▁role ▁in ▁cultiv ating ▁the ▁bog . ▁In ▁the ▁Middle ▁A ges ▁some ▁places ▁at ▁the ▁edges ▁of ▁the ▁bog ▁were ▁dra ined ▁for ▁growing ▁r ye . ▁The ▁d rain age ▁caused ▁soil ▁sett ling ▁and ▁the ▁area ▁became ▁more ▁vulner able ▁to ▁flo od ings . ▁Between ▁ 1 3 6 0 ▁and ▁ 1 5 0 0 ▁parts ▁in ▁the ▁n ortheast ▁were ▁was hed ▁away ▁by ▁the ▁D oll art . ▁ ▁In ▁the ▁ 1 6 th ▁century ▁large - scale ▁pe at ▁har vest ing ▁began . ▁The ▁F ris ian ▁method , ▁using ▁can als , ▁was ▁introduced . ▁At ▁first ▁most ▁pe at ▁har vest ing ▁was ▁done ▁at ▁the ▁river ▁Hun ze ▁near ▁the ▁city ▁of ▁G ron ingen . ▁The ▁pe at ▁could ▁be ▁transport ed ▁to ▁the ▁city ▁via ▁this ▁small ▁river . ▁In ▁the ▁ 1 7 th ▁century , ▁West er wol de ▁came ▁under ▁control ▁of ▁the ▁city ▁of ▁G ron ingen ▁and ▁the ▁pe at ▁har vest ing ▁became ▁more ▁large - scale d ▁Johan ▁de ▁la ▁Hay e ▁and ▁Johan ▁S ems ▁designed ▁a ▁line ▁right ▁through ▁the ▁western ▁' leg ' ▁of ▁the ▁bog , ▁de ▁S ems lin ie . ▁De ▁S ems lin ie ▁is ▁a ▁straight ▁line ▁between ▁Wolf s bar ge ▁( a ▁village ▁near ▁the ▁Z uid la ard erme er ) ▁and ▁Ter ▁Ap el . ▁Now ad ays ▁it ▁is ▁the ▁border ▁between ▁Dr ent he ▁and ▁the ▁Province