Investigation of Salinity Consequences Resulting from Drainage Systems Using Numerical Models

Land drainage practices represent a suitable technique that can assist managing the water table and control salinity levels. Until the last few decades, mainly the positive aspects of drainage performance have been addressed rather than negative impacts. Despite the positive effect of drainage systems on agricultural land, nowadays, drainage water flow containing too much salt constitutes a serious concern for the environment, including the accumulation of salt deposits and environmental contamination and destruction. Measured data from observation wells drilled around a drainage system were investigated to understand the effectiveness of drains to decrease the salinity level of groundwater using data analysis and simulation. The results indicate that the salinity level of the drained land considerably decreased to $4.4–137.7\mathrm{dS}{\mathrm{m}}^{-1}$ within 3 years (2010–2014). In contrast, annually over $244.3\mathrm{t}{\mathrm{ha}}^{-1}$ salt load has entered into the environment; this is expected to create a salty layer of 10 cm thickness over 1,000 ha, adjacent to the outlet, due to the operation of drainage.