Behnaz Asefjah; Yahya Esmaeilpour; Ommolbanin bazrafshan; Hossein Zamani
Abstract
The past decade has seen a major revolution in vegetation monitoring using satellite imagery, resulting in quantitative indicators of vegetation with a professional processor in a web-based interactive development environment. In this study, using MOD13A1 and MOD13Q1 products of Modis sensor, the trend ...
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The past decade has seen a major revolution in vegetation monitoring using satellite imagery, resulting in quantitative indicators of vegetation with a professional processor in a web-based interactive development environment. In this study, using MOD13A1 and MOD13Q1 products of Modis sensor, the trend of temporal and spatial changes of NDVI and EVI indices in Fars province in a period of 16 days from 2000 to 2020 was coded and processed monthly in Google Earth engine system. The results of this study showed that the average index of NDVI index is from minimum 0.11 to maximum 0.495 and the average index of EVI index is 0.1. According to the results obtained in this survey, in all the years from 2000 to 2020 in January, NDVI and EVI values had the highest values compared to other months, so that in January 2019 and January 2020, the highest EVI values averaged 0.22 and the NDVI values Was estimated to be 0.18. The lowest monthly average values of both indices occurred between 2000 and 2005, which indicates that the vegetation has been severely degraded during these years. The results of spatial changes using EVI index showed that the level of vegetation in Fars province in different months varied from 10,000 square kilometers to 22,000 square kilometers and from the perspective of NDVI index from 15,000 square kilometers to 30,000 square kilometers.
faeze Ghasem Nezhad; Fazeli Mehdi; Omolbanin Bazrafshan; Mohammad Parvinnia
Abstract
Drought monitoring by the Standardized Runoff Index (SRI) presents some uncertainties, mainly dependent on the choice of the probability distribution used to describe the cumulative precipitation and on the characteristics of the dataset. In this study, uncertainty analysis for estimation of the hydrologic ...
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Drought monitoring by the Standardized Runoff Index (SRI) presents some uncertainties, mainly dependent on the choice of the probability distribution used to describe the cumulative precipitation and on the characteristics of the dataset. In this study, uncertainty analysis for estimation of the hydrologic drought characteristics (intensity, duration and frequency) was performed. Four distribution functions, two time period (30 and 49 years), six time scales (3, 6, 9, 12, 24 and 48 months) and Latin hyper cube sampling (LHS) method ware used. For each event at per year and month, was generated 50000 random sampling.Then, lower and upper bands of certainty was calculated for confidence level of 95% . In addition to the drought characteristics (intensity, duration and frequency) were calculated for six time scales, four distribution functions and two length of time series . Investigation of the longest duration and highest intensities showed that an increase time scale led to decrease the frequencies of drought classes and as a result increase drought intensity and duration . Further, no significant difference in the assessment of intensity and duration was between various distribution functions, meanwhile significant difference was between normal compared to weibull and gamma for the estimation of drought frequency in short time scales (3 and 6 months). Results of this study emphasized that considering drought intensity and duration, the normal distribution function, 24-month time scale and 30-years’ time series had the largest uncertainty for hydrologic drought estimation.
hosien شظهیه; omonabin bazrafshan; Abdolreza Bahremend; Arash Malekian
Abstract
The purpose of this study is the effects of the morphometric factors on peak discharge in 108 hydrometric stations in the southern watersheds, Iran. After homogeneous tests and random data, a time period (from 1983-1984 to 2013-2014 was chosen and used to choose the best probability distribution function. ...
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The purpose of this study is the effects of the morphometric factors on peak discharge in 108 hydrometric stations in the southern watersheds, Iran. After homogeneous tests and random data, a time period (from 1983-1984 to 2013-2014 was chosen and used to choose the best probability distribution function. Overall, the 84 morphometric and geometric parameters were calculated in ARC GIS software. In this research, the structural equation modeling with the least approach in smart – PLS software was used to check the most effective factors on the annual maximum discharge. 18 variables were identified as effective factors on the maximum discharge. between more than 84 structures, the effect of the focus time structures, positive height ratio, miller slenderness ratio structures ,the main river- slope characteristics , elevation number and the main river-slope height properties are negative than can predict overall the %46 of the annual maximum discharge changes in the watershed areas of Iran s southern parts. These factors affect directly on the flood in the total focus time about %38 thus, the most effective factor on the flood discharge is the focus time factor that should be considered in the flood management in Iran s southern areas.
shahla dehghan pir; omonabin bazrafshan; arashk hlizadeh
Abstract
Ground water depletion and water shortage are two problems in Hormozgan province which have occurred due to the irregular use and inappropriate management of demand and supply of water in agricultural sector. This research explored the balance of agriculture virtual water trade (imports and exports of ...
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Ground water depletion and water shortage are two problems in Hormozgan province which have occurred due to the irregular use and inappropriate management of demand and supply of water in agricultural sector. This research explored the balance of agriculture virtual water trade (imports and exports of virtual water) and its value in two catchments with different climate in north (Baraftab catchment in Hajiabad) and east (Payab-E Roodan catchment) of Hormozgan province. Based on the results, most of the volume of virtual water in northern catchment is related to wheat and Palm fruit with the amounts of 14 and 0.18 million cubic meters, respectively. Most of the volume of virtual water in the eastern catchment of province is related to Palm fruit (0.8 million cubic meters) and citrus (0.6 million cubic meters) and most of the volume of imported virtual water is related to wheat and rice. Also, Baraftab and Payab catchments are the exporter and importer of virtual water, respectively so that the amount of the balance of trade of virtual water in two mentioned catchments are -11.94 and 17.83, respectively. 64% and 67 % of fresh water in two Baraftab and Payab catchments is consumed to produce the agricultural products. The amount of water self-sufficiency index of virtual water is 86% and 81% and the amount of water shortage index is 66% and 69% in Baraftab and Payab catchments, respectively. These results reveal the severe water shortage in these two catchments.
