Behrooz Sari sarraf; Tahereh Jalali Ansaroodi
Volume 6, Issue 19 , September 2019, , Pages 163-185
Abstract
Introduction In the recent decades, the growth of the industrial activities and the increase in greenhouse gases have imbalanced the Earth's climate which is called the phenomenon of the climate change. This phenomenon directly affects the hydrological parameters. While climate change directly affects ...
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Introduction In the recent decades, the growth of the industrial activities and the increase in greenhouse gases have imbalanced the Earth's climate which is called the phenomenon of the climate change. This phenomenon directly affects the hydrological parameters. While climate change directly affects surface water resources through changes in the major long-term climate variables such as air temperature, precipitation, and evapotranspiration, the relationship between the changing climate variables and groundwater is more complicated and difficult to quantify. The large amount of water is needed in different parts of arid and semi-arid regions provided through groundwater resources. In recent decades, the quantity and quality of water resources have been reduced by unprotected exploitation. In addition, climate change and global warming increase the severity of the problem. Therefore, the predicted effects of climate change on groundwater recharge play an important role in the management of these resources in the future. In this study, Global circulation models, HadCM3 under A2 and B2 scenarios, were used for investigating the impact of climate change on groundwater recharge rates between 2017 and 2030, in the Tasouj aquifer. Methodology In this study, to investigate the climate change in Tasouj basin, the required data were obtained from two sources including Global model output AOGCM which was based on the HadCM3 model and the observed data of the precipitation and temperature of Tabriz synoptic station with the statistical length of 1961 to 2016. To downscale the general circulation modal, the statistical method of SDSM was used. The Hydrologic Evaluation of Landfill Performance model (HELP) simulates all of the important processes in the hydrological cycle including surface runoff, evapotranspiration, vegetative growth, soil moisture storage, and vertical unsaturated drainage for each discrete layered soil column. In general, the modeled hydrologic processes by the program can be divided into two categories of surface and subsurface processes. The modeled surface processes are snowmelt, interception of rainfall by vegetation, surface runoff, and evaporation of water. The modeled subsurface processes are evaporation of water from the soil, plant transpiration, vertical unsaturated drainage. Vegetative growth and frozen soil models were also included in the program to aid modeling of the water routing processes. The required general data included growing season, average annual wind speed, average quarterly relative humidity, monthly normal mean temperatures, maximum leaf area index, evaporative zone depth and latitude. Result According to the simulation of Hadcm3 model, during the period of 2017-2030, the average monthly temperature in all months of the year will increase in the studied area. The highest amount of heating in the average temperature will happen in July about 2 degree Celsius. The highest decrease in precipitation will occur in April and May about 9 mm than the base period. The highest percentage of precipitation in Tasouj basin is used for evaporation. During 14 years of the prediction, the year 2020 has the highest and the year 2029 has the lowest amount of evaporation. In terms of runoff caused by precipitation, the year 2023 with 9.69 percent of precipitation will have the highest runoff. The lowest and highest amount of recharge will respectively happen in 2021 and 2027. The depth of water precipitation is significantly affected by soil moisture and with increasing soil moisture; the depth of water percolation to soil will decrease. The soil moisture content is negative in 2027. Consequently, the highest amount of recharge due to precipitation will happen in Tasouj basin. In the base period, the year 1990 had lowest precipitation and the year 1963 had the highest precipitation. Due to having a negative soil moisture storage in 1990, of 148 mm of annual precipitation, about 76.28 mm was spent for recharge. The amount of runoff is almost zero in this year and the rest of precipitation is evaporated. Despite the high annual precipitation in 1963, due to the high moisture content of the soil, the amount of recharge is only 4 percent of precipitation and most of the precipitation changes to runoff and evaporation. The status of evaporation, runoff and recharge in 2022, as the forecasted most precipitation year, is similar to 1963. Discussion and conclusion In recent years, the climate change has led to significant changes in the weather and the condition of surface and underground water resources in different locations. The response of the groundwater resources to drought and climate change is not as rapid as that of the surface water, but considering that the renewability of these resources takes much longer than that of the surface water, the impact of long-term drought on groundwater resources is much more serious than that of the surface water resources. Therefore, the monitoring of the condition and maintenance of the sustainability of these resources is important. In this way, by using a step by step approach, the impact of climate change on recharge, evaporate, and runoff for the 2017-2030 period was investigated and the simulation result showed that with increasing temperature and decreasing precipitation, of three parameters of evaporation, recharge, and runoff, the evaporation dominated the other parameters. But the high consumption of basin and the increase of temperature and precipitation decrease prevented Tasouj aquifer from returning to its balance. Therefore, a principle planning to control the harvest and treatment of aquifer by underground dam and artificial nourishment is necessary
Mohammad Omidfar; Hashem Rostamzadeh; Behroz Sari Sarraf
Volume 5, Issue 15 , October 2018, , Pages 135-152
Abstract
Abstract
Introduction
Flood phenomenon is one of the atmospheric hazards whose frecuncy is remarkable in the northwest of Iran and every year, there are a lot of Casualties and financial losses on different parts of the study area. The aim of this study was the feasibility of using the new Doppler ...
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Abstract
Introduction
Flood phenomenon is one of the atmospheric hazards whose frecuncy is remarkable in the northwest of Iran and every year, there are a lot of Casualties and financial losses on different parts of the study area. The aim of this study was the feasibility of using the new Doppler radar technology to predict the short term flood phenomenon and send timely warning to the relevant organizations and residents of the flood prone areas. To this end, Tabriz Radar products, which can be expanded in a three dimentional structure based on the direction and speed of movement and water content of cloudes in the event of flood of the gallezar village, were selected and carefully monitored. The resuls showed that due to the ability of the radar to penetrate into the clouds and its appropriate spatial and temporal resolution, depending on the formation location and the speed of development of super cells, flood phenomena can be detected several hours before the occurrence. In case of coordination with the crisis organization and prompt warning, it can decrease its damages.
In recent years, Doppler weather radar is one of the new remote sensing technologies that can give valuable information about cloud and type of precipitation. The new technology of meteorology radar can be fruitful in the identification, monitoring, and early warning, and, eventually, reducing damage inflicted to the environment. Therefore, this study aimed to evaluate the efficiency of the products of Doppler radar in monitoring the cells of showery severe rain-producing clouds. The aim of this study was also to evaluate the performance and functional advantages of radars in monitoring and analyzing the characteristics of flash flooding covective cells in the northwest of Iran. For this aim, the production or incoming , direction of motion, and attenuation of floodable convective cells in the study area were monitored by 15-minute time steps by three main radar products including maximum display (MAX), surface rainfall intensity (SRI), and precitipation accumulation. The obtained results can be applied in establishing scientific information and missions in establishing rapid meteorological warning system and, hence, making required decisions in reducing casualties brought about by flood.
Methodology
The area under study is part of the northwest of Iran that is located in the effective range of Tabriz radar. According to the power of the radar waves, its effective range can be used up to 250 km radius. For analytical studies, like this study, it is applicable to the whole range of the northwest of the country. A variety of radar products produced by the radar reaches to more than fifty products. Each product has different output specifications and performance with graphics, charts, and meteorological signs. Of these products, about 20 products are generated and stored by Tabriz radar. Some of the applied products in this study will be briefly discussed. The maximum product of the exhibition is displayed on a graphical screen after processing. It contains information which displays the maximum height and interior density of the cloud. Surface rainfall intensity product showed the intensity of precipitation at a specific level. For this purpose, a surface close to the ground was determined and by the equation between Z-R, the value of z reflection was transformed to the intensity of the rainfall. To achieve the objectives of the study, Azarshahr flood event, which occurred in 2017, was selected using the currently reported weather codes in synoptic stations in the studied area. In sampling, there was an atempt to place cases in different geographical distances and directions with respect to the radar. For the close monitoring of the showers, from the early days of the reported barrage above, the radar products were examined with 15-minute intervals. On the basis of these images, time and place, route, time and peak locations of the activities, and the death of rainfall cell were monitored.
Result and Discussion
In this study, floodable convective cloud cells producing heavy rain showers grew within a few hours from small cumulus clouds (type one without rainfall), into cumulonimbus flood-causing clouds, along with heavy rainfall and hail. The 4 April 2017 flood event convective rainfalls, which created heavy rains in small area was selected. Naturally, in the selected case, the rest of the stations had meager amount of rainfall that was not possible to recognize these convective cells with satellite images or by synoptic maps. Doppler radars had tremendous role in detecting, routing, and monitoring of the maps. Indeeed, with proper management and timely warning, a significant amount of the casualties caused by the phenomenon can be decreased. Cooperation with the crisis organization and prompt warning can also decrease its damages.
Conclusion
Doppler radars have great potential to improve the quality of the rainfall data because of the ability of producing data with a spatial resolution of less than 500 m and 15-minute temporal resolution and its wide coverage. The results showed that the flood event which occurred on April 4th, 2017 was a local rainfall. It was formed in a short time and at a relatively small scale and was invisible by meteorological observations and satellite images. Primary cloud cell (cumulonimbus) of an intense shower rain was formed in the early hours of the morning and gradually was grown and reached the strongest form in the afternoon and early evening and created an intense flood in the form of a shower rain. After intense rainfall event, the cloud cells became weak and collapsed. In some cases, the peak of its convective clouds got to 10 km.
