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A. Łajczak

downstream as far as the mouth of the last Carpathian tributary, at the present time. Directly below this tributary outlet, the Vistula is almost critically overburdened with suspended load. Further down the course of the river, however, the amount transported has become stabilized (Fig. 3). Due to dam construction work, suspended load transportation has been reduced in the Upper Vistula in recent decades by 20-50%, and in the Lower Vistula by 50%.

2. Auerage rates of suspended load sedimentation. The area limited by a hypothetical transportation curve for suspended load (a situation without sedimentation) and the real transportation curve, indicates the suspended load sedimentation rates along the Vistula. The detailed data concerning depositing rates in successive river valley stretches between the suspended load gauging stations or between the mouths of the

Fig. 10. Average rates of suspended load sedimentation, AS, in successive stretches of the inter-embankment zonę of the Vistula between gauging stations for load measurements. The rates of

sedimentation are expressed:

ASi — t yr^-1 (for the whole stretch of the inter-embankment zonę), AS₂ — t km^-1 yr^-1 (for 1 km of the zonę length). YASi and ZAS₂ — cumulative rates of sedimentation,

1 — sedimentation expressed as AS^ 2 — sedimentation expressed as AS₂, 3 — lASi values,

4 — XAS₂ values, 5 — sedimentation rates before 1968, 6 — sedimentation rates after 1969 (downstream of the Płock/Kępa Polska gauging station), (a-p) — gauging stations for

suspended load measurement on the Yistula (for their location see Fig. 1)