investigating the environmental sustainability of spreading human settlements in zayandeh-rud river basin

1. introduction the meaning of sustainability is an effort to reach the best results in human and environmental programs which are considered to be for present and future. zayandeh-rud is the most important and vital river in esfahan area which is used in agriculture, industry, providing drinking water and all other economic sectors. this river is originated from the zagros mountains – zardkooh bakhtyari – and ends in gav khooni wetland. following the development of human settlements (namely human and agricultural structures) and developing new water resources for different purposes many alterations have happened in the natural environment. these changes have caused a change in the use of the land in this natural area and also have negatively affected the sustainability of the environment. this research will investigate the environmental consequences of the development of human residences in zayandeh-rud basin, from 2002 to 2013. land use alterations with distinct divisions in two periods in 2002 and 2013, with considering the basin in 3 sectors (upper, middle, lower) are analyzed. based on this research finding, human settlements both in terms of residential or agricultural (farming and forest) use have been developed in different parts and many original lands and farms in the basin have been used by human activities. the raw data in this article has been used from the land use map by “national forest and land organization”. the data have been gathered in 2002 and 2013 and the experts’ views are used in doing and finishing this research. 2. study area zayandeh-rud river is a vitally important river for agricultural developments as well as domestic water supply and economic activity in west-central of iran. it is a completely closed basin having no outlet to the sea. the river is about 350 kilometers long and runs in a roughly west–east direction, originates from zagros mountains, west of the city of isfahan, and terminates in gavkhooni wetland to the east of the city. the zayandeh-rud contains more water than any other river in central iran. the zayandeh-rud river originates from zagros mountains (4500 meters higher than the sea level) which is located in the most western parts and flows in a west to east orientation to the iran’s central plain and finally ends in the most final point of the basin in gaav khooni marsh. the length of river is 350 kilometer and area of basin is about 41500 square kilometers. the zayandeh-rud river basin, in central iran has a semi-arid climate and large agricultural, industrial, and domestic water uses. the zayandeh-rud basin with 26917 kilometers width is located in gaav khooni marsh basin in central desert of iran. zayandeh-rud basin is limited from north to salt lake basin, from western and western south to karoon and dez basins, from east to daghe sorkh and siah kooh desert basins, and from south to shahreza basin. the climate of this basin is varies a lot. whereas chehelgerd area in west of basin has more than 1400 millimeters rainfall, in the east of basin near gaav khooni marsh is less than 100 millimeters. from 26917 kilometers area of zayandeh-rud basin, %93 is located in esfahan and %7 is located in chaharmahal and bakhtiari province. population of the basin in 2006 was 3668000. about %98 are in isfahan province and %2 resides in chaharmahal and bakhtiari province. 3. materials and methods in this research two methods are used, library research (book, papers, basic data collected from “national forest and land organization”) and field research (observation, and interview with experts). all the basic data of this research are based on “land use national plan” from the “national forest and land organization”. in addition, the experts’ views were used in all the phases of the research. having used etm images and field work, “national forest and land organization of iran” created land use map of whole of iran. these maps were made between 2002 and 2013 and confirmed officially. the study target in this research is zayandeh-rud river basin. border of study area was specified with spot goals of research and views of experts. then this border was mapped in “google earth” and the study area's border of research was extracted from basic map of national forest and land organization of iran”. study area of research was divided into three section as follows, the upper section is from zayandeh-rud river springs to cham- aseman dam, the middle one is between cham- aseman dam to limit of isfahan city in east middle of baraan plain and thee lower section is from middle of baraan plain in east of isfahan to the end of gaav khooni marsh. land use alterations are analyzed with distinct divisions in two periods in 2002 and 2013, with considering the basin in three sectors (upper, middle, lower). land use basic map in “national forest and land organization” had twenty-two items that were merged and reduced to nine land-users. change detection was done in arc gis software using :union: program and exhibited the map, table and descriptive information. 4. results and discussion the comparison of land use map in 2002 and 2013 of total of study basin indicates that dry farming, agriculture, forest, residential settlements and marsh land uses have increased while water surface, canebrake, and deserts as well as rangelands have decreased. in the upper section, explosion of human settlements and revolt of nature in the recent decade have increased. human land use such as agriculture and farming and human settlements increased to 140258 hectares and water surface and canebrake, deserts and rangelands land use decreased to 141262 hectares. in the middle section, because of human density and spread of human settlements, whole of land use increased and only desert land use decreased. in lower section, farming (agriculture) land use, forest, marsh land, residential settlements and dry farming increased while rangelands, desert, water surface & canebrake and plantation forests decreased. 5. conclusion the results of the study indicate that spreading of human settlements in zayandeh-rud river basin altered all of the land use and influenced environmental sustainability. in this time (2002-2013), desert, rangelands and water surface & canebrake land use decreased while farming (agriculture) land use, forest, residential settlements and dry farming increased. land use changes occur in all parts of zayandeh-rud river basin, but, most of variation happened in the upper section of area. this area includes zayandeh-rud river springs in isfahan and chahar-mahal and bakhtiari province to cham- aseman dam, between zayandeh-rud dam and isfahan city. with this process of spreading of human settlements without spotting the capacity of environment and nature, we will face with the destruction of environment and ecological in future. this process of development is dangerous for human and environmental sustainability in zayandeh-rud river basin. the development of the human residence and overuse of the natural resources bring about the destruction of nature and the natural ecosystem. misbalancing the ecosystem in such a short time has misbalanced the sustainability of water resources and plant, animal and human ecology has been negatively affected, too. considering all of these factors, the continuity of developing of the residences and the alteration of the land use will heavily damage the sustainability of the environment in zayande rood basin.