مجله ترویج و توسعه آبخیزداری
پیاپی 27 (زمستان 1398)

Soil erosion and its impacts have led to a growing need for a better understanding of different soil and water conservation measures. To deal with this issue, implementing diverse products including various kinds of geotextiles with distinctive properties would be a proper alternative to gain the conservation goal. Geotextile is one of the geosynthetic products that in addition to its synthetic form can be manually produced from natural materials and used in geotechnical projects. Despite the widespread application of this product and the compatibility of its biological type to the environment, fewer researches have addressed them in Iran. Therefore, this study tries to review the geotextiles and their application in slope stabilization and reduction of runoff and soil loss. Hope to use this alternative measure for soil and water resources management in Iran by understanding its properties and conservation mechanisms.

In recent years, due to the increasing frequency of droughts in arid and semi-arid regions of the country, the water level of the lakes has dramatically decreased, and in addition to environmental damage, it has also challenged the economic and social sectors of society. In this study, drought events were quantified by standardized precipitation index (SPI), chinese Z index (CZI), Modified chinese Z index (MCZI) and Z-Score index (ZSI) using monthly and annual rainfall data of five synoptic stations (Yasuj, Gachsaran, Dehdasht, Sisakht and Likak) and one pluviometry station (Margoon and Dishmuk) those which are related to Kogilueh and Boyerahmad Meterological organization. The results showed that ZSI, CZI and SPI have a similar trend in all stations and the curves of these stations were well coincident with each other and had a very good fitness that was not same for MCZI. Then, iso-duration and iso-intensity maps of drought (drought zoning) were prepared for determination of the drought susceptible areas as well as forecasting the future status based on the four studied indices by the ArcMap application for annual periods.

Lake Urmia is considered to be the largest domestic lake in Iran and one of the most important and most valuable ecosystems in Iran and the world. The lake has been undergoing dramatic changes over the past four decades due to rising temperatures, high rainfall changes, and droughts in the basin, and is facing a drying crisis today. In this research, factors influencing the occurrence of drought crisis in the lake and effective strategies for reducing and preventing the destruction of this lake are presented. This study is aapplied research and its statistical population is supervisors of rural households (2130 people) and experienced experts in the field of Lake Urmia. The sample size of households were estimated to be 152 by Morgan table. Sampling method was used for collecting a sample of female households with a proportional assignment and expert sampling method in the form of a snowball. The research instrument was a questionnaire whose validity was confirmed based on previous researches and opinions of professors and experts and used to determine the reliability of the Cronbach's alpha coefficient. Data were analyzed using SPSS software. In addition to descriptive statistics, inferential statistics were used. The results of this study showed that the factors affecting the drying of Lake Urmia in terms of experts, rainfall shortage and drought with a mean of 52.6 in the first priority and high population density with an average of 2.52 in the ninth priority and in terms of households' supervisors, 7 in the first priority and cultivating water-based products with an average of 3.14 in the ninth priority. Also, planting low-water products with 15.64% in the first place and opening dams with 6.66% in the tenth place, according to experts, and transferring water to the lake with 16.66% in the first place and covering anchoring with 4.89% in the ranking Tenths of the households' supervisors were considered as ways to rehabilitate Lake Urmia. 

Rainfall erosivity is usually expressed in terms of erosion indices based on rainfall characteristics. Various indices have been presented so far, among which the erosive factor (R) in the global soil loss equation (RUSLE) is more popular in the world. The aim of this study is modeling of rainfall erosivity index using 27 sinoptic station and trend analysis with Mann-Kendal test during 1951-2014. A modified Fornier index, which can be calculated on the basis of monthly rainfall, was used by reviewing worldwide research and also by the lack of stations. After calculating the rainfall erosivity factor, the rainfall erosivity map was mapped and semi-variogram map with GS+ software was used to show the spatial correlation. For interpolation of erosivity index was used from IDW, GPI, LPI and Krigging. Root mean square error indices and mean absolute error values were used to select the best mediation method. The results showed that the Kriging method with root mean square error of 0.8 and absolute mean error of 0.8 is the best method. Thus, the country can be divided into five regions which semi-arid regions have the highest rainfall erosivity. Also, these regions have a increasing trend of rainfall erosivity

In hydrological systems (watersheds), which is complex and at the same time, our understanding of the components and processes within it is always uncertain, the use of soft computing methods is an appropriate tool for modeling and estimating environmental variables such as suspended sediment load (SSL) of rivers. The Intelligent geospatial system of the SSL simulator is specialized software for storing, simulating, and managing the SSL data of rivers in the country. This software is completely designed and coded using GIS open source libraries in the .NET Framework, Visual C# programming language environment in a fully targeted way, and all the steps necessary for a successful modeling of the MLP artificial neural network (the multilayer perceptron) such as loading time series, clustering, statistical analysis of data, simulation and error evaluation are included. The SSL simulation of this system can be performed on a single-variable basis (simply based on flow discharge) or multivariable (flow discharge, temperature, precipitation, etc.) in a daily scale. The system, which has been written for nearly 7,000 lines of code so far, can serve as a national infrastructure for simulating and managing the SSL of all the country's hydrometric stations used by relevant organizations.

In the present study, considering the importance of wind speed forecasting, one of the important factors especially in the discussion of evaporation in watershed, is the construction of water structures and dams ponds so For this purpose we use the SARIMA linear time series models and non-linear SETAR linear time series models to predict wind speed of Ahwaz synoptic station with a statistical period of 22 years 1988-2002. Correctly fitted Sarima models were selected based on self-correlation and partial correlation functions and independent residue test (Logon-Box). The SETAR models were also used to assess the adequacy of the remaining models of the model. The results of the evaluation of the matched models showed that the SETAR model (2; 6.2) with the coefficient of explanation of 0.74 compared to the SARIMA linear model had a precision It is acceptable to predict the monthly wind speed of Ahwaz synoptic station.

Paying attention to stakeholder participation and identifying affecting factors on nonparticipation of rural communities and eliminating its implementation barriers in watershed management projects enable the potential of intellectual, executive, supervisory and indigenous knowledge of stakeholders in different stages of studies, implementation, evaluation and maintenance. This will reduce costs, guarantee success and make projects more effective. In order to achieve this goal in this study, affecting factors on nonparticipation of rural communities in watershed management plans were prioritized from the viewpoint of stakeholders by analyzing four indices and twelve sub-indices with Likert spectrum in Gheshlagh watershed located in the north of Fars province. The frequency and relative abundance of indices and sub-indices were determined in SPSS software (version 23) and the t-test was used to determine their significance. Then, the relationship between each index and its sub-index was determined using correlation coefficients and Friedman nonparametric test was used to prioritize the effective indexes and sub-index. The results showed that in the prioritization of indicators from the stakeholder point of view, "educational-promotion", "economic", "social", and "design-executive" indices were the effective factors, respectively and in subprioritization of sub-categories "lack of training of basin residents on related plans and objectives" and "ethnic and local differences", had the highest and lowest priority in nonparticipation in watershed planning, respectively. In order to sustainable participation of rural communities in watershed management projects, it is necessary to develop a comprehensive program of training and solve the "economic" problems of stakeholders and promotion of practical actions.