جستجوی مقالات مرتبط با کلیدواژه « مدیریت جامع حوزه های آبخیز » در نشریات گروه « آبخیزداری، بیابان، محیط زیست، مرتع »

Land suitability is the coordination of land characteristics with existing land use that aims at development without degradation, so that the natural talent of the land along with economic potential determine the type of land use (Babapour & Khorasani Alamdari, 2013). The importance of assessing land status and its potential becomes apparent when, if land potentially lacks potential for a particular use, its implementation would lead to environmental degradation, even in spite of the socio-economic need for that use (Brazier & Greenwood, 1998). Also, the challenge in the field of sustainable agricultural development is the issue of food security, whose importance, due to the growing trend of population in the country and increasing food needs, doubles (Halabian & Ismaili, 2018); Therefore, in this regard, it is necessary to evaluate the ecological potential for agricultural use based on the correct principles, patterns and instructions, compare it with current uses, and determine their compliance and non-compliance in order to use it properly based on the natural capability of the region and prevent further degradation and erosion. It seems (Kamyabi va Khosh Agha, 2017). The purpose of this study was to investigate the spatial status of rainfed arable lands in the Chehelgazi Sub-basin according to the proposed models and instructions and to use the GIS in order to assess land suitability, provide planning models and make management decisions in the field of development, in line with natural resources and sustainable agriculture, and in accordance with the reality of agricultural system in Iran.2-

In this study, first, a map of rainfed arable lands under the Chehelgazi Sub-basin was prepared and adapted according to the proposed patterns and instructions in the spatial adaptation of arable lands. Finally, using GIS software, the status of alignment or non-alignment of agricultural lands in the region with the proposed patterns and instructions, as well as the dominant cultivation of the region was determined. The map and percentage of agricultural lands were also determined.3-

After examining the spatial status of arable lands in Chehelgazi sub-basin according to the proposed patterns and instructions in the field of adaptation, the results show that, in terms of slope status, 64.15% of the total land is in line with the proposed instructions, on a slope of less than 16%. In terms of altitude, 37.78% of the lands with a suitable slope are located at the proposed height. In terms of river condition, 29.43% of lands with suitable height and slope are located at a suitable distance from the river. In terms of radiation status, 8.29% of the lands in line with the proposed slope and height are located in the flat, north and west directions. In terms of rainfall status, the total area of ​​the basin is in line with the proposed instructions in rainfall of more than 350 mm.In terms of communication status, most of the lands are located at a direct distance of less than 10 km. Finally, out of the total area of ​​31117.94 hectares of rainfed arable lands of Chehelgazi Sub-basin, assuming low impact on the slope or sunshine, 29.43% of the total lands have the necessary conditions in terms of slope, height and distance from the river and road.4-

The results show that the the Chehelgazi Sub-basin is generally in poor condition in terms of the development of rainfed agricultural land use; therefore, considering the importance of adapting the user to the relevant goal in order to increase proper performance and increase production, it is suggested that the patterns and guidelines introduced in this research for principled planning and correct decision making as well as training, promotion and implementation of useful projects related to land management and prevention of the destruction of natural resources and the environment should be considered and developed based on the reality of the agricultural system of Iran.

Developing an understandable and comprehensive conceptual model for watershed health assessment is one of the main priorities of many various managerial and policy making projects in the world including the mega project on the integrated watershed management of Iran. Towards this, the present study as the pioneering research in the country has been conducted to customize the reliability, resilience and vulnerability (RelResVul) conceptual model based on hydrological data to assess watershed health. To this end, firstly the long-term data of discharge of the Shazand Watershed that located in Markazi Province was prepared and the flow duration curve was accordingly derived. Secondly, the appropriate thresholds of low and high flow discharges as prerequisites for watershed health assessment were applied to the RelResVul conceptual model. Hence, the reliability (Rel), resilience (Res) and vulnerability (Vul) indicators were calculated for four node years of 1986, 1998, 2008 and 2014. Finally, the general health state of the Shazand Watershed and its different sub-watersheds was zoned on the basis of two low and high flow discharge criteria through the geometric integrating of the mentioned indicators. The results showed that for the four study years respectively, 59, 53, 68 and 66 % of the watershed in terms of low flow discharge as well as 19, 22, 54 and 38 % of the Shazand Watershed in terms of high flow discharge were situated beyond relatively healthy state. The watershed health index assessment indicated the moderate and relatively healthy states with improving trend for low flow discharge criterion and moderate healthy state with constant trend for high flow discharge criterion. In addition, the results were verified the spatial changeability of watershed health state in different sub-watersheds for the study years.

Comprehensive watershed management programs need to take into account the sediment and related process in sediment management paradigm. Whilst, the dominant processes on sediment yield has not been considered in watershed scale yet. Accordingly, sediment connectivity is an emerging concept in sediment management that has been accounted in recent years to investigate the sediment transfer from different sections of watersheds. Sediment connectivity is defined as the integrated transfer of sediment across all possible sources to all potential sinks in a system over the continuum of detachment, transport and deposition processes. The structural connectivity is therefore a concept derived from sediment connectivity which investigates potential of sediment particles displacement across a watershed on the base of anatomy of watershed's system. Naturally, identifying sectors with similar sediment connectivity patterns support applying similar and integrated sediment control mitigation strategies. The present research was planned to investigate the structural sediment connectivity in Taham Watershed in Zanjan Province for year 2014. To calculate the structural sediment connectivity, the Digital Elevation Model (DEM) and C Factor layers were used and the results were assessed according to field observations and surveying in several times. The results of the validity of the structural sediment connectivity map showed there were acceptable agreement between Field Index of Connectivity (FIC) and Index of Connectivity (IC). In addition, IC map with respective max, min and mean values of 1.02, -8.24 and -5.95, showed 32 percent of the study area had a high structural sediment connectivity that generally have been dispersed in western parts of the study area. Regarding to rapid appraisal and being low cost of IC calculation as well as identification of primary sediment sources, the structural sediment connectivity is a very useful concept for sediment management of watersheds of Iran.

Watershed management practices (WMPs) include methods to create, enhance, and maintain vegetation to reduce surface runoff in the watershed. The implementation of WMPs at the watershed scale is an ongoing challenge that needs to take into account trade-offs between hydrological and economic objectives using optimization algorithm. This research demonstrate a methodology and decision support tool that suggests the optimal location of biological watershed management practices (including improvement rangeland cover) which minimize the cost and simultaneously reduce surface runoff to target levels cases (i.e. 10%, 15%, 20% and, 25%) at watershed scale. The decision support tool (SWAT-GA) consists of a semi-distributed hydrologic model, Soil and Water Assessment Tool (SWAT) which simulation of runoff in watershed, a genetic algorithm (GA), which serves as the optimization engine for the location of biological watershed management practices across the rangeland of the watershed. The proposed method was then applied to Taleghan watershed with an approximate area of 900 km2 that located in Alborz Mountain, Iran. Results indicate watershed management practices should use in 22%, 35%, 48% and 62% of total area of watershed to reduction 10%, 15%, 20% and 25%, respectively. The maximum decrease and increase runoff after the implementation of WMPs have been occurring in the spring and summer, respectively. Using this decision support tool, for each level of target goals, decision makers can select the optimal combination of watershed management practices.