جستجوی مقالات مرتبط با کلیدواژه "همدان" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

The paper is conducted to investigate the coverage and the seed bank in the areas the Riparian of the Gyan river in Nahavand city in Hamadan province. Five sampling sites along the river were determined. At each site, a transect perpendicular to the river flow and along each transect at least 6 plots of 1 square meter (three on each side of the river) are established. The Soil sampling was done from two depths of 0-5 and 5-10 cm at 10 points randomly from each plot. The soil samples are cultivated in the greenhouse the seeds germinate in them and are identified. Then diversity indices, calculated for cover and soil seed bank in each plot. Each of the above factors are compared in the intervals of 0-10, 10-20 and 20-30 meters from the center of the river by one-way ANOVA. Also, Sorenson's index is used to check the similarity of the species composition of cover and the soil seed bank of the Riparian area. The results show that the highest diversity related to the soil seed bank is at a depth of 0-5 cm at a distance of 10-20 meters, which is due to the dominant of Cyperus difformis annual plants at this depth. The percentage of similarity of surface-ground cover in the areas of Riparian and seed bank of the first depth and the second depth (20-7) percent, which was very low due to the washing of seeds by the river currents and the movement of seeds by grazing. This study showed that recovery of the vegetation of the river riparian is possible via the soil seed bank.

Ranges are considered as the natural and renewable resources, despite being in renewable resources group, due to inappropriate exploitation in many parts of the world, they have been destabilized and destroyed. The purpose of this study was to find ways to protect rangelands in Hamadan province. General approach of this research is descriptive and analytical, it has mainly used qualitative methods and emphasized on the participatory approach to increase the accuracy and depth of the results. Due to the ability in providing a reasonable framework for developing solutions the "SWOT" analysis method has been used in the research study. In many studies, to identify SWOT factors (strengths, weaknesses, opportunities and threats) and determining strategies only depends on previous studies or researcher's views, but in this research to determine the elements or factors of SWOT and identification of approaches a set of methods was used, including: "brainstorming" holding in a session, "Participatory rural appraisal" (PRA) workshop in 8 session, and 15 questionnaires completed by experts. In the next step, factors of SWOT quantified by "AHP" method and completing of 18 questionnaires of paired comparison in Saaty's scale was done by experts, this method is the combination of SWOT with AHP. Accordingly, in the matrix of SWOT analysis 20 strategies were introduced. The most important factors of the strategies which have presented based on need for comprehensive participation and views of the people, restore confidence in the government and nation in terms of natural resource management, using the power of NGOs, use of new techniques and social networking for conservation of ranges, power sharing and decentralization for make decision about natural resources and suitable distribution of operational experts to office centers in smaller areas (Dehestan). It also has proposed creating the"engineering supervisor of natural resources" and the supporting of the specific service companies of rangelands.

Fertile soil, like water as the most basic element of human life, is a one of God’s blessings entrusted to man that has been unfortunately left to neglect and degradation. Efforts are made in this study to investigate soil properties in the arable land around the City of Hamadan in order to identify the factors involved in its degradation over the past 60 years. To this end, the extent of fertile soil degradation during this period was initially estimated using aerial photos taken in 1955 and satellite images recently taken. A review was then conducted of the rules, regulations, and codes, and the pertinent amendments on land use change. It was found that more than 4000 hectares of the best agricultural lands have been devastated due to land use change over the past sixty years at least partly as the result of numerous ambiguous laws and regulations that allowed inappropriate approval of comprehensive urban plans. It is, therefore, suggested that a veto right should be given, as a short-term measure, to the representative(s) of the Agricultural Jihad Ministry on the Article 5 Commission and other similar commissions, and that all such commissions must be discontinued and replaced with a professional commission of agricultural and urban development experts, as a long-term term measure. The commission shall not only be mandated to review all the existing laws but must also draft and submit to regulatory bodies a comprehensive fault-free law that safeguards arable lands. The commission shall also be in charge of issuing permits for any necessary changes in land use.

The purpose of this study is analyzing the trend of drought characteristics in Hamedan Province In this regard, the corrected standardized precipitation index (SPImod) was calculated based on the monthly precipitation data from 11 synoptic and rain gauge stations during the period of 1985-2013. Drought characteristics, including severity, duration and interarrival time were defined and extracted based on the SPImod. The Sen’s estimator was used to estimate the slopes of trend lines. The results show that in most of the stations, drought duration had a non-significant decreasing trend, while the drought severity in over half of the stations had a non-significant decreasing trend. The drought interarrival time witnessed a non-significant decreasing trend in all of the stations, except at the Varayeneh station, which experienced a significant increasing trend at 1%. The monthly rainfall experienced a non-significant increasing trend in most of the stations except Keyto which experienced a non-significant decreasing trend.

These days, application of geomorphology in regional development has attracted the attention of all planners. Role of geomorphology in recognition of desert regions the method of developing these regions by surveying type / unit and fascias can confirm them as being desert on not. This becomes important when in sensitive regions whereas the recognition of the border between deserts and other regions is impossible and somehow difficult. For this reason the desert plain of Shara has been surveyed from geomorphologic point of view to be able to determine the type of the recognition of desert regions using geomorphologic data. Investigation Shara region using by Topography maps 1:50,000 and 1:25000 scale is Located then are analyzed aerial photograph 1:20000 and photo satellite and Arc Gis9 software Excel, filed observation in the bioclimatic. Shara plain is a natural occurrence with a slope of less them (%2) which is located between the full of slopes around the regions like Alvand Shazand and vessal which is most probabably our subsiding region located in the east of Hamedan province. Considering the geological, climatologically, hydrological, soil characteristics the present pediment has been developed as expanded under hydro geomorphologic and morphodynamical conditions and unit, type and geomorphologic fraise like those seen in central regions of grebe like playas can be well separated and recognized in it. In this study the continuance of the concepts related to the past of land, the condition of present balance, type and processes and that the region is in the threshold of which changes has been observed and has been stated regarding to geomorphologic time and location scales of the region. Moreover whit collecting and surveying present sources using aerial and satellite photographs and field works the geomorphologic desert plain of Shara has been divided to plain and playa. From recognizable types of the plain unit we can refer to Fans and pediment cone and from playa unit to Kavir and desert. The facials of the Fans, ending Pediment, alluvial trases Shaheds hills clay extensions (like Degh) saltish extensions are the geomorphologic features of Shara desert plain which is well distinguishable. Due to such features Shara region is one of the desert regions of the country and by considering the geomoropological indicators we can easily separate the desert from no desert.

Nowadays, wise scheduling of water resources is an important task for sustainable development. In this scope, accurate knowledge about daily evaporation from surface water is important for optimum agricultural products. Shortage or lack of evaporation sites, quality of the data and gaps in pan observations force the researchers to use prediction models. In this work, three different time series were applied for estimating daily pan evaporation in Hamedan province (Ekbatan dam, Kooshk-Abad and Agh-Kahriz). Evaluations of time series data indicated that pan evaporation of all stations, contains no seasonal trend. Based on the results, the ARIMA showed the highest performance in estimating the daily pan evaporation for the selected sites. With respect to the obtained errors, the best time-series structure were ARIMA(1,1,1) for Agh-Kahriz and ARIMA(2,0,1) for Ekbatan dam and Kooshk-Abad, respectively. The calculated R2 and RMSE for selected sites were 0.93 and 2.44 mm/day for Agh-Kahriz, 0.93 and 1.23 mm/day for Ekbatan dam and 0.92 and 1.03 mm/day for Kooshk-Abad. For the selected model, the Mean Percentage Errors (MPE) varied between 5.85 to 6.92 percent, which denotes models overestimation versus the measurements. The standard deviations of the best performance model are: 0.15, 0.14 and 0.13 mm for Agh-Kahriz, Ekbatan dam and Kooshk-Abad, respectively.

Estimation of design flood is the first step in hydraulic structures and flood control projects designing. On the other hand، estimation of runoff and flood، need to precipitation and design rainfall informations. Therefore، with respect to the spatially variations of rainfall and providing Depth–Area–Duration relationship، we can obtain suitable patterns of rainfall for estimation of design rainfall values in various locations. In this study، after gathering all storms in Hamedan، Qazvin and Zanjan provinces، 9 maximun and overall storms from 50 storms were selected. The results showed that between all of storms،the November 5،1994 storm is maximum and overall than others. The number of stations varies from 116 – 125 of 169 total stations in different storms. After drawing rainfall accumulation curves for climatology raingage stations، the hytograph curves were drived for noun recorded stations. After that the rainfall maps provided for 9 storms. Finally Depth–Area–Duration curves provided using rainfall maps. Using this curves were derived rainfall amount in any region and duration.

Study of vegetation changes of grazed and ungrazed rangelands is most important in range management programs. Vegetation changes were studied for four years (1996-99) inside and outside of the exclosure in Gian rangelands of Hamadan province. Measurements were made in permanent plots that have been established in study areas since 1996. Forage production was measured in randomized plots each year. Data were compared whit T test analysis. Results showed that there were significant differences in total cover of perennials during study period inside exclosure and the cover increased about 80 percent. The cover of all plant forms, such as shrubs, grasses and forbs increased significantly inside the exclosure in this period. The cover of perennials increased about 16 percent outside of exclosure during this period too, but there were significant differences in shrubs and grasses and no difference in forbs. Decreasers and increasers increased and invaders decreased inside, but outside of exclosure there was an opposite trend. Frequency of good quality plants increased inside and decreased outside. Range condition increased from poor to fair inside and decreased to very poor outside of exclosure. A positive and negative trend was observed inside and outside the exclosure area. In second year of study, rainfall was greater and In final year annual precipitation was more than first year but seasonal rainfall that is effective in growth, was less than the first year. Relationship between species canopy cover and annual and seasonal rainfall evaluated, however the correlation coefficient between rainfall and some species was significant. Overall, in comparison inside and outside, exclosure improved vegetation condition, forage production and range condition, under this climatic condition. Because of good precipitation condition of these years, it is necessary to continue the study to cover a series of drier years.