Hamzeh Noor; Mahmood Arabkhedri; yahya parvizi
Abstract
IntroductionImplementation of watershed management measures in Iran to reduce the damage caused by the misuse of natural resources has begun many years ago and is still ongoing. Evaluating the performance of previous remedial work is essential for better planning of future watershed management projects. ...
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IntroductionImplementation of watershed management measures in Iran to reduce the damage caused by the misuse of natural resources has begun many years ago and is still ongoing. Evaluating the performance of previous remedial work is essential for better planning of future watershed management projects. In this regard, due to the monitoring of soil loss, runoff and sedimentation at slope and watershed scales, a suitable platform has been provided to assess the effects of watershed management measures. Material and methodsThe Kakhk paired watershed with an area of 217 ha is located at a distance of 300 km from Mashhad City and 35 km southwest of Gonabad City.The Kakhk paired watershed consists of two sub-watershds, the control and the treatment. A series of biological and structural watershed management measures have been implemented in the treatment sub-watershed. While the control sub-watershed is exploited according to the custom of the region. In this research, the impact of different watershed management measures on the soil loss, sediment yield and hydrology in the Kakhk paired watershed were evaluated. For this purpose, the recorded data of suspended sediment and discharge at the watershed scale, as well as the data of soil loss (by standard plots and erosion pins) and runoff (standard plots) were analyzed at the hillslope scale. Results and discussionThe results at plot scale showed that the average annual soil loss of the two treatment and control sub-watersheds is 0.05 and 0.27 ton.ha-1.y-1, respectively. These results indicate that the soil loss in the control sub-watershed is 536% higher than the treatment sub-watershed. The amount of runoff yield in the control sub-watershed was calculated to be 138% more than the treatment sub-watershed. At watershed scale, the results showed that the total amount of suspended sediment output from the control and treatment watersheds is 379 and 85 tons, respectively, which indicates the average specific sediment of 0.4 and 0.1 ton.ha-1 in the control and treatment watersheds, respectively. The volume of runoff in the control sub-watershed is 1.3 times more than treatment sub-watershed. On the other hand, despite the difference between the treatment and control sub-watersheds in soil loss, run-off production and sediment yield, the role of maximum events in soil erosion and runoff production in both sub-watersheds is very significant. So that one to three erosive events in both studied sub-watershes are responsible for more than 80% of the soil loss in the slopes and the production of runoff and sediment yield of watersheds. ConclusionThe results showed that a total of 136,000 m3 of runoff storage and 294 ton of suspended sediment control were achieved as a result of watershed operations in the treatment sub-watershed. Therefore, it can be stated that the watershed management measures carried out in the treatment sub-watershed on the one hand have reduced soil erosion and runoff production on the slopes compared to the control sub-watershed. This action has been done through increasing the vegetation, increasing the roughness of the land surface, reducing the carrying capacity of the flow and settling the materials being transported. Further, the flow from the slopes enters the waterway and is kept by watershed management structures, and as a result, the sediment yield and volume of runoff in the treatment sub-watershed is less than the control sub-watershed.
Hamzeh Noor; Ali Dastranj; Saeed Sadeghi
Abstract
Flood control projects, artificial recharge of ground water aquifers, and optimizing the efficiency of water and soil resources are the most important benefits that have been achieved as a result of the construction of flood spreading stations in the country. The aim of this research is assessment ...
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Flood control projects, artificial recharge of ground water aquifers, and optimizing the efficiency of water and soil resources are the most important benefits that have been achieved as a result of the construction of flood spreading stations in the country. The aim of this research is assessment and determination of effectiveness of Jajarm flood spreading project. For this purpose was the economic evaluation of flood spreading project using Net Present Value (NPV) and Benefit/Cost/ ratio studies in Jajarm Station. The social impacts of the Jajarm flood plan were also assessed through a popular questionnaire. Results showed that NPV was 262258 million Rials with discount rate according to the Central Bank. This shows that the Jajarm flood project is economically justified on the basis of economic evaluation and that investment is economical. The evaluation of the impacts of the floodplain project from the view point of the users of the project margin, also indicates that the people of the region are relatively satisfied with the project. Particularly people's satisfaction with the role of the flood spreading project in reducing flood damage to residential, land and communication areas in the region is significant.
Hamzeh Noor; Ali Bagherian Kalat; Aliakbar Abbasi
Abstract
Rangeland exclusion is one of the watershed management methods that is applied for range rehabilitation. However, most rangeland hydrology studies have been focused on exclusion effects on soil loss at plot scale, whereas their effects on sediment yield at micro-watershed in seasonal and annual scales ...
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Rangeland exclusion is one of the watershed management methods that is applied for range rehabilitation. However, most rangeland hydrology studies have been focused on exclusion effects on soil loss at plot scale, whereas their effects on sediment yield at micro-watershed in seasonal and annual scales have rarely been considered. The present study was conducted in two sub-watersheds under exclosure and open grazing treatments, with area of 1.0 and 1.1 ha, respectively, in Sanganeh Watershed, Khorasan Razavi Province, Iran. Runoff and sediment associated with 56 storm events occurred during 2006 to 2016 were estimated at the main outlet of the watershed. The results showed the significant decreasing effect of exclosure treatment on sediment yield at micro-watershed scale (p≤0.05). So that, 582% decrease in sediment yield was obtained in exclosure treatment compared to open grazing. Results also showed seasonal and annual variations of exclosure on hydrological processes so that, maximum and minimum differences in sediment yield among study treatments were founded. The results of this study suggest that livestock grazing management during sensitive seasons as well as rangeland exclosure, if its social problems are resolved, is a practical solution to reduce watershed sedimentation.
