Analysis of the Effectiveness of Interceptor Drain on Vegetation Changes (Case Study: Salt Marsh in Qazvin Plain)

Climatic conditions and soil properties such as salinity are very important and influential factors in vegetation of any region. The salinity of the groundwater and the accumulation of salts in the surface layers of the soil due to evaporation and capillary rise have caused salinization in a part of Qazvin plain that has had adverse effects on the growth of plant species in an area of ​​60,000 hectares. In order to control the devastating effects of Salt Marsh development in the area, interceptor drain has been constructed in the central Salt Marsh core. The purpose of this study was to analyze the Effectiveness of Interceptor Drain on Soil Salinity and Vegetation Changes during 5 years with 10 exclosures. To investigate the effects of drain construction, the statistical analysis was performed in a factorial randomized complete block design. The results show that the electrical conductivity of deep soil is 18% more than the electrical conductivity of surface soil. The results of comparing the average soil electrical conductivity based on Duncan's method showed that the average soil electrical conductivity was highest in 2013 and the lowest in the fourth year after the beginning of the study. Since the main source of soil leaching in the area of ​​excavated crops is runoff, therefore the most important cause of soil electrical conductivity variations with different years can be related to the amount of spring rainfall. The results of statistical analysis showed that the electrical conductivity of the soil decreased gradually by passing years in the constructed exclosures. The results of variance analyses of vegetation percentages in exclosures showed that the constructed interceptor drain has had a significant effect on vegetation changes during the studied years and the spatial effectiveness of the drain on vegetation changes has been 300 m.