Rezaali Domehri Vasati Kolaei; Mohammad Jafari; Hossein Arzani; Seyed Akbar Javadi; Mahmood Arabkhedri
Abstract
The purpose of this study was to compare the condition and management of rangeland before and after replacing the soil condition assessment method in the soil factor of the four-factor method in order to determine the most appropriate rangeland condition method. Rangeland status assessment was performed ...
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The purpose of this study was to compare the condition and management of rangeland before and after replacing the soil condition assessment method in the soil factor of the four-factor method in order to determine the most appropriate rangeland condition method. Rangeland status assessment was performed for both conditions in Poshtkuh rangelands of Mazandaran and then the status, rangeland management methods and their management and improvement programs were proposed and compared with each other. The results of rangeland condition assessment before replacing the soil condition assessment method in soil factor showed that rangelands had poor and very poor condition with a negative tendency and artificial rangeland management method and rehabilitation programs, mulching and seeding were proposed. The results of rangeland condition assessment after replacing the soil condition assessment method in the soil factor showed that the rangeland condition was in the middle and poor class, for which natural and artificial rangeland management methods were proposed, respectively. For the natural rangeland method, periodic-delayed and periodic-rest grazing systems were proposed based on the average status of the rangeland, and the breeding programs of the artificial rangeland method have not changed and are the same as the previous method. The results of comparative statistical analysis showed that there was a significant difference between the mean score of soil factor before and after replacement in the 95% confidence interval, . This method can be used as a method based on quantitative-qualitative evaluation to identify the functional and structural characteristics of ecosystems.
Marziyeh Haji Mohammadi; Aliakbar Nazari Samani; Arash Zare Garizi; Hamidreza Keshtkar; Mahmood Arabkhedri; Amir Sadoddin
Abstract
The SWAT model is widely used to simulate watersheds and evaluate the impact of conservation watershed management practices. In this model, the simulation of the watershed processes is based on hydrological response units (HRUs) which are created by overlaying land use /land cover, soil and slope maps. ...
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The SWAT model is widely used to simulate watersheds and evaluate the impact of conservation watershed management practices. In this model, the simulation of the watershed processes is based on hydrological response units (HRUs) which are created by overlaying land use /land cover, soil and slope maps. Meanwhile, in the HRUs definition steps, these units become conceptual and lose their spatial location and continuously. This approach is a useful and often inevitable way to simulate large and heterogeneous watersheds in terms of computational efficiency. However, if the aim is spatializing and evaluating the effectiveness of management methods on runoff, sediment and other pollutants in medium to small basins, it is necessary to know the exact location of HRUs. The purpose of conducting this study was present a new approach to defining spatial and independent HRUs and compare the simulation results based on this method with the standard form of the model. In the new approach, independent and spatial HRUs are defined through pre-processing procedures in GIS and uniquely named soil units. The model results of both approaches were very similar and no significant difference was observed in the model outputs in Taleghan watershed. The Nash-Sutcliffe coefficient of the simulated runoff and sediment at the outlet with the standard approach was 0.75 and 0.64, respectively. While, it was obtained 0.74 and 0.61, respectively for the new approach. The definition of spatial HRUs by applying the proposed method provides more tangible and practical outputs, which is more beneficial for identifying the critical areas as well as locating conservation practices compared to the conceptual HRUs approach.
