Agriculture University in Kraków Department of Water Engineering Andrzej Strużyński, Maciej Wyrębek Agriculture University in Kraków Department of Water Engineering Evaluation of the Nida River main current below the outlet of the perpendicular channel

XXVIII School of Hydraulics Localization XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics Main hydrological parameters Nida River basin XXVIII School of Hydraulics 23-26 September 2008, Krąg The area of the Nida River basin - 3862.8 km2 - Brzegi (km 97.8) - 2259 km2, - Motkowice (km 76.1) - 2499 km2 , - Pińczów (km 56.8) - 3352 km2 . The length of the Nida River - 151.2 km Characteristic flows: in Motkowice: Q50% = 130 m3/s, Q1% = 375 m3/s, in Pińczów: Q50% = 150 m3/s, Q1% = 450 m3/s. The average slope of the valley in the middle delta region I = 0,0007

XXVIII School of Hydraulics Localization of the object XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics Main hydrological parameters Nida River characteristics XXVIII School of Hydraulics 23-26 September 2008, Krąg The Nida River slope – 0.00067 the discharge: during summer – 6 - 9 m3/s bankfull discharge – 40 – 60 m3/s mean diameter – 0.6 mm

XXVIII School of Hydraulics Main hydrological parameters Nida River characteristics XXVIII School of Hydraulics 23-26 September 2008, Krąg mean diameter – 0.6 mm

XXVIII School of Hydraulics Main hydrological parameters reservoir XXVIII School of Hydraulics 23-26 September 2008, Krąg The area of the reservoir – 10 ha capacity – 160 000 m3 designed maximum depth – 1.93 m measured maximum depth – 1.5 m average depth – 1 m actual outflow – 170 l/s needed outflow trough the additional duct – 150-450 l/s the discharge during floods – 750 l/s actual retention – 8 days needed retention – 2-4 days the agreement for the intake water from the Nida River during winter – 272 l/s during summer – 1000 l/s

XXVIII School of Hydraulics Governing equations CCHE2D XXVIII School of Hydraulics 23-26 September 2008, Krąg The CCHE is an analysis system for two-dimensional, unsteady, turbulent river flow, sediment transport, and water quality evaluation Continuity equation: momentum equations:

XXVIII School of Hydraulics Governing equations CCHE2D XXVIII School of Hydraulics 23-26 September 2008, Krąg Reynolds stresses are approximated based on Boussinesq's assumption: There are two zero-equation eddy viscosity models adopted in CCHE2D model. The first one is the depth-integrated parabolic model, in which the eddy viscosity vt is calculated by the fallowing formula:

XXVIII School of Hydraulics Governing equations superposition of potential flow XXVIII School of Hydraulics 23-26 September 2008, Krąg flow potentials: where: w1 – potential flow in river, w2 – potential flow in channel, U – average velocity in river, z – imaginary variable, q – discharge per unit width, b – half width of the channel. where: φ – velocity potential, ψ – current function.

XXVIII School of Hydraulics CCHE2D modelling XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics CCHE2D modelling XXVIII School of Hydraulics 23-26 September 2008, Krąg profiles up: longitudinal in river down: longitudinal in channel with cross-section of Nida River

XXVIII School of Hydraulics CCHE2D results XXVIII School of Hydraulics 23-26 September 2008, Krąg case 0 river Q = 8 m3/s channel Q = 0.001 m3/s

XXVIII School of Hydraulics CCHE2D results XXVIII School of Hydraulics 23-26 September 2008, Krąg case 0 river Q = 8 m3/s channel Q = 0.001 m3/s

XXVIII School of Hydraulics CCHE2D case 2, Qr = 8, Qc = 0.45 [Q3/s] XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics CCHE2D case 3, Qr = 8, Qc = 0.75 [Q3/s] XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics CCHE2D case 4, Qr = 40, Qc = 0.75 [Q3/s] XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics CCHE2D case 5, Qr = 70, Qc = 0.75 [Q3/s] XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics CCHE2D case 2, Qr = 8, Qc = 0.45 [Q3/s] results – comparing XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics CCHE2D results XXVIII School of Hydraulics 23-26 September 2008, Krąg maximum safe velocity [m/s] 0.42 0.42 0.42 0.49 0.52

XXVIII School of Hydraulics Results XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics Results XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics Main hydrological parameters Nida River characteristics XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics CCHE2D results XXVIII School of Hydraulics 23-26 September 2008, Krąg case 4, 5 case 3 case 1, 2

XXVIII School of Hydraulics Results XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics 1. Few conclusions XXVIII School of Hydraulics 23-26 September 2008, Krąg The results of performed modeling in cases 1 and 2 approved the possibility of using the proposed conduct during low flow conditions in river and reservoir. The results calculated in case 3 indicate that flow from the channel would overcome parameters of bed stability. As shown in case 4 results the conduct should not be used in high flow conditions appearing in the river. There would be possible to perform short term outflows of needed Q=0.75 [m3 s-1] of which influence would be easily supplement within the natural processes of aggradation of bed material. In case 5 there is a backwater in the conduct. The drown outlet will increase flow resistance in the pipe (in CCHE2D modeled as channel). This would decrease the risk of using the conduct in flood conditions in the Nida River. The CCHE2D modeling was finished with results which could be compared with Chezy calculations as well as with superposition of potential flow method. The problem of instability of the model wasn't solved in performed modeling session. The results taken from created mesh should be verified on new mesh of higher density localized close to the outlet of the channel.

XXVIII School of Hydraulics 2. Few conclusions XXVIII School of Hydraulics 23-26 September 2008, Krąg

XXVIII School of Hydraulics 2. Few conclusions XXVIII School of Hydraulics 23-26 September 2008, Krąg Thank you for your attention