جستجوی مقالات مرتبط با کلیدواژه "drought" در نشریات گروه "مهندسی آب"

Planning the cultivation pattern and water rights allocation in the irrigated lands by the Khansar Sarcheshmeh springs requires knowledge of the discharge of the springs, estimated based on the Standard Precipitation Index (SPI) in this research. The relationship between the SPI index, precipitation, and discharges of Khansar Sarchesmeh springs has been evaluated over three different periods to estimate the groundwater resources and inflow to the streams. In a year with normal or near-normal climatic conditions and average annual rainfall between 295 to 494 mm, the average annual discharge of Sarcheshmeh springs is expected to be between 12.8 and 24.3 million cubic meters (average of 18.1 million cubic meters) with 67.5% probability and a frequency of 1.5 years based on the extreme value distribution. For a year with average dry climatic conditions (270 mm average annual rainfall), the predicted average annual discharge of Sarcheshmeh springs is 11.9 million cubic meters with a 9% probability and a frequency of 11 years. In extremely dry climatic years (with an occurrence frequency of 28 years), the discharge of Sarcheshmeh springs is expected to decrease to less than 10.1 million cubic meters per year. In normal and close to normal conditions, with average rainfall in the range of 236 to 326 mm in the first six months, the average annual (water year) discharge of Sarcheshmeh springs is expected to be 18.5 million cubic meters (ranging from 15.3 to 21.8 million cubic meters with a 67.5% probability based on the extreme value distribution). According to the results of this research, rainfall of less than 168 mm occurred in the first half of the water year is a warning of the occurrence of a moderate to extremely dry drought with an annual discharge of less than 11.6 million cubic meters that can be distributed in the streams. Precipitations of more than 394 mm during the first half of the water year also indicate the likelihood of a moderate to extremely wet year, with an annual rainfall of more than 28 million cubic meters. Results of the research indicate that less than 168 mm of rainfall in the first half of the water year signals the potential for a moderate to extremely dry drought, with an annual discharge of less than 11.6 million cubic meters that can be distributed in the streams, while more than 394 mm of precipitation during the same period suggests the possibility of a moderate to extremely wet year with an annual rainfall of more than 28 million cubic meters.

Today, due to climate change, we are witnessing limited water resources such as droughts and floods in all parts of the world. From the past until now, dams have been used for water storage, electricity production, and agricultural and industrial uses, which, along with their advantages, will cause environmental damage. The construction of dams will divide the basins into engineering and natural basins, and one of the approaches of this research is to explain the differences and performance of these two types of basins in terms of water resources and drought indicators. The purpose of this research is to review and evaluate the existing indicators and provide an integrated index including the influencing factors of drought, which was chosen as a case study due to the sensitive location of the Zayandeh Rood watershed in the central plateau of Iran. The imbalance between resources and consumption, especially in recent years, is considered as the main factor aggravating drought. The integrated drought index includes various factors such as meteorological and hydrological factors and is verified using agricultural factors. The results showed that in the studied natural basin, the correlation value of the index based on rainfall and evaporation and the validation index is 0.52 and 0.53, respectively, while the correlation of the bivariate index and the validation index is 0.66. In the studied engineering basin, the correlation difference varies from 0.26 and 0.41 respectively for the indices based on rainfall and evaporation to 0.91 for the bivariate index.

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).

Drought as a natural phenomenon is one of the most important challenges in water supply, especially in arid and semi-arid climates such as Iran. In this study, the hydrological drought has been investigated in the western sub-basins of Lake Urmia using the Surface Water Supply Index (SWSI) from Oct. 2009 to Sep. 2019. For this purpose, annual precipitation data, snow water equivalent, surface runoff, and reservoir storage (or changes in groundwater storage) have been used. The methodology of the study is based on the SWSI index, remote sensing using Google Earth Engine, determining the snow cover area using the NDSI index, and analyzing the drought trend using the Mann–Kendall trend test. The results showed that according to the weights of the components obtained by the Analytic Hierarchy Process (AHP), precipitation is the most important factor in the study area in hydrological droughts. Also, according to the SWSI index, during the 10 water year period, wet, extreme drought, and severe drought conditions have not occurred in the study area and generally, in 54% of the cases near-normal conditions, in 19% of the cases incipient drought conditions prevail and in the next ranks are abundant and moderate drought conditions with respectively 14% and 13% incidence. Also, the wettest water year was from Oct. 2018 to Sep. 2019 and the driest water years were from Oct. 2016 to Sep. 2017 and from Oct. 2011 to Sep. 2012. In addition, in all studied sub basins except Zolachay, the near-normal hydrological condition was the most common condition during the study period. Also, the results of Mann-Kendall non-parametric trend test showed that only in the Baranduzchay and Rashkan-Talkhab sub basins, the trend of hydrological drought time series has been increasing (increasing humidity).

Drought is one of the most important climatic phenomena that is caused by climatic anomalies. Which occurs periodically due to lack of moisture due to reduced rainfall. Drought duration may vary from month to several years. Therefore, by monitoring and evaluating the drought, the damage caused by it can be reduced. Drought is one of the most important and destructive phenomena that in recent years has left many economic and social effects in the city of Islamabad, West. Therefore, in this study, the drought situation of Islamabad West using rainfall data in 30 years (1991 to 2020) using DIP software on an annual basis of drought status based on PNI, SPI, ZSI, CZI was used as a measure to monitor meteorological drought. The results showed that these indicators were consistent with each other, so that based on the above indicators, the results show that in Islamabad West in 1999 and 2014, the most severe drought occurred in the statistical period. In 2005 and 2008, drought occurred with a moderate drought situation.

Droughts are the most important challenge in Iran's water supply. In this study, in order to identify the synoptic mechanism of occurrence of climatic droughts in Iran, daily and monthly precipitation data of meteorological stations of provincial centers (sample) and NCAR data analyzed for the period of 1960-2015 were used.  First, the dry periods of the stations were identified by the method of difference between the means and rate methods. Also, to determine the blocking systems, Tibaldi-Multeni index was used and to identify the blocking systems, three quantitative, limit and continuity triple filters were used. Reduction of rainfall or no precipitation in periods of 20 days or more in the cold season leads to severe and very severe droughts in Iran. Synoptic analysis of the study sample indicated that the Atlantic-European region (as a region affecting the synoptic operators affecting Iran's rainfall) and the Pacific have the highest frequency of the blocking system. With the establishment of blocking systems in the cold season of the year, the thickness of the atmosphere (500-1000 hpa) has increased by 10 to 30 geopotential meters and the east winds dominate the Iranian atmosphere instead of the west winds. This change in wind direction leads to the failure of systems such as polar wind and polar front to enter the synoptic area of ​​Iran.  Therefore, with the formation of blocking systems and the resulting blocking conditions of synoptic, drought in the coming wet year is determined and drought damage can be reduced by risk management and predication.

Establishing a local water market in the agricultural sector is a promising solution to increase the economic efficiency of water in the event of drought, water shortage, and reduced agricultural productions. With the opportunities created in the water market, farmers will rent and sell this scarce input by improving the methods of water supply management and will work to provide water that can be sold in the market. In addition to managing surface water resources, this reduces farmers' pressure to use groundwater resources. Due to the importance of this issue, in the present study, the economic effects of the formation of the local water market in the five regions of Tehran province under the conditions of drought, water shortage, and reduced crop production in Tehran province were evaluated. This work was done by using a combined economic model of Statewide Agricultural Production (SWAP), hydrological model of Water Evaluation and Planning (WEAP), and related statistical data to the years 2013-2019. The results showed that with the establishment of the local water market and balancing agricultural water trade between the study basins of Tehran province, the negative consequences of drought in the use of available water resources are reduced by about 12/7 percent compared to the base period. In addition, the establishment of the local water market as a customary and legal institution in Tehran province, despite the transfer of surplus water resources from the eastern and northern basins (M1 and M2) to the southwestern basins of Tehran province (M3, M4, and M5), caused increasing the reliability of farmers' access to irrigated water and preventing the reduction of profitable crops (tomatoes, corn, watermelon, and sunflower) in optimal cropping patterns. Also, this structural institution by realizing the policy of sharing agricultural water resources and increasing the “profit to water ratio index” from 5/89 to 11/06 percent, reflects optimally allocates the issue of allocation and optimal management of water resources between different agricultural activities in the five basins of Tehran province. Finally, according to the positive and effective results of the local water market in the management of water resources and agriculture, the implementation of the preparations for its formation is proposed to the relevant authorities and organizations in Tehran province.

Due to the frequency of drought in Iran and acceleration of its impacts during the last decades, Iranian legislator has enacted some laws to control the droughts. However, this kind of legislative approach to the management of drought faces some challenges that hinder establishment of a determinant and constructive legal order in this field. Introducing five elements of a suitable model for legislation in drought management, the article found out that firstly the drought has not yet been problematized as a legal matter for the country’s legal system and the current laws regarding the drought have addressed it in a deficient and haphazard manner. Secondly the current body of laws have not provided appropriate legal mechanisms for prevention, mitigation, adaptation, institutionalization and empowerment, and compensation of drought which makes the country vulnerable to future droughts. To overcome these challenges some legal reforms are needed. One of the necessary steps is enactment of a comprehensive law on drought management to address these deficits and also integration of drought management into the related laws like the development plan laws to achieve a comprehensive and collaborated legal order in management of this natural disaster.

The present study aims at investigating the groundwater reservoirs in Khanmirza Plain under drought conditions in regard of the fluctuations in the rivers leading to Khanmirza Basin using WEAP Software. In order to actualize this goal, 2007 was chosen as the base year. Then, the scenarios were evaluated within a 30-year time span (2007-2037) using the WEAP model. The results of the first scenario showed that at least 50% is required for bringing about balance in the water level of Khanmirza Plain’s aquifer through implementing a plan for reducing the area under cultivation. The second scenario shows that not only the plain does not reach a stable balance state but also the water needs of the farmlands cannot be perfectly supplied by the implementation of pressurized irrigation and increasing the irrigation efficiency in the entire plain. Moreover, the third scenario is also reflective of the insufficiency of the implementation of an artificial recharge plan on Khanmirza Plain for reaching balance in the groundwater.

Drought is one of the natural disasters that cause great damage to human life and natural ecosystems and is different from other natural disasters. The main differences in the gradual impact of drought over a relatively long period are the impossibility of determining the exact time of onset and end and the geographical extent of its impact. On the other hand, the lack of an accurate and acceptable global definition of drought has added to the complexity and confusion of this phenomenon. And the severity of droughts was determined and described based on drought indices ZSI, PNPI, SPI. These indicators are consistent with each other so that based on the above indicators. the results show that in Shahid Abbaspour Dam in the wet years (2007-2008) the most severe drought occurred in the statistical period. SPI index of drought periods Shows more, so it is a more sensitive index than ZSI and PNPI and has a higher sensitivity and more complete classification in the study of dry periods.

Droughts affected by climate change are among the most devastating weather events, causing significant damage both in natural resources and in human life. In this study, in order to investigate the effect of climate change on drought, both precipitation and temperature future period (2030-2050) were calculated with CanESM2 model under RCP8.5 scenario in the Douganbodan station in Gachsaran city. Then, drought was evaluated with Standardized Precipitation-Evapotranspiration Index (SPEI) during the base (1985-2005) and future periods in different time series. Finally, severity and duration variables of drought were analyzed for the calculation of joint probability and return period with the multivariate copula function. The results show that monthly temperature under RCP8.5 scenario has increased by 2.2°C and precipitation has been reduced by 5.5%. Drought evaluation results show that the number of dry and wet periods is reduced by increasing the length of the scale, but the longest period increases. Also, the number of drought periods relative to the base period have increased under the RCP8.5 scenario. The Frank function was selected as the best fitted function with the mean values of the three fitting indicators, RMSE (0.38), NSE (0.9) and AIC (-101.9). The results of analysis of joint return period of a drought event with a severity of 10 and duration of 10 months for the base period and RCP8.5, respectively, were 5 and 4 years, that indicate a decrease in the return period of severe drought and their increase in future under RCP8.5 scenario relative to the base period.

The aim of this study was the evaluation of drought effects through SPI index assessment on the water quality of the Dez River. For the determining the drought, ten-year meteorological data (2005-2014) were achieved through the weather stations of Hussainiya, Dezful, and Shush and for impact evaluation of drought on the water quality of the Dez River, discharge statistics and qualitative parameters related to seven hydrometric stations along the Dez River achieved through Khuzestan Water And Power Authority. The mean frequency of dissolved anions and cations in the hydrometric stations of the Dez River achieved like HCO3>SO4>Cl and Ca>Na>Mg. The variance analysis of the water qualitative parameters showed that the effect of station and year on the amounts of discharge, EC, TDS, SARIW, pH, Cl, HCO3, Ca, Mg, Na, and SO4 had a significant difference (P

Calculation of stronger indices requires extensive meteorological data that may not be recorded in some areas, but in most areas rain gauges record rainfall data. In this research, the RDI and SPEI indices simulated with acceptable accuracy using the SPI index (only rainfall data is required for its calculation). Simulation was performed using generalized estimating equations (GEE) and then validation of these simulation models was performed using different goodness of fit measures (NSE, RMSE, MAE, R2 and comparison with 1:1 line (using t-test)). The calculated values of different goodness of fit measures indicated the acceptable validity of fitted GEE models. Comparison between goodness of fit parameters and validation coefficients indicated that, in general, the SPEI model has better than RDI model. Models validation showed that the difference between simulated and observed data was not significant at 5% significance level. Results indicated the better performance of simulation models in arid region of the Fars province.

In this research, impact of drought on groundwater quality investigated on irrigation usage in Hashtgerd plain aquifer. First, using Thiessen-polygon method and precipitation values of 6 weather stations in Hashtgerd plain, total average monthly rainfall for a period of 30 years (1985-2015) was calculated. Average monthly of groundwater levels for a period of 23 years (1991-2014) were calculated using 8 observation wells data and Thiessen-polygon method. Climatological drought calculated by SPI and groundwater drought calculated by GRI. Based on results, the longest climatological drought with durability of 2 years, severity -2.73 (SPIsum), density -1.365 (SPIavg) and total average monthly rainfall 157.70 mm were in the water years 1998-1999. The most severe groundwater drought was in the water years 2010-2014 (4 years durability) with severity -6.10 (GRIsum), density -1.53 (GRIavg) and groundwater average monthly level 1180.26m. On 12 months period, correlation between groundwater levels and rainfall amounts were significant with time-lag of 11 months. In June of water year 2013-2014 with extreme drought condition, water quality of 16% aquifer area was appropriate to use plants irrigating but 84% was inappropriate while in December, 100% aquifer area was inappropriate as irrigation water quality. Based on LSI, in June and December of all studied years, water quality of 100% Hashtgerd plain aquifer area, it was possible to formation of calcium carbonate sediments.

Governing the risks of extreme events is of importance to advance climate change adaptation. In March 2018, some seventeen years after the beginning of Iran’s devastating drought, the Council of Ministers enacted the Act on Water Shortage Adaptation. The purpose of the act is to balance consumption of the limited resources for apportioning the shortage to the users, equitably. What this article does not critique is the act’s approach to moving from confronting-with-drought to living-with-drought practice. What will be questioned is the approach to act implementation. While the paper review the act’s main articles, it will address the overlooked factors that need to be considers in the implementation phase. It is shown that the most important scientific principle in the common-pool resources’ legislation is to understand the social and behavioral processes that govern the resources. For example, what is the resolution mechanisms if people go rivalry and fall into conflicts? This is exactly what is missing in the act.

In this study, to evaluate the effects of climate change on temperature, precipitation and future droughts in Shadegan Basin, output of the MPI-ESM-LR، BCC-CSM1-1 and NORESM1-M general circulation models under diffusion Scenarios RCP4. 5 and RCP8. 5 is used. The outputs of general circulation models are downscaled using LARS-WG software. To evaluation of drought, the standardized precipitation index (SPI) is used for the base period (1986-2005) and Future period (2020-2039) and in time scales of 6, 12 and 24 month. The results showed that the maximum temperature and minimum temperature increased in all months the future period under RCP4. 5 and RCP8. 5 scenarios in the Shadegan Basin. Precipitation changes do not show a general increasing or decreasing trend. The results showed that under RCP4. 5 scenario and in time scales of 6, 12, and 24-month, respectively 17. 16, 14. 70 and 18. 74 percent of all months the future period would be dry. In addition, Under RCP8. 5 scenario and time scales of 6, 12, and 24-month, respectively 16. 45, 17. 03 and 15. 21 percent of all months the future period will be dry. The months of dry under RCP4. 5 and RCP8. 5 scenarios in future period, in time scale 6-month respectively 2. 27 and 1. 56 percent will be increase, in time scale 12-month respectively 2. 77 and 0. 44 percent will be decrease and in time scale 24-month respectively 2. 00 and 5. 53 percent will be decreased. So anticipated under climate change in future period, the number of drought months is less than the number of months with normal and wet conditions.

In this paper, the meteorological droughts of four selected stations in Khuzestan based on the annual precipitation index (SIAP), Normal precipitation (PNPI) and precipitation anomalies (RAI) in a 32-year statistical period (1983-2003) were investigated. Drought index coefficients and frequency and severity of drought were determined based on each indicator. Each of the indicators was calculated at the stations. The results showed that frequency and sequence (continuity period) of drought were different in different degrees according to the index of (SIAP) in Dezful in the statistical period. In the PNPI survey, Abandon droughts were more frequent than other stations. The most severe drought occurred in Ahwaz based on this indicator. According to the RAI index, the frequency of drought in Dezful is greater And due to the severity of drought in Omidieh, the highest severity of drought occurred. Finally, among the three indexes studied, the highest drought persistence is related to the( PNPI) index

The aim of this study is to review the effect of excessive withdrawals and recent droughts on groundwater reservoirs of Saveh Plain. The 7 stations were selected between the monthly rainfall data in Saveh plain. In this research, at the time scales of 3, 6, 9 and 12 months for indices CZI, ZSI, MCZI, SPI, the droughts were considered using DIP software. The drop amount of the groundwater level in Saveh aquifer during 22 years (1992-2014) has been approximately 31/86 meters. Statistic of wells during two 10-year periods (1991-2001 and 2001-2011) was taken into account. With two 5-year period, we can conclude that in 1991-1996 years the upper regressed charts and the process is very slow first drop in five years but in the second 5 years has been a steep slope times and in the 2001 to 2011 with the same or slightly steeper slope continues because wells are unauthorized and uncontrolled exploitation. In a review of quality groundwater was used AqQa software that Piper diagram indicates calcic facies is in the study area, and Durov diagram shows a sudden increase in total dissolved solids and close to bicarbonate type that can be due to the formation concerned or leakage from a probable underlying semi-confined aquifer or mixing with another source which requires further reviews.