جستجوی مقالات مرتبط با کلیدواژه « Climate Change » در نشریات گروه « مهندسی آب »

General Circulation Models (GCMs) are indispensable tools for understanding future climate change. However, the utilization of GCM output data requires an evaluation of its accuracy in comparison to observational data. The aim of this study is to compare the outputs of 13 CMIP6 models with observations using two bias correction methods called Quantile Mapping and Linear Scaling, along with a Bayesian model averaging approach. To explore the future changes in temperature and precipitation variables in the Khazar basin, climate model simulations in two scenarios, SSP245 and SSP585, were chosen. The results show that the quantile mapping method, despite its better performance in modifying climate models, is inefficient at the stations where the bias is unstable over time and the correction is not done properly. Also, using the Multi Models Ensemble (MME) provides a higher level of accuracy than individual models. Although averaging models after bias correction reduces the extreme fluctuations of the time series, it has better accuracy and performance than the second method (averaging models before correction and then applying bias correction). The findings show that the average precipitation in the Khazar basin for the two scenarios, SSP585 and SSP245, is not statistically different from the observational periods and ranges from 0% to 6% for both the near-future periods (2050–2021) and the far-future periods (2080–2051). The average temperature will rise 1.67 and 3.14 (1.8 and 3.65) ℃ more than it did during the observational periods for the near-future (2050-2021) and far-future (2051-2080) periods, respectively, under the SSP245 (SSP585) scenario.

Controlling water consumption in agricultural sector requires an appropriate understanding of the interplay between water resources, water consumption and agricultural economy. This study aimed to develop two hydrological and agro-economic models in the Mahabad study area (located in south of the Lake Urmia) in order to investigate the effects of climate change on the volume of water entering the Mahabad dam, explore long-term changes in gross irrigation needs, and study the impact of the crop pattern change on the gross irrigation need and the agricultural economy of the region. The results showed that if the agricultural water consumptions are controlled up to the year 1419 (Persian Calendar), the increase in the volume of water entering the Mahabad Dam under the climate change scenarios A1B and B1 can reduce the current withdrawal from surface and groundwater sources. It would also promote the possibility of release from the Mahabad Dam to partially provide the environmental flow of Lake Urmia. We further found that the net value of the crop production in the past years was much lower for wheat and barley compared to other crops, which explains the lack of economic justification for the cultivation of these two crops. The amount of production and the net value of sugar beet production showed a significant growing trend, which is in a clear contradiction to the policies of reducing agricultural water consumption by 40%. In case of increasing the cultivated area of water-rich crops in the region, the greatest stress on groundwater resources will be under the climate change scenario A2.

In this research, a new framework of socio-hydrological modeling framework has been developed in order to evaluate the performance of human-water systems. For this purpose, a comprehensive hydrological model has been developed by combining SWAT and MODFLOW models to simulate surface and underground water resources. Then by using Value-Belief-Norm Theory, the effective factors in the water consumption behavior of farmers are identified. Finally, by combining the SWAT-MODFLOW model and the Agent-Based Model based on the theory of VBN, the behavioral pattern of farmers in choosing the type of cultivation and irrigation method has been evaluated. The theoretical framework of the VBN theory and the behavioral rules of agents in ABM are designed based on the data collected from Mahabad plain farmers through field questionnaires. Afterward, an analysis and investigation were conducted on the response of the socio-hydrology model that was developed, utilizing climate change data from the 6th IPCC report and the ACCESS-CM2 model, for the planning horizon. The results showed that those farmers who are below the poverty threshold try to improve their unfavorable economic situation by choosing profitable crops for farming. Therefore, if no fundamental change is made in management policies in the future, the climate change will reduce the profit within the agricultural sector and the pattern of cultivation will change towards crops with high profits and yet high water consumptions. If the management methods remain unchanged in the future, the yield of the crops, the income of the farmers in the region, and at the same time the inflow to Lake Urmia from the Mahabad River will decrease significantly. Therefore, it is recommended to adjust the management policies as a way to deal with the effects of the climate change. In general, the results of the present research can be considered for future planning and policies and for estimating how changes in economic and psychological factors for farmers affect the restoration of Lake Urmia.

Nowadays, drought as the most destructive and damaging consequence of climate change has increasingly affected the earth. One of the most important strategies for dealing with devastating droughts is understanding and adapting to them, which can greatly reduce their negative effects. The aim of this quantitative and applied research is to examine and analyze the adaptation status of farmers to drought and identify solutions to deal with it through a case study among farmers in the Zayandehrud river basin  in Isfahan province. The statistical population of the research consists of all farmers in the east of Zayandehrud basin (villages of Nokhodabad, Hasanabad, Haratmeh, Joshan, and Mazrae Cheh) of whom 200 were selected as a completely random sample to achieve the research objectives. The main tool for collecting data in this study was a researcher-made questionnaire. For analyzing the collected data, the mean comparison test, frequency distribution table, and exploratory factor analysis method were used in SPSS software. The results of the research showed that the calculated mean for the adaptation of farmers to drought was 2.165, statistically significantly lower than the average level at a confidence level of 95 percent. Exploratory factor analysis revealed that six main factors are identified as the most important key solutions for improving how farmers are adapting to and coping with drought in Zayandehrud basin, explaining 71.88 percent of the dependent variable variance. These factors, in order of importance, are financial-organizational policies (17.533 percent), educational-promotional policies (12.946 percent), technical-agricultural policies (12.421 percent), infrastructure (10.697 percent), strengthening social institutions (9.188 percent), and enhancing local participation (9.096 percent).

The Caspian Sea level (CSL) fluctuations are driven by reciprocal hydro-meteorological processes which extend not only over the entire catchment area but also far beyond. According to the research literature, CSL has dropped approximately 3 m in the short-term period of 1929-1977. The origin of CSL changes and the future of these changes are still being debated. In this study, changes in precipitation, runoff, and evaporation in the catchment area, river discharge, sea surface temperature (SST), and also CSL change were investigated over 40-year. Study results revealed two major changes in the increasing trend of SST anomalies. With an increasing trend in the CS level with 0.03 slope, the results indicated an increase in SST by more than 1.5°C during the study period, which can be a response to the increase in air and land surface temperature on a regional and global scale. The decline in river discharge levels has also been significant in recent decades. These changes were more obvious in the volga river, which provides more than 80% of the CS balance. Reconstruction of long-term CSL change with daily water level data between 1981 and 2020 through fluxes also showed that the average sea level rise was about 20 cm/yr in the 1981-1995 period while a decrease of 6 cm/yr during the 1996-2020 period was clearly visible in the results of the water balance equation. Moreover, according to the observed peak values of the four parameters of precipitation, evaporation, runoff, and SST, the trend of increasing sea surface temperature and decreasing precipitation (with a slope of -1.8 mm/40yr) is more consistent with CSL change.

Estimating the available water plays a vital role in planning water resources projects. The first step in assessing water availability is to calculate runoff in catchments. Moreover, it is necessary to study the effects of climate change on water components such as runoff since climate change directly affects the hydrological components and water resources. In this study, the status of the inflow to Tashk-Bakhtegan lakes as one of the most important lakes in the country was investigated. Because generation of runoff is a complex concept due to its nonlinear and multidimensional nature, various theoretical and physical models have been developed to predict runoff. The high dependence of these physical models on numerous parameters and maps, practically challenfged their efficiency in basins with limited observations. On the other hand, models based on artificial neural networks and fuzzy inference systems are considered applied tools that can help hydrologists in such circumstances. In this study, FFBPNN and ANFIS models and their combination with PSO and GA metaheuristic algorithms have been investigated in evaluating the runoff in historical conditions and under RCP and SSP climate change scenarios.  The obtained results showed that the FFBPNN and ANFIS models combined with the PSO algorithm (ANFIS_PSO) using precipitation, minimum temperature, and maximum temperature as inputs had better performance compared to other models with different inputs. The values of the correlation coefficient, root mean square error (m3/s), Nash-Sutcliffe coefficient and Kling Gupta were respectively 0.99, 2.07, 0.99 and 0.98 in the training period and 0.94, 3.61, 0.91 and 0.88 in the test period and 0.98, 94. 2, 0.97 and 0.98 in the training period and 0.93, 3.87, 0.85 and 0.88 in the test period. The results of this study can be used in investigating the effects of the above mentioned scenarios on important basins of the country and consequently in planning and managing water resources in the context of climate change.

Climate change and its intensifying impact on the hydrological cycle have been acknowledged in recent years. Considering the importance of available snow to the water resources recharge, especially in semiarid regions, evaluating climate change impacts on snow cover area (SCA) has gained significant attention. In this study, a methodology is presented which is capable of evaluating the impact of climate change on SCA. To collect historical data, MODIS snow products are used. To evaluate the impact of climate change on SCA, the turning points of SCA time series are detected using the Standard Normal Homogeneity Test; and the trend of historical data is analyzed using Mann-Kendall and Sen’s slope tests. To project the future SCA (2021-2099) under climate change considering precipitation and temperature as inputs an Artificial Neural Network-based model is developed. The proposed methodology is tested in sub-basins in Iran. Analyzing the present SCA (2000-2020) the results showed that the SCA’s turning points are only detected in two sub-basins of Tashk-Bakhtegan-Maharloo in 2007 and Gavkhooni in 2008, respectively. Moreover, a significant decreasing trend of SCA is detected during winter in the majority of sub-basins. According to the results, most sub-basins will experience a significant reduction in their future SCA under all climate change scenarios. In other words, compared to the historical SCA, the average future SCA will increase by 100 percent in RCP 4.5 scenario while decreasing by 20 percent in RCP 8.5 scenario.

Investigation of future drought trends and variations under climate change scenarios plays a key role in developing management strategies for minimizing drought's negative societal and economic impacts. Therefore, this study aimed to assess changes in drought characteristics such as the frequency of dry and wet periods, and the trend of drought index based on fuzzy drought index (at time scales of 3, 6, and 12 months) under SSP3 and SSP5 scenarios of CMIP6 during the 21st century. The data of 6 synoptic stations in Karoon River Basin during 1991-2014 have been used in this study. Assessing the reliability of climate models for drought monitoring with fuzzy drought index in the base period showed that the highest correlation coefficient (CC>0.90) and the lowest root mean square error (RMSE<0.14) are found at 3 and 6 month time-scales. In addition, monitoring the drought conditions of the basin under climatic scenarios in future periods revealed an increasing trend (at the 95% confidence level) and the wetness frequency in the northern, northwestern, and western of the basin is more likely to decrease. Over the periods 2046–2072 and 2073-2099 the result of the non-parametric Mann-Kendall test for the scenarios of SSP3_7.0 and SSP5_8.5 was 1.64. Therefore, due to the increasing trend of fuzzy drought index changes to dry conditions in Boroujerd, Safiabad, and Kuhrang stations, the risk of drought during the periods 2073-2099 and 2046-2072 are higher. Accordingly, water managers and farmers should adopt strategies in order to reduce the damages. The results of this research can be valuable in adopting policies and planning for sustainable management of water resources affected by climate change.

Since the water resources systems are most affected by the climate change phenomenon, the organizations which manage the social and ecological demands of water can greatly impact the adaptation to this phenomenon. The adaptive capacity of a water resources system is influenced by various factors and the improvement of each of these factors would lead to an increase in the adaptation capacity of the entire system against the climate change and accordingly less vulnerability against it. In this article, the barriers to the adaptation of the water resources system of the Qarrangu basin against climate change have been identified from the perspective of administrative institutions related to water resources management and the causal relationships between these institutions have been investigated. The study was carried out in the framework of qualitative research strategy and based on thematic analysis method and interviewing the key people in the organizations in charge of the water management in the watershed. Using purposeful sampling under the snowball method and conducting 20 interviews, the theoretical saturation was achieved. Aiming at more reliability 2 more interviews were also conducted but no extra information was acquired. The results show that adaptation barriers in the studied basin can be categorized in three main groups; barriers caused by the attributes of actors, by the characteristics of the water resources system structure, and by the environmental characteristics. Finally, using the system dynamic analysis approach, the causal relationships between the barriers have been identified and solutions have been proposed to overcome such.

Global warming changes precipitation and temperature patterns. In this study, the linear scaling post-processing method was used to correct the biases of seven climate models (GCMs) under the Coupled Model Intercomparison Project Phase 6 (CMIP6). Also, the performance of these models was evaluated for simulating temperature and precipitation in the Hamedan-Bahar plain in the baseline period of 1990 to 2014. Three performance indicators (mean square root error, Nash-Sutcliffe, coefficient of correlation) were used to quantify the models᾽ reproducibility to climatic parameters for the historical period (1990–2014). Based on the results, CMCC-ESM2, MIROC 6, and NorESM2-MM models were selected and their ensemble were used to project temperature and precipitation in near (2026–2050), mid (2051-2075) and far futures (2076-2100) under three socioeconomic shared pathway (SSP) 1–2.6, 2–4.5 and 5–8.5. Based on the obtained results, in all three periods, the average precipitation decrease in summer is higher than the other seasons, and the highest amount of decrease will occur in the mid future period under the SSP5-8.5 scenario (67%). Moreover, the minimum and maximum temperatures increased in all three future periods and under all three scenarios. The highest increase of temperature occurred in January and February. Predicting climate parameters using selected models in this study can be a basis for planning and managing water resources and developing the necessary measures to climate change adaptation in Hamadan-Bahar region.

Nowadays with regard to the climate change issue and also the scarcity of available and usable water, the conjunctive use of surface and groundwater resources is regarded as one of the critical approaches in water resources management. In this respect, the surface water-groundwater interaction is one of the prominent and fundamental components in conducting appropriate analysis of water resources balance and finally their management. In this paper, the Lenjanat sub-basin considered as a study area that is located in the Ghavkhouni Basin in Iran. The weighting method of GCM models under the fifth report of the Intergovernmental Panel on Climate Change (IPCC) was employed to investigate the precipitation and temperature changes due to climate change and the LARS-WG model was hired to provide the microscale output of GCM models. Investigating the surface water-groundwater interaction was carried out through the connection of WEAP and MODFLOW models. Thereafter, through the usage of climate results from the climate change scenarios of RCP2.6, RCP4.5 and RCP8.5 and also implementing the management policies in the form of management scenarios in the future, along with the reduction of 20% and 40% in the area under cultivation, the system performance is assessed for the near future. The findings reveal increasing in temperature and precipitation in the future. The rate of surface water-groundwater interaction will be increased in the future under disparate management and climate change scenarios. Moreover, the maximum rate of the surface water-groundwater interaction is observed for the scenario following the current trend and also the scenario of climate change RCP4.5. Based on the outcomes, the higher the river flow and the groundwater abstraction, the more the aquifer drains the river and consequently increases the interaction of surface and groundwater. Therefore, the results indicated that the recharge effect of the river on the aquifer in the study area and on the other hand uncontrolled pumping of groundwater resources, conjunctive management of water resources can reduce the negative effects of groundwater scarcity, but it is necessary to reduce of cultivated areas and cultivation pattern prevented uncontrolled abstraction of groundwater in this sub-basin.

Adaptation to climate change in official organizations of countries requires a set of process reforms, and it includes water sector as well. Emphasizing the need to improve the country's water governance, competence of the official water organization and prioritizing no-regret measures as well as using a bottom-up approach; the present article attempted to identify the processes required for adaptation of this sector to climate change. The most important findings are: 1) in the development of macro-level documents, there is not any defined process in which water sector controls new loads on water resources, 2) climate change should be recognized in the law of Ministry of Energy and it should be modified with new concepts such as: "sustainable exploitation" and "carrying capacity", 3) providing the ground to promote "organizational learning" and "organizational flexibility", 4) There is a need to define "water governance" in accordance with respect to the country’s features and provide its legal and institutional frameworks, 5) risk and uncertainty are inevitable parts of climate change. It is essential to create the necessary processes for management and decision-making under these conditions like robust decision making, 6) before any structural change in this organization, theoretical bases of some of the related key concepts like "integrated water resources management", “management of the hydrological cycle at farm and basin scales” are required to be customized and 7) finally, such an adaptation requires new literature in the country's official water organization and the formation of a new type of weltanschauung at the policy-making processes.

The importance of adaptation to climate change in the agricultural sector due to its vulnerable nature to climate risks is more than other economic sectors. Adaptation strategies in the agricultural sector should be designed and applied in a way that reduce losses and also sustain the livelihoods of the vast majority of working households. Due to the existence of different criteria, it is necessary to use decision-making techniques in order to prioritize and ultimately select adaptation strategies. Therefore, the purpose of this study is to investigate the criteria and prioritization techniques to identify the most appropriate climate change adaptation strategies in the agricultural sector. This qualitative research was done by content analysis of literature using MAXQDA software to identify criteria, prioritization technique and finally selecting climate change adaptation strategies in the agriculture sector. Based on findings, indicators of climate change adaptation strategies are divided into two main costs and benefits categories. In the cost category, emphasis was on the criteria of the minimum cost of implementation, maintenance, and other costs. Also in the benefits category, the criteria are divided into five sub-categories: institutional-political, environmental, social, economic, and climatic. Based on the results, different methods and techniques have been proposed to prioritize and select appropriate strategies. However, it is not possible to recommend one of them in all situations, but this choice should be made in accordance with the situation, purpose, and level of available information resources. For this purpose, the strengths and weaknesses of the most common methods of prioritization and selection of adaptation mechanisms to climate change are presented. These methods including multi-criteria analysis, hierarchical analysis, economic analysis, and network analysis, have been discussed in this study to better identify and select the most suitable set of strategies.

Climate change directly affects the hydrological components and water resources and plays an important role in exacerbating potential hazards such as drought and flood. Therefore, it is necessary to study the effects of climate change on hydrological components such as runoff. In this study, the runoff in Tashk-Bakhtegan basin, as one of the most important ecological basins in the country, was investigated in terms of climate change using the SWAT model. Simulation was performed for the near future (2021-2050) by applying climate change conditions in GFDL-ESM2M and IPSL_CMA5_LR models under RCP2.6 and RCP8.5 scenarios and in GFDL-ESM4 and IPSL_CMA6_LR models under SSP1-2.6 and SSP5-8.5 scenarios. The calibration and validation results of the SWAT model using R2, NSH and RMSE indices were in the ranges of (0.70-0.99), (0.51-0.98) and (0.9-14.4 m3/s), respectively which indicated the high accuracy of calibration and validation of the model. Examination of the status of climatic variables of precipitation and minimum and maximum temperature in the conditions of climate change showed an increase in temperature (1.51-2.91 °C) for all models and scenarios and a decrease in precipitation (0.05-11.15 percent) in most models and scenarios. Simulation by SWAT hydrological model in climate change conditions showed runoff decline in all 4 stations under SSP scenarios and runoff rise in 3 stations under RCP scenarios. Given that the climate data of SSP scenarios have recently been made available, the results of this study can be useful to extend the research to the effects of these scenarios on important basins of the country and as a result of policy and planning of water resources under influence climate change.

Due to global warming and the occurrence of climate change and its effect on meteorological variables, especially rainfall, which is a key parameter in urban infrastructure design and water resources management, studies in this area are very important. It is now possible to predict future rainfall using the output of climate change models; this is however accompanied by many problems including lack of easy access, being large scale and the need for spatial and temporal micro scaling, increasing error, and imposing risk to urban flood management structures. Therefore, the application of a weather generator model with the ability of climatic models in simulating future precipitation using observational and recorded data has been considered in this research. In the present study, the non-parametric K-NN WG model was used which produces data outside the observational range by using two mechanisms of shuffling and perturbing. In this model, observational short-term precipitation data of Mehrabad station with a time duration of 10 minutes to 3 hours were used to predict short-term precipitation in the future. The results were compared with the output of the PRECIS regional climate model for the years 2070-2100 under emission scenarios A2 and B2. The results showed an increase in the intensity of future precipitation compared to the present time and moreover proved the capability of the WG model used in the study compared to the output of the PRECIS regional model. These results were evaluated using appropriate statistical tests.

Nowadays, population growth and increasing the level of social welfare have led to increased and unpredictable demand for water resources that may disrupt the water resources availability. Therefore, conjunctive use based on the scenario planning method can increase the reliability of the water resources utilization in the presence of uncertainties. In this study, the outputs of three atmospheric-ocean general circulation models have been used to assess climate change effects on the Dasht-Afzar of Fars province. In this regard, the LARS-WG model has been applied to downscaling climate models under RCP4.5 scenario. Then to select the best scenario for groundwater resources reclamation, the WEAP model has been used to simulate possible and probable integrated management scenarios for the next 5 years. These scenarios were; 1) Continuation of the current condition, 2) Development of irrigation network, 3) Construction of artificial nutrition ponds, 4) Water transfer from Salman Farsi dam to neighboring cities, 5) Consumption management, 6) Construction of Kavar dam upstream Salman Farsi dam, and 7) Simultaneous implementation of scenarios 2 to 4 in the consumption management scenario conditions. Performance criteria as well as fuzzy sustainability index were employed to evaluate each scenario's outputs. The results indicated that climate change could not be considered as the main factor in the downward trend of groundwater level. Also, the only scenario that can stop that trend is a 35% reduction in agricultural consumption. In the consumption management scenario, the construction of the Kavar dam will be allowed to store a maximum of 30% of the average flow rate to the Salman dam. Because otherwise, the resource management problems and costs related to the Salman Farsi dam will be increased.

Climate change and its effect on droughts has led to overuse of groundwater resources and endangered the sustainability of these resources. Climate change studies shows that the recent attempts are not solely concentrated on “impact assessment” and “adaptation” is winning more focus in the studies. Accordingly, presenting appropriate strategies is of importance for increasing of surface and groundwater conjunctive use system adaptability with adverse effects of this phenomenon. In the present study, the adaptability of cyclic and non-cyclic conjunctive use systems with the aim of increasing groundwater sustainability while reducing costs and water shortage have been compared by considering climate change scenarios. In this regard, in order to simulate climate change in the Basin of Abhar River, precipitation and temperature variables are extracted from the results of three global atmospheric circulation models under RCP2.6 and RCP8.5 greenhouse gas emission scenarios in the period 2021-2031. Data spatial downscaling was performed using the M5 decision tree algorithm. In the next step, the Wavelet-M5 hybrid model was used to predict runoff values for rainfall-runoff modeling. The Kharrufa method has also been used to calculate evaporation in future seasons. In the next step, these values were provided as input to the cyclic and non-cyclic multi-objective optimization models. Results showed that, CSS operation strategy improves the conjunctive use system adaptability, compared to the optimal operation strategy which employs the NCSS approach, so that in the cyclic approach, the sustainability of the groundwater resources is guaranteed by about 18% more than of the same in the non-cyclic approach.

In this paper, the Impacts of Climate Change and Human Activities on Runoff Reduction (ICHRR) are quantified using three approaches based on regression, climate elasticity and water balance models. These approaches are based on finding the location of the occurring an abrupt statistical change (breakpoint) in runoff time series. In this paper, the effect of locating the breakpoint(s) on the mentioned quantified impacts is studied through sensitivity analysis. The performance of the mentioned three approaches is evaluated by applying them on Zayandehrud river discharge which is subjected to significant human induced changes such as dramatic increase of the area of agricultural lands and inter-basin water transfer projects. The water balance model is calibrated and verified for the period of 1976 to 1984. The sensitivity analysis shows that among several years with potential of the occurring a breakpoint, considering the year of 2006 as the breakpoint, the estimated values of ICHRR are more realistic. These results are in accordance with the observations including the time series of climate variables, agricultural land areas and inter-basin water transfer discharge. Also, if the impact of inter-basin water transfer on increasing runoff is removed from the runoff time series, the impact of climate change on runoff reduction based on all the three approaches is mostly close to zero.

The aim of this study was to investigate the Intensity of the effect of climate change using CMIP5 group models under RCP scenarios on groundwater resources in Varamin plain. The output of these models was downscaled by LARS-WG .For this purpose, the period(1989-2005)was used as a base period to select the regional model and the period 2050-2021 to study the NISTOR index in the future. The results showed that the EC-EARTH model has a high performance in simulating temperature and precipitation in the study area of CMIP5 series under three scenarios RCP2.6, RCP4.5 and RCP8.5 for the next period. On average, the average temperature in the study area, under the scenarios RCP2.6 and RCP4.5, respectively, predicted an increase of 1 to 1.2 ° C compared to the base period, while the same temperature increase based on the most pessimistic scenario That is, RCP8.5 in the period 2050-2020, an average increase of about 1.5 degrees was predicted compared to the base period. Also in future periods, an increase in precipitation was observed in the early months of the year to late spring and a decrease in precipitation in autumn. Overall, the RCP4.5 scenario showed slightly more annual precipitation increase over the next 30 years than the base period over the other two scenarios. Also, the results of the NISTOR index, considering the effective rainfall, and De-martone index showed in all three scenarios, the intensity of effects of climate change on the groundwater resources of Varamin plain in the future is significant