Quality and fluctuations of groundwater level at the humid margin of Damghan Haj Aligholi desert

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1 Available online at European Journal of Experimental Biology,, (): ISSN: 9 CODEN (USA): EJEBAU Quality and fluctuations of groundwater level at the humid margin of Damghan Haj Aligholi desert Darioush Ghorbanian, Mohammad Khosroshahi and Ehsan Zandi Esfahan Research Center for Agriculture and Natural Resources, Semnan, Iran Desert Research Division, Research Institute of Forests and Rangelands, Tehran, Iran Rangeland Research Division, Research Institute of Forests and Rangelands, Tehran, Iran ABSTRACT Damghan Haj Aligholi Desert is about Km, of which Km comprises the humid area (margin). To investigate the fluctuations of groundwater level, wells were drilled at the humid margin of south and southwest of desert. The changes in ground water level were measured at the beginning and half of each month in comparison to the constant level embedded at the edge of each well, and its hydrograph was depicted. According to the statistics taken from wells during April to September ( months), fluctuations in water level compared to the initial level (water level in April ) were calculated for each month. Our results showed that the rate of water level fluctuation depended on the climate and topography of the region. The highest and the lowest water level of the wells were recorded from the second half of to the first half of and from December to mid-january, respectively. The type of vegetation surrounding each well was affected by the mentioned fluctuations in addition to the percentage of water minerals and the depth of groundwater level. Also, canopy cover percentage and density could be effective in increasing or decreasing the rate of groundwater evaporation. The groundwater is hyper saline with an EC of.9 to 7 ds/m and a ph of.7 to.. The reduction of incoming waters to the desert due to the consecutive droughts and the prevention of runoff entering because of watershed management operations and dam construction have resulted in decline of groundwater level and it may cause many problems in the future. Keywords: desert, groundwater level, canopy cover, Damghan, Iran INTRODUCTION Playa is the term used for barren regions of deserts. It is also called Kavir (Jafari, ). Also, they are flat areas developed in the alluvial plains of arid regions and they may have been placed on lake sediments belonging to earlier times (Klinesly, ). These surfaces have no vegetation (Zahmatkesh et al., ), characterized by saline water and saline soils (Ahmadi, 99). Large surfaces of desert areas are devoid of vegetation due to physical harsh conditions within the deserts such as compacted soils, high salinity and unpredictable cycle of flooding or drying. As a result, the growth of many plant species has been restricted to the coastal and adjacent areas of deserts (Lichvar et al., ). Adequate moisture together with the drainage of saline areas surrounding desert provides the possibility of establishment and growth of some species tolerant to salinity (Kevin and Richard, 99). Shallow saline underground aquifers are considered as important factor in the salinity of arid soils (Jafari, ). Generally, in playas, evaporation is more than incoming water. If precipitation increases higher than evaporation, in this case, permanent and temporary lakes will be created (Ahmadi, 99). Damghan Haj Aligholi desert is located in the south of Damghan. This desert like other playas has the characteristics of lake. Its shallow lake could be observed in some seasons of the rainy years. Surface and groundwater of the study area is saline with lots of minerals. If incoming

2 Darioush Ghorbanian et al Euro. J. Exp. Bio.,, (): runoffs in the wet season are entered with delay and excessive harvestings of groundwater are controlled, groundwater level will have less fluctuations and soil salinity in the surface horizon will be decreased. During the last three decades, saline groundwater has been mixed with fresh water mainly due to the uncontrolled and illegal harvestings of groundwater in the surrounding of saline region, providing the risk of salinization in prone agricultural lands (Ghorbanian and Jafari,7, Zehtabian et al., ). MATERIALS AND METHODS A: The selection of locations (sites) Considering geomorphological features, the humid area was selected where, in addition to presence of constant humidity, reflects the general situation prevailing in the desert. B: Collection of meteorological data, surface and grounwater resources, geological studies, vegetation and soil data C: Hydrogeological investigations: Using images obtained from Google Earth and their calibration with field data, and also considering topographic maps, the hydrographic network of surface water was depicted and the lithological type of the formations was determined. To evaluate the changes in groundwater levels and determine the type and amount of minerals, a number of wells were drilled around the playa. The groundwater level measurement was started immediately after digging wells and continued twice a month for a year and a half. Then, fluctuations in the water table in different months as well as the rate of increase and decrease in groundwater level of the studied wells were measured and calculated. Given the potential impact of rainfall on groundwater minerals, water sampling for laboratory analysis was performed on both wet and dry seasons. The southwest and west margin of Damghan Haj Aligholi desert was considered for this study as reference area. This desert lies between longitudes ' to ' E and latitude 9' to ' N. The general slope of the desert is southwest and it has an altitude between - 9 m. a.s.l. Considering the hydraulic slope of the study area (south), the accumulation of water and salts is mainly observed in the southern margin. Accordingly, the southwest margin of the desert, approximately km in length, was considered for project implementation. Climatology: Average rainfall in the province is mm, less than one-sixth of average rainfall in the world (.% of the total rainfall in the world) and half of Iran's rainfall (% of total precipitation in Iran). The average rainfall of the synoptic stations was. mm during September - September, indicating a considerable reduction of rainfall in the province. According to the monthly rainfall data of the synoptic stations, it is observed that a considerable reduction of rainfall has occurred from April until 9 in all mentioned stations. But in late September, with the occurrence of cloudbursts at Semnan, Damghan and Shahrood stations, a considerable increase of rainfall was observed as compared to the control period. This issue has a direct impact on the flooding of watersheds, finally leading to the increased water intake to the playa and desert. According to the ombrothermic curve of the synoptic stations, the average temperature reached its peak in at all stations and in the same month, the average total rainfall was the lowest. Also, according to the mentioned curves, almost five months of the year faced wet conditions and 7 months of the year had dry conditions. Two dry periods were observed in the months of October and November, and April,,, July and in most of the stations. In September, the precipitation curve of Damghan, Shahrood and Semnan stations is above the temperature curve, indicating a rainfall abnormality in the mentioned stations. In other words, the mentioned stations have faced a sudden increase in rainfall in September. Although it was a short term cloudburst, its amount in this month was considerable. Floods caused by September rainfall significantly affect the quantity and quality of ground water Geohydrological studies: Groundwater studies were conducted by drilling wells and considering the condition and vegetation of the humid margin of desert. Considering the hydraulic slope of the study area (from north to south), the southwest margin of the desert was considered for project implementation. Wells were drilled within the study area Table ). To measure the groundwater level in the dry season, drilling of wells continued to a depth of approximately cm below the water level. Next to each well, a constant level was considered by concrete blocks. The groundwater level measurement began immediately after drilling wells. Dust storms and the entry of sediment and

3 Darioush Ghorbanian et al Euro. J. Exp. Bio.,, (): Table : Coordinates of the studied wells Geographic position Latitude Longitude Number wells plant debris into the wells as well as wild animals falling into wells were the main problems of inventory. Fluctuation of water table: The process of increasing and decreasing groundwater level, as the most important determinant of vegetation establishment, was discussed and considered. Accordingly, according to statistics obtained from wells, from April to September (over months), the rate of water level fluctuations compared to the initial level (water level in April ) was calculated for each month by the following equation: d = d-d d=groundwater level to the edge of well in April d= groundwater level to the edge of well in The result of this relationship, and calculations show that if is positive, groundwater level has risen and if is negative, groundwater level has dropped below the initial water table level (Table ). Average increase or decrease in the depth of groundwater level was determined each month by the formula as follows: d d = d of each month indicates the rise or fall of water levels in the Based on the results of the above calculations, studied wells. Therefore, in each month, the average water level in the study area was determined (Table ). RESULTS According to the results, the average ground water level during (. cm) and (. cm) was higher than that of April. But in July, the groundwater level had a decreasing trend compared to April and the greatest drop in water level reached to. cm in January. Again, in March it was accompanied with rising water level (. cm compared to April ) but it still had a significant reduction compared to April. In April, the water level reached to cm compared to March but it showed a decline of. cm in comparison with April. Average ground water level decline in, July, and September of was estimated to be. cm,. cm, and. cm, respectively. Average water level decline in September was calculated to be -. cm as compared to September, indicating water level decline in this period.

4 Darioush Ghorbanian et al Euro. J. Exp. Bio.,, (): Table. Fluctuations in the groundwater level (cm) of wells during different months /9/ // // March // February // December // November // October // September /9/ // July // /7/ // April // march // date sink 7 9 Table. Monthly water level rise and fall (cm) in the wells March 7. February December November October September July April March 7 9 d d Our results showed that the rate of water level fluctuations depends on climate and topography of the region. The highest and the lowest water level of the wells were recorded from second half of to the first half of and from November to mid-january, respectively. These fluctuations show changes in different wells. It seems that the type of vegetation established around each well depends on these fluctuations in addition to the minerals and the depth of groundwater level. Also, it seems that the density and cover percentage can be effective in increasing or decreasing of groundwater evaporation. The key issue in most wells is the gentle slope of decline in groundwater level from spring to late autumn. Table. water chemical characteristics of the studied profiles in Damghan Haj Aligholi desert Mg Ca Na K SO Cl HCO EC ds/m ph Sample Characteristics No No No No No No No 7 No No 9 No No No No No No No No 7 No Number of laboratories Reservist According to the water analysis of the wells, very high EC is the most important limiting factor, indicating a very poor water quality in terms of vegetation. However, some plant species are able to be established and survive in such hard conditions. Around well #, having the highest EC, Halocnemum strobilaceum has been established

5 Darioush Ghorbanian et al Euro. J. Exp. Bio.,, (): mainly on small and low-height dunes. Wells #,,,,, and have a lower EC and are more suitable for the establishment of plant species (Table ). DISCUSSION Humid margin is of characteristics of deserts (playa) including Damghan Haj Aligholi desert (Ahmadi, 99). Soil salinity is higher in desert center (Ahmadi, 7). High groundwater level and consequently shallow soil moisture are the most important indicator of desert margins. Critical depth is low therefore (Jafari, ), high evaporation causes severe soil salinization. In other words, with the increasing decline in groundwater levels, water salinity increases (Abadeh et al., ). Fluctuation of water table is a function of flowing water and groundwater evaporation (Zahmatkesh, G.A. et al., ), transpiration, runoff and flood entering from surrounding watersheds, and withdrawal of groundwater aquifers around Playa. According to the results of geohydrological studies, decline in water table indicates a negative balance between incoming water and outgoing water. Geomorphological conditions of desert margin especially within the south, southwest and west of the desert also indicate a decline in groundwater levels over the past decades. Reduced rainfall in watersheds leading to the desert, in comparison with long-term climate data (Hoseyni et al., ), exploitation of groundwater aquifers and high evaporation rates are the most important factors in declining water table (Zehtabian, et al., and Abadeh et al., ). Climate data indicate the occurrence of drought conditions in watersheds surrounding the desert. Based on climate data of September, the number of cloudbursts has increased in the watersheds surrounding the desert; therefore, the occurrence of flooding has not been unexpected considering vegetation condition and dry soil in late summer. Therefore, large volumes of flood entered from watersheds surrounding the desert, cause groundwater salinity in addition to the rising water table and increasing the area of humid margin. The general slope of the desert is south and southwest, and consequently the area of flat and saline lands is higher in northern and eastern areas with a lower depth of water table. In addition, the decline of groundwater table is one of main factors of dust occurrence (Mahmoodi, et al., ). Susceptibility to wind erosion also receives attention due to the silty-textured soil in some areas. The soils having % of silt are considered as the most erodible soils. In the area, with the decline in groundwater levels and abundant sodium, soil dispersion occurs that could be a great source of dust production. Abundant minerals in this process will create many problems. Therefore, in addition to planning to avoid declining water table, protective measures such as the creation, restoration and development of the vegetation seems necessary. The highest and lowest water level was recorded from second half of until mid- and from November to mid-january, respectively. These fluctuations showed changes in different wells. Zahmatkesh et al., () determined the measurement time of minimum and maximum water table from to November. This change depends on climate conditions, the amounts of incoming water and also the area of desert. It seems that the vegetation established around each well depends on these fluctuations in addition to the soil factors, percentage of minerals of water and the depth of groundwater level (Toranjzar et al., ). According to the results, it can be concluded that in addition to the microclimate of the region, cover percentage and density can be effective in increasing or decreasing groundwater evaporation (Shirmohammadi, and Samiei Moghaddam, ). REFERENCES [] Abadeh,M.,Onagh,M.mosaedi,A., Zeynoddini,A.(), Journal of Agricultural Sciences and Natural Resources, years of,no. [] Ahmadi, H.(99), Applied Geomorphology (Volume II wind erosion), Universitty of Tehran press, Page 7. [] Ahmadi,A. akhavan ghalibaf,m., ekhtesasi, M.R., ebrahimi, Z.(7) Assessment of mineral erodible playa evaporite facies Tabas, Proceedings of the National Conference of wind erosion and dust storms, university of yazd. [] Toranjzar, H.,Jafari, M., Azarnivand, H., Ghannadha, M.R.,(), Desert Magazin, Vol., No, Page 9 to [] Jazirehei,M.H.(),Forest plantation in dryland, Universitty of Tehran press, Page. [] Janighorban,M.(), Seidlitzia rosmarinus Suitable for desert reclamation plant, Third National Conference on Environmental. [7] Jafari,M(), Reclamation of Aridlands,university of Tehran press, Page 7 [] Hoseyni, S.M.,and etc(), Journal of Meteorological Organization of Semnan Province, The Bureau of Meteorology forecasting and climate research and applications, Page. 7

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