Warning messages

Updated on 08 Aug 2024
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Warnings W2000-W2099

Warning code	Message	Info / troubleshooting / details - what do I do to resolve!
W2000	Poor model convergence	The model has failed to converge to a solution within the defined tolerances at at least one location for the current time step and may be the onset of instabilities within the model. Full details of the location and magnitude of the convergence error are found in the diagnostics (.zzd) file; a greater description of their meanings is given in Convergence information. NB The error code number 2000 is only output to the diagnostics panel/information file (.exy) and not the diagnostic log file (*.zzd).
W2001	Conduits with variable x-section are not permitted	The cross section of a conduit varies between adjacent sections. The direct steady method cannot solve this situation and assumes that the first (downstream-most) cross section applies for all sections in the reach. The pseudo time stepping steady method should be used if this approximation is unacceptable.
W2002	Conduits with variable bottom friction are not permitted	The bottom friction of a conduit varies between adjacent sections. The direct steady method cannot solve this situation and assumes that the bottom friction for the first (downstream-most) section applies for all sections in the reach. The pseudo time stepping steady method should be used if this approximation is unacceptable.
W2003	Conduits with variable top friction are not permitted	The top friction of a conduit varies between adjacent sections. The direct steady method cannot solve this situation and assumes that the top friction for the first (downstream-most) section applies for all sections in the reach. The pseudo time stepping steady method should be used if this approximation is unacceptable.
W2004	Conduits with variable friction forms are not permitted	The friction formula of a conduit varies between adjacent sections. The direct steady method cannot solve this situation and assumes that the friction formula for the first (downstream-most) section applies for all sections in the reach. The pseudo time stepping steady method should be used if this approximation is unacceptable.
W2005	Conduits with variable side friction are not permitted	The side friction of a conduit varies between adjacent sections. The direct steady method cannot solve this situation and assumes that the side friction for the first (downstream-most) section applies for all sections in the reach. The pseudo time stepping steady method should be used if this approximation is unacceptable.
W2008	Water level below invert. label(node) = 'l'('n'); water level = 'x'	The water level has been calculated as below the conduit invert level and indicates that the solution is potentially unstable - the pseudo time stepping steady method will try to recover from this condition; however, if the problem persists then the following steps could be taken: check the data at 'label' for errors; improve the initial conditions; reduce the timestep or distance step; use the direct steady method or move from a previous steady result to the required flow/stage using an unsteady run. Also, check the invert level is consistent with the adjoining unit; insert a weir if appropriate.
W2010	Poor interpolation u/s of 'label' max u/s area of area1 -> area2	The cross section area at the sections between which an INTERPOLATE section is required differs by a factor of two or more. Such large changes in area suggest that further survey data are necessary.
W2012	Flow over side spills not calculated	The direct steady method has detected flow was possible over the side spills listed in the diagnostics file (filename extension '.zzd'), but does not calculate such flow.
W2013	Very small change in flow resulting from correction (answer not found) at 'unit' 'label' q_reach = 'x' q_calc = 'y'	This indicates that the structure at 'label' is very insensitive to changes in head (obsolescent tidal drainage sluice units only). Check that the data for this unit are correct.
W2014	Unit attached to labels ''label1","label2'' running dry; water depth set to Dmin value of 'x' metres	The water level at a bernoulli loss in the direct method has been calculated as being below minimum depth. The water level has been reset to minimum depth; you are advised to check the reults and model schematisation in this area.
W2016	Steady file could not be opened, probably owing to file open to other user	Also check the read and write file attributes for the '.zzs' file.
W2017	Extra sections need to be added by the user	The direct steady method added additional sections to improve accuracy. It is recommended that extra sections are also added to the datafile as listed in the diagnostics file (filename extension '.zzd'). The INTERPOLATE unit may be used to provide the additional data.
W2018	Indeterminate reaches have been found	The direct steady method located indeterminate reaches as listed in the diagnostics file (filename extension '.zzd'). The water levels and flows in these reaches are undetermined. This may be because zero flow has been imposed upstream of a structure.
W2019	Water level rose beyond the max level of section data. Solution computed assuming extra 3m wall for non-CES sections, or max depth x 1.5m for CES sections, at max breadth	Calculated water level exceeded the section data maximum and used the 'glass wall' vertical extension of dflood (or the CES multiplier for CES sections). The section labels at which this condition occurred are listed in the diagnostics file (filename extension '.zzd'). The survey data should be extended at these sections, particularly those with no spill attached (this is indicated inthe zzd file also).
W2020	Water level >3m above max level of section data for at least one section.	Calculated water level exceeded the section data maximum, including the 'glass wall' vertical extension of dflood (or the CES multiplier for CES sections). The section labels at which this condition occurred are listed in the diagnostics file (filename extension '.zzd'). The survey data should be extended at these sections. This may cause mass inconservancy at the sections involved.
W2021	Warning. The solution will be found with an accuracy of 'x' cm. If you want to increase the accuracy for the direct method, decrease maximum tolerance at line number 2	A direct method tolerance of between 0.01m and 0.1m has been specified (General System Parameters, or "Direct Method Convergence Parameter" in the Parameters tab of the 1D Simulation interface). This indicates that the solution is not as accurate as is recommended. Note that a tolerance of greater than 0.1m will generate a fatal error.
W2023	Zero areas in Bernoulli Loss unit attached to labels ''label1'' and ''label2''. Zero flow will be imposed.	A zero area has been calculated at one or both nodes of the bernoulli loss unit - this usually indicates the water level is below the invert; zero flow is imposed at this unit.
W2024	'x' extra sections gave insufficient accuracy between 'label1' and 'label2'	The direct steady method was unable to obtain normal accuracy between 'label1' and 'label2'. The calculated upstream water level is not converging quickly enough. If this message occurs during the final iteration then the data at these labels may require attention.
W2025	Data error found in RNDSC gate not open at highest water depth label = 'label'	The direct steady method requires the gate to be open at the highest water depth. The program may open the gate to 0.1m, although the user should alter the datafile as appropriate to the physical conditions. Obsolescent tidal drainage sluice units only.
W2026	CONDUIT and RIVER units should not be directly connected together; labels involved are 'label1' and 'label2'	One is advised to insert a junction, loss unit or appropriate structure between conduit section and river units. NB A river section attached to a geometric conduit unit will cause a fatal error.
W2027	No rules are currently valid for RULES unit associated with label 'label' at model time 'x' hrs.Unit will use previous setting of 'x'	Check that the rules applied cover all eventualities
W2031	'x' reservoir unit(s) in the network. Note that the flow from/to reservoirs is not calculated in the current version of the direct method	The unsteady or pseudo time stepping steady methods should be used if reservoirs are hydraulically significant features of the network with the current boundary conditions.
W2032	Water level outside channel boundary. label(node) = 'label'('n'); water level ='x'	The applied water level is below bed level or above the section maximum, and is probably an indication of model instability. This could be due to poor initial conditions or a data error. The error may be avoided by using a non-zero minimum water depth (General System Parameters, or via the Parameters tab on the 1D Simulation interface).
W2033	Warning; zero area calculated at node 'label'	A zero cross sectional area has been detected - check the RIVER data. If this message recurs several times and it seems to cause errors in the run then the minimum depth must be set to a positive value in the General System Parameters, or via the Parameters tab on the 1D Simulation interface.
W2034	N overbank spill unit(s) in the network. Note that no calculations are performed for overbank spills in the current version of the direct method	The unsteady or pseudo time stepping steady method should be used if spills are hydraulically significant features of the network with the current boundary conditions.
W2035	The HT boundary at 'label' is at the upstream end of a reach. This is not permitted	The direct steady method requires flow:time boundaries at the upstream end of reaches. Upstream stage time boundaries may cause indeterminacy and are not recommended in most cases.
W2036	The QH boundary at 'label' is at the upstream end of a reach. This is not permitted	The direct steady method requires flow:time boundaries at the upstream end of reaches. Upstream flow head boundaries should not be used.
W2037	The qt boundary at 'label' is at the downstream end of a reach. This is not permitted	The direct steady method requires stage time or flow head boundaries at the downstream end of reaches. Downstream flow time boundaries may cause indeterminacy and are not recommended in most cases.
W2039	no. of split parameters ('w') + no. of ht + qh boundaries ('x') does not equal no. of join parameters ('y') + no. of qt boundaries ('z')	The direct method cannot resolve the network. The cause of this condition is usually explained by the error messages displayed prior to this message. Often this is caused by in-line reservoirs in the model, or other configuration not conforming to the direct method rules. The direct method will not solve the parts of the network which are incorrectly defined and therefore the results must be checked for reaches not solved. Using the pseudo-timestepping steady state solver may be more appropriate.
W2040	Split estimates are wrong at the junction involving 'label'	The direct steady method requires that in initial conditions the total inflow and outflow at a confluence are equal. This situation should normally be resolved internally.
W2042	Illegal tidal constituent at line 'l'	There is an error in the tidal boundary data at line 'l'. Check the datafile. See the Help file for a list of valid Tidal constituents.
W2043	Warning at line 'l'. Decreasing cross section distance	A decreasing cross-chainage value has been detected in the cross-section data. Check the data entry.
W2044	Above line'l': different values (+/- 20 %) for Mannings n encountered within one panel. Make sure L/R panel markers do not appear within an arch.	Differing values of Manning's n (of over 20%) have been entered within the same panel. You are normally advised to insert panel markers when the Manning's value changes. Note that panel markers may not appear within bridge arches.
W2045	Water level at or below reservoir invert. It has been reset to the invert 'x' m at label 'label'.	The water level within a reservoir has been reset to the invert level + minimum depth. This may be caused by poor initial conditions, or the reservoir outflow exceeding the reservoir volume. Reducing the timestep may assist the latter, as may setting the reservoir emptying factor to 1 (Low Flow Options tab on the 1D Simulation interface). Note that this message may appears a maximum of 50 times.
W2046	n lateral inflows unit(s) in the network; note that lateral inflows are set to zero in the current version of the direct method	Lateral inflows to Muskingum routing units are ignored in the direct method. Use the pseudo-timestepping steady method if preferred.
W2047	Non-rectangular control section used with notional weir. This is not available. A rectangular control section has been assumed.	An exponent exceeding 1.5 has been entered for the notional weir, indicating a non-rectangular control section. The calculation for critical depth does not take this into account.
W2048	Very small change in heads results n large change in flow during the run downstream water level close to the critical value. Results must be examined carefully. Label/s involved label1, label2	The downstream depth at a notional weir is within 5mm of critical depth, or (in steady timestepping mode only) the flow difference between successive iterations has exceeded 20%. Consequently, the results may lose accuracy.
W2050	Ratio between upstream and downstream areas exceeds 2.0 at at least one berlos. This may cause a lack of convergence and reduced accuracy. Check the unit data.	The upstream area in a Bernoulli loss unit is greater than double the downstream area. This may cause convergence problems due to oscillations between successive iterations; the user is advised to check the Bernoulli loss input data to verify the area inputs.
W2051	Estimated theta value is very large; this will be reset to (2*pi).	Theta is the parameter used in Suter's pump curve method, which lies in the range [0,2pi). It is likely to be greater than 2pi only in the case of rounding errors, so rounding it down to 2*pi is appropriate.
W2052	MSL is outside FSR range (0.27 to 239)	The MSL (main stream length) used in the FSR time-to-peak calculation is outside the valid range. However, the equations used will still calculate the Tp value based on the value entered (as long as it is positive). You are advised to check the input data.
W2053	Soil is outside FSR range (0 to 0.5)	The soil index used in the FSR percentage runoff (PR) calculation is outside the valid range. However, the equations used will still calculate the PR value based on the value entered (as long as it is between 0 and 1). You are advised to check the input data.
W2054	Urban fraction should not be > 0.808	The urban fraction used in FSR or the urban extent used in FEH (e.g. for PR, Tp calculations) is higher than the valid maximum (0.808 and 0.5, repsectively). However, the equations used will still use the value entered (as long as it is less than 1). You are advised to check the input data.
W2055	RSMD is outside FSR range (15.6 to 118)	The RSMD (Residual Soil Moisture Deficit) used in the FSR Tp calculations is outside the valid range. However, the equations used will still use the value entered (as long as it is greater than 10). You are advised to check the input data.
W2056	CWI is outside expected range (50 to 150)	The CWI (Catchment Wetness Index) used in the FSR/FEH calculations for baseflow and percentage runoff is outside the valid range. However, the equations used will still use the value entered. You are advised to check the input data.
W2057	Rainfall Profile duration is expected to be the storm duration	A user-input rainfall profile has been entered for an FSR/FEH unit, but the duration (number of items in profile * time interval) does not equal the input storm duration. However, the user-input profile will still be used in calculating the quick runoff hydrograph.
W2058	Model convergence criteria were not met for one or more timesteps during the run.	The model did not converge at one or more timesteps during the simulation. Details of when, and where the model was least convergent are given in the diagnostics (*.zzd) file. You are advised to check the model in these areas, and the extent of the non-convergence (e.g. DH and DQ values).
W2059	Catchment area is outside FSR range 0.038 km2 < fsr catchment area < 9868 km2	The catchment area in an FSR/FEH boundary (used in the peak flow, base flow and ARF calculations) is outside the valid range. However, the equations used will still use the value entered (if positive). You are advised to check the input data.
W2060	Conveyance decreases by x% at level y m, depth z m	A decreasing conveyance with increasing depth was encountered (if decreasing conveyance check is switched on); this may be caused by a large increase in width with a small increase in area in the cross section and can cause convergence problems near this depth. The problem may be alleviated by inserting a panel marker, if appropriate. One can also select the "Enforce increasing conveyance" option from the Low Flow Options tab on the 1D Simulation interface, which will set the conveyance to the previous value.
W2061	S1085 is outside FSR range (0.19 to 118)	The S1085 (10%-85% stream slope) value in an FSR boundary, used in the time-to-peak calculations, is outside the valid range. However, the equations used will still use the value entered (if positive). You are advised to check the input data.

Warnings W2100-W2999

Warning code	Message	Info / troubleshooting / details - what do I do to resolve!
W2100	Invalid value given for modular limit; internally calculated value will be used during run.	A modular limit value of less than 0 or greater than 1 has been entered for a round-nosed or crump weir. The program will calculate the [variable] value of modular limit, rather than using a fixed value.
W2201	Friction law not specified correctly in bridge attached to labels label1, label2. Friction law assumed to be Manning's	The keyword on the 4th line of a bridge unit must be 'MANNING' (case sensitive). No other friction law is currently valid, and Manning's equation will be used. Check the data file.
W2202	Bridge calibration factor set to zero. Bridge attached to labels label1, label2 will have no effect.	The bridge calibration factor has been set to zero. Thus no headloss will be applied at this bridge, and therefore the bridge has no effect.
W2203	There is insignificant flow through the arches at USBPR bridge downstream of node label1. You should check bridge and culvert data or consider modelling the culverts as separate units.	The flow through the flood relief culverts is significantly higher than that through the bridge arches, and the flow through the arches may be misrepresented. You are advised to check the input data/dimensions of the arches and culverts; if the flow through the culverts is expected to be large, it may be preferable to model them separately.
W2204	Bridge downstream of label1 is surcharged. Afflux calculation may be inaccurate.	The calculated water level at a USBPR bridge unit has exceeded the bridge soffit. The method is not validated for surcharged bridges, and therefore may not be accurate. You may wish to consider modelling the bridge as an orifice.
W2205	Extrapolating base curves, base coefficient may not be reliable. Blockage ratio = m at bridge connected to labels label1, label2	The blockage ratio, m, in a USBPR bridge unit is less than 0.2. The USBPR method does not provide for such blockage ratios and the base coefficient, Kb, is extrapolated from the published values.
W2206	Extrapolating pier curves, pier coefficient may not be reliable Pier ratio J = j. Using del K (max)= 0.4 at bridge connected to labels label1, label2	The pier coefficient in a USBPR bridge unit is greater than 0.4 and has been reset to its maximum, 0.4.
W2207	Extrapolating pier sigma curves, sigma coefficient may not be reliable Using sigma (min)= 0.6 at bridge connected to labels label1, label2.	The blockage ratio in a USBPR bridge unit is less than 0.4 for a positive pier ratio, j. The pier sigma coefficient has been reset to its minimum of 0.6.
W2208	Extrapolating skew curves, skew coefficient may not be reliable. Blockage ratio = m at bridge connected to labels label1, label2.	The blockage ratio, m, in a USBPR bridge unit is less than 0.3 for a non-zero skew. The USBPR method does not provide skew coefficient values for such blockage ratios, which have therefore been extrapolated from the published values.
W2209	Failed to load convey.dll.
W2211	Failed to free memory in CES dll.
W2212	CES dll magic number error.
W2213	CES dll version error.
W2214	Failed to set Flood Modeller in CES.
W2215	Bad gauge data at time x hrs. Gauge unit at label1 disabled/record skipped.	The data for a gauge unit has fallen outside the user-defined limits. Depending on the strategy applied on such an occurrence (STRICT or PARTIAL), the whole gauge updating unit has been disabled, or the bad record skipped.
W2216	Gauge limit "PARTIAL" incompatible with "GRADIENT" option. "STRICT" limit enforcement applied	For a gauge unit, PARTIAL correction (i.e. interpolation of bad data) is not valid if the limits of validity are being applied to a gradient. Thus, if non-conformant data is found with the GRADIENT option, the gauge unit is disabled.
W2217	No method file specified for gauge unit. Using default parameters	The method file used to specify the gauge parameters has not been specified - this should be entered in the unit form; otherwise, the default parameters as listed will be used.
W2229	Value of trash screen height is set to 0; areas will be calculated using piezometric head.	A trash screen is being used for a culvert inlet unit, but its maximum height has not been set. The velocity through the trash screen will be calculated using the piezometric head, which may be significantly greater than the trash screen soffit and therefore give unrealistically low velocities (as opposed to using the true area of the trash screen).
W2235	Variable Percentage Runoff Flag is expected to be FIXED or VARIABLE	The PRFLAG keyword in an FSR/FEH unit must either be 'FIXED' or 'VARIABLE' (case-sensitive). A FIXED percentage runoff will be used by default. Check data file.
W2236	Optimum number of internal calculation points in the reach is n. The maximum allowed number is 100. You could try increasing the timestep or decreasing the reach length.	The absolute maximum number of internal calculation points for a Muskingum unit is 100; either a user-entered maximum, or the optimum number of subnodes exceeds this. If the latter, a shorter reach length will lead to a lesser optimal number of subnodes.
W2237	MUSK-RSEC data error. Reference flow and bankful flow proportion are both zero. Setting bankful flow proportion to 1.0 and using bankful flow to calculate distance step.	For the Muskingum Routing Section (MUSK-RSEC) unit, the number of subintervals is calculated using bankfull proportion or maximum discharge. At least one of these must be specified (and positive).
W2238	Warning: panel at offset x has very small width	The panel beginning at a cross-chainage of x is less than 1mm wide. Check the input data.
W2260	WARNING: for culvert bend losses Loss coefficient should be less than 0.5. Current value is x	The recommended maximum k-value for a culvert bend loss is 0.5. A maximum value of 3 is allowed.
W2261	WARNING: Backflow encountered at culvert bend or loss unit.	Reverse flow has been encountered at a culvert bend or loss unit. This may indicate the onset of an instability.
W2262	WARNING: Backflow encountered CULVERT OUTLET unit.	Reverse flow has been encountered at a culvert outlet loss unit. This may indicate the onset of an instability. The unit may also be inappropriate for reverse flow.
W2263	WARNING: Backflow encountered at CULVERT INLET unit; outlet control equations will be imposed.	Reverse flow has been encountered at a culvert inlet loss unit. This may indicate the onset of an instability. The unit may also be inappropriate for reverse flow.
W2264	Level below culvert invert; resetting depth to dmin.	The level upstream of a culvert bend unit has been calculated as below the culvert inlet. It has been reset to minimum depth. This may indicate potential instabilities in the model.
W2266	Level below culvert invert; resetting depth to dmin.	The level upstream of a culvert outlet unit has been calculated as below the culvert inlet. It has been reset to minimum depth. This may indicate potential instabilities in the model.
W2267	No sub/supercritical depth could be found at node label1	No bounds could be found for supercritical or subcritical depth at the section, therefore not being able to guarantee finding a solution for critical depth. Critical depth may be required for culvert inlet losses, the transcritical solver, or the normal/critical depth boundary.
W2268	d/s end of a reach is neither a junction, structure, loss nor a boundary. Direct supercritical method cannot yet handle this; label involved: label1	An error was found in applying the supercritical depth calculation in a downstream direction for the direct method - the unit at the downstream end of a reach was not valid - check connectivity.
W2271	Failed to find a minimum of the energy function at label label1	A solution could not be found for the energy equation at node label1. The energy equation is used in the direct method transcritical solver at a subcritical (upstream) to supercritical (downstream) transition
W2272	Energy equation failed to converge to a subcritical/supercritical soln at node a energy equation failed to converge to a subcritical soln at node label1	The solution to the energy equation did not converge at node label1. The energy equation is used in the direct method transcritical solver at a subcritical (upstream) to supercritical (downstream) transition
W2273	Defaulting to critical depth at node label1	During the supercritical part of a reach, the direct method transcritical solver calculated a depth that was either above critical depth or below bed/invert level. The depth has been reset to critical depth by default.
W2274	Water level in Bernoulli loss unit is lower than or the same as the previous level	The water levels in the Bernoulli Loss unit input table are not in ascending order. Check input data.
W2274	Bernoulli loss area x sq m is smaller than the previous area y sq m	The areas in the Bernoulli Loss unit input table are not in ascending order. This may cause inconsistencies in interpolating areas during the computational phase. Check input data.
W2275	Two levels have zero upstream area Upstream area corresponding to level x m has been increased to 0.001 sq m	Two consecutive areas in the Bernoulli Loss unit input table have been entered as zero. This may cause inconsistencies during the computational phase - the second area has been increased to 0.001sq m. Check input data.
W2276	Water level set to adjacent lowest bed level+0.01:x	The water level upstream of a bridge unit calculated by the Direct Method was below the bed level - this has been reset to x, 1cm above bed level.
W2277	This is the last appearance of a message of the type: conduits are not permitted	A maximum of 50 warnings are output relating to variable parameters not being permitted within a conduit reach for the Direct Method.
W2278	Zero calibration coefficient: no flow	A calibration coefficient (multiplicative factor) has been set to zero for the crump or flat-v weir unit; therefore zero flow will be imposed at this unit.
W2279	Reference velocity exceeds 3 m/s at at least one berlos. This may cause a lack of convergence and reduced accuracy. Check the unit data.	The upstream velocity (calculated as discharge/[reference area]) in a Bernoulli loss unit is greater than 3m/s. The user is advised to check the Bernoulli loss input data to verify the area inputs, and hence the feasibility of this velocity.
W2280	Estimated theta value is negative; this will be reset to zero.	Theta is the parameter used in Suter's pump curve method, which lies in the range (0,2*pi). It is likely to be less than zero only in the case of rounding errors, so rounding it up to zero is appropriate.
W2281	No flow possible with zero coefficient	A calibration coefficient (multiplicative factor) has been set to zero for the obsolescent tidal drainage sluice unit; therefore zero flow will be imposed at this unit.
W2282	Minimum/initial timestep has been reduced/increased	An inconsistency was entered in the adaptive timestepping times. The hierarchy must follow: minimum timestep <= initial timestep <=save interval. The timesteps have been adjusted accordingly as described.
W2283	Conduit section should be entered anti-clockwise from invert centre line. Section has been reversed	A conduit section unit must have the data entered from the centre of the invert, in an anti-clockwise direction, to the centre of the soffit. If the second cross-chainage value lies to the left of the centre, this and all subsequent cross-chainage values have been reversed; if the soffit level is lower than the invert level, the data is assumed to have been entered backwards, and the order of all input points has been reversed. You are advised to check the input data.
W2286	Reservoir/Pond area x sq m is smaller than the previous area y sq m	The areas in a reservoir or pond unit should be entered in ascending order. Otherwise, inconsistencies in interpolating areas/volumes may occur. Check input data.
W2287	Two levels have zero area. Area corresponding to level x m has been increased to 0.001 sq m	Two consecutive areas in the Reservoir or Pond unit input table have been entered as zero. This may cause inconsistencies during the computational phase - the second area has been increased to 0.001sq m. Check input data.
W2288	Warning: Initial water levels upstream of RESERVOIR/POND unit are not all equal. Initial level of x m will be used.	The initial conditions file contains different levels for one or more nodes in a Reservoir or Pond unit. The initial water level used is that specified for the first node in the unit.
W2289	Discharge coefficient set to zero	The coefficient of discharge, Cd, has been set to zero for the sluice or round-nosed weir unit; therefore zero flow will be imposed at this unit.
W2290	Opening is zero - no flow possible	The gate opening has been set to zero for the obsolescent tidal drainage sluice unit; therefore zero flow will be imposed at this unit.
W2291	Warning: Initial water level at label l1 of x m is higher than the crest of the SPILL. This may cause initial instabilities	One is normally advised to begin simulations with no flow over lateral spills, since otherwise this may lead to initial instabilities. However, it is acknowledged that this may not always be practical, e.g. for continuous simulation models. In such cases, it is imperative that good initial conditions are provided, and use of the hot-start functionality is recommended.
W2292	Failed to converge to normal depth at node l1; normal depth calculated x; slope y; Friction slope z.	A solution could not be found within the required accuracy (<1mm) for normal depth at a NCDBDY unit. The final parameters used in equation are supplied further information. If is calculated as being below bed level, it reset to level.
W2293	Linear interpolation with rainfall data/DEPTH specification not allowed. BAR data format enforced.	Linear interpolation of rainfall data is not valid - one must specify rainfall data as bar-chart type.
W2294	Crump, Flat-V weir at l1 is not connected at u/s [d/s] node to a river section. Velocity heads may be calculated incorrectly. Use of remote nodes is recommended	The Crump Weir and Flat-V Weir units both use a discharge relationship based on total head. Therefore, velocities, and hence areas need to be obtained. These are normally obtained from the adjoining unit; however, if this is not a channel unit, this is not possible, unless remote nodes (labels 3 and 4) are specified as channel units, from which to obtain the upstream and downstream areas respectively.
W2295	5D (5×storm duration) of hours is greater than 192hrs. Seasonal PMPs have been extrapolated from FEH table and may be inaccurate	The Catchment Wetness Index (CWI) calculation for a PMP involves estimated antecedent rainfall of a duration of 5D. The FEH rainfall tables are provided for durations of up to 192 hours, therefore anything beyond this is extrapolated from the values given.
W2296	Error in rule X. WARNING: string Y can be interpreted as a numerical value and as a node label. Using numerical value of Z.	When using logical rules units, it is not permitted to reference node labels that can be interpreted as numbers, since these are often read as numeric values, and not recognised as a node label. As well as labels such as '1000', labels containing a single 'D' or 'E', but otherwise numeric, such as '20D400' may be interpreted as [exponentiated] numbers.
W2297	Date/time set in Tidal Boundary unit used in preference to those of the simulation event	It is recommended that a Tidal Boundary uses an event-based time, rather than that specified in the data file. However, this can be overridden with the data file entered date/time by leaving the appropriate check box unchecked in the unit form. The user should verify that the correct date/time is being used.
W2298	Data interval is less than one minute; PMP ratios held at the 1-min value. PMPs may be inaccurate - a longer data interval is recommended.	The PMP calculation involves estimated rainfall at each data interval, using the FEH EM ratio tables. The minimum duration in these tables is 1-minute, and for shorter durations these values are extrapolated from the values given.
W2299	Storm duration (x hours) is not an approximate integer multiple of dt (y hours). Using nearest integer multiple.	The storm duration for a PMP must be an odd integer multiple of the data interval, to allow for a symmetrical storm profile. If the storm duration is not an integer multiple (to within 0.05hrs) of the data interval, it is rounded up to the nearest integer multiple. If then this turns out to be an even multiple, a fatal error is generated.
W2300	Areal reduction factor equation for short durations (0.25-0.5hr) called. Duration = x hours. PMF results may be inaccurate.	The areal reduction factor (ARF) for a PMF is required at each time interval, which may result in a short effective storm duration. The usual equation (from Keers & Westcott) is not valid for durations less than 0.5 hours, so the ARF for shorter durations is interpreted from the graph in FEH Vol 4 Fig 3.4.
W2301	The adaptive timestepping parameter avitr should be greater than minitr	The adaptive timestepping parameter avitr denotes the maximum number of iterations at which convergence is achieved before the method tries increasing the timestep. If avitr is less than minitr, a solution is never achieved in less than avitr iterations, and therefore the timestep will never increase.
W2302	Time to peak, tp, is not an integer multiple of the data interval. The unit hydrograph peak, Up, may possibly be significantly reduced. You are advised to check the U-H data and consider a user-input (observed) time to peak if appropriate.	For the triangular unit hydrograph (UH), convolution of rainfall with the UH may miss the peak of the unit hydrograph if the peak occurs between two data intervals and lead to underestimation of the peak flow. This can be rectified by selecting a time-to-peak that coincides with a data interval. The modeller is advised to check the sensitivity to the time-to-peak. Note that the s-curve method used in ReFH also alleviates this problem.
W2313	Zero modular limit	The modular limit in the manhole unit has been set to zero. This may give unrealistic results.
W2314	Modular limit set to unity or greater. Flow will always be modular	The modular limit in the manhole unit was set greater than or equal to 1. This will force modular flow for the outlet.
W2315	Negative loss coefficient entered - this will be reset to zero	The loss coefficient in a manhole unit was set to zero; zero headloss will therefore be applied.
W2317	Downstream flow area in floodplain section constrained by modular limit or downstream constraint factor.	In a floodplain section unit, the downstream water level is below crest level or only slightly above. The downstream area used in determining friction flow has therefore been replaced by a factor (downstream constraint, or modular limit if the former not set) of the upstream flow area.
W2318	Initial adaptive timestep not read from file - using ief value.	The initial adaptive timestep was set to be read from the adaptive timestepping file but could not be found/read. The simulation has therefore defaulted to using the value set in the 1D Simulation File (*.ief).
W2319	Downstream constraining factor not set for floodplain section - using modular limit	The downstream constraint was not set in a floodplain section unit. For low downstream water levels, the downstream area used in determining friction flow has a lower limit of modular limit × upstream flow area. It is recommended that the downstream constraint factor is set.
W2320	Reservoir updating unit not connected to a reservoir.	An updating (gauge) unit with ’r;Reservoir’ option set is not connected to a reservoir unit. The updating unit will therefore be ignored.
W2321	Conduit slot dimensions (dh or height) calculated or entered incorrectly.	When using a conduit slot, an invalid dimension for the slot has been calculated (or entered). This has been replaced by a default value as stated in the specific diagnostic message.
W2322	Failed to read event data	An error occurred opening/reading the 1D event data file (.ied). Data in this file has been ignored. To trigger a fatal error in such instances, insert the line FailOnIEDError=1 in the formsed.ini file ([Preferences] section) This .ini file is installed to C:\Users\<user>\AppData\Roaming\Flood Modeller (or <user>\AppData\Roaming\ Flood Modeller* ).
W2323	Unrealistic density input	A density value of less than 900kg/m3 or greater than 1100kg/m3 has been set in a River section unit. The value has been reset to 1000kg/m3.
W2531	Cannot find an upstream condition from which to start supercritical integration	The direct method transcritical solver requires a prescribed upstream water level if the upstream end of a reach is supercritical. This can be specified if the upstream boundary is a QTBDY by entering a third column for stage, field columns 21-30. This requires editing of the data file in a text editor.
W2532	Model start time is NOT t=0. Hydrograph start time IS t=0	This provides the user with a warning that the model simulation start time is not zero, but the hydrological boundary-generated hydrograph does start at t=0. This may be as required, but may also mean that the start of the hydrological boundary is not as required. The modeller is advised to use the time delay functionality in the hydrological boundary or start the simulation at t=0 if the hydrograph is required to coincide with the model start time.
W2533	Warning: Volumes not calculated/output for Muskingum sections in file	The volume output option has been selected, but the model contains Muskingum sections. Volumes are not calculated for Muskingum units, so the total volume or mass balance may therefore be misrepresented.
W2534	Errors occurred opening/writing to file f1	Check that the file name f1 is not opened by another application, and also that read/write access is allowed for the current user.
W2535	c0 scaling factor input error.	The c0 scaling factor (smoothing factor) is used in Muskingum units to provide a minimum wavespeed, to aid stability at low flows. The value entered is as a proportion of maximum in-bank wavespeed and must be between 0 and 1. It is not recommended to exceed 0.5.

Notifications N3000-N3099

Notification code	Message	Info / troubleshooting / details - what do I do to resolve!
N3002	Very small change in heads results in large change in flow at u1 l1.	A large rate of change of flow with respect to head was detected in the direct method at unit u1, label l1. This indicates that the results may be very sensitive to head.
N3003	Percentage runoff calculated as negative value therefore set to zero	The calculation of percentage runoff (PR) in FSR/FEH resulted in a negative PR value, which was reset to zero. This could be caused by a small CWI value or low precipitation.
N3006	NOTE: End of backflow at CULVERT INLET unit.	This indicates the time at which backflow stopped in a culvert inlet unit. This should be used in conjunction with warning W2263. The modeller should also consider the frequency and duration this occurrence, and whether backflow is appropriate at the time. This could indicate model instability.
N3007	NOTE: End of backflow at CULVERT OUTLET unit	This indicates the time at which backflow stopped in a culvert outlet unit. This should be used in conjunction with warning W2262. The modeller should also consider the frequency and duration this occurrence, and whether backflow is appropriate at the time. This could indicate model instability.
N3010	Simplified method used to compute solution at one or more sections	The convective acceleration term in the momentum equation was simplified due to a high Froude number (greater than the lower Froude number trigger point) being attained. This generally results in a hydraulic jump being smoothed out over a number of nodes, and may therefore result in a less accurate solution at high Froude numbers. The user should consider using the Direct Method Transcritical Solver, if an accurate steady-state solution is required.
N3012	Zero flow beyond l1 (osetqh)	Zero flow has been applied by the Direct Method at node label l1 and all nodes upstream of this
N3013	Transcritical point(s) occurred at one or more locations Any additional recommended sections tabulated above may be overstated	The direct method transcritical solver detected the listed transcritical locations and type. Additional sections involving these nodes may have been recommended in an earlier message, although this recommendation may be superseded by the detection of the transcritical point.
N3014	EVENT DATA FILE READ FAILED. See top of diagnostics (*.zzd) file for more info	A read error occurred for the event data (.ied) file(s) specified earlier in the diagnostics (.zzd) file. Check that the *.ied file exists and is not locked out by another application. The model should be rerun to take into account this event data.
N3015	Simulation event date/time overrides that set in Tidal Boundary unit	It is recommended that a Tidal Boundary uses an event-based time, rather than that specified in the data file. However, this can be overridden with the data file entered date/time by leaving the appropriate check box unchecked in the unit form. The user should verify that the correct date/time is being used.
N3016	Tidal Boundary unit used but no event date/time exists. You are advised to check that the date/time in the TIDBDY unit is appropriate.	No valid event-based time was specified (i.e. absolute time used) in the 1D Simulation/*.ief file. The tidal boundary is therefore using the date/time specified in the data file. The user should verify that the correct date/time is being used.
N3017	Tidal boundary used with the direct method. You are advised to ensure that the tide is in ebb to avoid reverse flow.	The direct method will not work with reverse flow, and will be driven by the level in the tidal boundary. This could result in a very high head being applied at the downstream end, leading to high water levels upstream (if practically, reverse flow would be applied at the time). Steady-state tidal models are not recommended.
N3018	2D Input Data check completed - simulation option not chosen Program execution terminated normally.	The TUFLOW link was chosen with the 2d data check option. The simulation was not run, but terminated after the 2d check phase.
N3019	Note: A user-input PMF time to peak is assumed to already contain the 0.67 adjustment factor	The time-to-peak (Tp) for an FEH PMF simulation is adjusted from the instantaneous UH Tp by a factor of 0.67, when calculated. However, if specifying a user-input Tp, the user should take this into account before entering the value (i.e. the software does not apply the adjustment factor to an Observed Tp).
N3025	Minimum flow has been applied at this boundary	A flow-time boundary (QTBDY) has the minimum flow value set, which has been invoked due to the input flow value falling below this.
N3026	Initial adaptive timestep read from input file	The setting for the initial timestep for an adaptive time stepping run has been obtained from the adaptive timestep file, as opposed to the event file.
N3027	2d timestep read from tcf file	The TUFLOW timestep has been read from the TUFLOW control file (.tcf) and not the 1D Simulation File (.ief). Setting the 2d timestep to a negative value in the 1D Simulation File allows this.
N3028	Data points omitted from deactivated section areas	The deactivation markers were set on one or more river section units. Any data points falling outside these deactivation markers are ignored.
N3029	Duplicated units found	The same unit(s) were found in both the event data file(s) (.ied) and the main data file (.dat). The latter (and any second occurrence in the *.ied file) are ignored.

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Table of contents

Warnings W2000-W2099
Warnings W2100-W2999
Notifications N3000-N3099