Reza Chamani; Mehdi Vafakhah; Seyyed hamid reza Sadeghi
Abstract
Today, drought has become one of the hot topics of global concern, but its impact on the provision of services and functional health of watersheds in the face of this natural disaster has been less evaluated. Accordingly, in this study, the effect of drought on the Efin Watershed health has been evaluated ...
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Today, drought has become one of the hot topics of global concern, but its impact on the provision of services and functional health of watersheds in the face of this natural disaster has been less evaluated. Accordingly, in this study, the effect of drought on the Efin Watershed health has been evaluated based on changes in Reliability (Rel), Resilience (Res) and Vulnerability (Vul) indicators in the period 2005-2019. Based on this, the rainfall data of three rain gauge stations were interpolated using Inverse Distance Weighting (IDW) for the watershed and sub-watersheds. Standardized Precipitation Index (SPI) was then determined based on the mean and standard deviation of monthly data and was used to calculate the Rel, Res and Vul indicators. Finally, the overall health status of the watershed was determined by calculating the geometric mean of these indicators. The annual results showed that Efin Watershed in terms of Rel, Res and Vul indicators extends between 0.83-0.92, 0.17-0.33 and 0.24-0.54, respectively. The RelResVul index also has values between 0.37-0.53. The average watershed health indicator in this period was also calculated to be 0.42, which indicates mean watershed health condition. Spatial variations of watershed health also showed that Rel, Res and Vul indicators fluctuated between 0.85-0.86, 0.21-0.24 and 0.76-0.78 in different sub-watersheds. The results of rainfall analysis of the region, indicate that due to the relative stability of rainfall, the impact of human intervention and intensification of watershed health threatening factors, more than ever effect on the current situation and if not addressed will have harmful effects.
Fahimeh Mirchooli; Seyed Hamidreza Sadeghi; Abdulvahed Khaledi Darvishan
Abstract
Soil erosion is an important subject in water and soil conservation researches which is influenced by natural and anthropogenic factors. Hence, knowledge on soil erosion amount enables the identification of critical areas and prioritization of measures. One of the effective factors in the evaluation ...
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Soil erosion is an important subject in water and soil conservation researches which is influenced by natural and anthropogenic factors. Hence, knowledge on soil erosion amount enables the identification of critical areas and prioritization of measures. One of the effective factors in the evaluation of soil erosion is slope and length (LS) which could be calculated using different methods and algorithms, so the selection of the best method to provide proper estimation is important. However, the comparison of the performance of the different estimation methods has not been sufficiently considered. Therefore, the present study was conducted to calculate the LS factor and evaluate its effect on estimations of soil erosion in the Shazand Watershed using four common algorithms viz. Renard et al. (1997); Desmet and Govers (1996); Moore et al., 1991, and Böhner and Selige (2006) in geographical information system. The results of this study while confirming the difference of about 15 times among performances of various algorithms, indicated that the mean soil erosion using the algorithm of Renard et al. (1997); Desmet and Govers (1996); Moore et al. (1991), and Böhner and Selige (2006) were 4.95, 19.47, 1.73, 1.34 t ha-1 yr-1 in case of the stability of other factors of RUSLE model. Considering the calculated amounts of slope length on the topographic map, the Desmet and Govers (1996) algorithm performed better than other algorithms in LS calculation for the study watershed. It clearly verified the necessity of selecting pertinent procedures for the calculation of input factors for the precise estimation of soil erosion.
Seyed Hamidreza Sadeghi; Zeinab Karimi; Zahra Hashemiarian
Abstract
Annually, high amount of soil is washed out by erosion from the watershed. Implementation of appropriate management methods to control soil erosion is therefore essential. Application of economically-effective and environmentally friendly amendments to soil is one of the solutions and new technologies ...
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Annually, high amount of soil is washed out by erosion from the watershed. Implementation of appropriate management methods to control soil erosion is therefore essential. Application of economically-effective and environmentally friendly amendments to soil is one of the solutions and new technologies to control soil erosion. However, the comprehensive assessment of the impact of commonly used soil amendments on soil erosion has not been conducted. The present study therefore aimed to assess the performance of combined application of polyacrylamide powder (6 gm-2) and vermicompost (24 gm-2) in comparison with individual application of the polyacrylamide and vermicompost as well as control (without amendments) condition to control runoff and soil erosion under laboratory condition and on a clay-loamy soil. The study variables of runoff, soil loss and sediment concentrations were measured under a simulation rainfall intensity of 80 mm.h-1 and duration of 8 minutes. The results indicated a statistically significant effect (p=0.00) of all study treatments on the reduction of runoff, soil loss and sediment concentration from the study small plots. The combined effect of polyacrylamide and vermicompost on runoff and sediment concentration was also found greater than that recorded for soil loss.
Seyed Hamid Reza Sadeghi; Seyedeh Laleh Razavi; Mohammad Mahdavi
Volume 1, Issue 2 , July 2009, , Pages 78-86
Abstract
Many different runoff prediction methods are being used among which SCS model has been applied throughout the globe. It is therefore very important to evaluate the circumstances and input specifications under which such models could be applied. The present study was conducted to investigate the role ...
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Many different runoff prediction methods are being used among which SCS model has been applied throughout the globe. It is therefore very important to evaluate the circumstances and input specifications under which such models could be applied. The present study was conducted to investigate the role of rainfall main characteristics on accuracy of SCS model in runoff prediction for Kasilian and Darjazin watersheds. For this purpose, the simultaneous rainfall-runoff data were selected and the storm runoff was estimated using determining rainfall characteristic, providing Curve Number map and calibrating the model. In order to determine the effects of rainfall characteristics on model output, the standardized values of regression coefficient (β) of the best fitted multiple regression, developed between rainfall circumstances and maximum storage index coefficient, were determined. The results of the study showed the depth, maximum rainfall in concentration time, maximum 30 minutes intensity, 2nd quartile and 1st quartile have the highest rate of effectiveness on model output respectively.
