Fatemeh Einloo; Ali Salajegheh; Arash Malekian; Mohsen Ahadnejad
Abstract
Urbanization has led to development the impervious surfaces and subsequently changes in urban hydrology. The aim of this study is investigate the effect of land use change and urbanization on the changes of runoff peak discharge in Zanjan City Watershed, Iran. In order to, Landsat Thematic Mapper (TM) ...
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Urbanization has led to development the impervious surfaces and subsequently changes in urban hydrology. The aim of this study is investigate the effect of land use change and urbanization on the changes of runoff peak discharge in Zanjan City Watershed, Iran. In order to, Landsat Thematic Mapper (TM) images and Aerial photos of 1956, 2000 and 2012 has been processed by using IDRISI Selva and Geographic Information System software and land use maps prepared in six land use class and the trend of land use changes and urbanization determined. To analysis the hydraulic and hydrology behavior of three periods of land use changes and urbanization on the changes of runoff peak discharge, Stormwater Management Model (SWMM) was used. After the SWMM model calibration based on observation rainfall-runoff events, the results of model calibration and verification, confirmed the accuracy of the model simulation. The results of land use change and urbanization trend of Zanjan City Watershed show that urban areas in 2012 compared to 2000 and 1956, respectively, has increase 22.59 and 923.88 percent and in 2000 compared to 1956 has been increased 543.06 percent. The results of SWMM model show that land use change and urban development has led to increase the runoff peak discharge, so that the average change in runoff peak discharge show that it increase in 2012 compared to 1956 and 2000, respectively, 96.85 and 475.52 percent and in 2000 compared to 1956, 194.288 percent increase in average of runoff peak discharge is observed.
M. Navidi; F. Sarmadian; Sh. Mahmoudi
Volume 62, Issue 2 , October 2009, , Pages 299-309
Abstract
Sustainable exploitation of land resources is directly affected by considering soil quality which finally will also conclude environmental protection. Therefore, assessing different soil quality aspects which are sensitive to various land management practices seems too important. In this study, some ...
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Sustainable exploitation of land resources is directly affected by considering soil quality which finally will also conclude environmental protection. Therefore, assessing different soil quality aspects which are sensitive to various land management practices seems too important. In this study, some selected soil quality indicators have been compared in five land use systems including untouched rangelands, semi degraded rangelands due to grazing, rangelands that converted to rainfed agriculture, abandoned rainfed agriculture and an irrigated wheat farm in eastern Qazvin province, Iran. Samples were taken from the surface layer (A horizon) of soils in a completely randomized design with four replications. Statistical comparisons of the results revealed highest decrease in soil organic matter and total nitrogen owing to abandoned rainfed agriculture that showed 74% and 70% decline, respectively. Eventually the abandoned rainfed agriculture meets the sharpest slump in some soil properties such as cation exchange capacity (CEC), available phosphorous, total porosity and thickness of A horizon. Meantime the most increase in bulk density was also in recent land use. According to the results, the negative effects of inappropriate land use changes were led to soil productivity decline and will cause undesirable consequences in soil quality. So maintenance of soil quality is critical to environmental sustainability and this should be done on the basis of recognition all features that reduce its quality.
M. Momeni; M. Kalbasi; A. Jalalian; H. Khademi
Volume 62, Issue 1 , June 2009, , Pages 137-153
Abstract
The discharge of total suspended sediments (TSS) and dissolved nutrients from watersheds into receiving waters is a serious problem when natural vegetation is degraded by agriculture or overgrazing. This study was conducted in Soolegan Watershed to investigate land use change and overgrazing effects ...
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The discharge of total suspended sediments (TSS) and dissolved nutrients from watersheds into receiving waters is a serious problem when natural vegetation is degraded by agriculture or overgrazing. This study was conducted in Soolegan Watershed to investigate land use change and overgrazing effects on phosphorus loss (dissolved & particulate), particle size associated loss of P and effect of time of rainfall on total dissolved P concentration in runoff. Much higher runoff, sediment and nutrient losses observed under cultivated land and HDP (high degraded pasture) than those under MDP (moderately degraded pasture). Contribution of particulate phosphorus exported from micro plot via surface runoff was increased by decreasing plant cover. Largest amount of dissolved phosphorus loss measured in HDP (16.4 mg/m2) and particulate P loss in cultivated land (301.3 mg/m2). Concentration of total dissolved phosphorus (TDP) in runoff was significantly (p
