مجله ترویج و توسعه آبخیزداری
پیاپی 35 (زمستان 1400)

Investigating the problems of watershed residents is one of the strategic issues of governments, which is undoubtedly a necessary step in providing appropriate management strategies in this regard. The present study was conducted to investigate the economic and social problems of the Doeiraj River catchment area. In this study, the strengths and weaknesses within the catchment area and the opportunities and threats of the external environment were identified using the available statistics and reports, field visits and preparation of questionnaires, in order to achieve the goals. Then, IFE and EFE matrices were formed and strategy formulated in the SWOT analysis process. The findings of the SWOT analysis show that a total of 18 strengths and opportunities can be identified as advantages as well as 17 weaknesses and threats as limitations for the management of the watershed management of the Doeraj catchment area. After determining the final coefficient of factors in the matrices, the WO strategy (minimum-maximum) was determined. This strategy is the second type of strategy which combines opportunities and weaknesses. In fact, the appropriate strategy is designed using opportunities to eliminate weaknesses. Finally, three solutions were presented: 1- Paying attention to the catchment area in order to increase people's income through tourism and 2- Providing appropriate management programs to reduce erosion and use lowwater cultivation. 3- Proper implementation of the integrated watershed management plan and transfer of agricultural water to these areas, in order to increase production and agricultural resources as well as people's income.

This research has done to study the relationship between dust storms frequency and climatic factors included monthly rainfall data, monthly average temperature, monthly maximum temperature, maximum wind speed, frequency of dust occurrence from internal Sources and SPI in northern, Central and coastal part of Jarrahi watershed (cities of Ramhormoz, Omidieh and Mahshahr port) in Khouzestan province were investigated. First of all linear trend in time series using Mann-Kendall test was assessed. Then, using Pearson correlation, the dependence of the dust storm and climatic factors was studied and with path analysis beta weight or participation of each factor in explaining the variance of dependent factor. The results showed that, except in the occurrence of dust phenomena, linear trend is not observed with a gradient (Sen's Slope) of 2 days in 10 years and Pearson correlation confirmed the significance of the dependence of the occurrence of dust on climatic factors at 1% level. The results of the path analysis indicate that two factors of mean temperature and monthly maximum temperature, directly and indirectly, affect the maximum wind speed by more than 50% of explaining the variance of dust storms. The result of a partial correlation matrix showed with temperature effects control none of the climatic factors in storm dust except maximum wind velocity is significant. Thus, the average monthly temperature and maximum temperatures not only directly but indirectly cause changes in other climate factors. Totally climatic factors explain 15% of the variance in the frequency of storm dust.

The purpose of this research is to study the feasibility and method of using xanthan biopolymer as an alternative for oil mulch in controlling or mitigating soil wind erosion. Xanthan is a biodegradable biopolymer made of Polysaccharides which is produced by bacteria and is used as stabilizer. The ability of different concentrations of xanthan in reducing the erosion, was examined by wind tunnel tests at speed of 7 to 15 m/s. To do so, xanthan gum suspension was sprayed on the surface of sand samples collected from sandy hills of Segzi plain in Isfahan and samples resistance to wind erosion were tested by wind tunnel after being dried. The test results indicated that a resistant crust is formed on sample surface due to spraying xanthan biopolymer, so that 2 gr/m2 of this biopolymer can reduce erosion up to 98 percent compared to untreated sample. Application of xanthan doesn’t need any advanced equipment and it can be sprayed cold. Cost of mulching with oil mulch in March 2020 to March 2021 was estimated to be 13 times more than mulching with xanthan gum. According to environmental standards, this biopolymer is also safe for using on soil resources.

In arid and semi-arid regions where there is low rainfall with inappropriate distribution, one of the ways to use floods is to spread them in susceptible areas. The aim of this study is to find the best place for flood spreading using GIS and decision-making methods in Farimaneh watershed. For this purpose, the slope, topography (altitude levels), geology, land use type, soil permeability, geomorphology, geological formations, vegetation, and soil factors were used. For weighting the quantitative variables, fuzzy logic with trapezoidal and triangular membership function, and for qualitative variables, fuzzy logic with hierarchical analysis was used. Flood spreading prone areas were presented using GIS and the concepts of layer integration from fuzzy logic, Boolean logic, and overlay index methods. To determine and prioritize susceptible areas the Boolean operators AND OR, fuzzy AND OR, Fuzzy algebraic and sum-product, fuzzy gamma from 0.1 to 0.9, and multi-criteria evaluation was used. By comparing the obtained results with the observational data, it was concluded that the Fuzzy and, multi-criteria evaluation and fuzzy gamma 0.8 and 0.9 methods were most consistent with the observational data and among these methods, the multivariate evaluation method was found to be more appropriate. Also, among the parameters, slope, vegetation cover, and permeability had the highest weights.

The land surface is one of the main elements that located on between the atmosphere and lithosphere. Changes in land surface characteristics affect surface water balance. In particular, change in the nature of vegetation affect interception and transpiration. Change in vegetation distribution alter the balance between soil-induced fluxes and obtained through canopy processes. Changes in evapotranspiration, soil evaporation, re-evaporation from interception, etc. affect runoff and soil moisture. Then these affect a variety of other processes by linking to the surface energy balance. In order to investigate the surface-atmosphere interactions in hydrological scales, it is necessary to use surface models, which have been developed with the aim of determining the lower atmospheric boundary conditions for numerical-atmospheric models. This study intends to present and introduce land surface models on a regional and global scale. The method of the present research is descriptive-review and means of collecting information, documents related to the subject. Studies show that land surface models are used to provide simulations of water balance, energy balance and carbon balance for further study and understanding on a regional and global scale, which can be effectively applied and recognized by these models at different Temporal-spatial scales, it is possible to study the relationship between the surface of the earth and climatic models, hydrology, and as a result, a better understanding of the behavior of their two components.

Watershed management in Iran requires a new attitude toward its management patterns. The implementation of existing sectoral policies in the country has increased the pressure on the quality and quantity of valuable natural resources. However, in the current situation, the country's watersheds, with their current management patterns, are still in unstable situation.The existing management challenges suggest the fact that watershed management is still facing a major crisis in Iran and has not been able to improve the health status of watersheds. Structural weakness of organizations, weakness of rules, lack of evaluation, monitoring and accurate monitoring can be the main root of these problems. Therefore, the main purpose of this paper is to address the necessary to conceptualize integrated watershed management approaches by collecting available documentation and findings. Then, the structure and administrative framework with appropriate strategies have been formulated based on identifying effective factors in the success and failure of managerial patterns. Changing the attitude from an island approach to an integrated approach in watershed management, increasing the internal and external cohesion of organizational structures, utilizing stakeholder participation-oriented management models and formulating relevant supporting laws are effective factors in the effective implementation of integrated watershed management. Increasing the sustainability, resilience and health of watersheds depends on the implementation of the principles of integrated watershed management.The achievements of this study can be a clear policy for managers and politicians in the country's natural resources.

Soil erosion and its consequences are the main problems to the development of the country. Achieving sustainable development is not possible without the conservation of soil and water resources and reducing land degradation. However, most soil and water conservation methods are engineered regardless of biological methods' capabilities to control soil and water loss. Therefore, in the present study, an attempt has been made to review the performance of soil microorganisms as a biological method in soil and water conservation on the practical components in soil and water loss in the soil erosion process as a review study. The review results showed that the cyanobacteria, bacteria, and fungi in the soil are effective in inhibiting the process of erosion and runoff by improving soil stability components. Therefore, the empowerment of soil surface against the erosion of rain and runoff with soil crust development reduces and inhibits soil erosion. The use of soil microorganisms can be used as an effective and compatible solution with ecologists of watersheds in the implementation of management proceeding to conservation the soil and water of the country.