ESTIMATION OF HYDRAULIC PARAMETERS OF ARMORED LAYER FORMING IN MOUNTAIN RIVERS AND STREAMS Wojciech Bartnik, Andrzej Strużyński Krakow Agriculture University

PLAN Introduction Bed load Characteristics of bed load Field and laboratory measurements Velocity profile during change of bed parameters Conclusions

INTRODUCTION Hydraulic parameters of armored layer forming can be described on basis of stochastic nature of bed load movement proposed by Gessler. The purpose of laboratory experiment was to describe the change of velocity profile and basic hydraulic parameters during armoring process.

BED LOAD Stochastic nature of grain movement – turbulence...

BED LOAD Stochastic nature of grain movement – loops, sweeps...

BED LOAD Gessler’s function

BED LOAD Shields curve, Wang’s equation, Bartnik’s modification

FIELD MEASUREMENTS Tenczyński Stream

FIELD MEASUREMENTS Tenczyński Stream

FIELD MEASUREMENTS Tenczyński Stream

FIELD MEASUREMENTS Tenczyński Stream

FIELD MEASUREMENTS Krzczonowski Stream – upper part

FIELD MEASUREMENTS Krzczonowski Stream

FIELD MEASUREMENTS Krzczonowski Stream

LABORATORY MEASUREMENTS Flume dimensions: l2.0 x 0.5 x 0.6 m (glass walls) Flume rig: micro-propeller flow-meter slope measurements Bed slope, water surface slope Discharge: max 0.13 qm s -1 Trap for bed load Artificial grains Ø – 4 to 8 cm

LABORATORY MEASUREMENTS artificial and natural grains

LABORATORY MEASUREMENTS artificial and natural grains

BED ROUGHNESS artificial and natural grains Profile-meter AG-1

BED ROUGHNESS comparing roughness with K

BED ROUGHNESS observation of critical stresses

VELOCITY PROFILE DURING CHANGE OF BED PARAMETERS bed load transport influences roughness (K)

VELOCITY PROFILE DURING CHANGE OF BED PARAMETERS U/U max = A log (y/Y) + B B becomes constant -B = 1.12 ± 3% A = 39.3 K A = 6.38 (Y/K)

VELOCITY PROFILE DURING CHANGE OF BED PARAMETERS U/U max = A log (y/Y) + B

CONCLUSIONS The interaction between bed load and flowing water creates the actual flow parameters. Bed roughness acts on flowing water more significantly after armouring process. Small fractions hidden and packed in bigger ones make bed roughness smaller. During flood after uncovering armour coat mass transport appear due to even higher bed velocity. Scouring process grows stronger then before. After flood accumulation zones appear and river flow direction changes due to flow concentration.