مجله ترویج و توسعه آبخیزداری
پیاپی 10 (پاییز 1394)

The aim of this study is the spatial analysis of rainfall in wet and dry months of the year in south-west Iran especially khouzestan. To this end, the model of Markov chain is used. In Markov chain, it is assumed that the climate has only two states: dry or wet. For instance, rainfall has only two states: it rains (1) or it will not rain (0).There is not a third state. The statistical years are not the same in this research and change from 10 to 50 years. Twenty stations are selected in Khuzestan and the surrounding provinces (synoptic and climatology).The three months of the summer are not included in calculations because the precipitation was zero or near zero. As the result of that, the reoccurrence of dry periods is generally longer than that of the wet ones. In the other words, dry periods last a long time in south-west Iran. Regarding area, long dry periods cover a wide area in the southwest while the area covered by short-term periods is less. When the length of time of periods increases to possibly 8 days, the changes are reversed and the longer time the probability of 8-day aridness takes, the more area it covers and the shorter time it takes, the less area it covers.

Several factors leads to negative changes in the quality and quantity of natural resources which leads to the severe decline and destruction of vegetation cover, soil, and ultimately reduce income of beneficiaries, destructive flooding, nomads and villagers migration to the cities and poverty of beneficiaries. The aim of this research was investigation effective socio- economic factors on degradation of watersheds in Iran based on questionnaire and the standpoint of natural resources managers and experts. Sampling was randomly from the managers of natural resources and Watershed Management Department (21 cases), and natural resource expert and professionals (71 cases). Validity of questionnaire was obtained using Cronbach's Alpha coefficient from the standpoint of managers and experts, 0.80 and 0.85, respectively. This research was conducted based on questionnaire and data analysis was performed using SPSS version 16. Managers believed that extra livestock with 210 score, degradation of vegetation cover with 208, overgrazing with 203, landuse conversion of rangelands with 197 and early grazing with 176 score were the most important factors on degradation of watersheds in Iran, But experts believed that landuse conversion of rangelands with 963 score, overgrazing with 888, degradation of vegetation cover with 819, extra livestock with 787 and early grazing with 760 score were the most important factors on degradation of rangelands. The overall conclusion from the viewpoint of managers and experts is improper management of grazing and plowing and landuse conversion were the main facor of rangelands degradation, respectively. Also both groups believed that in the discussion of improper management of grazing, extra livestock is more important factor in degradation of rangelands than inappropriate time of utilization.

Water resources are one of the most important resources in the continuity of life and socio - economic development. Without using of this valuable resource obtaining of growth and prosperity will be impossible to achieve. Main target of this study is to analyze the knowledge of traditional methods of small water resources and to provide enough water for various purposes. Method of research is based on documents library experience and local observations by studying 14 cases of traditional water storage with benefitcost model. Results showed traditional structures are in public owner ship and due to their material, these structure have main role to supply water for different uses especially agriculture. In areas using these structures, yield increased by 2 to 4 times comparing normal condition. The benefit and cost ratio was 1.7 in minimum, 7.1 in maximum and 3.5 in average. Results of pilot study showed that 17.1% of interviewed people believed that the effect of such structure on their income was moderate and 83.1% said that this effect was high. So they want to participate in optimization of structures.

One of the fundamental pillars of Projects is evaluation discuss as a tool to measure and evaluate the impact of plans and programs been implemented according to the objectives. The study area is located in Dareh Khersan watershed of Masjed Soleiman in the Khuzestan province. The goal of this project is to evaluate the performance results of watershed management in this basin. Before doing the project, initial conditions and amount of erosion and sediment was calculated using modified PSIAC. Then the field visit was done in several stages of the basin and biological, mechanical and biomechanical performed operation including seeding, plantation, seedling, check dam, gabion and terracing were recorded on the field. Then the synthesis and effect of each of the watershed operation on erosion and sediment reducing were evaluated using modified PSIAC. Such as 201 check dams, 7 gabions and 32 terraces are studied and measured. Also range condition by 4-factor method, range trend by balance method, forage production and typology were studied and evaluated. The results are as follows: Before watershed operation the rate of specific sediment and erosion especially in sub basin 1 has been respectively 13.45 and 34.16 tons per hectare per year, but after watershed operation has declined respectively to 5.39 and 13.69 tons per hectare per year. The rate of total of sediment and erosion has declined in sub basin 1 respectively, from 33625 to 13475 tons and 85707.67 to 34226.56 tons per year too. In sub basin 2 the rate of specific sediment and erosion has been respectively 14.08 and 34.94 tons per hectare per year before watershed operation. But after watershed operation has declined respectively to 5.79 and 14.37 tons per hectare per year. The rate of total of sediment and erosion has declined in the sub basin 2 respectively, from 29939.12 to 12303.37tons and 74244.52 to 30537.03 tons per year too. The plant cover area has fair condition in comparison with the previous poor condition. The production has increased to 195 kg/hec from the last 97 kg/hec.. Range trend has a positive condition where were negative in the previous. Moreover the cover’s density has increased from 25% to 37%.

Flood risk management deals with cases such as; analysis, management and declining the social impact of flooding. Gorchay Ramian watershed due to the countless floods was selected for this study. The purpose of this research was identifying factors, which affect zoning of flooding potential and flooding potential prioritization of sub-basins by using AHP method. As deficiencies caused because of being subjective and selective attention of experts in this field have been plunged, also integrating sub-basins prioritization with respect to the weight of each indicator in achieving the objectives can be provided. Analyzing the final weight from AHP approach has shown that, hydrometorological criterion with weight of 0.65 compare to morphometric criterion is more important in this study area and rainfall intensity for the time of concentration sub-criterion was the most important of these criteria. Based on the final ranking, flooding potential zone constitute almost 27 percent portion of the catchment, which most of them are situated in mountainous and upland areas, this is due to the high weight of two sub-criteria of rainfall intensity for the time of concentration and precipitation with return period of 25 years in comparison with other sub-basins. The proposed method in this study, in addition to improving the accuracy of identifying flooding potential areas, can help in understanding the processes involved in catchment.

Iran after glorious Islamic Revolution by compiling high level documents such as the Five-Year Development Plans (FYDP) has tried to change his position to a developed country in accordance with the requirements of cultural, geographical and historical and Islamic moral principles. These FYDPs according to the conditions and priorities of the country have had several considered sections by the governments. One of the most important sections refers to the existing problems and future goals in agriculture, environment and natural resources fields. Therefore, assessing the attention of the FYDPs to soil conservation and watershed management leads to holistic understanding about appropriateness between the past planning and natural resources facts and issues. This assessment showed authorities do not have comprehensive and precise understanding about role of watersheds, soil and water conservation and watershed management in gross domestic product and sustainable development. So, there are no precise and unambiguous approaches in FYDSs to protecting natural resources and have been satisfied to general, quantitative and inadequate legislation.

A conclusion of studies which conducted in Iran in the field of snow, snowmelt models and snow modeling that reported in scientific journals, as well as domestic and foreign conference papers has been presented in this study. This review paper is necessary and crucial to avoid duplication studies and to acquire comprehensive vision and familiarity with the research which conducted in this field. In addition, managers and planners by using the information and results of this research can be more firmly into the decisionmaking, planning and policy projects and plans on the implementation of their action. The results showed rapid advances in snowmelt-runoff modeling due to the climate change issues and researcher’s interest to simulate the world climatic and snow hydrology changes. There are a variety of models and methods in the field of snow modeling. Identifying the appropriate models and tools to easily simulate snowmelts need a comprehensive study and analysis in this regard. So, the present research has been formulated to investigate the literature of snow, snow models and the conditions of models application including topography, land use, land cover and data spatial and temporal scales by using the resources and documentation available to the country of Iran. The present research was conducted based on articles which published in magazines, conferences, various internet sources, models instructions and reports of different projects. Thorough literature review various models of urban snowmelt models to hydrological models adapted to specific purposes was observed. The results showed that in general the calculation of snowmelt are summarized in the three major temperature index (degree-days), energy balance and combination of temperature index and energy balance (combined method). Overall, in accordance with the conditions and objectives of the study one method and its application can be taken to comprehensive evaluation of snow researches.