Hydrology
Firooz Abdolalizadeh; ََAli Mohammad Khorshiddoust; Saeed Jahanbakhsh
Abstract
In the current research, to investigate the future climate of the Urmia Lake catchment, the maximum and minimum temperature, rainfall and drought in the basin were projected for the period of 2015-2099 using NorESM2-MM climate model under the scenarios of SSP. The downscaling output of the model was ...
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In the current research, to investigate the future climate of the Urmia Lake catchment, the maximum and minimum temperature, rainfall and drought in the basin were projected for the period of 2015-2099 using NorESM2-MM climate model under the scenarios of SSP. The downscaling output of the model was done using the quantile mapping method and their accuracy was evaluated in the simulation of the base period (1990-2014) using the monthly diagram and RMSE and NRMSE indicators. The evaluation of the results showed that: the minimum and maximum temperature of the basin under the pessimistic scenario (SSP5-8.5) until the end of the century and under the optimistic scenario (SSP1-2.6) until 2075 have an ascending trend and then a descending trend. Average maximum and minimum temperature of the basin in the near future (1.0 to 1.8) and (1.1 to 1.8) ℃ and in the far future (1.5 to 4.8) and (1.3 to 4.3) ℃ will increase. The annual rainfall in the future period does not have a significant trend, but the average rainfall of the basin in the optimistic scenario will increase by 16.5% in the near future and 8.9% in the far future and in the pessimistic scenario will increase by 1.8% in the near future and 7.2% in the far future. According to the SPEI index, in the future period, under the optimistic scenario, moderate drought will have an ascending trend, severe drought will have a descending trend, and under the pessimistic scenario, the drought will have a descending trend.
Reza Aghayari Samian; Ali Mohammad Khorshid Doust; Saeed Jahanbakhsh Asl; Aida Hosseini Baghanam
Abstract
The aim of this study was to predict changes in temperature, precipitation and evaluate the effects of climate change on the status of surface runoff in the Aras catchment. Climatic conditions were simulated in LARS-WG software environment under RCP8.5 scenario. Using the modified Trent White experimental ...
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The aim of this study was to predict changes in temperature, precipitation and evaluate the effects of climate change on the status of surface runoff in the Aras catchment. Climatic conditions were simulated in LARS-WG software environment under RCP8.5 scenario. Using the modified Trent White experimental model, the amount of potential evapotranspiration was estimated for both observation and simulation periods. To ensure the validity of the model, the mean error orthography (RMSE), and the determination coefficient and Nash-Sutcliffe efficiency coefficient (ENS) were used. Also, modeling of surface runoff changes in GIS software environment and SWAT plugin was performed. After forming hydrological units (HRU), the baseline model for surface runoff changes was selected to calibrate and validate the model. The results show that by modeling climatic data during the simulation period, the amount of temperature, evapotranspiration and transpiration will increase, and in contrast, the amount of precipitation has occurred and the flow rate will decrease superficially. The results of validation showed that the accuracy of the model in the selected stations was high and for the precipitation parameter due to its discontinuous nature, the correlation between the data is less than the temperature parameter and different. The results of hydrometric modeling of the basins showed that the Nash-Sutcliffe value is close to 1 and the correlation coefficient between the data is 0.99, which indicates the high efficiency of the model for simulating and estimating climate change and its effects on surface runoff.
Said Jahanbakhsh ASL; Mohammad Hossein Aalinejad; Vahid Sohraabi
Abstract
1-IntroductionDetermining the temporal change of snowmelt or agriculture water equivalent of snow, predicting flood, and managing the reservoirs of a region is of utmost importance. Some major parts of the western sections of the country are located in the mountainous region and most of the precipitations ...
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1-IntroductionDetermining the temporal change of snowmelt or agriculture water equivalent of snow, predicting flood, and managing the reservoirs of a region is of utmost importance. Some major parts of the western sections of the country are located in the mountainous region and most of the precipitations of this region occur in the form of snow in winter. The runoff resulting from snowmelt has an important role in feeding the rivers of this region and it has a significant share in developing agriculture and the economy.Scientific studies have shown that climate change phenomena have significant effects on precipitations, evaporation, perspiration, runoff, and finally water supply. As the demand increases, climate changes, greatness, frequency, and the damage resulting from extreme weather events, as well as the costs of having access to water increase, as well. Therefore, evaluating the runoff resulting from snowmelt and the effect of climate change seems necessary for managing water resources.2-MethodologyGamasiab basin is located in the northeast part of the Karkheh basin originating from the springs in the vicinity of Nahavand. Its basin has an area almost equal to 11040 square kilometers that have been located in the east part having 47 degrees and 7 minutes to 49 degrees and 10 minutes geographical longitude and from the north part, it has 33 degrees and 48 minutes to 34 degrees and 54 minutes geographical latitude. This basin has an altitude between 1275 to 3680 meters.In this study, snow-related data required for simulation were derived from the daily images of the MODIS sensor. To this end, first, the snow-covered area of the Gamasiab basin was measured during the 2016-2017 water years using the process of satellite images obtained from the MODIS sensor in the google earth engine system. All geometric justifications and calibration processes of images were applied precisely in the mentioned system. In the next step, the output of the GCM model scenarios was utilized for calculating temperature and precipitation changes in future periods. These CMIP5 kind models were under the control of two RCP45 and RCP85 scenarios and were downscaled with LARS-WG statistical model.Moreover, to investigate the uncertainty of models and scenarios, the best models and scenarios were selected for producing temperature and precipitation data of future periods; accordingly, the outputs of the models for future periods (2021-2040) having the basis period of (1980-2010) were compared using statistical indexes of coefficient of determination (R2) and Root Mean Square Error (RMSE). The results were entered into the SRM model as the inputs. In addition, temperature and precipitation data of meteorological station of the studied region as well as the daily discharge of the river flow of hydrometric station of Chehr Bridge (as located in the output part of Gamasiab basin) were used during the statistical period of October 2016 to May 2018. 3-Results and Discussion Using Digital Elevation Model (DEM) of the region and the appendage of Hec-GeoHMS in GIS software, firstly, flow direction map, flow accumulation map, and stream maps were drawn and the output point (hydrometric station of Chehr Bridge) was introduced to the border program of the identified basin and the basin was classified based on the three elevation regions.Producing temperature and precipitation data of future periods requires a long-term statistical period; accordingly, the meteorological station of Kermanshahd was selected since it was in the vicinity of the studied region. To be confident in the ability of the model in producing data in future periods, the calculated data had to be compared with the observed model and data in the studied stations. The capabilities of the LARS-WG model in modeling the mentioned parameters of this station confirmed the observed data. Moreover, the ability of the model in modeling precipitation was very good and acceptable; however, the most modeling error was related to the precipitation in Mars.In the next phase and compared to the basic periods, the mean of changes in average precipitation and temperature was measured in the studied stations during January and Juan of 2015 to 2017(for which simulation had occurred); as an index of changing the climate, this was entered into the SRM model under climate change conditions. During the simulation period (January to Juan), it had been predicted that the precipitation parameter would decrease and the temperature parameter would increase.4-ConclusionThe results of this study indicated that using the MODIS sensor could provide an acceptable estimation of the snow cover level of the Gamasiab basin, which lacked snow gauge data. Moreover, the results of simulation with the SRM model showed that the model could simulate the snow runoff in the studied region. As the main purpose of the study, the effect of temperature and precipitation in future periods was well stated considering the uncertainty of CMP15 series models and scenarios. The results of temperature changes indicated an average increase of 1.8 C. the results of precipitation also indicated an average decrease of more than 5%. However, decreasing precipitation in the cold months of the years had been predicted severely so that the reduction of precipitation in February was of utmost importance for feeding the snow cover and rivers, which had been estimated to be 20%. This happened while increasing precipitation was mainly related to the hot months of the year whose amount was insignificant and didn`t have that much effect on the runoff. Accordingly, due to the increases in temperature and decreases in precipitation in cold seasons, the results of runoff simulation have indicated a 24% reduction for 2016-2017 and a 29% reduction for 2017-2018 water years.
Alireza Donyaii; Amirpouya Sarraf
Abstract
1- Introduction Climate evolutionary theory reveals that climate change has already been evident in the planet's history, but when opposed to historical climate changes, the climatic changes of the last century have two unique characteristics. First, through the nature of the ongoing climate change, ...
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1- Introduction Climate evolutionary theory reveals that climate change has already been evident in the planet's history, but when opposed to historical climate changes, the climatic changes of the last century have two unique characteristics. First, through the nature of the ongoing climate change, human actions play a significant role Second; the speed of recent climatic changes is greater, so that, many changes will be occurring in the Earth's atmosphere during a short term [Telmer et al. 2004]. Nowadays, global warming has significant effects on precipitation and runoff yield and water resources due to the increased concentration of greenhouse gases [Donyaii et al. 2020]. The average meteorological parameters, in particular the annual or seasonal components of temperature, precipitation and runoff, play a significant role in the hydrological cycle and are typically used as an indicator for climate change evaluation on the water supplies available to Iran now and particularly in the future [Donyaii et al. 2020]. Based on the IPCC Fourth Assessment Report Models [AR4], a number of studies have been undertaken to examine the effect of climate change on the hydrological components of watersheds in Iran. In contrast with the Fifth Assessment Study [AR5] models, these models, along with older pollution scenarios, have limited resolution. Therefore, in the watersheds of Iran, climate change experiments with higher resolution climate models under the latest pollution scenarios [RCPs] of the AR5 seem appropriate. According to historical evidence of Gorganroud's high flood capacity in the province of Golestan, Iran, the recognition of the impact of climate change on the watershed's hydrological regime is important for water resource planners. 2- Methodology 2-1- Study area and data set The Gorganroud Watershed is located in Golestan Province, Iran. In this study, the Soil and Water Assessment Tool [SWAT] was employed for hydrological simulation of the watershed based on the downscaled outputs [using the Bias Correction and Spatial Disaggregation [BCSD] method] of fifth assessment report climate change model [MIROC-ESM] for historical and future periods. The trend analysis of hydro-climatic records was done according to the non-parametric Mann-Kendall test. The future projection was conducted for the near [2025-2050], mid [2051-2075], and far [2075-2100] future periods related to historical records in the period of 1985-2005. 2-2- SWAT set-up and calibration, validation and uncertainty analysis In this study, runoff was estimated using the Soil Conservation Service [SCS] method. The Manning equation and Muskingum method were utilized to calculate flow velocity and routing phase, respectively. On the other hand, the SUFI-2 algorithm was employed to calibrate and analyze the sensitivity, and uncertainty of the SWAT model. The sensitivity analysis is based on linear approximation and the degree of uncertainty is calculated by two factors called r-factor and P-factor. The calibration and validation were performed using runoff data in the periods of 1995-2015 and 2016-2019, respectively. The coefficients of determination [R2] and Nash-Sutcliffe [NS] were used as the objective function to determine the goodness of fitness. 2-3- Climate Change scenarios and AR models In the AR5 new emission scenarios based on emission forcing level until 2100 were employed. In order to investigate the future climate change, the Model for Interdisciplinary Research on Climate-Earth System Models [MIROC-ESM] was selected among the newest extracted models presented in the AR5, because the result of this model in Gorganroud watershed showed the highest agreement with observational data. This model consists of four emission forcing scenarios [RCP2.6, RCP.4.5, RCP6.0 and RCP8.5. 3- Results and Discussion 3-1- SWAT sensitivity analysis, calibration and validation analysis Seventeen parameters were chosen for SWAT sensitivity analysis using the 500 simulations of SUFI-2. Results showed that the parameters CN, SOL_BD and SOL_K have the highest relative sensitivity. Based on the results, the coefficients R2 and NS for runoff simulation were estimated to be 0.79-0.77 and 0.74-0.71 in the calibration and validation stage, respectively. Therefore, the results of the model are acceptable and its uncertainty metrics is satisfactory in general. The study results showed that the model has estimated the amount of peak discharge less than the actual amounts, which is confirmed by the average monthly simulated discharge during calibration and validation periods. The results also showed that more than 50% of the observational data in both calibration and validation phases are bracketed by the 95PPU uncertainty estimation band, which indicate a rather acceptable degree of certainty in simulation. 3-2- Climate change simulation results and trend analysis In the near and mid-future, there are increasing changes under the RCP2.6 scenario, but the trends of rainfall are not statistically significant at the 5% level. In the far- future a significant increasing trend is observed under the RCP2.6 scenario, meanwhile in far-future under the RCP4.5 scenario there are increasing changes, but the trends are not statistically significant. In the mid and far future under the RCP6.0 scenario, a significant increasing trend has been observed. Finally, in the mid- future under the RCP8.5 scenario, there is a significant increasing trend. However, the increasing changes in the near and far-future periods are not statistically significant at the confidence level of 95%. The trend analysis of variables indicates that the amount of rainfall will decrease in this watershed during the future periods by the end of the 21st century. The most decreasing alterations in the rainfall and the highest increase in the temperature are achieved under the highest concentration of greenhouse gases [RCP8.5]. Moreover, in the near, mid, and far future, the runoff changes are decreasing under the RCP2.6 scenario, but the trend is not statistically significant. In the mid and far-future periods under the RCP4.5 scenario, there is a statistical significant decreasing trend in runoff; however, the decreasing variation in the near future is not significant. In the near, mid, and far future under the RCP6.0, runoff variations are declining, but the trend is not statistically significant. In the far-future period, under the RCP8.5, there is a significant decreasing trend; however, in the near and mid-future, runoff declining changes are not statistically significant. Reduced rainfall and increased temperature in the watershed will reduce the rate of runoff in the future periods in such a way that the security of the inhabitants of the region will be severely affected. 4- Conclusions Results of evaluation criteria [R2 and NS] showed that the SWAT performance for the simulation of runoff in the Gorganroud watershed was not satisfactory, but it was in an acceptable range. Climate change simulation indicated a decreasing trend for rainfall in all future periods, but this trend was not statistically significant. The temperature variable in all RCPs had an increasing trend. However, temperature trend analysis under the RCP4.5 scenario during the near and mid- future and under the RCP6.0 scenario during the near, mid, and far-future showed a significant upward trend. Runoff under the RCP4.5 scenario during the mid to far-future and under the RCP8.5 scenario during the far-future period followed a significant downward trend. Runoff during the near-future period under the RCP4.5 scenario and throughout the near to mid-future under the RCP8.5 scenario, had declining variations, but its trend was not statistically significant. In general, these results indicated that the amount of temperature will follow an increasing tendency; while rainfall and runoff will follow a decreasing movement in this watershed by the end of the 21st century.
Mohammadreza Goodarzi; Atiyeh Fatehifar
Volume 6, Issue 20 , December 2019, , Pages 57-78
Abstract
1-Introduction The assessment report fifth of the Intergovernmental Panel on Climate Change shows that global warming has led to a change in the water cycle due to increased greenhouse gas emissions. In the present time, with the increase of industrial activities and the neglected environmental issues, ...
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1-Introduction The assessment report fifth of the Intergovernmental Panel on Climate Change shows that global warming has led to a change in the water cycle due to increased greenhouse gas emissions. In the present time, with the increase of industrial activities and the neglected environmental issues, the effects of climate change have become more evident and poses this phenomenon as a global difficult. Increasing the probability of occurrence of extreme climatic events such as flood and increasing the frequency and intensity of the effects of climate change. Due to changes in climate and global warming, the probability of heavy rainfall and consequently the risk of flood due to incorrect drainage system and physical and environmental factors have increased. Therefore, the study of the region's climate is important given the new scenarios and flood frequency analysis with suitable statistical distributions for future planning. 2- Methodology In the present study, the effects of climate changes on the runoff of Azarshahrchay Basin with CanESM2 model under RCP2.6, RCP4.5 and RCP8.5 release scenarios assessment report fifth (AR5) of the Intergovernmental Panel on Climate Change (IPCC), with Statistical down scaling model (SDSM), for the period 1976-2005 and 2059-2030 by the hydrologic model SWAT have been investigated. The accuracy of the simulation was evaluated with three indicators: Root Mean Square Error (RMSE), Coefficient of Determination (R2) and Nash–Sutcliffe Efficiency (NSE). An analysis of the frequency of maximum annual flood for both base and future periods using their probability distribution function (PDF) and the Easyfit model. In this model, 5 types of probability distribution including Normal, Normal Log, Pearson, Log Pearson Type 3 and Weibull were used. The best distribution for each basic and future time series were ranked and selected by using three Chi-square, Kolmogorov–Smirnov, Anderson–Darling tests. In order to study how the maximum flood discharge regime changes in the base and future periods were used two indices: 1) The probability and the return period in the equal flows 2) Intensity of flow in the equal return periods 3- Results The obtained factors of the three RMSE, R2, and NSE indicators showed the good performance of the SDSM model in the down scaling the large-scale data. Investigating the performance of the SDSM model in the downscale of the Azarshahr station's climate data with a Coefficient of Determination and Nash–Sutcliffe of 0.99 and 0.98 for temperature for the period 1990-2001 and 0.86 and 0.83 for precipitation in the period 1976-2005. The simulation results showed a rise in temperature during the period 2030-2059 under scenarios and the highest increase was related to RCP8.5 (0.23°c). Also, rainfall at a station increased by 7.44 percent to RCP2.6 and at another station decrease by 7.57 percent to RCP8.5. The performance analysis of the SWAT model indicates a good accuracy of the model in runoff simulation with R2 and Nash 0.6 on average. The results of the 2.1% increase in runoff and the maximum flood peak and the probability of flood events in March and April (late winter and early spring) have been shown by the SWAT model. Results of the study of the regime of maximum annual flows (frequency and intensity) by fitting probabilistic distributions with the lowest error rate for the base distribution period of the Weibull, future period RCP2.6 distribution Log Pearson Type 3, RCP4.5 Log Normal and RCP8.5 Log Normal as best distribution are selected. Also, the frequency and intensity of flood have increased. In the return periods of constant, the maximum discharge increased, and in maximum discharge constant, with increasing return period (1000 years), the discharge rate significantly increased. So, in the 500-year return period is expected a 98% increase in maximum discharge RCP8.5 future period than base period. The most critical scenario is RCP8.5 scenario. 4- Discussion and conclusion The results indicate the impact of climate change on the basin in the future period. Therefore, knowing the increase in precipitation intensity, the flood risk increases. The occurrence of terrible floods due to climate change have caused many damages in different parts of the world in recent decades. The results of this study, like other previous studies, confirm that climate change is significant, especially with the increasing frequency of floods, governments, organizations, and educational centers need to take appropriate measures to eliminate or reduce the effects of climate change and adaptation to extreme events such as floods.
Mahin Naderi; Alireza Ildoromi; Hamid Nouri; Soheila Aghabeigi Amin; Hossein Zeinivand
Volume 5, Issue 16 , December 2018, , Pages 61-79
Abstract
Abstract Intr4oduction Changing the environmental conditions of a natural ecosystem influences the hydrological responses such as flooding and the extent of erosion and sedimentation of the area. One of the models used to investigate the effect of land use change and climate change on runoff is SWAT ...
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Abstract Intr4oduction Changing the environmental conditions of a natural ecosystem influences the hydrological responses such as flooding and the extent of erosion and sedimentation of the area. One of the models used to investigate the effect of land use change and climate change on runoff is SWAT model which is a hydrological simulator and a continuous and semi-distributive time-space model with a physical base. Understanding the relationship between land use change and its causative factors and its secondary effects on hydrologic regimes provides essential information for land use planning and sustainable management of natural resources. Investigating the amount and trend of the changes and its effect on the hydrological processes in the basin is a way to predict the state of future changes and provide more effective plans for the sustainable development of the water resources in the basin. The construction of the Garin Dam in the Garin Basin, the risk of filling the sediment reservoir with sediment, reducing its useful life due to seasonal floods, and the effect of basin land use and climate change were the reasons for choosing this area for this research. The purpose of this study was to study the land use and climate change in the studied watershed and determine the effect of these changes on the runoff rate of this watershed in order to better it correctly. Garin Dam is located in the Zagros in the province of Hamedan. It includes the catchment area of the Sarab Gamasiab River to the Garin Reservoir Dam and its area is up to the 22,000 m2. The Garin land basin is mainly mountainous and its range of height ranges from 1833.9 to 3429.2229 m above sea level. Materials and Methods SWAT model input data included climatic and hydrological data (daily precipitation, maximum and minimum temperature, relative humidity, wind speed, dew point, and solar radiation). In this study, the ten year data of Nahavand synoptic station was uased. Topographic maps, digital elevation model (DEM), soil and land use were also used as the input of the model. A digital elevation model (DEM) was extracted using a topographic map of 1: 250,000 of the Garin River basin. SWAT CUP software was used for the calibration and validation of the SWAT model. The calibration data was from the years 2002 to 2007, but the validation data was from 2008 to 2010. In order to determine the degree of the sensitivity of the flow parameters in the SWAT model, SUFI2 software SWAT CUP were used and the sensitivity of the selected 24 parameters were measured. The Elimination of the parameters which had less sensitivity, was based on the calibration process. According to the P-value and T-Stat criteria, the sensitivity of the parameters were determined. The land use maps of 1986, 2000, and 2014 were prepared at the previous stages, and the Markov chain and the CA Markov filter were used to map the land use in 2042. In this research, the outputs of the Hadcm3 model were used to predict Garin's future climate. In addition, the SDSM statistical method was used to fine-scale the output of the general atmospheric circulation models. The SWAT model was also used in the range of calibrated parameters to simulate runoff caused by climate change in Garin basin under two A2 and B2 scenarios. After micro-sampling, the SWAT model was converted and t analyzed for the scenarios. Then, the results of the model implementation with different scenarios and the results of model implementation with the current climate conditions were compared Results and Discussion Regarding the results of the statistical indices, NS index was 0.95. P and R factors were respectively 0.47 and 0.03, and the coefficient of determination (R2) for observed and simulated floodguns was 0.6. Accordingly, the results were confirmed in the calibration phase. The validation phase was conducted to verify the correctness of the selection of the parameters during the calibration period between 2008 and 2010. Given that the Nashatcliff coefficient for Garin's catchment area at the calibration and validation stages were respectively 0.95 and 0.66, , the results were satisfactory and the SWAT model was able to simulate surface runoff in Garin River Basin. In general, due to an increased forest use, an increased permeability and water drainage to the surface and deep water aquifers, and an increased evaporation and transpiration, the amount of runoff has decreased. Regarding the results of temperature, rainfall, and runoff of the next period, it can be seen that in months when rainfall is reduced and the temperature increased, the amount of runoff in the coming period also decreases. The main reasons for this discrepancy can be attributed to the difference in the intensity of land use change as well as the extent of the altered land area, which, given the mountainous nature of the area in the Garin land basin, can be compared to other areas with flat lands with agricultural uses. It is concluded that the effect of climate change in the Garin dam basin is greater than the change in land use due to its mountainous nature. Conclusion The results of the study of the effect of land use change on runoff in the Garin basin indicated that there was a daily and monthly decline in the amount of runoff. The results of the study of the effect of climate change on runoff in the Garin western basin also indicated that there was a daily and monthly decline in the amount of runoff. In both A2 and B2 scenarios, the monthly average temperature, especially in the first and last months of the year, had an increasing trend and rainfall decreased in the spring and winter. It can be attributed to the increased temperature and evaporation, and decreased rainfall. It can also be seen that there was a decline in the average monthly runoff in January, February, April, May and December, with a decreased rainfall, but there was an increase in the average monthly runoff in June, July, August and September, with an increased rainfall. In addition, the effect of land use change on the reduction of runoff in the upcoming period is lower compared to the change effect under A2 and B2 scenarios. It will affect the climate change of the runoff more flatly and the reduction of runoff is more affected by climate change. According to the information obtained from these predictions, it is possible to properly manage the watershed and adopt appropriate management measures in accordance with the conditions of this watershed, prevent unauthorized land use changes, and reduce the damage caused by the phenomenon of the climate change.
Mahin Naderi; Alireza Ildoromi; Hamid Nouri; Soheila Aghabeigi Amin; Hossein Zeinivand
Volume 5, Issue 14 , June 2018, , Pages 23-42
Abstract
Introduction
In a natural ecosystem, changing the environmental conditions of that ecosystem influences hydrological responses such as flooding and the extent of erosion and sedimentation of the area. One of the models used to investigate the effect of land use change and climate change on SWAT runoff, ...
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Introduction
In a natural ecosystem, changing the environmental conditions of that ecosystem influences hydrological responses such as flooding and the extent of erosion and sedimentation of the area. One of the models used to investigate the effect of land use change and climate change on SWAT runoff, the SWAT model is a hydrological simulator and a continuous and semi-distributive time-space model with a physical base. Understanding the relationship between land use change and its causative factors and its secondary effects on hydrologic regimes provides essential information for land use planning and sustainable management of natural resources. Investigating the amount and trend of the changes and its effect on hydrological processes in the basin is a way to predict the state of future changes and provide more effective plans for sustainable development of water resources in the basin. The construction of the Garin Dam in the Garin Basin and the risk of filling the sediment reservoir with sediment and reducing its useful life due to seasonal floods and the effect of basin land use and climate change on the reason for choosing this area for this research. The purpose of this study was to study the land use and climate change in the studied watershed and determine the effect of these changes on the runoff rate of this watershed in order to better manage it.
Study of Area
Garin dam dam is located in the province of Hamedan and is located in the mountain range of Zagros mountains. This area includes the catchment area of Sarab Gamasiab River to the Garin Reservoir Dam and its area is up to the 22,000-square-meter Garin Garin Dam, the Garinland basin is mainly mountainous and its range of elevation ranges from 1833.9 to 3429.2229 meters above sea level.
Materials and Methods
SWAT model input data include climatic and hydrological data (daily precipitation, maximum and minimum temperature, relative humidity, wind speed, dew point and solar radiation), which is ten years in the study of statistics related to the synoptic stations Skinheads Became Topographic maps, digital elevation model (DEM), soil and land use are also needed as model inputs. A digital elevation model (DEM) was extracted using a topography map of 1: 250,000 Garin River basin. Calibration and validation of the SWAT model in SWAT CUP software. The study used calibration data from 2002 to 2007 and 2008 to 2010 for validating the model. In order to determine the degree of sensitivity of flow parameters in the model SWAT using SUFI2 software SWAT CUP sensitivity analysis for 24 parameters election, the results of the sensitivity analysis on the Elimination of parameters that has the less sensitive they are, the calibration process decision It is accepted. According to the P-value and T-Stat criteria, the sensitivity of the parameters is determined. Land use maps of 1986, 2000, and 2014 were prepared in the previous stages, and the Markov chain and the CA Markov filter were used to map the land use in 2042. In this research, the outputs of the Hadcm3 model were used to predict Garin's future climate. In this research, the SDSM statistical method was used to fine-scale the output of the general atmospheric circulation models. The SWAT model was used in the range of calibrated parameters to simulate runoff from climate change in Garin basin under two scenarios A2 and B2. After micro-sampling, the SWAT model was converted and the model was analyzed for the scenarios. Then, the results of model implementation with different scenarios and the results of model implementation with the current climate conditions were compared
Discussion and results
Regarding the results of statistical indices, NS index is equal to 0.95, P factor and R factor were respectively 0.47 and 0.03 respectively, and the coefficient of determination (R2) for simulated and simulated floodguns was 60 / 0. Accordingly, the results were confirmed in the calibration phase. The validation phase was conducted to verify the correctness of the selection of parameters during the calibration period for the period 2008-2010. Given that the Nashatcliff coefficient for Garin's catchment area at calibration and validation stage was equal to 0.95 and 0.66, respectively, the results were satisfactory and the SWAT model was able to simulate surface runoff in Garin River Basin. In general, due to increased forest use due to increased permeability and water drainage to the surface and deep water aquifers and increased evapotranspiration, the amount of runoff has decreased. Regarding the results of temperature, rainfall and runoff of the next period, it can be seen that in the months when rainfall is reduced and the temperature increased, the amount of runoff in the coming period also decreases. The main reasons for this discrepancy can be attributed to the difference in the intensity of land use change as well as the extent of the altered land area, which, given the mountainous nature of the area in the Garinland basin, can be compared to other areas with flat lands with agricultural uses. It is concluded that the effect of climate change in the Garin dam basin is greater than the change in land use due to its mountainous nature.
Conclusion
The results of the study of the effect of land use change on runoff in the Garin basin indicate that the amount of runoff is decreasing daily and monthly in this catchment area. Also, the results of the study on the effect of climate change on runoff in the Garinwestern basin indicate that the amount of runoff is daily and monthly in this catchment area. Considering that in both scenarios A2 and B2 the monthly average temperature, especially in the first and last months of the year, has an increasing trend and rainfall has decreased in the spring and winter, this decrease can be attributed to the increase in temperature which Following this, evaporation also increases and decreases in rainfall in this catchment area. Regarding the results, it can be seen that the average monthly runoff in months when rainfall decreased in January, February, February, April, May and December, and in the months when rainfall increased As of June, July, August and September, the amount of runoff will increase compared to the current period. It is also observed that the effect of land use change on the reduction of runoff in the upcoming period is lower compared to the change effect under A2 and B2 scenarios and will affect the climate change of the runoff more flatly and the reduction of runoff is more affected by climate change. According to the information obtained from these predictions, it is possible to properly manage the watershed and adopt appropriate management measures in accordance with the conditions of this watershed and to prevent unauthorized land use changes and reduce the damage caused by The phenomenon of climate change.
Samaneh Poormohammadi; Mohammad Taghi Dastorani; Alireza Massah Bavani; Hadi Jafari
Volume 4, Issue 12 , December 2017, , Pages 89-110
Abstract
Extended Abstract Introduction Climate change has a huge impact on all aspects of human life. Some of its impacts can be reduction in the surface and ground water resources of the country, changing the amount, timing, and type of precipitation, and influencing water quality. It can also lead to the increased ...
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Extended Abstract Introduction Climate change has a huge impact on all aspects of human life. Some of its impacts can be reduction in the surface and ground water resources of the country, changing the amount, timing, and type of precipitation, and influencing water quality. It can also lead to the increased droughts, increased demand for water, changes in the management of water resources, sea level rise and its complications, and extreme maximum and minimum temperatures. The aim of the present study was to evaluate the impact of the climate change on rainfall and minimum and maximum temperatures using 15 atmospheric general circulation models under two scenarios, including A1B and B1, between the years 2011-2039. Methodology For this purpose, through the use of beta statistical distribution of rainfall changes and based on the probability of 20, 50 and 80%, the minimum and maximum temperatures, were calculated from 15 general circulation models. Standard errors, absolute errors, and Nash-Sutcliff coefficients were determined for simulated data on the base and the upcoming periods. Next, of the 15 climatic models, the minimum temperature changes (ΔTmin), the maximum temperature changes (ΔTmax), and rainfall variation ratios (ΔP) for A1B and B1 scenarios for 12 months were extracted from the Lars model. The introduction of the climatic scenarios in the family scenarios of the A1 group, a rapidly growing economy and the growth of the population that will peak in the mid-21st century and decline thereafter introduces new and more efficient technologies. In this family, economic issues are more emphasized and opinions are rather global rather than regional. Three different subgroups for group A1 are based on the type of technology used in the 21st century, the intensification of the use of the fossil fuels (A1FI), the use of non-phosphate energy sources (A1T), and the use of fossil and non-fossil sources in a balanced manner (A1B). Results and discussion The results showed that, with the probability of 20 to 80% and under both A1B and B1 scenarios, the minimum and maximum temperatures are rising and the rain is falling. In addition, the increase in the minimum and maximum temperatures under A1B was more than that of the B1 scenario, but the reduction in the precipitation under B1 was more than A1B. The results also showed 19 to 22% decrease in precipitation, minimum temperature of 13 to 20%, and a maximum temperature of 2.4 to 6.4% compared to the baseline of the Tuyserkan catchment. In Table 1, the percentage change in climatic parameters under the influences of A1B and B1 scenarios and in relation to the base curriculum is presented. Under A1B scenario, and with the probability of the occurrence of 80%, there is 19.1% decrease in precipitation, 4.6% increase in maximum temperature, and 20% increase in minimum temperature in future periods. In addition, under B1 scenario and with the probability of occurrence of 80%, there is 22% decrease in precipitation, 13% increase in minimum temperature, and 4.2% increase in maximum temperature. Table (1) Assessment of the percentage change in climate parameters relative to the base curve Scenarios Probability of occurrence Precipitation (%) T_max (%) T_min(%) A1B 20 -3.8 1 7.2 50 -13.7 2.8 14.5 80 -19.7 4.6 20 B1 20 1.5 -0.9 7 50 -20 1.5 7.7 80 -22 4.2 13 Conclusion Generally, it can be argued that the climate change in future periods will increase the minimum and maximum temperatures and reduce the rainfall in Tuyserkan Plain. Consequently, these changes in temperature and precipitation will affect plain water resources. The most important of change is the change in the seasonal precipitation pattern and temperature rise in cold seasons. These changes will also have a significant impact on the region's cropping pattern, as the dryland cultivation is limited, due to the reduced rainfall, and its time will vary with time variations.
Mahtab Safari Shad; Mahmoud Habibnejad Roshan; Karim Solaimani; Alireza Ildoromi; Hossein Zeinivand
Volume 4, Issue 10 , June 2017, , Pages 81-98
Abstract
Climate change has altered the earth’s hydrologic cycles, especially its temporal and spatial distributions. Therefore, prediction of its future changes is very important. This study investigated the effects of climate change onthe precipitation, minimum temperature, maximum temperature, and runoff ...
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Climate change has altered the earth’s hydrologic cycles, especially its temporal and spatial distributions. Therefore, prediction of its future changes is very important. This study investigated the effects of climate change onthe precipitation, minimum temperature, maximum temperature, and runoff in three sub watersheds in Hamadan, Bahar Watershed. To this end, the WETSPASS model was used to estimate runoff and the LARS-WG model was used to predict climate variables between the years of 2014 and 2043. The results showed that the HadCM3 model with the largest weighting coefficient and the lowest error has the highest efficiency in simulation of precipitation and temperature. According to the scaled down measurements, in the next period, the average minimum and maximum temperatures will respectively increase up to 1.22 ºc and 0.9 ºc and the total rainfall will decrease about 8%. The results of the impact of the climate change on the future of the watershed's hydrology showed that runoff volume for all three sub-watersheds under the A2 scenario and the first and second sub-watersheds under the B1 scenario is going to decrease. For the third sub-watersheds, in contrast, it is going to increase. In addition, while total runoff input to plain will decrease by 36 % under A2 scenario, it will increase by 8 % under B1 scenario which will affect the watershed's water resource system changes. The remarkable thing is the reduction in rainfall in the winter and in the spring, disassembling the temporal distribution of the rainfall, and increasing the temperature. Accompanied by land use changes, it can have a significant negative effect on the future water resources management.
Saeed Jahanbakhsh Asl; Alimohammad Khorshiddoust; Mohammad Hossein Alinejad; Farnaz Pourasghr
Volume 3, Issue 7 , October 2016, , Pages 107-122
Abstract
Saeed Jahanbakhsh Asl[1]* Alimohammad Khorshidoust [2] Mohammad Hossein Aalinejad[3] Farnaz Pourasghar[4] Abstract Temperature and precipitation are two important parameters in hydrology and water resources. The impact of climate change on these two parameters has been the subject of many studies and ...
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Saeed Jahanbakhsh Asl[1]* Alimohammad Khorshidoust [2] Mohammad Hossein Aalinejad[3] Farnaz Pourasghar[4] Abstract Temperature and precipitation are two important parameters in hydrology and water resources. The impact of climate change on these two parameters has been the subject of many studies and studying atmospheric general circulation models is one of the best methods to estimate its effects. In the studies of climate change, lack of uncertainty in various stages of evaluation for the effect of climate change reduce certainty and confidence of the final outputs. In this study for analyzing the effects of climate change on precipitation and temperature in Shahrchay basin and the effects of the uncertainty related to general circulation models, six atmospheric general circulation model and 3 scenarios, A1B, A2 and B1 were downscaled by using LARS-WG. For evaluating the uncertainty of the models and scenarios, the output of models in the future and based period were compared by monthly statistical indices, coefficient of determination (R2) and Root Mean Square Error (RMSE) and the best models and scenarios for producing temperature and precipitation data were selected for the period 2011-2030. As the results, the HADCM3 model under scenarios A1B was used for precipitation and the MPEH5 under scenarios A2 for temperature production. The results of this research showed that in the future period rainfall will be reduced about 9 millimeter, while the minimum and maximum temperature will increase 1.05 and 0.87 °C respectively. Disruptions of rainfall distribution and high temperature have significantly negative consequences than rainfall reduction. [1]- Professor in Department of Meteorological, University of Tabriz, (Corresponding Autor), Email:s_jahan@tabrizu.ac.ir. [2]- Professor in Department of Meteorological, University of Tabriz. [3]- Meteorological Graduate Student of Tabriz Universit, Email:aalineghad63@yahoo.com. [4]- Climatology Ph.D., Meteorology Directorate General of East Azerbaijan Province.
