Purpose　In　complex　watersheds　with　multiple　types　of　waterbodies,　the　effect　of　river　damming　on　the　distribution　pattern　of　heavy　metals　in　sediments　and　their　potential　ecological　risks　are　inconsistent,　leading　to　an　inability　to　accurately　manage　heavy　metal　pollution.　The　aim　of　this　study　was　to　reveal　the　driving　mechanisms　of　hydropower　reservoirs　on　the　distribution　of　heavy　metals　in　sediments　and　their　ecological　risks.　Materials　and　methods　Characterization　of　the　spatial　distribution　patterns　of　Cd,　Cr,　Cu,　Ni,　Pb,　and　Zn　and　evaluation　of　their　ecological　risks　in　surface　sediments　were　conducted　to　explore　the　role　of　dam　construction　and　operation　in　modulating　heavy　metal　pollution　in　the　Jiulong　River　Basin　(JRB)　using　sequentially　extracted　European　Community　Bureau　of　Reference　(BCR)　extraction　scheme,　geo-accumulation　index　(I-geo),　and　potential　ecological　risk　(RI).　Results　and　discussion　The　results　showed　that　hotspot　patchiness　pattern　of　sediment　heavy　metal　contents　highly　matched　the　reservoir　distribution　but　not　for　the　non-dammed　south　river　of　the　JRB.　Ecological　risk　assessment　demonstrated　the　RI　of　sediment　heavy　metals　in　the　reservoir　was　markedly　higher　than　those　in　the　mainstream　and　its　tributary　(p　＜　0.05),　and　the　potential　ecological　risks　were　dominated　by　Cd,　followed　by　Pb　in　the　sediments　of　three　waterbodies　(reservoir,　mainstream,　tributary).　Moreover,　BCR　heavy　metal　fractionation　showed　bioavailability　of　heavy　metals　in　Xipi　Reservoir　sediments　was　much　greater　than　that　in　downstream　reservoir　sediments.　The　reason　for　this　phenomenon　was　mainly　attributed　to　the　elongation　of　hydraulic　residence　time　(HRT)　in　this　reservoir,　which　promoted　suspended　solid　sorting　by　grain　size　and　consequent　deposition,　facilitating　adsorption　of　finer　sediments,　with　more　bioavailable　heavy　metals　falling　onto　the　upper　sediment　layer　in　the　reservoir.　Conclusions　In　brief,　dam　construction　and　operation　reinforced　the　accumulation　of　heavy　metals　and　aggravated　potential　ecological　risks　in　reservoir　surface　sediments.　These　findings　deepen　current　understanding　of　the　driving　mechanism　of　reservoirs　for　sediment　heavy　metal　pollution　and　confer　the　probability　to　precisely　control　sediment　heavy　metal　pollution　for　management　practices　in　the　multitype　waterbody　catchment.