مریم عاشق معلا

In current effluent discharge standards of the most countries such as Iran, self-purification capacity of rivers have not been considered. These standards developed a similar effluent discharge standard for all of the rivers without considering hydrological and hydraulic conditions of rivers.
In this paper in order to show the importance of self-purification capacity and differences between the rivers, in developing effluent discharge standard, two rivers- Gheshlagh River in Kurdistan and Sabzkooh River in Chaharmahal Bakhtiari- as samples were selected., and with applying Qual2kw model, current Iran effluent discharge standards were used to simulate the state of each river. The simulation showed that compliance with this standard maintain an appropriate qualitative condition of Gheshlagh River but in Sabzkoh River, due to the large number of pollution sources, these standards not only does not help to maintain the water quality but will have a very negative impact on water quality. Then Using simulation of river quality, the authorized appropriate limit based on self-purification capacity and the number and type of pollutants were estimated and showed that to develop accurate and efficient standards the self-purification capacity, the number of pollution sources, the amount of waste load and other different conditions of rivers also should be considered.

Investigation of land form characteristics of each region help to have a better recognition of its environmental attributes and such studies could help us in land evaluation and planning. Being familiar with process of these studies is one of the crucial information for each expert dealing with environment. In this paper the basic maps needed for physiographic studies are prepared in a region of Ilam province using topographical map (1:50000) and Arc view software. Then the maps were analyzed and land form parameters were compared with ecological model for urban, industrial and rural development. Results show that this region has suitable capability for development considering land form parameters.

Nowadays, with the increasing effluent discharge into the rivers, the need for a proper quality management for controlling the effluent discharge is highly essential. There are different methods to manage the quality of rivers, but hasy decision making without any program wont have a suitable result. If there is a regular procedure for water quality management, there wont be any interested decisions, overlapping, or management shortcomings. In this paper, a regulated schema for the management of inappropriate quality conditions in rivers has been offered., In this schema, the important management key features such as considering the hydraulic conditions of the rivers, the optimum usage of the river self-purification, calculating the total maximum load in the river, simulation and execution of the strategies in rivers using an appropriate model, and a multi criteria decision making based upon the results of applying that strategy in the model have been used. This schema is comprehensive and is extendable to all rivers.

Fire in forests and rangelands degrades vast part of natural resources. Although predicting the exact time and location of fire occurrence is a difficult task due to various parameters affecting wildfires، but application of Geographical Information System enables us to identify and control areas with high fire potential. The purpose of this study was to achieve a fire hazard map، developed by integrating several data layers such as topography، climate، vegetation cover and socio- economical factors. Some forest sites of Guilan province of I. R. Iran were selected for the study project due to their high cover density and their frequent fire occurrence history. Because the fire influencing parameters do not affect fie occurrence and distribution equally، a multi criteria method was used to grade them. The Fuzzy Analytical Hierarchy Process (FAHP) was used to consider uncertainties and to weight the criteria within 0 and 1 values. After calculating the Fuzzy weights and allocating them to the raster maps of the influencing parameters، finally the weighted informational layers were integrated and overlaid in the GIS. To assess accuracy of the applied method، the final fire hazard map was compared to further layer consisting of areas with high fire frequency during the last five years. Results showed that 66% of the hazard fire points were completely overlaid on sites with high and vey high fire risk، which reveals the capability of the study method in predicting forest fire potential. Furthermore، short distance between forests، roads and residential areas، identified as the main factors affecting fire occurrence and forest degradation more than the topographical parameters.

Land use is one of the main factors by which man has affected his environment, and historically the most important land use change induced by human has been the destruction of forest areas and changing them into arable lands and settlements.In this research, assessment of trend of changes in land cover of Arasbaran protected area is carried out by use of three time series of satellite images. The most important land cover classes distinguished in the area are river, orchards, settlements, farms, bare lands, rangelands and forests.Findings show that the reduction of valuable forest areas of Arasbaran which is noticeable in the period of 2002 to 2006, grows with much higher speed in 2006 to 2008 in a way that in only two years, more than 10 percent of forest land cover has disappeared which this destruction trend is very considerable.