Dear Experts
I have continuous discharge series of last 2 years along with the rainfall.
I want to understand the LULC impact on discharge, so can I use HEC-HMS to understand it.
Can anyone let me know the procedure to use the HEC-HMS or else any other software of same kind.
@Ayurzana: Can you please send those articles
Yes I will prepare all those LULC map but how to proceed with those.
It would be better to use a distributed hydrologic models that has urban representation to see the impacts of land use and land cover change. You may try DHSVM or VIC model.
Dear Mishra: My watershed is in Mountainous region so what you suggest. As I have some data constraints also.
Do you thing using LULC and Rainfall with Runoff data is enough for DHSVm or VIC model.
I think there shouldn't be any issue in using DHSVM model with urban scheme.
Dear Vikram,
What kind of impact of LULC change on the discharge do you want to investigate? I am afraid that 2 years is not enough to see any significant effect of LULC change on the discharge. It basically means that you have to compare year 1 with year 2 to understand the impact of LULC change and that does not seem to be very reasonable (also given initialization problems, other influencing factors such as climatic variability and change, etc.). Or do you want to use those 2 years for model calibration and validation and assess impacts of possible future LULC changes on the discharge?
A distributed hydrological model would indeed be a better choice and would also enable you to investigate effects of land use pattern changes where the land use distribution (% crop land, % forest etc.) does not significantly change.
Best wishes,
Martijn
Dear Booji: I do agree that 2 year doesn't make difference in LULC But can you let me know what best I can do.
I wanted to use present LULC and use present discharge to forecast future or decade back LULC scenario.
Dear Vikram,
Your approach will probably depend on your research aims. Are you interested in the impact of historic LULC changes on the discharge or in the impact of future LULC changes on the discharge?
In general, when modelling impacts of LULC changes on hydrology, it is important to show that the model is able to simulate streamflow and other relevant processes in an appropriate way (and for the right reasons) and that the model is able to simulate LULC impacts on hydrology. For the latter purpose, you typically need a model where LULC is explicitly incorporated in the model and two time periods with different LULC pattterns. The approach then might be to simulate both time periods with the original LULC pattern (case 1) and to simulate both time periods with differnt LULC patterns (case 2). The expectation is that case 2 will perform better than case 1. For this approach you will need sufficiently long discharge and meteorological time series and at least two (different) LULC maps for two different time periods.
Dear Vikram,
What i'd like to say is that there are many modeling platforms that could model hydrological impacts of LULC. The main challenge is what data/knowledge support you have to do it well.
Ideally you'd have at least have field data on the water balance (not just streamflow) for different land-use types.Take a look at Giambelluca's papers from south-east Asia.
Without this, any model could give you very erroneous results, so please be aware of that and don't try to suggest any policy choices based on models built with very little data/knowledge. Doing a sensitivity and uncertainty analysis on these type of models is an absolute necessity.
Dear Vikram
Hec-HMS technical paper has reported SCS method and other methods including LULC factors in hydrological estimation. It consists details of how LULC data are used to identify curve number. I think that this reference is very useful in your case. In addition, HEC-GeoHMS calculates the grid Curve Number which supports the use of SCS method.
However, it depends on which flow would you like to estimate: flood flow or monthly flow with this 2 years data and weather it is continuous simulation or event simulation. If it is continuous simulation with reasonable time step, the results may be acceptable. For monthly flow, I am afraid that the data are too short to suggest any solution. However, sensitivity analysis is a good idea.
Good luck.
Phuong
Dear Phuong Cu
Thanks for your suggestion.
I would like to say that, I have data on daily basis so now can you suggest me further, and also can you send me the related report or papers.
Dear Vishal
May I know what kind of field date will require and also please send me paper or else link of Giambelluca's papers.
You could use hec hms, however for greater insight you should try swat model http://swat.tamu.edu/
Dear Vikram, 2 years I think it's not enough to understand how land changes affect flow
Good luck.
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