Pedram Attarod; Mahdieh Garoosiha; Mohammad Javad Mehdikhani; Samira Beiranvand
Abstract
We investigated the trend analysis of rainfall characteristics in the Hyrcanian region of northern Iran in a 33-years period (1987 to 2019). Annual, seasonal, and three 11- years periods (1987-1997; 1997-2008; 2008-2019) were analyzed using data recorded at eight synoptic weather stations of Astara, ...
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We investigated the trend analysis of rainfall characteristics in the Hyrcanian region of northern Iran in a 33-years period (1987 to 2019). Annual, seasonal, and three 11- years periods (1987-1997; 1997-2008; 2008-2019) were analyzed using data recorded at eight synoptic weather stations of Astara, Rasht, Anzali, Ramsar, Noshar, Babolsar, Ghaemshahr, and Gorgan. The Mann–Kendall (MK) non-parametric test was used to determine the rainfall trends. The mean annual rainfall was 1143 mm with the highest and lowest amounts recorded in Anzali (1694 mm) and Gorgan (529 mm), respectively. The MK test demonstrated no significant trends for annual rainfall in each station and the whole region (MK value: 0.32). Rainfall of 11-year periods showed slight differences (1140, 1145, and 1146 mm for the three consecutive periods). Rainfall and the number of annual events per year illustrated positive significant correlations in all weather stations (mean r = 0.58). The mean annual number of rainfall events was 118 with a mean rainfall event of 9.5 mm increased by approximately 0.5 mm (5%) during the recent period. In the Hyrcanian zone, 21% and 31% of the annual rainfall were less than 10 mm and larger than 40 mm, respectively. 34% of yearly rainfall (383 mm) was recorded in the first half of the year and the largest amount of seasonal rainfall was in autumn (43% of total annual rainfall). Plant communities, forest ecosystems, and agricultural activities in the Hyrcanian region will definitely be affected by any change in precipitation.
Azam Tabarzadi; Meghdad Jourgholami; Alireza Moghaddam Nia; Baris Majnounian Garagiz; Pedram Attarod
Abstract
Many environmental challenges such as stormwater runoff and flood risk, chemical and particulate pollution of urban air, soil and water, the urban heat island, and summer heat waves are exacerbated in urban environments. Runoff from heavy rainfall in many parts of the world lead to erosion, sedimentation ...
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Many environmental challenges such as stormwater runoff and flood risk, chemical and particulate pollution of urban air, soil and water, the urban heat island, and summer heat waves are exacerbated in urban environments. Runoff from heavy rainfall in many parts of the world lead to erosion, sedimentation and transportation of elements that forest covers is the most important factor in controlling it. In this research, the qualitative and quantitative characteristics of runoff in Chitgar forest park have been investigated. For this purpose, runoff discharge, physicochemical parameters including total suspended solids, total dissolved solids, pH, and chemical parameters including calcium, magnesium, sodium, potassium, nitrate and phosphate were measured and analyzed during three storm events. The results of the present study indicated that the average values of the measured parameters were 1988.3 l / h, 40.64 mg/l, 2064.8 mg/l, 7.75, 2.95 mg/l, 2.23 mg/l, 584.4 mg/l, 5.71 mg/l, 1.36 mg/l, and 0.71 mg / l. Also, the correlation between parameters showed that there was a strong relationship between measured parameters, with the highest correlations between calcium with discharge (0.66) and total dissolved solids (0.69) and sodium with pH (0.7) and total dissolved solids (0.65). Comparison of the results obtained from this study and with those of other studies on water quality status of different rivers indicates that the qualitative pattern of urban runoff and also the relationships among the qualitative parameters of urban runoff are very different from surface runoff of rivers.
