تازه های تحقیق
عنوان مقاله [English]
The excessive usage of groundwater has led to some problems in recent years such as the salinization of wells water, drying of aqueducts and springs. Due to the importance of groundwater, some important studies have been conducted accordingly; the oldest belongs to the Greek philosophers. There are also some articles in this field of Iranian scholars such as Abourihan and Hamdollah Mostofi. Pierre Perrault and Edme Mariotte were the first who wrote about the origin of groundwater in France in a scientific way. Moreover, significant studies have been carried out in this regard including Nayak (2006) investigated the Godavari Basin in Maharashtra province (India), Zhang (2009) studied the Pear Basin in China, Potop (2011) explored a study in the Czech Republic, Jang (2012) conducted a study in the Pingtung Plain in Taiwan, Sinha (2014) investigated Valapattnam Basin (India), and Yang (2012) carried out a study in the plain of Beijing. In Iran, as well, Khosravi (2014) in the Garmsar plain and Javdanian (2016) in the plains around the city of Isfahan, have conducted important studies in this regard. Although groundwater issues are attributed to humans in most of these studies, but it seems that besides the negative effects of some human activities, they have somewhat moderated the decline in groundwater levels in recent years. Despite the fact that the usage of groundwater in the Safiabad plain dates back to a few hundred years,
there has not been any significant studies conducted in terms of its groundwater. In this study carried out through field and library methods, it was attempted to investigate the changes of groundwater level in this plain, so that the human positive effects could be identified in this field whose results could be utilized in better controlling and managing groundwater.
To do the research, firstly, the studied region was determined using field studies as well as topographic and geological maps. Statistics related to the groundwater levels of 27 years (1992 -2016) were obtained from the North Khorasan Regional Water Authority, and the data on agricultural activities was collected from the Esfarayen Agricultural Jihad Department and the climatic statistics were sourced from the Safiabad Synoptic Meteorological Station. The data regarding smart meters was obtained by interviewing with North Khorasan Regional Water Authority experts. That part of this study, which was related to cultural issues and cash penalties, was conducted through interviews with farmers. The statistical analysis, the preparation of hydrographs and figures were processed using Minitab, Excel, and SPSS software.
3-Results and Discussion
Safiabad plain is one of the northeastern plains of Iran, where the usage of groundwater is common there. The hydrograph consideration of this plain indicated that the its groundwater level has been decreased by about 6.9 m since 1989. In the study of changes regarding the groundwater levels, the first hypothesis which comes to the mind, is the effects of precipitation on these changes. Based on meteorological statistics, regression coefficient and histogram precipitation of this plain follows the normal distribution. Therefore, in recent years, the main cause of water table decline in this plain is the over-extraction of groundwater. The reduction of groundwater levels has led the Regional Water Authority administrations and farmers do some policies. Making concrete channels and water pipelines was the first step in this issue which causes saving 6 percent of the usage of groundwater in this plain.
Also, according to the statistics, 42% of the farm lands of Safiabad plain are irrigated by modern systems, which would save 8.8% water consumption in this plain per year. The change of cultivation type was another policy that was applied since 2006. In 2017, pistachio gardens were replaced with the cultivation of grains and saffron replaced sugar beet; through these changes, about 40% were saved in the water resources of this plain. The imposition of cash penalties was another Regional Water Authority policy that saved 5% of the groundwater in the plain. Cultural issues are also other important cases that if implemented appropriately, can have a sustainable impact on the exploitation of water resources. However, no considerable action has been taken so far in this regard. The use of smart meters is one of the newest methods of groundwater control that was firstly used in 2003 in Safiabad plain. Although the effect of using this method was not significant until 2011, however, since this year, for the first time, the hydrograph of the plain showed the positive reflections to the use of this controlling method and groundwater level was matched with the data fitting line and sometimes reached to the levels higher than it.
Safiabad plain is one of the northern Khorasan plains, which is faced with a sharp decrease in the groundwater aquifers. Farmers and government agencies sought to control the level of water consumption in the plain by creating concrete channels and pipes for transferring water through the channels, using new methods of irrigation, changing in cultivation, cash fines, cultural actions and the installation of smart meters. The results indicated that by transferring water through the use of pipes and concrete channels, new irrigation methods, changing the cultivation type, cash penalties, cultural issues, using smart meters, respectively, 6%, 8.4%, 40%, 5%, 2% and 45% of water consumption was saved and overall, 105.4% of the water consumption has been saved in this plain. However, the hydrograph consideration of this plain showed that the groundwater level is still decreasing. More detailed studies indicated that some causes of this decrease were due to the high thickness of the unsaturated soil, causing a large amount of water not to reach into the saturation zone; however, the main reason for this issue is the increase of cultivation area in this plain. In other words, farmers in this plain have been saving water by taking some activities, but having increased the area under cultivation, the amount of groundwater consumption has continued as much as the past. Furthermore, the results of the research showed that among human actions, only the installation of smart meters has had a significant effect on the hydrograph of this plain, so that since 2011, for the first time, the level of groundwater has passed the fitting line.