جستجوی مقالات مرتبط با کلیدواژه "سناریوهای انتشار" در نشریات گروه "اکولوژی"

Rainfall intensity-duration-frequency (IDF) curves are used to plan, design and operate water resources projects or to protect various engineering projects against floods. Curves created from past climates cannot be valid for the future climates unless they are updated with future climatic trends. The purpose of this study is to investigate the effect of climate change on IDF curves in Zahedan Synoptic Station. First, the fractal behavior of precipitation at the station was investigated and the results showed that the maximum intensity of precipitation follows the monofractal behavior. Theoretical error was calculated by the method of relative difference (RD) and the results showed that the errors are within the allowable range, then the curves are extracted for the base period (1982 to 2019) and for the return period of 2, 5, 10, 50, 100 and 200 years. Further, future precipitation data (2021 to 2055) were predicted using HadGEM2-ES general circulation model, from the CMIP5 series of models, under the RCP4.5 and RCP8.5 emission scenarios, and using LARS-WG statistical downscaling model. Based on future data, IDF curves for the future were extracted employing the fractal theory. Comparison of base and future period curves showed that the average maximum rainfall intensity in different durations and return periods increased by 22.9% under RCP4.5 scenario and decreased by 11.1% under RCP8.5 scenario.

IntroductionThe historical trend of Iran annual average temperature of shows a 0.05 °C.year-1 increase which indicates that future emissions of greenhouse gases will continue to increase temperature and consequently cause to climatic change in the country. This change in environment will have a serious impact on different growth and development processes of crops. Increasing temperature could affect physiological processes like photosynthesis, respiration and partitioning of photo-assimilates. The negative impacts of climate change on potato production are reported in the literature. The present study was conducted to quantify the potential impacts of climate change on phenology, growth and tuber yield of potato.
Materials and MethodsThe climate projections of Hadley Centre Coupled Model version 3 (HadCM3), France and Institute of Pierre Simon Laplace (IPCM4), United Kingdom, was used to simulate the future conditions based on A2, B1 and A1B SRES (Special Report on Emissions Scenarios) scenario at three time periods including 2015-2045 (2030), 2046-2075 (2060) and 2076-2105 (2090)with a baseline of 1988-2012 (2012). For each period, the year shown in the parenthesis was considered as target year. The SUBSTOR-Potato model, one of the sixteen models embedded within the DSSAT (v4.5) program, was used to simulate the baseline and future yield and growth characteristics of potato. The model was calibrated and validated during 2012 and 2013 with two different farm experiments. In these experiments, the effects of different amounts of nitrogen fertilizer on yield and morphological traits of three potato cultivars were investigated. Six levels of nitrogen fertilizer (0, 50, 100, 200, 300 and 400 kg urea. ha-1) and three commonly planted potato cultivars in the region (Arinda, Santeh and Agria as early, medium and late maturity varieties, respectively) were studied as a factorial arrangement based on a randomized complete block design with three replications. Several criteria were used to quantify the difference between simulated and observed data. The root mean-squared error (RMSE-N (%)) was computed to measure the coincidence between measured and simulated values, while mean deviation (RMD) was calculated to evaluate the systematic bias of the model and model efficiency (ME) to estimate the model performance in relation to the observed mean.
Results and DiscussionThe evaluation of the SUBSTOR-Potato model showed adequate accuracy for simulating tuber yield, LAI, DTA and DTH of potato (Table 3). The results showed that the RMSE-N (%) was low for all the parameters. In both GCMs, number of days from planting to anthesis stages of potato decreased in compare to baseline of Fereydoon-Shahr region. Modeled values of day to anthesis in all scenarios and models (except B1 scenario in HadCM3 model) showed a decrease over the time, with the lowest amount in 2090. Under all scenarios and GCMs, the length of planting to harvest period will be declined in compareto baseline. Tuber yield will decline in compare to the baseline with a reduction range from 11.21% to 27.53% for HadCM3 model and from 12.60% to 30.58%for IPCM4 model. In HadCM3, B1 scenario in 2030 had the least difference with the baseline period (29.15 t ha-1) (Table 5), which is about 11.21% lower than the current condition. In IPCM4 model, the highest tuber yield was simulated under B1 scenario in 2030 (25.48 t ha-1), which shows a reduction of about 12.60% in compare to the baseline. A2 scenario in both GCMs showed the lowest tuber yield in 2090 (21.13 t ha-1 for HadCM3 and 20.24 t ha-1 for IPCM4), means a drop of 27.53% and 30.58% in tuber yield in compare to the baseline. In fact, in A1B, A2 and B1 scenarios, a decline of 20.29%, 27.53% and 16.04% in tuber yield for HadCM3 and a reduction of 20.88%, 30.58% and 17.90% for IPCM4 model was simulated, respectively.
ConclusionThe results indicated that tuber yield of common varieties of potato under all scenarios (A1B, A2 and B1) in both GCMs and during the evaluated years will decline in compare to the baseline in Fereydoon-shahr region.

Climate change impacts on precipitation and temperature world-wide are not yet well understood (especially for precipitation), due to their complexity and regional variability. In this study In order to explicit the impact of climate change on Precipitation and temperature in Iran, 15 AOGCM whose greenhouse gases scenarios ran under A2, A1B and B1 were used. Monthly precipitation and temperature data were calculated for 21 synoptic stations for two future periods (2016-2045 and 2070-2099) under all of three scenarios. Result showed that increases in temperature during summer months are higher in comparison with the winter months for both future periods. All three emission scenarios predict same increase in temperature (approximately 1 to 1.5oC) for the first future period while A2 and B1 scenarios predict the highest and lowest increase in temperature over the period of 2070-2099, respectively. It is expected that mean temperature of Iran increases about 3.5oC for the areas close to Caspian Sea and central regions and 4.5oC for other regions under the A2 critical scenario. It is also found that precipitation amounts will be increased in Gilan province and also slightly in Ardabil Province under second future period while the precipitation amounts will be decreased in other regions. Generally, it can be concluded that annual precipitation volume of Iran will be decreased about 1.02 (0.25 percent) and 16.52 billion cubic meter (4.13 percent) for the first and second periods, respectively.