اولویت بندی مکانی زهکشی زیرزمینی در محدوده پروژه آبیاری و زهکشی البرز

In order to produce the world’s growing population food demands, it would be necessary to increase the productivity. Most of this increase should be gain by funding for improving irrigation and drainage at current fields. High costs of these projects and the funds’ limitation make challenges to conduct the projects; so in order to have optimized use of the limited funds, it would be necessary to spatial prioritize the projects. At the current study spatial prioritization of subsurface drainage within the Alborz irrigation and drainage project was evaluated by using geographical information system (GIS). Prioritization was done based on the electrical conductivity and depth to water table. After determining limitations for effective factors on positioning, the interpolation done and interpolated maps were exported. After complexion of the interpolated maps for different factors, the prioritization map for conducting subsurface drainage was gained. The geostatistical analysis tool of ArcGIS software was used for interpolation. According to the results the kriging method had acceptable results for interpolation. After positioning the locations with various prioritizations, it founded that an area about 10300 ha (about 54.64 % of total area) was in the 1st and 2nd prioritizations. Generally these lands were at the northern half of area near to Caspian Sea. The main problems of these lands were salinity, swamplands or mixture of these two factors. According to the positive effect of drainage on rice productivity as one of the main crops of the area, conducting subsurface drainage systems for higher priorities is suggested.