MODIS is too coarse if your lagoons (we call them billabongs in Australia; others call them ox-bow lakes) are anything like mine with a width of 30-100 m. See http://www.irrigation.org.au/IAL_IDC_Conf_2009/Soppe,%20Richard%20Abstract%20100.pdf.

Hi Patrick, tanx for ur paper it was quite educative; but as someone who is not a GIS specialist how do i describe my lagoon of interest with regards choosing the right method of remote sensing for my study.

Hi colleagues, i need to evaluate the change in depth in the lagoon due artisanal dredging that has been ongoing over a period of time. Some professional advice to guide my line of though and available options will be highly appreciated.

Airborne idar bathymetry is the best method, but note that the lidar pulse penetrates only to 3 Secchi depths in turbid waters. If the lagoon is small, you could use a small boat with a plumb line or acoustic depth sounder. If you can relate changes in shoreline (water boundary) to depth changes, then airborne or satellite imagery might be useful. Direct estimates of lagoon depth with satellite images would not be accurate. The following article might be useful:

Klemas,V. (2011). Beach profiling and LIDAR bathymetry: An overview with case studies. Journal of Coastal Research, 27, 1019-1028.

Tanx alot sir, i will check it up.

LiDAR has been used to measure depth successfully in coastal and other clear waters. Hence its good for bathymetry in such waters. However if there are any chemical or suspended solids that are leading to differences in light dispersal within the water column then LiDAR is no use at all. For Australia that means most inland waters cant apply this technology becuase we highly dispersive clays.

There are lots of old papers that talk about using classification of Landsat bands such as 3 and 7 to detect water. The intensity of the pixels is calibrated against water depth via ground truthing. In one of our studies we used a large lake which was routinely measured for its depth to do this ground truthing, but ideally more spatial coverage is needed for this truthing.

I uploaded our 2010 report which uses NDVI MODIS, Landsat and on-ground lake depth data to calibrate wetland inundation models. Follow the link below if you are interested - the section on "Lachlan IQQM Model Build and Calibration" on the pdf file starts at p. 237 out of 310 pages. If you can also establish some bathymetry relationships, where you know what depths relate to areal extent of inundation you can essentially follow how the lake (or lagoons, which we model as well) change over time

Technical Report Lower Lachlan wetlands scoping study. Final Report.

Thanks Patrick, i'll go through the document and see how far i can breakthrough into making a final decision on my methodology. Thanks again sir.