tool in diagnosing hydromorphological challenges. Also, the morphological quality index provides the conditions for evaluating the morphological condition, but it is not enough for the general hydromorphological classification alone, and it should be integrated through the use of a special method to evaluate the changes in the hydrological regime.
Nahid Ahmadi; Hossein Mostafavi; Khosro Piri; Hossein Zeinivand
Abstract
Introduction: By considering the vital role of water for sustainable development, but the lunched infrastructure projects of Integrated Water Resources Management Plans in recent years have not been able to completely maintain the balance between human consumption for socio-economic activities and water ...
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Introduction: By considering the vital role of water for sustainable development, but the lunched infrastructure projects of Integrated Water Resources Management Plans in recent years have not been able to completely maintain the balance between human consumption for socio-economic activities and water needs of natural ecosystems to guarantee the sustainable life for riverine ecosystems. In this regard this research investigated the hydrological effects and ecological consequences of the construction of dams in the upstream basin of Jiroft Dam as the key water supply zone in the western Jazmurian watershed, which is also known as Halil-Rud River.Martials and Methods: In this research the significance of the long-term changes of the mean annual discharge in the rivers of the study area at the hydrometric stations of Solatni, Baft, Hanjan, Meydan, Qale-Rigi, Konarooiye and Hossein-Abad, as well as the alterations in the mean annual precipitation of rainfall gauges in the period of 38 years (1980-2018) have been analyzed by Mann-Kendall Test and then 33 hydrological parameters (based on daily discharge of Hossein-Abad hydrometric station in the mentioned period) as indicators of ecological needs (which is affected by the Baft and Jiroft reservoir dams) have been analyzed by using the variability range approach and IHA software in two periods before and after the construction of the dams.Results: According to the Mann-Kendall test results, although the mean annual discharge in the rivers upstream of Jiroft dam has had a significant drop at the level 95 and 99% of discharge during the past 38 years, but the trend of change in the mean annual precipitation in the same period, except one station (Hanjan), was not significant that this difference is due to the negative effects of dams construction and it was also confirmed by the output of the IHA model. It should be noted that based on the output of the mentioned model, 33 hydro-ecological features of Halil-Rud river flow showed fundamental alterations since the operation of Jiroft Dam (1992), but the operation of Baft Dam upstream of Jiroft Dam in 2008 has led to intensification negative effects of flow characteristics (outside the acceptable range of ecological variability) in Halil-Rud River.Discussion: In order to prevent the magnification of the water crisis, the cumulative effects in the construction of chain dams should be considered by using hydro-ecological approaches, as well as the water allocation programs, especially the environmental flows should be revised according to the upstream developments of each dam basin, so that the sustainable socio-economic needs as the goals of integrated water resources management would be provide and also the health and survival of the natural ecosystem would be guaranteed.
