Sasan Amini; Rafat Zare Bidaki; Rasoul Mirabbasi; Marym Shafaei
Abstract
In this study, we applied the vine copula structures for multivariate analysis of flood characteristics. For this purpose, the hydrographs of 98 flood events recorded at Landi station in Bazoft watershed, in Chaharmahal va Bakhtiari Province, were selected and the flood characteristics, including peak ...
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In this study, we applied the vine copula structures for multivariate analysis of flood characteristics. For this purpose, the hydrographs of 98 flood events recorded at Landi station in Bazoft watershed, in Chaharmahal va Bakhtiari Province, were selected and the flood characteristics, including peak flood (P), flood volume (V), flood duration (D) and time to peak (T) were extracted. Then, the best fitted distribution on each variable was selected by Kolmogorov-Smirnov test. In the next phase, the C-vine and D-vine structure were created considering three (P,V and T/D) and four variables (P,D,T and V) in changeable orders. In this way, the flood volume and peak were considered in a constant combination, and flood duration or the time to peak were consideredchangeable in tri-variate joints. In the four-variable joints, different combinations of all four variables were used. We used Gumbel, Frank, Joe, Clayton, Gaussian and t-student copula functions to combine these variables. The results obtained from the theoretical joint were compared with the experimental joint of that compound. Results showed that the best permutations of C-vine and D-vine copulas are similar in trivariate models TPV, (NSE=0.913), and the Gumbel and Gaussian copulas have selected as the best-fitted copula at the edges. In four-variate cases, the best C-vine and D-vine structures were PVTD and PTVD, (NSE=0.989) and the Gumbel and Gaussian were the abundant copulas in both of C-vine and D-vine models. The results indicated that the four-variate vine structures have higher concordance with the empirical copula than the tri-variate structures.
Delaram Ziaei; Rafat Zare Bidaki; Aliasghar Besalatpour
Abstract
Knowing the amount of runoff and sediment generated from different lands is an important step in land use management. Since it is not always possible to measure these values, modeling parameters, will be a way to achieve watershed comprehensive management. Beheshtabad watershed in Chaharmahal & Bakhtiari ...
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Knowing the amount of runoff and sediment generated from different lands is an important step in land use management. Since it is not always possible to measure these values, modeling parameters, will be a way to achieve watershed comprehensive management. Beheshtabad watershed in Chaharmahal & Bakhtiari province with different land uses such as range land, agriculture, gardens and urban area is an important part of Northern Karun Basin. In order to simulate the amount of runoff and sediment generated in different land uses, SWAT model was used. Discharge and sediment data of weather and hydrometric stations located in the area was used for sensitivity analyses and then to calibrate and validate model by SUFI-2 algorithm. NS and R² coefficients obtained for runoff calibration are respectively 0.69, 0.71 and for runoff validation are 0.65, 0.67 and for sediment are 0.72, 0.73 in calibration, and 0.66, 0.71 in validation, that confirmed model ability to accurately estimate of flow, runoff and sediment in the study area. The results showed that dry farming lands with average runoff and sediment of 190 mm, 24.5 tons per hectare per year respectively, has the highest and gardens with an average of 80 mm runoff has the lowest sediment yield of 1.63 tons per hectare in the year.
Delaram ziaei jazzi; rafat zare bidaki
Abstract
Soil erosion along environmental problems. The consequences of soil erosion can be examined from a variety of perspectives.the cost of soil erosion is divided into two categories of on-site and off-site costs. Soil erosion affects the production cycle and economics directly and indirectly. The purpose ...
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Soil erosion along environmental problems. The consequences of soil erosion can be examined from a variety of perspectives.the cost of soil erosion is divided into two categories of on-site and off-site costs. Soil erosion affects the production cycle and economics directly and indirectly. The purpose of this study was to estimate and compare direct and indirect economic losses of soil erosion in different land uses in the Beheshtabad Basin.To achive this, first sediment production by each landuse was initially determined by using SWAT model. NS and R² model coefficients for calibration were 0.72,0.73, and 0.66,0.71 for validation. Then direct loss of erosion was calculated based on the method of replacing the main soil organic fertilizer (NPK) by chemical fertilizers and indirect loss of erosion based on the loss caused by sedimentation behind the check dams inside the basin and reservoir dams outside the basin. According to the results, the highest amount of economic loss of soil erosion was related to rainfed farms equivalent to 56 million Rials per hectare Due to the fact that these lands are located on high slopes and also incorrect agricultural operations .The least amount was related to gardens,equal to 4.5 million-rials/hectare that indicated the importance of trees crown covering and observing the proper slope in the construction of gardens in the soil conservation. In this basin,excess grazing and improper utilization of rangelands have led to high erosion rate and sediment production in upstream rangelands and 3.33 million-Rials/hectare economic losses of erosion in this land use.
Ahmad Ghanbari; Rafat Zare Bidaki; Afshin Honarbakhsh; Vafa Mahmoodinejad
Abstract
Check dam is the most costly watershed management practice. This research was an attempt to evaluate the effectiveness of individual check dams in different watersheds of Chaharmahal-va-Bakhtiari. 11 criteria impacting upon check dams’ individual efficiency were considered: check dam location, ...
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Check dam is the most costly watershed management practice. This research was an attempt to evaluate the effectiveness of individual check dams in different watersheds of Chaharmahal-va-Bakhtiari. 11 criteria impacting upon check dams’ individual efficiency were considered: check dam location, check dam stability, longitudinal profile fixing, check dam's coefficient of sediment storage, check dam's crest to be perpendicular to channel's axis, spillway dimensions, check dam strength, anchorage, check dams built according to channels' cross section, consistency of spillway center with stream alignment and apron length. The importance of each criterion for each check dam’s efficiency was measured using analytical hierarchy processes. 41 cement- masonry and gabion check dams constructed previously in different parts of the province were selected and were scored based on these criteria. Then by multiplying the weight of each criterion by the score each check dam received on that criterion, the distance of performance of each check dam from expected efficiency was computed. Results show that check dam's crest perpendicular to stream axis and consistency of spillway center with stream alignment averagely gained the highest score but longitudinal stream fixing and correct spillway dimensions gained the lowest score. And the location of check dams with the weight of 0.214 and apron length with the weight of 0.035 gained the highest and lowest weights, respectively. Economic assessment of check dams were done by comparing their final score in efficiency and the size of material used for that. It was revealed that small check dams constructed by consideration of designing principles showed more efficient and cost effective than huge check dams.