My aim is to estimate the DOC of a river either with its discharge and/or spm
It's for a tropical river and I don't have the C content of soil.
I uploaded a paper you might find interesting to your question. I had a couple files on DOC in my other computer but most of my knowledge is from the internet since I learned that DOC was an issue with water treatment systems. I believe that the coastal streams that I am used to may have DOC issues as they are black water streams, and marine terrace terrain is dominated by 55% wetlands where organics are accumulated and also many old ditches that were used to drain wetlands that probably feed dissolved organics into the channel system during storm events primarily. Without more information, I would not suggest to overgeneralize the effect of streamflow on your DOC and dissolved particulate matter question, but rainfall/runoff events often act as the driving force to move particulate materials into the stream systems, and possibly move the dissolved component in the stormflow. But there is also a substantial dilution effect in rainfall/stormflow so even though the loading is likely increased, the concentration may not be increased due to the amount of added flow. DOC is not my specific expertise, but there is likely a relationship with streamflow rates, and this could depend on the hydrologic circumstances on the land, presence of wetlands, land uses, storm intensity, time since last major freshet, etc. Rainfall and streamflow are primary energy and driving forces in nutrient cycling between land and streams. In heavily gullied channel systems without floodplain access may have more energy, but these entrenched streams may have limited particulate matter sources unless the storm energies are severe enough to deliver particles as compared to streams and rivers that regularly have access to valleys that flood and can float and move their organic particles.
Thanks you William. It is nice to have your findings about this question. I was also looking more specifically about a relationship between Q and SPM to estimate the DOC of my river, but the relation is may be not so straightforward. To be slighlty more precise, I have 30 years of data on Q, SPM at a quit high resolution (daily measurement) and two years of data with Q, SPM, DOC and POC and would like to model my missing DOC value for the previous 28 years in order to see how a Dam could have affect the carbon concentration of downstream.
I would take the Q at the time the SPM, DOC and POC are collected. Look then at the range of Q that you have with values, and does it represent the high flows, moderate and low flows. You might do a flow duration curve and then plot where the Q values are that were sampled at the same times as SPM, DOC and POC. Unless there is a very strong relationship for the 2 year data and this same relationship seems to hold well with the 30 year data, I am uncertain how reliable modeling missing data might be. Do you have a handle on how efficient the dam would be at reducing DOC? DOC is not one of my major experiences so I would rely on you or the other responders. I guess my question might be you have 30 years of Q and SPM, and 2 years of Q, SPM, DOC and POC. Besides the relationship of Q and SPM, how close are DOC and POC related to SPM?
Thanks Wiliam. I saw a strong reduction of SPM with the dam, as well as a high quantity of sediment trapped. I will have a closer look on my data anyway. I also may get the C soil content, and with it, it is possible to estimate the DOC with some empirical relation established by Ludwig and Probst (1998 6https://core.ac.uk/download/files/437/12041645.pdf ). thanks again for your support.
Hi Marie
Cecile Picouet has done spm, trace elements and DOC surveys at several stations on the niger river in the mid 90s.She was in Bamako at the ORSTOM center at a time I was also over there. We done several field trips together.
You might find her work as a PhD doc somewhere, or in some paper.
Easy to search with google scholar or Harzings
Gil Mahé
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