semiaridsemidiscretesemiflumidsemihumidsemiimpermeablesemiperched water tablesenilesenile riversensible tempraturesensitivitysensorseparting weirsepartionsepticsequencesequent depthsequential samplingservice gateservice lifeservice spillwaysettle able solidssettling basinsettling reservoirsettling solidssettling velocityshadowshadow areashaftshaft aerationshaft spillwayshallow gullyshallow watershallow water equationshallow water waveshamalshamal windshanksharpsharp crestsharp crest weirsharp crest weir with constractionsharp crested rectangular weirssharp crested weirsharp crested weirs with contractionshear strengthshear stressshear vane testshear velocitysheetsheet erosion