مجله ترویج و توسعه آبخیزداری
پیاپی 41 (تابستان 1402)

One of the most common and conventional methods of artificial feeding of aquifers is the flood spreading method, which feeds underground water tables, increases the quantity and quality of vegetation, and improves the soil of the plains. This study aimed to investigate the effect of flood spreading on the process of quantitative changes in vegetation cover and the effects of flood spreading on the soil seed bank in the Sarchahan flood-spreading area of Hormozgan Province over a 25-year period (1996–2022). Sarchahan flood dissemination station is located 90 km north of Bandar Abbas. The investigation method was such that the flood-spreading area of Sarchahan was chosen as a treatment, and a similar area in its vicinity was selected as a control in terms of vegetation and soil, which only had silage. In this research, 4 irrigation networks and three dams, in each network (flood spreading area) and 3 transects in each dam and 10 plots of 4 m2 in each transect to measure different vegetation parameters as sampling units within the flood spreading system in a random systematic way and the same number of transects and plots in the non-drained field were selected as witnesses and measurements and statistics were carried out. In order to check the seed bank, soil samples were taken from 20×20 cm microplots and from 0 to 5 and 5 to 10 depths from the four corners and the center of each plot. Soil samples were planted in the greenhouse of Hormozgan University to check the seed bank, and after germination and identification of plant species, all vegetation cover and seed bank data were analyzed with the help of SAS software. The results showed that the effect of flood spreading on the coverage percentage, production rate, litter percentage, rock and gravel percentage, density per hectare and sediment depth was significant at 1% level and the coverage percentage, production rate, litter percentage, density per hectare and sediment depth in the control treatment were 19.56, 42.6, 1.49%, 5438 bases, and 0.64 cm respectively after flood spreading operation, respectively. 2, 3.9, 2.8, 2.6 and 17.3 times increased. A comparison of the average biological indicators of vegetation in the first and second soil depths among the different treatments using the independent t-test at the 95% level showed that the biodiversity of vegetation in the first and second soil depths at the flood-spreading site was more meaningful than witness that of the witness site. Simpson and Shannon's biodiversity, Sheldon's and Brillion's uniformity indices, and Menhinick's and Margalf's richness index were significantly higher than the control at both depths in the flood spreading site.

Iran has an area of about 165 million hectares and is located in arid and semi-arid regions. According to the latest data provided by the Natural Resource and Watershed Management Organization, about 110 million hectares of the area of Iran is at risk of desertification. At present, more than 32 million hectares of the country's deserts are more than 32 million hectares, of which over 5.7 million hectares are highly exposed to wind erosion and are considered as dust storm sources. In general, desertification refers to the development in which natural resource areas are confronted with intensification of soil erosion, a reduction of fertility, and exit from the production area. Iran is one of the countries in the world where the desertification rate is high. In order to seriously deal with the phenomenon of desertification and implement desertification plans, desertification activities should be considered as economic activities, while creating a context for the return of investments, it follows the cooperation and participation of the people. A research project was defined and implemented in the Research Institute of Soil Conservation and Watershed Management Research Institute with the aim of applying and developing successful model/models of dealing with desertification and the economic development of desert areas in Iran and the world. In this plan, the most successful models implemented in the world were examined and finally, the economic desertification plan of the Kubuqi desert in Inner Mongolia, which has been successfully implemented in China, was chosen as a model to be examined in some desert of Iran. However, it is not possible to use a single method for all desert areas. Due to the diversity of deserts, including factors of desertification and resource capacity, the use of experience and executive components of successful plans should be customized for the target area. The success of the Kubuqi model, which has been carefully examined in the analysis of management processes, attracts private investors and people’s participation. On the basis of the analysis results, Reza Abad village in Biarjmand city, Shahroud district, Semnan Province was selected as a pilot region to conduct preliminary studies and provide a development model for desert reclamation, which will be discussed in this paper.

It is essential to understand the characteristics of regional winds in order to prevent the effects of wind degradation, which is a significant factor in the degradation of arid and semi-arid land. The main aim of this study was to determine the status of erosive wind and the sand drift potential and its relationship with dust emission areas. Annual wind roses showed prevailing winds from the west, southwest, and northwest. In addition, the annual storm roses showed that the erosive winds were mainly in the west, southwest, and northwest directions. In winter and spring, a multidirectional wind regime is blowing. According to the calculation of the sand drift potential using the Fryberger & Dean equation, wind erosion drift is categorized into the low-to-moderate class, with the resultant sand drift in the southeast direction. Mean quantitative sand discharge rate was 8.9 Ton.m.Yr-1. Based on overlaying vegetation cover, wind velocity, geomorphology, and sand-sea maps, the area with the most potential dust emission was determined. In most areas, dust emissions coincide with wind erosion hot spots. In addition, the variability of wind direction has caused longitudinal sand dunes (Seif and Silk) to form. Therefore, the abrasion of the ground surface by sand drift on the plains with sparse vegetation covers activates the dust emission process in the study area.

Watershed management is one of the most efficient methods of sustainable land management. In the current research, was evaluated the economic and social effectiveness of implementing watershed projects in the Gelevard sub-basin, Nekarud watershed, Neka city. The statistical population of this research included 2775 households and the sample size was 280 household heads. Data analysis was conducted using SPSS software. The results showed that the effectiveness of watershed management measures in preventing the reduction of flood damage and the level of satisfaction with the mechanical and biomechanical operations implemented in the study area have the highest priorities in terms of average rank. Correlation coefficients (R2= 0.60, P-value= 0.01) examination showed a high correlation between the implementation of watershed management operations and creating incentives for the residents of the village to stay in the village and reducing migration from the village. The results of the Kruskal-Wallis test showed no significant difference (Chi-square-1.32, P-value=0.72) between the effect of watershed management activities on improving people's living conditions in relation to the way of participation and the type of participation of the respondents in executive measures. Summarizing the results of this research showed that watershed management activities in this watershed improved people’s living conditions, increased the motivation of village residents to stay in the village, and reduced migration.

Placement of mountain Qanats in river alluvium is one of the reasons for the seasonality of these Qanat. Therefore, in the summer season, when the demand for water for agriculture increases, the water in these canals decreases or dries up. Underground dams are structures that block the natural flow of underground water, creating water reserves in the basement and increasing the water level in the wet period and use it in the dry period. It is believed that they will improve the flooding of canals in the summer. There is therefore a need to find suitable solutions for accessing new sources of water and its storage. The purpose of this research is to use an underground dam to feed the canals in the Taghenkoh Mountains area in Firouzeh city of Khorasan Razavi province. With this assumption, canals were prioritized for integration with underground dams using the analysis hierarchical processes method (AHP) and WASPAS decision making methods. First, the important and effective criteria in the construction of the underground dam were identified, and then the value of the criteria was determined using the AHP, and the criterion of the depth of the underground dam with a value of 0.32 was assigned the highest relative importance among these criteria. The site was prioritized based on the characteristics and relative importance of the criteria based on the WASPAS method, the Farang Qanat site was ranked first with a score of 3.01.

Erosion and sediment transport is an important river phenomenon and is very important for river engineering and management projects. The morphological changes that occur due to the construction of cross structures in the flow path are the response of the river to establishing a balance between erosion and sedimentation. Therefore, the reaction of the river should be evaluated before any structure is built along the river. In the current study, the hydraulic conditions of the river in a 5 km long path from the Kabudkamer River in Zarand Saveh in Central Province before and after the construction of hydraulic structures in the flow path were modeled using the geometric data of 200 cross sections in the HEC-RAS software. Hydraulic parameters such as water level, water surface width, flow velocity, bed shear stress, Froude number, hydraulic depth, and velocity were evaluated before and after device construction. The results showed that in the case of creating a structure and obstruction, the flow speed decreases as the flow approaches the dam, while after passing over the dam, the flow speed increases. Therefore, in this case, the erosion will increase after the overpass. In the absence of a barrier, the flow speed was almost constant before reaching the section with an overpass in the blocked state, but after passing this section, the flow speed increased. The construction of gabion dams in river basins has reduced the peak flow of floods with different return periods. As the return period increases, their effect on the reduction and control of floods decreases.

Floods are of great importance in studies related to the use of water resources, flood management and the construction of dams, and the safety of structures related to dams is dependent on accurate hydrological studies. This study used geostatistical methods to determine the average maximum daily rainfall in the Amuqin catchment basin in Ardabil province as an input to the WMS model in order to estimate the maximum flood discharge. The Amuqin basin, which has an area of 78 km2 is located in the central part of Ardabil province, to determine the curve number of the basin, land use maps and soil hydrological groups (B, C, D) were integrated in the GIS environment. These maps were prepared using the Idrisi32 software and Landsat 8 satellite images. The basin curve number was estimated as 78.7. Different geostatistical kriging and global cokriging methods with circular, exponential, Gaussian, and normal models, weighted distance image method (IDW), Global Polynomial Interpolation (GPI), Local Polynomial Interpolation (LPI), and Radius Axis Relation Method (RBF) using geographic information system software were used to determine the average precipitation. The results showed that the normal Cokriging method has the lowest error for different return periods, then the average maximum daily rainfall for the basin was calculated using the normal Cokriging method for different return periods. Considering the rainfall-runoff events at the regional level in the calibration (RE=7.17, RMSE=0.44) and validation (RE=2.51, RMSE=0.0042) stages, was confirmed the accuracy and validity of the flood estimation by the model.