Showing 4 results for Pajouhesh
M. Pajouhesh, H. Shekohideh, Z. Heydari,
Volume 25, Issue 3 (Fall 2021)
Abstract
Land use changes identifying to assess and monitor sensitive areas for sustainable planning and land management is essential. Remote sensing and the use of GIS technology as some of the most common methods in the world in monitoring land changes, especially, in the study of large areas. In this study, the trend of spatial land use changes in the area of Karun 3 dam was investigated. in the before and after the construction periods and dam intake using remote sensing and GIS over 27 years. In this study, the satellite imagery of Landsat 5 TM sensors from 1991 and 2008 and Landsat 8 OLI sensors in 2018 were analyzed and processed. Using object-oriented classification with land use maps for the three periods 1991, 2008, and 2018 with the overall accuracy of the Kappa index of 0.93 and 0.89 percent for 1991, 0.94, and 0.88 percent in 2008 and 0.93, respectively, and 0.86% in 2018 was prepared. The results showed that the water use of the region with an area of 37.68 square kilometers is increasing and agricultural lands and residential areas with an area of 1349.04 and 226.56, respectively, forest lands with an area of 1041.49 remained as the dominant cover of the region and rangelands by going through a decreasing trend of increase in both periods after forest use, with an area of 878.87, they had the largest area. According to the obtained results, it can be said that the construction of the Karun 3 dam has caused the flooding of agricultural lands and their conversion to another use, as a result of which the villagers were forced to migrate due to losing their jobs and abandoned residential areas become other uses.
T. Tahmasbi, Kh. Abdollahi, M. Pajouhesh,
Volume 26, Issue 2 (ُSummer 2022)
Abstract
The runoff curve number method is widely used to predict runoff and exists in many popular software packs for modeling. The curve number is an empirical parameter important but depends largely on the characteristics of soil hydrologic groups. Therefore, efforts to reduce this effect and extract more accurate soil information are necessary. The present study was conducted to integrate fuzzy logic for extraction runoff curve numbers. A new distribution model called CNS2 has been developed. In the first part of this research, the formulation and programming of the CNS2 model were done using the Python programming language environment, then the model was implemented in the Beheshtabad watershed. This model simulates the amount of runoff production in a watershed in the monthly time step with the fuzzy curve number and takes into account the factor of rainy days, the coefficient of management of the RUSLE-3D equation, and the soils theta coefficient. The results indicated that the model with Nash-Sutcliff 0.6 and the R2 coefficient 0.63 in the calibration set and Nash index 0.53 and R2 coefficient 0.56 in the validation set had appropriate efficiency in runoff simulation. The advantage of the model is that distributive and allows for the identification of areas with higher runoff production.
M. Kyanpoor Kal Khajeh, Me. Pajouhesh, S. Emamgolizadeh,
Volume 26, Issue 3 (Fall 2022)
Abstract
Humans are always trying to change land to use natural resources to meet their needs. One of the land use changes that take place in order to benefit from sustainable water resources is dam construction. Dam construction has many positive and negative consequences for the environment from the beginning to use. The objective of this study was to investigate the effect of Gotvand Dam on the problem of collision of water flow path with salt domes and large volume accumulation of salt behind the dam lake. Images of the Landsat 5 satellite TM sensor for 1991, Landsat 7 satellite ETM+ sensor for 2008, and Landsat 8 satellite OLI sensor for 2020 were used to classify images, and prepare land use maps of the studied basin. Reviewing and evaluating the land use maps of the study area showed that agricultural lands are being developed after the operation of the dam. Also, barren lands were decreasing as well as the area's water content was increasing during the study period. In the second period of study (2008-2020), the population of the regions with an increasing area has been increasing. Also, the rangeland and meadows had a decreasing trend during the first and second periods. The results of classification accuracy using the object-oriented method for three periods of 1991, 2008, and 2020 were obtained as 0.92, 0.97, and 0.93, respectively. In general, it can be stated that the construction of the dam has increased the area under cultivation of land and by increasing population and urbanization in the construction area of the dam, destruction and reduction of rangelands occurred.
S. Esmailian, M. Pajouhesh, N. Gharahi, Kh. Abdollahi,
Volume 27, Issue 3 (Fall 2023)
Abstract
Awareness of the number of changes in runoff and sediment on different slopes can be useful in modeling the production of runoff and sediment. Therefore, this study was conducted to investigate the production of surface and tunnel runoff and sediment in saline and sodic soils on different slopes. Saline-sodic soil was collected and transported to the laboratory. Laboratory experiments were performed on a soil bed in a rectangular flume at three different slopes (5%, 10%, and 15%) under simulated rain (30 mm/h) for one hour. An analysis of variance was used to investigate the effect of slope on runoff and sediment production, and the means were compared using Duncan's test at the five percent level using SPSS version 26 software. The results showed that there was a significant difference between the slopes of the runoff (P<0.001) and sediment (P<0.001). In the first minute of the experiments, due to the lack of moisture in the soil, the amount of runoff was low, but over time, the amount of runoff increased. It is because the pores are blocked by the dispersion of soil particles owing to the presence of sodium ions, which ultimately leads to a decrease in permeability. Similarly, in the last few minutes, outflow from the tunnel was observed, and this flow occurred only on slopes of 10% and 15%. The amount of sediment was also low in the first few minutes, which could be related to the low amount of runoff and the lack of sediment particle removal. Nonetheless, after the lapse of time, its amount increased, and the primary reasons were reduced permeability, increased runoff, and removal of fine particles from the soil surface.
