Aiming to evaluate bassin catchment capacity in arid region, I want to assess water flood characteristics (Discharge, hydrogram, volume) for different return periods (T=2, 5, 10, 20 years). Stream and basin are usually dry.
What are different techniques used to evalaute flow?
You can use the daily rainfall to calculate watershed runoff using the Curve Number method. For this, you need detailed information on Soil Drainage class, land use, and stream network. You can use use GIS is the model runoff over the watershed and then accumulate the runoff to assess stream hydrograph for the time series of flows. By sorting the rainfall as return period, you can evaluate potential magnitude and duration of flood events. You can also use complex simulation models to predict, but they need stream flow information to calibrate and validate.
Dear Ali
In arid zones rainfall runoff models generally do not work that well see this paper by Qurashi et al called "Application of the Kineros2 rainfall–runoff model to an arid catchment in Oman" in the Journal of Hydrology (2008) 355, 91– 105. It can be downloaded from here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.547.7070&rep=rep1&type=pdf
I think that it is best (and more accurate) to use statistically based methods to estimate design flood flows in arid zones. You can estimated the Mean Annual Flood (MAF) either from observed flow data or a regression equation where MAF is correlated with catchment area and/or mean annual rainfall and sometimes other catchment characteristics (e.g. mean slope).
You then apply a growth factor to the MAF to get the design flood flow for the return period that you require. A paper entitled "Regional flood frequency analysis in arid and semi-arid areas" by Farquharson et al. in the Journal of Hydrology Volume 138, Issues 3–4, October 1992, Pages 487-501 is very useful as it gives growth factors for arid zones.
The paper by Meigh et al. entitled "A worldwide comparison of regional flood estimation methods and climate" in Hydrological Sciences Journal 42(2) April 1997 is very also useful. It can be downloaded from here: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.399.4143&rep=rep1&type=pdf It provides relationships for the MAF for arid zones and also the details of the arid zone growth curve.
Combining the MAF with the growth factor for a particular return period will give you the peak design flow but it won't give you a hydrograph shape! This paper by called "A Method Of Estimating Design Flood Hydrograph Shape In An Arid Region" by Walters in Water International, Volume 14, 1989 - Issue 1, provides a useful and simple method based on observed flood hydrographs in wadis in Saudi Arabia.
I hope that this is of help.
Darren
Dear Dr Bahmed,
Interesting question, although it would have been constructive should you provide with additional information such as the presence of baseflow.
From a rainfall-flooding functioning perspective there is a need to evaluate which is the role of precipitation in the flooding response. That is an important question that only water itself can tell you.
Among others, there is a need to evaluate the isotopic (and chemical) signature of precipitation, and compare it to that of flooding water. Whatever model you apply it should be in agreement with such signatures.
Please find additional information in the following publication, should you need any additional discussion, please do contact,
get from Mexico, saludos,jjoel carrillor
Alconada-Magliano MM, JR Fagundo-Castillo, JJ Carrillo-Rivera, PG Hernández. 2011. “Origin of flooding water through hydrogeochemical identification, the Buenos Aires plain, Argentina”. Environmental Earth Sciences Journal. Vol 64:1 pp 51-71. DOI:10.1007/s12665-010-0817-7; ISSN:1866-6280;
Thank you for all, your responses give several approaches of flood estimation. However, I want to emphasize that stream is alaways dry, and flood occurs only when there is torrential rain that is observed betwwen two to five times a year.
I'll make more deep research on the subject, and I'll decide what is best approach to estimate it.
thanks
if the stream is dry and only runs after heavy rain events then you should do some field work to gauge the flood peaks: to do post flood field research see articles about it from Gaume and Borga (2008) and Borga et al (2008).
Once you can relate rainfall with flood peaks you can think about using some programs but they do not work very well in dry environments
Best regards
Joan
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