The Impact of Long-Term Irrigation on Changes of Ground Water Level and Soil Salinity in Northern Tunisia

2000 ◽  
Vol 14 (2) ◽  
pp. 175-182 ◽  
Author(s):  
M. Hachicha ◽  
C. Cheverry ◽  
A. Mhiri
2012 ◽  
Vol 479-481 ◽  
pp. 2441-2445
Author(s):  
Fu Sheng Liu ◽  
Guo Yuan Xu ◽  
Sheng Bin Hu ◽  
Wen Tong Huang ◽  
Min Hu

The groundwater can cause a significant threat to the safety of the tunnels excavated in water-rich areas. To investigate the impact of seepage to tunnels, the most important issues are calculations of the saturated surface and seepage flow. According to the great similarity between temperature field and seepage field in the theoretical foundation, differential equations and boundary conditions, the thermal analysis function of ANSYS could be used to calculate the non-pressure stable seepage based on the iteration method. The saturated surface and seepage flow through the lining are obtained by take a tunnel as an example, under using iteration method programming in ANSYS software. Additionally, on the basis of the correlation analysis, with the reduction of ground water level, the seepage discharge through the lining decreased sharply at the beginning, and then, the reduction trend gets inconspicuous. It has no obvious effect to decrease the water discharge by reducing the ground water level under this condition. Therefore, taking economic benefits into account, it is unadvisable to lower water level blindly. The optimal analysis of the actual conditions should be carried out in engineering practice. It has a certain reference value to the design and construction of tunnels in water-rich areas.


Author(s):  
Imran H. Durrani ◽  
Shahzada Adnan ◽  
Maqsood Ahmad ◽  
S. M. Khair ◽  
Ehsanullah Kakar

2020 ◽  
pp. 5-30
Author(s):  
V. A. Isaev ◽  
V. P. Belobrov ◽  
A. L. Ivanov

The analysis of long-term observations in the Kamennaya Steppe (over 125 years) for climatic parameters (air temperature and precipitation), ground water level, vegetation species composition revealed the main trends in their variability. Since 1969 there has been an increase in temperature and a reduction in temperature fluctuation during the year. Over the last 30 years, the difference has reached 1.90, and over the last decade it has grown by 0.40 due to the cold season. The amount of precipitation over the same 50-year period has not changed much. In total, an increase of 45 mm was observed over the decade (1999-2008). In the XXI century, there has been registered an increase in the amount of precipitation in the cold season by 12.7% and a decrease in the warm season, which creates certain prerequisites for climate continentality mitigation during the annual cycle. During the first 70 years of observations, the groundwater level in the well No. 1 was on average at the depth of 6.5 m (5.7-7.3 m). At the end of the XX century and at the beginning of the XXI century, there was marked a pronounced rise in the ground water level, the average depth was 3.8 m, which coincided with the growth of average annual temperature and an increase in total rainfall. In this period changes in the long-term regime of ground and surface soil moisture resultedin expanding the area of wetlands and hydromorphic soils on the territory of the steppe. The period of 2009-2018 is characterized by a continued increase in average annual temperatures and a decrease in precipitation, which may lead to a seasonal change in temperature and precipitation to milder and wetter winters and warmer and drier summers. Transformation of vegetation for 100 years of observations had several stages with a general trend to change the steppe grasslands to meadow-steppe, shrubs and woody species.


2020 ◽  
Vol 3 (2) ◽  
pp. 66
Author(s):  
Lisa Fitriyana ◽  
Bayu Prasetyo Afandi

Prambanan Temple is a cultural heritage located in Jogjakarta. Tectonically, the Special Region of Jogjakarta and its surroundings are an area with a fairly high level of seismic activity in Indonesia. Geotechnically, the soil in Jogjakarta is sandy with similar gradation. The thickness of the sand ranges from -50 m to -60 m. Whereas, the ground water level is located at a depth of -12 m during dry season and in rainy season, it rises from -6 m to -4 m. The impact of soil types and the high Ground Water Level (GWL) allow it for liquidation to occur during an earthquake. This study was conducted using liquefaction analysis, through Liquefaction Potential Index (LPI) method with ground water level variations. Before analyzing the liquefaction using LPI method, Peak Ground Acceleration (PGA) methods were used, and analysis could then be done through Cyclic Resistance Ratio (CRR) and Cyclic Stress Ratio (CSR) to obtain safety factors and the Liquefaction Potential Index analysis was then conducted. To analyze this liquefaction, earthquake data from 2004 to 2019 and the results of the SPT field test at the Prambanan Temple were needed. From the liquefaction potential analysis through Liquefaction Potential Index (LPI), the results showed that in CSR Seed & Idriss (1971) and CRR Tokimatsu & Yoshimi (1983), GWL 1 m at depths from 4.5 m and above, the potential of liquefaction occurrence was high. The largest PGA value was obtained based on the Matsuchka (1980) method on May 26, 2006 which was 0.102.


2012 ◽  
Vol 49 (3) ◽  
pp. 119-128
Author(s):  
Hiroyuki YOSHIMATSU ◽  
Wataru SAGARA ◽  
Takami KANNO

2018 ◽  
Vol 7 (2.25) ◽  
pp. 32
Author(s):  
Soundarya M K ◽  
Thanga Gurusamy.B

An attempt has been made to investigate both seasonal and long term ground water depletion pattern across the aquifers lying below geographical boundary of Chennai city. The Depth below Ground Level (DBGL) is used as an analyzing parameter for this investigation. This analysis is based on the data that has been made available to the public by Central Ground Water Board (CGWB) and Water Resources Department, Chennai, Tamil Nadu. Both graphical analysis and statistical based regression analysis has been carried out and the result has been presented in graphical and tabular form. Seasonal DBGL variation has been analyzed for the year 2016 after the popular Chennai 2015 December Flood event. It has been observed that the range of ground water level depletion is from 0.1 m per month at Broadway and up to 0.833 m per month at T.S.Campus locations during post monsoon season from January to May. Long term DBGL variation has been analyzed for duration of 22 years from 1996 to 2017. Statistical package for social sciences (SPSS) has been used to perform both linear and other regression analysis. Sustained decrease in ground water level has been observed at locations like Perambur Kodambakkam and Vallalar Nagar during the last two decades. 


Ground Water ◽  
2001 ◽  
Vol 39 (6) ◽  
pp. 801-801 ◽  
Author(s):  
William M. Alley ◽  
Charles J. Taylor

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