I am working on surface water balance of marginal grabens in northern Ethiopia. Here marginal grabens (about 2,500 km2) are transitional zone between the lowland (arid area) and northern highland (semi-arid area). The major lithological units of the escarpments are basaltic rocks. The escarpments have the same aspect, all looking towards the east direction. They recharge the graben bottoms, agricultural potential area.
Part of the water budget components, the representative rivers have been monitored since the last three years. However, there are ungauged streams contributing to the graben bottoms. In fact, there are a number of approaches available for prediction of ungauged catchments based on the spatial proximity, catchment area ratio and catchment characteristics.
I want you guys to share me your best experience (read or worked) on how to estimate the discharge of the ungauged rivers under the data-scarce geographical region.
With bets regards,
Hailemariam Meaza
Dear Hailemariam Meaza ;
you can use hydrological modeling to find the disharge in the ungauged river , but you need rainfall data and a good knowledge of morphology;
if you have not rainfall data you can use the available radar rainfall data available on net.
Dear Mehdi Keblouti ,
Thank you for your suggestion.
With bets regards,
Haile
Dear Hailemariam Meaza,
I agree with Dr. Keblouti. You should perform hydrological to your ungauged River basins. Indeed you are going to need a variety of data, amongst which data of soil characteristics, topographical data, morphological data, hydrological group of soil, hydraulic parameters for streams etc., depending on the hydrologic model-software you choose to use.
However, I would like to add that it is essential to perform some discharge measurements (preferably on rain days) to validate your model. Depending on the purpose of your research, they do not need to be too many; just enough to know that your model simulates your basin efficiently.
Individual discharge measurements can be carried out manually, by means of a propeller device, for the determination of the flow velocity, after determining the dimensions of the cross-section. You should always keep in mind that the measurement of water discharge, in such conventional manner, under flood conditions is practically not feasible.
Good luck with your research!
Kostas Kaffas
Dear Konstantinos Kaffas ,
I thank you for your answer and suggestion.
With bets regards,
Hailemariam
Dear pal,
I strongly agree with Konstantinos Kaffas that he stated briefly.
I want to mention some of the horological modeling software/tools such as SWAT, HEC-HMS, HBV, WMS, SCS-CN (sample paper attached), etc.
You are expected to collect flow records from direct measurement or recorded historical data from nearby similar catchment morphology for calibration/validation of the selected model for adapting your case.
See you in touch!
Dear Niguse,
I thank you for sharing me your experience. I will contact you in person.
With best regards,
Hailemariam
I understand that you have 3-year discharge data for representative rivers and are trying to estimate the discharge of the ungauged streams. As a simple approach and if you have corresponding rainfall data to your streamflow records and for the ungauged catchments, I suggest working out the runoff coefficient for the gauged catchments. Given that your ungauged catchments have similar characteristics as the gauged ones, you can then apply the RC to the ungauged catchments to get a quick estimate of their streamflow. If you proceed to apply hydrologic models, I would still recommend to use the RC to check the model's results. It is a bit of a crude check but very valuable to check whether your results are of the correct order of magnitude.
Dear Gerald Dörflinger ,
I thank you for your scientific suggestion.
With best regards,
Hailemariam
I agree with Gerald. Also You can estimate the correlation among rainfall and flow gauges in the period with simultaneous data. After that you can estimate the flow from the rainfall data. It should be note that the Technics and procedures for the estimation of flow series differs depending the objective of your work (estimation of flow frequency curve, estimation of monthly runoff series for water resources analysis, etc, etc).
Hello Alvaro,
I thank you so much for your compelling answer to my question.
With best regards,
Hailemariam
For a quick first-order estimate of total annual runoff from an ungaged stream; first plot the ratio R/P vs P, where R is annual runoff (in depth units; i.e. volumetric runoff vs. drainage area for the gage used) and P is annual precipitation (also in depth units), for each year of each of the gaged catchments on the same graph. For catchments in the same region with similar characteristics, the data points are likely to be close to a single curve on the graph. Then do a least-squares fit of a curve shape (see below) to the data. If annual Pn values (depth units) for the nongaged catchment are within the range of P values for the gaged catchments, then a vertical line at each Pn and the least-squares curve will intersect at a value of R/Pn, thus yielding a reasonable first-order estimates for Rn (in depth units; which are converted to volume units by multiplying by catchment area). For Pn values outside the range of P for the gaged catchments; then extrapolation of the curve shape to the Pn range might also yield fairly good estimates of Rn; though more uncertainty is associated with such extrapolations.
Selecting the functional form for the curve shape: you can do this empirically; choose a simple function; for example it could that a straight line fits the data reasonable well. For a more rigorously-based choice of functional form, google "Budyko water balance framework" --numerous articles on this framework have been published over the past few decades and are available on-line; the approach should be well-suited to your problem.
Dearest James,
I appreciate for the snappy explanation to my question.
With best regards,
Hailemariam
- Badges
- Science topic
- Similar topics
- Human-Computer Interaction
- Collaboration