The Study of Environmental consequences of water resources instability in the Zayandeh-Rud river basin

1-Introduction
Water is a major concern for sustainable development in the twenty-first century, as the experts in water issues will become the current crisis in the coming years a world war over water. Instability of water resources as drought or water shortage has affected many countries throughout history, especially the arid regions and has many damages and consequences in the economic, social and environmental aspects. Zayandeh-Rud basin in Iran central is region with water problems. Zayandehrood River that originates from the mountains Zardkuh Bakhtiary, Is the most important rivers of the region to develop of agriculture, and supply of industry and drinking water sectors and all of economic activities. Following Climate instability in recent decade and increasing pressure on river over time, is occurred Instability of agricultural water resources or droughts in recent years. In this research, is studied and compared the environmental consequences of water resources instability in the river basin, with use methods such as, the analysis of land use changes on two periods, Assessment of changes in the number of wells and the exploitation level of the underground water reserve and distributing questionnaires to analyze the effects indices of drought in the Downstream of the basin,
2-Materials and methods
In this research two methods are used, library research (book, papers, basic data collected from “National Forest and Land Organization” and “Iran Water Resources Management Co.) and field research (observation, interview with experts and Distribution of the questionnaire). Accordingly, investigated three methods the following:
2-1- Change Detection of Land Use: All the basic data of this section 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. 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. 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.
2-2- Changes of Underground Water: The basic data of this section earned from “Iran Water Resources Management Co. and Esfahan Regional Water Authority, and studied Changes in the number of wells, qanats and springs and removal level of the groundwater table and changes in reserve of groundwater aquifers in the Zayandeh-Rud basin in two statistical years 2006 and 2011.
3-2- consequences of water resources Instability on environmental indicators:
Statistical population of this section is villages in downstream part of Zayandeh-Rud basin. The population sample chosen based on Cochran formula and in the form of Stratified Probability sampling. Study Area in the down of the river (from Isfahan city to Gavkhoni marsh) is divided into two parts, Western and Eastern according to geographic, socio-cultural and political indicators; Then selected four districts in the ruling classes Research. From 33153 number of rural households Estimated 380 people to reduce 323 people during the study, due to the limitations and delete incorrect questionnaires, also estimated sample of settlements 25 villages. Questionnaires in the study area analyze and compare these indices in before and after the drought. In the following, analyzed average of research triple indices in SPSS software. Then result analyzed in one sample T-test and compared significant differences of Impact of drought in various rural districts with ANOVA test.
3-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 marshland uses have increased while water surface, canebrake, and deserts as well as rangelands have decreased. Study of underground water indicate that after the water sources instability has increased level the exploitation of groundwater aquifers. It increased in the middle and downstream sections of basin that river's flow is not permanent, as has been offset water shortages caused by drought by drilling and exploitation water from wells. In this context, between 2006-2011 drilled 9277 number new wells. During these five years, added 4.8 meters depth of wells and groundwater level has dropped about 5 meters. Analysis of qanat Statistics indicate that due to droughts, drain the water qanats almost halved, and the number of springs also have declined. To assess the environmental effects of Water Resources instability is used 13 Index. The highest impact of drought on environment indicators is in "drying qanats, wells and springs", "reducing the amount of surface water" and "Increasing the depth of water wells (decline in groundwater levels)” and The least effect is seen on the Indicators: "increasing of fire in the natural environment of the region" and "Reduction of medicinal plants". The average of environmental impacts of droughts is 4/24. The results show that no significant difference between rural districts in study area in terms of the impact of drought; this means that the rural districts in study area are relatively similar to the impact of the negative consequences of drought in various aspects.
4-Conclusion
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. Also, with increasing the exploitation of aquifers, escalate the cycle of water resources instability, drought and ecological unsustainability.