▁land ▁area , ▁virt ually ▁the ▁entire ▁landscape ▁is ▁ster ile ▁of ▁veget ation , ▁with ▁g ul ly ▁er os ive ▁fur rows ▁typically ▁in ▁excess ▁of ▁ ▁deep ▁and ▁ ▁wide . ▁Sh ifting ▁cultiv ation ▁is ▁a ▁far ming ▁system ▁which ▁sometimes ▁incorpor ates ▁the ▁slash ▁and ▁burn ▁method ▁in ▁some ▁regions ▁of ▁the ▁world . ▁This ▁de gr ades ▁the ▁soil ▁and ▁causes ▁the ▁soil ▁to ▁become ▁less ▁and ▁less ▁fert ile . ▁ ▁Ro ads ▁and ▁urban ization ▁Urban ization ▁has ▁major ▁effects ▁on ▁er os ion ▁processes — first ▁by ▁den ud ing ▁the ▁land ▁of ▁veget ative ▁cover , ▁alter ing ▁d rain age ▁patterns , ▁and ▁compact ing ▁the ▁soil ▁during ▁construction ; ▁and ▁next ▁by ▁covering ▁the ▁land ▁in ▁an ▁imper me able ▁layer ▁of ▁as ph alt ▁or ▁concrete ▁that ▁increases ▁the ▁amount ▁of ▁surface ▁run off ▁and ▁increases ▁surface ▁wind ▁spe eds . ▁Much ▁of ▁the ▁sed iment ▁carried ▁in ▁run off ▁from ▁urban ▁areas ▁( es pecially ▁roads ) ▁is ▁highly ▁cont amin ated ▁with ▁fuel , ▁oil , ▁and ▁other ▁chemical s . ▁This ▁increased ▁run off , ▁in ▁addition ▁to ▁er oding ▁and ▁de grad ing ▁the ▁land ▁that ▁it ▁flows ▁over , ▁also ▁causes ▁major ▁dis ruption ▁to ▁surrounding ▁waters h eds ▁by ▁alter ing ▁the ▁volume ▁and ▁rate ▁of ▁water ▁that ▁flows ▁through ▁them , ▁and ▁filling ▁them ▁with ▁chem ically ▁poll uted ▁sed iment ation . ▁The ▁increased ▁flow ▁of ▁water ▁through ▁local ▁water ways ▁also