I'm looking to estimate the runoff as part of my research study (PhD) by collecting the data on daily rainfall and land area of that particular place.
well, it depends on many things/values...
1. there is a need to realize that each impervious area has a different runoff coefficients (concrete 0,7-0,95; asphalt 0,7-0,95; stone-block paving 0,6-0,85; building roofs 0,75-1,00 - depends on author) .
2. as mentioned above, there are other surfaces in residential area like lawns, gardens permeable surfaces. You have to consider their spatial distribution, infiltration rate, compaction...
3. permeable surfaces in urban areas/catchments are ostensibly permeable. Their permeability strongly depends on the way and intensity of usage. For instance runoff from compacted soils can be similar to runoff from impervious areas. Urban soils do not have hydrophysical conditions comparing to "natural" soils.
4. i think, there is a need to consider a difference between "total impervious area" and "effective impervious area".
5. i do recommend to use not only rain/precipitation characteristics, residential area and runoff coefficient but also evaporation/evapotranspiration lost.
You may succeed but is it all builtup area or you have soil in between. If it is not totally builtup then you will have to do infiltration test as wel in different soils. you can use certain models to estimate runoff. what is teh aim to estimate recharge into river?
I think curve number method will be a better approach to estimate runoff from urbanised area, what you need to have is land use classification i.e. imperviousness and pervious land surface data. As you have mentioned that you have land area data you can do it very easily, else you can download google imagery to classify the land use/cover.
Everything will be just an approximation, so I think it would be enough that you calculate the surface area of urbanized area and calculate the percentage of this area in the surface of whole investigated region. In the case that area is not very large and that rainfall is rather homogenous in the area, also the relief -- in that case you could use percentage of urbanized area as percentage of total rainfall and such estimation would be just O.K.
well, it depends on many things/values...
1. there is a need to realize that each impervious area has a different runoff coefficients (concrete 0,7-0,95; asphalt 0,7-0,95; stone-block paving 0,6-0,85; building roofs 0,75-1,00 - depends on author) .
2. as mentioned above, there are other surfaces in residential area like lawns, gardens permeable surfaces. You have to consider their spatial distribution, infiltration rate, compaction...
3. permeable surfaces in urban areas/catchments are ostensibly permeable. Their permeability strongly depends on the way and intensity of usage. For instance runoff from compacted soils can be similar to runoff from impervious areas. Urban soils do not have hydrophysical conditions comparing to "natural" soils.
4. i think, there is a need to consider a difference between "total impervious area" and "effective impervious area".
5. i do recommend to use not only rain/precipitation characteristics, residential area and runoff coefficient but also evaporation/evapotranspiration lost.
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