Open Channel Hydraulics Solutions Manual Chow Pdf
Mariela Coxon
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Hello all: I know that it's tough to get any response for arequest like this, but I believe that your contribtion nomatter how scant will interest other subscribers: What are yourmost important reference books or reports etc? say less than 10.I would like to list some of them (if any) in a newsletter.To start, here are a few I use all the time:
I'd add "Principles of Surface Water Quality Modeling and Control" (Thomannand Muller),"Rates, Constants and Kinetics Formulations in Surface Water QulaityModeling" (Bowie et al.), and, of course, "The Enhanced Stream Water Quality Models QUAL2E andQUAL2E-UNCAS" (Brown and Barnwell).
- This, along with Mills et al. and Bowie et al., is a third very useful fate and transport referece, largely because of the extensive tables of chemical coefficients. Barnwell and company are to be congratulated on this great reference set.
- One of the truly great civil engineering texts, now likely out of print, but worth the effort if you can find it. It has applications of probability and statistics in all of civil engineering, including many in hydrology. Also, very good for the basis of derived distributions.
- A sleeper that isn't as well known as it should be, it presents the USGS methods of performing scientifically-correct statistics (not flood frequency stuff). Included are graphical analysis, alternative regression techniques, methods of detecting differences in data and time series, etc.
- Need 8 x 10 cycle log-log paper to make your data look really good, or odd-ball probability paper or polar coordinates or triangular coordinates or paper with months or weeks, in metric or U.S., etc. etc.? It's all here, for your xerox machine. I found this in a department store 16 years ago. There is a newer edition (and somewhat inferior edition because it doesn't have blank maps) that I don't have, but it still has most of the good graph paper. I use this all the time, and it is my only source for some kinds of probability paper and multi-log-cycle paper.
- It's true that there are several newer "BMP books" and manuals out since this one, but I keep coming back to it. The figures in this book are the basis for many of the figures in most of the newer references.
- I personally haven't used this text (partly because I haven't had it that long), but several people have recommended it to me as very useful. It does have a lot of detail about urban drainage and appurtenances.
- The flow routing section lacks modern computer methods, but this is the first open channel flow book that I turn to when I want the background and details for a topic. Henderson is also good for a different view point and explanation, but I don't think French is quite as good, even though his is the newest.
I would like to add an additional reference to the compilation. Estimating Manning n values is often taken for granted, but a sensitivity analysis will often show that they are critical. The only good reference I have found for these is:
Roughness Characteristics of Natural Channels, U.S.G.S. Water Supply Paper no. 1849, 1967. - color photos and descriptions for 50 stream channels for which roughness coefficients have been determined
I don't know of anything better, but I'd mention that 13 of Barnes' 50 color site photos and sets of cross-section data are included (in black and white) in R.H. French, Open-Channel Hydraulics, McGraw-Hill, New York, 1985, a somewhat more accessible reference. And there are similar photos (of different locations) in Chow's Open-Channel Hydraulics. But Barnes' WSP 1849 is indeed a classic.
Great blog. I work a lot with FEMA flood studies where a "no-rise" condition means no rise to the 0.00' comparing pre- and post-project modeling when determining if a conditional letter of map revision (CLOMR) is required. Frequently the post project model will have an identical cross section as the pre-project but will have a different critical depth and this can show as a 0.01 or greater rise which of course is not allowed if trying to achieve a no-rise. The models are all run in subcritical flow mode (a FEMA requirement). I have set both models to parabolic and also multiple methods but although I get different answers the rise still occurs. Adjusting computation tolerances courser does not help with matching the critical depth and adjusting finer appears to make the differences greater. Other identical pre- and post-project cross sections flowing at critical depth match elevations very well. Any thoughts on what is causing this would really be helpful. Thank you.
Chris, my bad, I found the top of bank was set differently between the two models. I do see this a lot and usually can find a tiny error between the cross sections and correcting that solved the problem.
Not sure what would cause that other than some difference between your cross sections. You might try copying the cross section from one geometry to the other geometry just to double check there is nothing different.
Sounds like maybe you have a downstream boundary or control in your model that is keeping the water high, level, and slow. Could be an error too. Check your htab parameters and make sure they cover the full range of ws elevations computed in the simulation. Especially the bridge and culvert htabs. Also make sure your computational interval is small enough. For a dam breach model, it should typically be 30 seconds or less.
Chris, do you know the basis for why HEC-RAS (and hydraulic modeling in general) defaults to the flow profile with the higher specific force value at a particular cross-section? Why can't the lower specific force value be just as correct? I've tried searching the HEC-RAS manual and other references but haven't had any luck finding an explanation for why the higher specific force governs.
Hi Chris- I am running a Hec-Ras model which I am having a divided flow computed for my cross sections and at one of my sections, just downstream of a box culvert my flow hits super critical and the divided flow is not computed. Can you think of any reason or way to fix this? The program wants to push the entire flow back through the channel rather than use the storage as defined outside of the banks. Any help as quick as possible would be greatly appreciated.
Hi, I have a project in unsteady conditions. I have a flow hydrograph for upstream as the boundary condition. But there is a drop downstream, and the only boundary condition is that critical depth occurs there. How can I model this?
This book covers one of the most powerful, yet relatively unknown features available in HEC-RAS: the HECRASController! The HECRASController API has a wealth of procedures which allow a programmer to manipulate HEC-RAS externally by setting input data, retrieving input or output data, and performing common functions such as opening and closing HEC-RAS, changing plans, running HEC-RAS, and plotting output. A companion Excel workbook provides VBA code that demonstrates the HECRASController subroutines and functions. Read more here: -the-hec-ras-code-2/
The standard step method (STM) is a computational technique utilized to estimate one-dimensional surface water profiles in open channels with gradually varied flow under steady state conditions. It uses a combination of the energy, momentum, and continuity equations to determine water depth with a given a friction slope ( S f ) \displaystyle (S_f) , channel slope ( S 0 ) \displaystyle (S_0) , channel geometry, and also a given flow rate. In practice, this technique is widely used through the computer program HEC-RAS, developed by the US Army Corps of Engineers Hydrologic Engineering Center (HEC).[1]
Under steady state flow conditions (e.g. no flood wave), open channel flow can be subdivided into three types of flow: uniform flow, gradually varying flow, and rapidly varying flow. Uniform flow describes a situation where flow depth does not change with distance along the channel. This can only occur in a smooth channel that does not experience any changes in flow, channel geometry, roughness or channel slope. During uniform flow, the flow depth is known as normal depth (yn). This depth is analogous to the terminal velocity of an object in free fall, where gravity and frictional forces are in balance (Moglen, 2013).[3] Typically, this depth is calculated using the Manning formula. Gradually varied flow occurs when the change in flow depth per change in flow distance is very small. In this case, hydrostatic relationships developed for uniform flow still apply. Examples of this include the backwater behind an in-stream structure (e.g. dam, sluice gate, weir, etc.), when there is a constriction in the channel, and when there is a minor change in channel slope. Rapidly varied flow occurs when the change in flow depth per change in flow distance is significant. In this case, hydrostatics relationships are not appropriate for analytical solutions, and continuity of momentum must be employed. Examples of this include large changes in slope like a spillway, abrupt constriction/expansion of flow, or a hydraulic jump.
Figure 3. This figure illustrates the different classes of surface water profiles experienced in steep and mild reaches during gradually varied flow conditions.[4] Note: The Steep Reach column should be labeled "Steep Reach (yn
The STM numerically solves equation 3 through an iterative process. This can be done using the bisection or Newton-Raphson Method, and is essentially solving for total head at a specified location using equations 4 and 5 by varying depth at the specified location.[5]
Using Figure 3 and knowledge of the upstream and downstream conditions and the depth values on either side of the gate, a general estimate of the profiles upstream and downstream of the gate can be generated. Upstream, the water surface must rise from a normal depth of 0.97 m to 9.21 m at the gate. The only way to do this on a mild reach is to follow an M1 profile. The same logic applies downstream to determine that the water surface follows an M3 profile from the gate until the depth reaches the conjugate depth of the normal depth at which point a hydraulic jump forms to raise the water surface to the normal depth.