Open Channel Flow and Coastal Engineering MCQs 2026

Manning formula for open channel flow relates

1. A Concrete strength and rebar ✓
2. B Velocity discharge hydraulic radius and slope ✓
3. C Bitumen penetration and ductility ✓
4. D Wind speed and runway length ✓

Manning roughness coefficient n lower for

1. A Smooth concrete lining ✓
2. B Rough vegetated channel ✓
3. C Loose boulder bed ✓
4. D Uncleaned natural swamp ✓

Hydraulic jump occurs when

1. A Depth constant always ✓
2. B Flow transitions from supercritical to subcritical ✓
3. C Only in pipes under pressure always ✓
4. D Only in air always ✓

Specific energy at a section is

1. A Depth plus velocity head relative to bed ✓
2. B Only pressure head in pipe flow ✓
3. C Only wind kinetic energy ✓
4. D Only building live load ✓

Froude number Fr equals

1. A Q / A only without gravity ✓
2. B Manning n only ✓
3. C V / sqrt(g y) ✓
4. D Reynolds number always same ✓

Critical depth occurs when

1. A Maximum channel width ✓
2. B Zero velocity always ✓
3. C Maximum Manning n ✓
4. D Specific energy minimum for given discharge ✓

Uniform flow in channel means

1. A Depth slope velocity constant along reach ✓
2. B Water surface horizontal always wrong ✓
3. C Only tidal oscillation ✓
4. D Only pressurized pipe flow ✓

Gradually varied flow profile depends on

1. A Only paint colour of lining ✓
2. B Only wind on building ✓
3. C Bed slope discharge and channel shape versus critical normal depth ✓
4. D Only railway cant ✓

Normal depth in uniform flow from

1. A Random choice ✓
2. B Manning equation balance for given Q and slope ✓
3. C Only seismic coefficient ✓
4. D Only FAR zoning ✓

Wide rectangular channel hydraulic radius approximates

1. A Width b always ✓
2. B Zero always ✓
3. C b/y always ✓
4. D Flow depth y ✓

Chezy formula alternative to Manning uses

1. A Chezy coefficient C ✓
2. B Only Darcy friction factor pipe only always ✓
3. C Only wind drag coefficient ✓
4. D Only CBR value ✓

Most economical trapezoidal section for open channel often derived assuming

1. A Circular pipe always only shape ✓
2. B Vertical walls infinite cost only always ✓
3. C No freeboard ever ✓
4. D Certain side slope and hydraulic radius depth relation ✓

Freeboard in canal design provides

1. A Zero safety always ✓
2. B Margin against wave and operational fluctuations ✓
3. C Only decoration ✓
4. D Only fish habitat only purpose ✓

Lining of canal reduces

1. A Flow capacity always decreases always wrong ✓
2. B Only increases roughness always wrong ✓
3. C Seepage losses and improves hydraulic efficiency ✓
4. D Only adds weeds always ✓

Tidal hydraulics in estuary involves

1. A Steady uniform flow only always ✓
2. B Only wind in desert ✓
3. C Only railway drainage ✓
4. D Oscillating flow from ocean tides ✓

Significant wave height Hs is

1. A Average height of highest third of waves ✓
2. B Minimum wave always ✓
3. C Single ripple only ✓
4. D Tsunami height always same statistic ✓

Littoral drift transports

1. A Only water offshore deep only ✓
2. B Only air wind inland only ✓
3. C Sediment along coast by wave action ✓
4. D Only railway ballast ✓

Groynes built perpendicular to coast trap

1. A All water permanently ✓
2. B Sediment on updrift side ✓
3. C Only wind ✓
4. D Only ships ✓

Seawall purpose is

1. A Protect land from wave attack ✓
2. B Increase wave height landward always purpose wrong ✓
3. C Only harbour shipping channel dredge ✓
4. D Only road camber ✓

Estuary is

1. A Dry desert wadi only always ✓
2. B Tidal mixing zone of river and sea ✓
3. C Mountain glacier only ✓
4. D Building basement ✓

Sediment transport in channels described by

1. A Only dissolved oxygen ✓
2. B Only chlorine residual ✓
3. C Bed load suspended load and wash load ✓
4. D Only bitumen fumes ✓

Shields parameter used for

1. A Concrete curing ✓
2. B Asphalt mixing ✓
3. C Wind on runway ✓
4. D Incipient motion of bed particles ✓

Chezy-Mannings relation n increases with

1. A Flow velocity always inversely n definition wrong direction question ✓
2. B Channel roughness ✓
3. C Channel slope always directly not definition of n ✓
4. D Water temperature only always ✓

Hydraulic radius defined as

1. A Width times depth only always without perimeter ✓
2. B Top width only ✓
3. C Flow area divided by wetted perimeter ✓
4. D Volume only ✓

Supercritical flow in channel is

1. A Slow deep always ✓
2. B Only in pipes always ✓
3. C Only tidal only ✓
4. D Rapid shallow Fr greater than 1 ✓

Broad crested weir used to

1. A Pave highway ✓
2. B Measure or control discharge in channels ✓
3. C Lay railway track ✓
4. D Build dam only always without weir type ✓

Venturi flume measures flow by

1. A Constriction causing head difference ✓
2. B Magnetic railway ticket ✓
3. C Wind pressure on building ✓
4. D Bitumen softening ✓

Afflux upstream of bridge obstruction is

1. A Decrease always ✓
2. B Only wind setup on lake unrelated ✓
3. C Only runway elevation ✓
4. D Increase in water surface elevation ✓

Scour at bridge pier caused by

1. A Only wind on deck ✓
2. B Only seismic shake only ✓
3. C Acceleration and vortices around obstruction ✓
4. D Only paint loss ✓

Riprap at channel bank protects against

1. A Only wind erosion always only ✓
2. B Erosion by flowing water ✓
3. C Only traffic load ✓
4. D Only building settlement ✓

Spur dike angled into stream redirects flow to

1. A Increase erosion same bank always purpose wrong ✓
2. B Stop river forever completely always ✓
3. C Only increase navigation always harmful ✓
4. D Reduce bank erosion on opposite side ✓

Regime theory in alluvial channels relates

1. A Width depth slope to discharge and sediment ✓
2. B Only concrete strength ✓
3. C Only wind load ✓
4. D Only runway friction ✓

Lacey wetted perimeter formula used in

1. A Airport runway length ✓
2. B Harbour berth width only ✓
3. C Alluvial channel design in Pakistan ✓
4. D Building column design ✓

Critical slope for given Q makes

1. A Always zero slope ✓
2. B Always infinite slope ✓
3. C Always subcritical only ✓
4. D Normal depth equal critical depth ✓

Hydraulic jump conjugate depths from

1. A Only energy equation alone always insufficient ✓
2. B Momentum equation across jump ✓
3. C Only Manning alone ✓
4. D Only wind chart ✓

Energy dissipation block in stilling basin creates

1. A Wave reflection at sea wall only unrelated ✓
2. B Wind turbulence only ✓
3. C Controlled jump location ✓
4. D Rail vibration ✓

Tidal range is difference between

1. A High water and low water elevation ✓
2. B Wind speed max min ✓
3. C Temperature day night ✓
4. D Traffic peak off peak ✓

Coastal sediment budget balances

1. A Only concrete production ✓
2. B Inputs outputs and storage along reach ✓
3. C Only steel import ✓
4. D Only labour cost ✓

Longshore transport driven by

1. A Only river discharge alone always perpendicular always wrong ✓
2. B Only gravity dam seepage ✓
3. C Oblique wave approach generating alongshore current ✓
4. D Only building HVAC ✓

Breakwater shadow zone may cause

1. A Automatic beach build always ✓
2. B Zero waves always beneficial always wrong tradeoff ✓
3. C Only increase ship speed ✓
4. D Down drift erosion from reduced sediment supply ✓

Salinity intrusion in estuary worsens when

1. A River flow low and tide high ✓
2. B Flood flow maximum always pushes salt out ✓
3. C Only wind from desert always primary ✓
4. D Only snow melt in desert none ✓

Open channel carriers in Pakistan irrigation include

1. A Only motorway drainage only always ✓
2. B Only airport taxiway ✓
3. C Branch distributaries minors and watercourses ✓
4. D Only railway culvert only ✓

Check structure in canal regulates

1. A Vehicle speed on highway ✓
2. B Water level and discharge downstream ✓
3. C Aircraft takeoff ✓
4. D Train timetable ✓

Cross regulator in canal system

1. A Controls water level upstream for rotation ✓
2. B Stops earthquakes ✓
3. C Measures wind ✓
4. D Tests bitumen ✓

Sediment excluder at canal headworks removes

1. A All water entirely wrong ✓
2. B Only fish always only ✓
3. C Only air ✓
4. D Bed load entering canal ✓

Wave refraction bends wave crests toward

1. A Always offshore deep always wrong ✓
2. B Mountain peaks ✓
3. C Shallower regions parallel to depth contours ✓
4. D Building roofs ✓

Wave diffraction occurs when

1. A Waves pass gap or around structure ✓
2. B Only in pipes ✓
3. C Only in concrete curing ✓
4. D Only in soil consolidation ✓

Run-up on beach is

1. A Train speed on upgrade ✓
2. B Vehicle stopping distance ✓
3. C Building drift ✓
4. D Max vertical swash extent on slope ✓

Coastal groin field design considers

1. A Only bitumen grade ✓
2. B Spacing length and sediment transport direction ✓
3. C Only rebar diameter ✓
4. D Only zoning FAR ✓

Subcritical flow is

1. A Tranquil deeper Fr less than 1 ✓
2. B Always shooting flow ✓
3. C Only in air ✓
4. D Only pressurized ✓