HEC-RAS T2: How To Calculate 100-Year Flood Flow and Water Level

hi there welcome back so today i'm going to show you how to calculate 100 year return period of flood flow and water level as well this is called flood frequency analysis so if you already have your time series data if you collect the time series data for a different stations you have to find out that if your model boundary is of certain length and if you have to find out some stations flow rate where we measured we have measured flow rate at the office stream of this model boundary or if it is possible close to the upstream boundary of the model is the best one so once you are collecting your flow rate for even 30 years or 40 years then you can perform that flood frequency analysis and how can you do that i'm gonna show you that one and for the downstream water level boundary we also have to collect the water level for a longer period right we may have water level for 15 minute interval or we may have water level which is daily or monthly whatever it is we need to have the maximum value of the water level for one year then we'll even we need even minimum value as well if we have the time series we can calculate the maximum value we can calculate the minimum value as well and then we'll perform some statistical analysis that is called flood frequency analysis using accidents probability and non-accidence probability so how can we do that i'm gonna do everything in excel right so i have the code i can do that in matlab or it is easy to do in python as well and you can you can use our programming language as well so either way it will be useful for you but i'm going to show you but most of the student or people they're familiar with excel they're comfortable in excel as well so i'm going to show you how can i do that and it's not that hard it's pretty simple and then i'll even use that 100 year return period of the flood values flow rate and water level and 50 year and if you want to calculate because once you have the equation then you can calculate for any year 500 year thousand year whatever it is so we have to develop that equation okay let me just quickly share my screen and show you what i have and how can i proceed with that one so from the study area i have what i did i collected okay i collected that water level so these are the values you can see these are basically here can you see that yeah these are water level values from 1965 to all the way to 2006 right but it is not completed but whatever it is what you have to do you have to be able to calculate that maximum value for each of these years right so for each year we have to be able to calculate so what i did i just splitted the year and i just see i splitted the year here manually because i can calculate it using matlab code i have the code that is not that hard it is pretty simple if you can write the code it will give you the maximum value for year and if you specify it will give you the minimum value as well so for each year i just calculated the maximum value and minimum value okay and for other years so i did it and next when i calculated that somehow right you have to have that maximum and minimum value you need maximum value for flood frequency analysis for the case that i'm gonna do in this across model so after that what i'm gonna do i just all right made it as a descending order for water level okay let me show you the water level i have this thing for discharge as well so here it is i'm going to calculate 100 year of flood water level so what i did i have the values for 41 years right the data i have but i don't have the value for 100 years so how can i calculate the water level for 100 years of a flood so i have to even right i have to do some calculation and then we can find that out so here's the equation i'll use that one not a problem this is a pretty simple equation so what i did here in order to do that i have to even make this in irrespective of the year we have to just arrange these water level values in descending order that means the maximum values will be here just forget about the year number right we can't even remember for which year the value is the maximum we don't need that we need only the values in a this in ascending order right in a descending for this case it is descending order i'm just arranging here and under giving the rank the first one the highest value will be rank one and then it will be just decreasing up to right the minimum value so once i have the value for water level i have the same case for flow rate as well let me show you that one so here i have also a value these are the flow rate okay i have the values for flow rate and these are the values i already tried this one see you can see the values and you can see the maximum and minimum value yeah apparently you may think okay this is the water level no this is the flow rate right see the maximum value is 696 these are the values in meter cube per second so these are yearly maximum values so i'm just extracting these values for upstream stations from office treatment stations and then i'm just stimulating these values as it is so i have two stations for flow rate and i also have two stations for water level as well so i'm just gonna show you the calculation for only one stations then we'll use that values in our model and we'll run it again and i'll show you what what will be the difference between the previous right simulation and the recent one so here it is the maximum value for 30-year period is 10 and 800. so that is the rank one and just um arranging right in a descending order and i have another station right this station id is 2 1 2 and then i also have the same value here you can see i have the same value the maximum i have 40 year for that station that is another station so as many station as you have it's i think useful it's necessary for this flood frequency analysis then your prediction of water level or flow rate will be more accurate to design that breeze clearance that's very important part of this modeling okay now what i'm gonna do i'm gonna follow this equation because i already have so the first thing you have to do you have to calculate the maximum water level or flow rate and arrange it in a descending order and give the rank as one two the minimum value will be the maximum rank okay so then i'm going to show the calculation for this one 30 or the value this one will be good i guess we have values for 40 years okay so here it is if i let me just uh show you that what i'm giving here the values in a maximum and as a descending order and here is the calculation of accidents probability so i'm going to calculate the accidents probability so what is accidents probability accidents probability is nothing but it's kind of probability a chance right the value should be within 1 the maximum value of probability is 1 we know that right so how can we define the accidents probability it is nothing but a probability that a value will be exceeded in a predefined future time so what will be the probability of a value like the maximum value of flow rate is 5207 right so let me calculate the accidents probability of that so the accident probability of the maximum value will be minimum because if you want to exit this value the probability is less right if you have a lower value then if we have any flood event so there will be a high probability that okay this flood will be exceeded right our 10 year flood or 20 year flood but if it is 100 year flood the value will be very high and the probability will be very less because you won't see any hundred year flood every year because that's why it is 100 year flood you'll see that type of flood peak in once in a 100 year right so that's why the accidents probability will be very less so what is the equation for calculating that one i'm going to show you that so since it is excel we can do the calculation so it is it will be the rank divided by m plus and what is the n n is the total number of the value right we have 40 so we have to divide so in excel i'm going to show you that so who are people who wants to see some calculation in excel is pretty simple so in order to write any equation in excel you have to provide equal sign and then m right so that's the column we have m i'm gonna give m and divide by n plus 1 what is n n is 40 plus 1 right if i hit enter it is going to give us this value and if i want to repeat all these calculations just click on and double click on that it will do the job for us right see the accidents probability of the minimum flow rate is almost one that means it will just it will be exceeded every year right we don't know we can calculate the return period then we'll see what will be the return period for this uh value 6.93 okay so then what we have to do since it is accidents probability and then we'll calculate the non-accidence probability so the non-accidence probability is nothing but 1 minus that value okay because we know the total value of probability is 1. so 1 minus this value so if i want to repeat everything and then so you see it is just opposing those values the accidents probability is this and the non-accident probability is this that means in a single year this water level it won't be exceeded by any other flow rate right this flow rate won't be exceeded exceeded with this uh value or any flood event so that's why the value is close to 1 this is the probability for right making sure that okay this event won't happen and then what will be the return period if you know the non-accidents probability right then it's pretty easy to calculate right the return period is 1 over p so what is the value of p it is the accidence probability and that's why i have to divide p accidents right 1 divided by that accidents probability it is the opposite of that one so we calculate this way to see okay that's the year see we have 41 here so if you have any flood event and the peak is these it will take 41 years you won't see this type of floor rate right every year you you can see once in 41 years so that is the return period of this peak but we want to design our breeze for 100 year of return period but we don't have the value so how can we extrapolate these values so we have to make this relationship in between these time series values right because we have values for 40 years so we can utilize these values and we can even extrapolate okay we have this trend and we can find out the value for 41 years or 400 year thousand years so if your observed value is more than this your prediction will be more accurate that's why you have to collect many stations and you can find which station has the maximum number of years right so the next thing we have to plot we have to be able to plot this right that's why we calculated this one i already plotted this everything and we'll figure it out see once you have this non-accidental probability and then you have that return period right and then we can plot it so i also have everything ready here i'm just going to show you quickly that is the plot after calculating you just copy right copy this flow rate and the return period so that's the relationship because we want to provide the return period and we want to get the value right so in the x-axis you have to provide your return period and in the y-axis you have to have your flow rate or water level whatever it is okay so here it is i'm gonna show you pretty quickly okay i'm gonna copy it so that you can understand that what i'm gonna do so i can put it there okay so that is the queue okay q alright i'm gonna plot this this way and insert and if you go to there and you can plot it like any splines anything okay or any curve but this time we'll plot that way and we'll fit the curve okay we'll fit the curve we won't even use any line anything that is what i did here right that is what i did and it will give us the relationship so once we have that because we have to calculate the relationship in between these two values then we can get the equation and once we will have the equation we can calculate the value for hundred year for thousand year okay this will be t return period and this will be in year okay so i'm giving the name and that will be q and in meter per second okay q means flow rate meter cube per second and i'm gonna just uh increase the number and you can see that pretty quickly so that you can it's visible okay so that's that so the next step is to right create a trend line how can you do that if you just right click or select one and right click add trend line so it will give you the default trend line as a straight line but we won't use that because we have to fix right we have to even feed the curve because see the variation is not like a straight line if you want to show the equation of the line see what it will show you that one display the equation and at the same time we have to display the correlation coefficient right in between these two so it is nine seven two two so even we can use the same equation it's pretty simple and if you want to fit more accurately you can even select any exponential logarithmic polynomial since it's look it's looking like polynomial so i'm going to select is that polynomial or you can select power as well i'm going to select polynomial and you can check that when you can change the power of the order right here you can change the order and it is going to fit more accurately see now it's looking like pretty accurate right it's a 9 9 r square you can check the r square 1 is perfect and for acceptable range it should be more than zero point six to one so okay i'm going to accept this one it's okay see so we have the values up to 45 years here but if i am gonna extend it so it will be it will be following right this trend and if i reduce see it is gonna down it is gonna show you the downward directions it won't help you so you have to test if i select this one or the two then i think it will be okay if you even fit it perfectly then your curve will be overfitting and it won't give you that so that will be another problem these are called statistical problems we won't need any overfitting problem if you perfectly fit if right fit your curve following every line and it won't give you more accurate results so we have to be able to find the equation for any line right even it is not high right the correlation coefficient is not that high it's okay but you have to be able to find and straight line is also good if this relationship is good but for this case i'm not going to select any straight line i'm going to select this equation 9 8 is okay so once you have that okay once you have that equation how can you calculate written period so i'm going to give you the value so here is the return period okay return uh period return period will be in year okay in year and then here it will be your full uh discharge okay it will be in uh cms meter cube per second that's it and what you have to do we'll use that equation i'm gonna give you because we don't have any value for even 50 years right so i'm going to calculate the values for 25 years because we have the value within 25 years so the value will get it will be within our measured values and then 50 year and then 100 here and then if you want right for any big breeze or for anything you need to even calculate 500 here we can check that and we'll use these values in our model and we'll see what is the effect of these values right and what will be the flow rate flow rate is nothing but see in this equation we can see the value of y it is the flow rate and the value of x is the value of return period so if i give the return period it will give me right it will give us the value of flow rate so how can we do that let me just uh quickly zoom in so that you can see it pretty easily right so i have to write this equation here how can i write that so the variable is x x means this return period so i'm starting with equal sign since i'm writing as equation then the first value will be minus right minus 1.1171 multiplied by it will be square of x means this value right this one and how can i put this square this is the square term then it will be plus and 174.81 multiplied by x again right this value 81 this value and then it will be minus 35.268 see i'm just giving the x value as return period and the coefficient are as as it is minus 1.1171 and square of return period plus 174.81 multiplied by the return period minus 30 this is the coefficient right 35.268 if i hit enter it is giving me this value and if i want to repeat everything just double click it is going to give us these values can you see that the curve fitting if i go up to 500 here it is giving me these values right which is wrong that's why what you need to do if you just use straight line if you instead of this one if you just uh change your trend line if you use straight line let me show you what it's going to give you that's why you have to test okay trend line so the value it is linear see if i want to delete the previous one i have this one if i want to delete that trend line and if i use my straight line see it is the most average straight line we have and if i wanna show the square root and the r square still it is good so for this case if i use this equation you will you will decide okay that is called from polynomial or polynomial equation and that is from linear linear equation okay it is also q flow rate so i'm comparing okay so that you can understand what i'm gonna do here so 134 134.3 multiplied by the return period plus 66.353 so this equation won't be negative anymore and see if i double click it will give us the value and that is the positive one so which one is accurate what do you think definitely the linear relationship is accurate here right so if you compare the 25 year return period value so from that polynomial we have 3 600 and we had 3 400 and for 50 year we have like uh 5900 and we have 6700 and 400 here we have 62 and we have more than that right this is linear so it is linearly increasing so this is where we have problem and here we can't get anything and we have even values 67 right so let me check you let me show you the actual value because we have the value of 25 years of return period right so let me find that value out so what is the return period of 25. so we have 20 here right we have 20. and what is the value of this it is 3300 right 3300 for 20 years of return period almost 20.5 years this means 21 years so if i add more right if i had four years it will be 25 years that means the value will be more than 3359 so for this case this is maybe accurate this is maybe accurate right i don't know which one is more accurate but for 100 year return period to be on the safe side which one you're going to select definitely if you want to select you should select right yeah for a hundred year return period we can go with our previous equation the polynomial equation but here you can see in since it is linear it is linearly increasing but the relationship is not linear here you can see most of these values are like non-linear here but for higher flow the equation is not polynomial so that's why in my previous plot see what i have used i use that value polynomial right that one exactly the same one i used previously so if you use the same one that is that is okay so we can select this value okay i'm selecting this value keep in mind that we have the flow rate this one and for water level okay we'll use this value six seven six two seven four or you can round it 63 okay sixty three hundred uh meter cube per second that is the 100 year of return period and we can use that as a 6 000 right and we can use that as uh 3600 so we are gonna use these values as this one so i'm going to create another table where i'll use my okay i'm going to create another table here so that you can understand what i'm going to do return period this is the flow rate and i'm going to round these two okay i'm gonna round around this as integer this one okay we can exactly use that or we can replace these values 36 3600 this is the manipulation because this is engineering okay so we can use our 50 5900 that's okay and we can use that uh 6300 okay because i'm just rounding uh within 50 63 100 so these are the values of what will be the value of water level in meter okay in meter from the datum if you have any specific data so for water level i have the values for 41 years and i already just earned these values as descending order so what will be the accidents probability as before the equation is written there right so that is the value of the rank and you have to divide these values by your number 41 number of data plus one so it will give you the accidents probability so the maximum value it will have less minimum accidents probability however the value with right the minimum value will have the maximum accidence probability that's why we're going to calculate the non-accidental probability which because most of the time we use that non-accidental probability so we don't want to exceed our value so that's why we need to test if our non-accident probability of our return period that we are going to use in our model is higher right so we are just caring about this one that's how we can just calculate so it will be 1 minus the accident's probability and then it's going to give us 97.6 right now 90 yeah 97.6 percent so if we have any value that is like close to this 6.72 so 97.6 out of 100 right it it won't exceed that is the probability it's close to 100 percent that can you can make sure that okay if you have any value it won't even exit for this return period let me just calculate the return period here that will be one divided by the accident probability so that is the 42 right so your make sure you are sure 97.6 percent sure that this value on the exit is right don't be won't be exceeded within 42 years so using these values i'm gonna even calculate the same way i calculated the previous values here copy and i'm just putting it there to plot and then i'm selecting this 2 and then i'm just inserting and plotting this as point see the scenario is different here for water level as well right so definitely it is not going to show you any linear relationship what is that is definitely non-linear polynomial i can see that even you can fit using your lock that's also because this is going to show you kind of log correlation right so you can use the log x's as well the y axis should be log and you can use even log log x is it doesn't matter whatever you like you can do that but you have to fix right and you have to test it and i'm gonna show you this one so that is the return period as it is mean r and that will be here and this time it is water level right this is water level but in meter and i'm gonna even select the trend line here add trendline and you can see i'm going to select the trend line if it is there and what will be the equation if i want to select this equation and i'm going to select see the relationship linear relationship is 0.57 so it is not acceptable right so we have to change it because i can see right i can see from my experience that this relationship is not linear anymore it is even not exponential right is it opposite so what is it so you can see the logarithmic option if i select that logarithmic it is gonna fit pretty accurately then you can see the 97 right so that's what we have so if i use the same technique here that i did for my other cases right so if i even want to show you the same type of calculation there if i select this 2 and i'm copying it and there i'm gonna show you the same thing instead of discharge this time it will be flow rate okay this time it will be water no it will be water level instead of flow rate so i'm gonna delete that and then we don't need anything any color no feel and here i'm gonna use the same equation so this time for the first time it will use we don't need to even test with linear relationship or not so it's going to be 0.7203 multiplied by this log right so you have to use that log 10 here it is definitely locked uh yeah it is log it will be log lon means it's log and then it will be x means the return period and then plus 4.505 okay so that's that five point this one if i double click we're gonna have this one so let me check if we have 25 years right so what what we're going to get if it is 25 years so this one okay the water level we have six point six one right since it is 25 years we got five point five one worth for twenty one years see the relationship is for 21 years it is this more than what we got for this one right so even we can fix that when we can change the relationship here that we have it doesn't matter if you want to change it instead of a logarithmic relationship you can even change it to the different relationship that's okay let me test you if i can select the trend line or we can select another trend line that's also okay and instead of this one we can even select power this time okay even we can select moving average whatever we can select we can fix it right we selected logarithm and we even didn't use anything but we can select power it will give you even different thing right so that's uh this is how we have to fix which one is giving you better results so i tested many times and i use even polynomial it's not going to give you the accurate result based on the value we have right so i tested everything and i'm gonna show you what i have tested here and maybe you are gonna see that maybe let me find it out okay it should be yeah so you can see that what i have used i use this one and i'm gonna get 98.57 i got 98.57 okay so this equation i have got if i copy that and if i put it there the value i have so this is the difference right this is the difference the difference we have if i increase that six you can see clearly and i'm going to compare with that equation so that is 0.88 okay that is zero point eight eight five two multiplied by that return period plus four point four eight six two and then no wait wait wait so that is the wrong thing i did i have to provide equal sign and then 0.8852 multiplied by that logarithmic okay this one and then it will be this value plus eight six 4.4862 then we are going to get this value five point seven c we have increased rail rate we increased the value a little bit so we can't even go with that one so four hundred here we have 6.2 and if you have multiple stations you can use that value for multiple stations right so for this case for this real world scenario or the breeze i'm going to design right the vertical clearance and the horizontal span and i'm going to calculate the scoring around the breeze pier so the maximum flow rate i got is i'll show you that one and the maximum water level i got 400 here is 7.85 okay that is different case because i have used another station as well i have many stations here i have many stations this is another one i have another one okay so i have many calculations so i'll use this for this calculation i'll use this value right which one is greater so 6.25 so i'm gonna copy this column and i'm gonna paste it there where i have this okay so we have these values so that will be five point seven two okay i'm gonna increase it five point seven five because to be on the safe side so i'm gonna use this as six and that is uh six point okay six point two five means now six point five okay that will be our 100 year return period so these are the values we just calculated here from large frequency analysis and then we are going to use this profile in our model let me show you that one as well okay how to create separate uh profile and plan and i'll run the model right at the same time using all these values just keep in mind we have 25 years 50 years and 100 here you can give these different options to your client because in order to design in a real-world case we have to give different types of options right and then based on the information and options you can even decide which one you are gonna use okay so that's that i'm gonna open my model that we have here you can see i have the model there and i have the geometry as before we can remember that one right so we have everything ready so i'm going to open the boundary condition right steady flow data if i open it you can see we have only one value 400 here right so 400 here i use 5 and 500 but this time we have 63 100 so i'm gonna add more profile right that is what because we are going to give this at the very office stream which is the number 20 right so how many profile you need we have three right we have three if you just provide the number and apply data it will give you that so that okay let me just edit the value of the profile name the first one i'm gonna give this as 25 so that you can even follow 25 year that will be 50 year so this is this is how we do things in real world cases and that will be 100 years so now you can remember okay which one is for which one okay so for 25 year we have the flow rate 3600 and for 50 year we have 5900 and for 100 years the flow rate is 6300 right so we have this values so what do we need right now we need to go to our water level right so i'm gonna save this what what i did say flow data it's saved and if you wanna even add your water level boundary condition you have to even do the same thing right click there and then what i did i use that water level boundary condition here known water level right since it is water level boundary condition we can give that right the boundary condition we've already provided what was that it was known what was level right and i already provided that values here so we know the 30 600 is for what is for 25 year right and that is the value 5.75 from the left that i'm reading that and putting it there and for 50 years of return period the value is 6.0 however for 100 here for this case we have 6.5 okay so that's it we have three different profiles and i'm now saving it i'm saving that flow data so if i run the model with this three condition i'll have three different profiles okay let me just go to run and open steady flow condition let me check the profile we have here now i'm gonna create different profiles okay we have one profile here i have to create three different profiles or plan right so that is the condition we have so here we have hundred year flood and if i create a new plan new plan it will be okay it will the new plan you can even select that way like 25 year 50 and 100 here okay 100 here you can give any name you want and then it is going to ask you id i'm going to give the id as as it is okay the id is already there so we have to provide zero two the previous one was that one see so now if i run so that will be my plan name okay it is gonna save in a separate model name dot zero two and if i just run it what will happen see the sub critical flow i'm selecting that one and i can check if i have the flow distribution as okay let me just change it to eight at the same time because this is new plan and eight is okay i'm going to select this as eight okay then i'm gonna select okay and i'm gonna save the plan since it is new plan then if you run it let's see if there is nothing wrong so it's checking right writing the geometry and then because we have different plans and it's gonna run pretty quickly see it took time eight seconds right but previously it was taking only two seconds at three i can remember that one because it is running for multiple years and it completed that one so let me just quickly open that how can you open that we can even open geometry we can open the cross section from here right so that is the cross sectional value you can see nice and clean that is the most upstream one and can you see that other information you can see you can see only one line there right you can see the lesson at the same time if i just to minimize these values you can see the legend let me quickly increase it a little bit so that you can even understand what i'm gonna show you okay i'm just displaying these values this way and i'm gonna close it i'm going to open the cross section from here you can see it's pretty clean and nice that is the most upstream section you can see the velocity right on the outer bank we have the maximum velocity and then if i go next if i go next it's going to give us the flow rate but the most important thing did you mention can you recognize that so we only have which one what a surface elevation that is right 25 years so if i go to options and here can you find anything here to change the profile in the plot you can even plot profile right we have this profile there and that profile you can see i'm just comparing side by side you can see there which one what a surface 25 year and this is the water surface elevation that is even energy level energy grid line for 25 years and it is showing the critical right it is almost also for 25 years the red dot but if you want to even show the other profile as well you have to go to options and then profiles and if you if you wanna you can change the plan you can do that so let me select the profile see we only have one profile if you want to select all and if you put it there now it will show you the three different profiles together right now we can compare which one is higher and which one is lower right definitely the water level with or flow rate with 200 here will be higher than that so you can see which one is 100 here the green right the upper one and the blue blue line is for 50 years and then the black one is for right 25s the blue and without without that star so we have this profiles so these are the options we have so you can select which one for which one if i select 100 if you won't understand by your naked eye you can select there and that is the 100 year definitely it should be the highest water level or profile level and if you select 50 year it is lower than that and if you select 25 here right so that's that this is the energy level if you want to see the right energy grid line you can see that if you see water surface elevation you can select water surface so that is the water surface elevation here 400 here if you want to see the water surface elevation for 50 years you can see that water surface elevation here and for 25 years you can see that 25 year is there so that is the 25 years and that is the 50 year that is the 100 year so if you want to design any breeze that is for 25 years and if you have any flood that is 400 here then definitely the breeze will be flooded right so it won't sustain it maybe collapse or it may be there may be different issues the breeze will be submerged so that's why you have to design the breeze at least 400 here then your breeze level the bottom part of the breeze will be here at least so i'll show you how to even design that level and after calculating all this thing we have to provide some factor of safety and based on this information if your water level is here because 100 year water level will be here and if your breeze is here then they're on right it won't pass any vehicle any water vehicle any ship on the passing right because it is just it will toss the bottom of the breeze so from that level when the flower level will be 100 here that means your water surface level will be here and from this level you have to fix your breeze clearance the bottom of the breeze right it will be there or yeah we will have that calculation based on the navigation route so from 100 year return period of flood level you have to fix the bottom cord of your breeze so then if your water level is higher even for 100 here flood definitely the size of the shift if it is for if it is allowed for class 1 navigation route or whatever the number of the navigation route definitely it will pass so that is the engineering decision you have to make and you have to give these options if it is 25 year it's there and if it is 100 year it will be there so these are the decisions you have to make as an engineer and you can even try that one so next time what i'll show i'll add the breeze right our bridge section will be there in between section number four and section number three here we'll provide our breeze so i'll use that breeze and culvert and i'll fix i'll show you how to insert the breeze piers and how to insert other information as a breeze so in the next tutorial i'll show that then i'll run the model again with breeze by this time you know how to write develop the geometry from survey data that we already have and i uploaded this survey data in the previous video you can click the link in the description then you will be yeah able to access that one and now we know how to you can you don't need to analyze this one if you have data sample data you can even analyze this flat frequency analysis or you can for this uh calculation you know the maximum and minimum value from this video you can directly use that but you know how to calculate this right flat frequency analysis that's that in the next video i'll call for breeze scoring and then there are different equation as well so you have to calculate this covering using empirical equation and using this model and you have to compare which one is giving you the highest value so to be on the safe side you have to use the highest value as well and after that we have to apply some factor of safety right so your calculation may be wrong or because we are using only the empirical equation but but in reality the situation may be different than what we are expecting here right that's that's why we have to apply usually we as an engineer we applied is the customs we apply right of factor of safety then definitely if the construction is okay as a design or as preferred by the other engineer structural engineer everything is okay and the construction is okay if the quality is maintained properly and then definitely the breeze will even sustain right if there is any flood 100 year return period of flood so that's that so you can try by yourself if you have any queried question you can just show it in the comment box or if you have any other issues you can even find different materials and for the best one is to go to help menu here and then you can find the menu all right how to enter geometry how to enter this thing and that thing so that's why alice prefer to yeah read their manual because they have some simple example but they sometimes yeah they also give you the data and values and you can even practice that one but maybe sometimes you'll have some issues with okay how to do this do that so you can even use this video series to repeat your task so good luck for you and then stay safe and see you in the next tutorial thank you very much for watching this video

Channel: Md Arifur Rahmahn

Views: 983

Keywords: flood frequency analysis, boundary conditions of hec-ras model, bridge sour by hec-ras model, 1D hec-ras model

Id: zJef5rdLF9A

Length: 48min 18sec (2898 seconds)

Published: Sat Sep 11 2021