For　the　allotypic　hybrid　type　bucket,　the　contraction　in　its　lower　bucket　and　diffusion　in　its　upper　bucket　cause　the　jet　flows　to　cross　and　impact　each　other,　so　the　contraction　ratio　of　lower　bucket　is　a　key　parameter　to　determination　of　the　jet　characteristics.　Systematic　model　tests　of　this　bucket　were　conducted　under　different　contraction　ratios　to　examine　the　variations　of　flow-diversion　ratios　of　the　upper　and　lower　buckets,　the　pressure　distributions　in　these　buckets,　etc.　This　paper　establishes　empirical　formulas　for　estimation　of　various　jet　characteristics　under　different　contraction　ratios,　and　demonstrates　the　variations　of　jet　trajectory　length　and　local　scour　depth.　©　Copyright.