1. A method comprising: evaluating data representing observed sediment erosion and deposition behavior in a hydrocarbon reservoir; adjusting a parameter value in a set of equations so that the output of the set of equations accurately matches the observed sediment erosion and deposition behavior for sediment sizes throughout a range of about 10 microns to about 10 centimeters, wherein the set of equations includes an equation representing a dimensionless rate of re-suspension of sediments from the sediment bed into the fluid flow, wherein the dimensionless rate of re-suspension for each of i size-defined sediment bins is calculated according to E s i = { 0 if ⁢ ⁢ Z i ≤ Z c a z ⁢ Z i ω - φ ⁡ ( Z i - Z c ) φ 1 + a z e m ⁢ Z i ω - φ ⁡ ( Z i - Z c ) φ if ⁢ ⁢ Z i > Z c where a z is equal to about 1.3×10 −7 , e m is a maximum value of the dimensionless rate of re-suspension, ω is a major Z exponent having a value selected from a range of 1 and 20, φ is a non-zero minor Z component having a value of 5−ω, Z c is a threshold value for initiation of re-suspension, and Z i is a variable having a value affected at least in part by the grain size of sediment particles in the respective bin i; defining a grain size distribution of an initial condition of a sediment bed in the hydrocarbon reservoir; applying the set of equations with the adjusted parameter value to the initial condition of the sediment bed, wherein outputs of the set of equations express how a fluid flow affects the erosion and deposition of sediments at the initial condition of the sediment bed; adjusting the grain size distribution of the initial condition of the sediment bed based on the outputs of the set of equations, to create a subsequent sediment bed condition having a grain size distribution associated therewith; re-applying the set of equations with the adjusted parameter value to the subsequent sediment bed condition a pre-determined number of times; re-adjusting the grain size distribution of the subsequent sediment bed condition after each re-application of the set of equations with the adjusted parameter value; creating a model of the hydrocarbon reservoir using the subsequent sediment bed condition; and outputting the model of the hydrocarbon reservoir.