I have worked with colleagues that used a 60 cm length of 10 cm diameter piston core liner capped and sealed at the bottom and suspended on a mooring to measure seasonal deposition rates in prodelta marine environments at the heads of several Baffin Island Fiords.

You have asked an interesting question that needs qualification. First, what type of sediments and what sizes are you interested in monitoring? Second, what length of time do you want to monitor the deposition (I am guessing it will be more than a few weeks)? What is the environment - depth, temperature, expected currents, salinity? How many locations do you want to monitor simultaneously?

While there are many, individual, commercial instruments for measuring marine parameters, you may want one that combines measurement of some of these parameters. This could be a custom design. The power distribution and communication design, alone, is not simple. Cabling and connections in a marine environment are typically fraught with challenges; many times they will end up leaking, which in a hypersaline environment will quickly corrode and short out electronics.