Akademik Veri Yönetim Sistemi
Tekirdağ Ziraat Fakültesi Dergisi, cilt.18, sa.4, ss.649-659, 2021 (Scopus)
Some site specific problems may arise in agricultural catchments where irrigation practices are intensive. Some causes such as shortcomings in irrigation water management, low irrigation efficiencies, heavy soil texture, insufficiencies in field drainage systems, etc. mostly result in problems of salinity in soil profile, waterlogging and groundwater salinity. Those problems negatively affect crop yield. In turn, drainage observations in space and time provide important information for sustainable water resources management. In this study, it is aimed at evaluating spatio-temporal characteristics in quality and quantity of groundwater in a large irrigation district area. In line with the objective, the study was conducted in the Akarsu Irrigation District (AID) area of the Lower Seyhan Plain (LSP), located in the south of Turkey. Irrigation has been practiced in the study area for more than 60-year. Irrigation scheme has been managed by adopting continuous flow regime so as to ensure continuous water supply for the growers at night and during the day. In this research, groundwater depth and groundwater quality data were collected from 108 drainage observation wells. Observations in each well were made four times a year, i.e. in February, April, July and October. It was figured out that severe drainage problems occurred in more than one-third of study area due to heavy winter rains. It was determined that depth of the groundwater was less than the critical levels (1 m) in the northern parts of Akarsu command area. On the other hand, areal averages of groundwater salinity were found to be quite low compared to the critical value of 5 dS m(-1). However, the average groundwater salinity reached at its lowest value in cool season, due to the dilution effect of rainfall in winter. Groundwater salinity was determined to be 5 dS m(-1) in the 15 to 26 % of the area throughout the year, except winter season. Total dissolved solid (TDS) in the groundwater body were found to be the highest at the end of the irrigation season, i.e. in October. Areal average of excess sodium, i.e Sodium Adsorption Ratio (SAR), in groundwater system was found to be less than the threshold SAR value of 13. Excessive irrigation water is discharged into the drainage channels during the night because the growers in the study area irrigate intensely during the day. Authorities in charge of irrigation management in the area are supposed to encourage irrigators to get used to nocturnal irrigation practices. Additionally, it was recommended that more effort be made in order to extend areas where sprinkler or low pressure drip irrigation systems are practiced instead of surface irrigation methods.