ia ▁and ▁f ec al ▁indicator ▁organ isms ▁like ▁E scher ich ia ▁col i ▁and ▁enter oc oc ci , ▁which ▁can ▁cause ▁g astro int est inal ▁ill ness . ▁In ▁fact , ▁a ▁positive ▁relation ▁between ▁time ▁spent ▁on ▁wet ▁sand y ▁be aches ▁and ▁the ▁inc idence ▁of ▁contract ing ▁a ▁g astro int est inal ▁ill ness ▁has ▁been ▁identified . ▁ ▁Top ographic ▁and ▁veget ation ▁alter ations ▁ ▁Gro omed ▁be aches ▁are ▁wider , ▁sust ain ▁substantial ly ▁less ▁veget ation , ▁and ▁have ▁fewer ▁and ▁fl atter ▁top ographic ▁features , ▁like ▁d unes ▁and ▁hum mock s , ▁than ▁ung room ed ▁be aches . ▁Natur ally ▁be aches ▁should ▁have ▁a ▁narrow ▁stretch ▁of ▁sand ▁closest ▁to ▁the ▁ocean ▁that ▁is ▁fl atten ed ▁by ▁the ▁t ide ▁below ▁the ▁extreme ▁high ▁t ide ▁line . ▁Bey ond ▁this ▁zone , ▁the ▁land ▁should ▁be ▁composed ▁of ▁veget ated ▁d unes ▁that ▁are ▁inf re qu ently ▁touched ▁by ▁t ides . ▁However , ▁mechanical ▁beach ▁clean ing ▁has ▁converted ▁many ▁be aches ▁into ▁much ▁wider ▁exp ans es ▁of ▁flat ▁sand , ▁most ▁of ▁which ▁remains ▁und ist urbed ▁by ▁the ▁t ide ▁and ▁void ▁of ▁veget ation . ▁Mechan ical ▁beach ▁clean ing ▁dest ro ys ▁veget ation , ▁hum mock s , ▁and ▁newly - formed ▁d unes , ▁leading ▁to ▁an ▁immediate ▁fl atten ing ▁of ▁the ▁landscape . ▁Mechan ical ▁clean ing ▁not ▁only ▁dam ages ▁existing