The Problem

The underlying problem in load estimation involves evaluating an integral. The amount (or load) of a constituent (e.g. sediment or nutrients) transported past a river cross-section during a time interval is given by:

where

L

is the integrated load during ;

L(t)

is the instantaneous load at time t;

K

is a units conversion factor;

Q(t)

is streamflow at time t, (usually relatively accurately known);

C(t)

is the average concentration of the constituent in the cross-section at time t.

Direct application of equation (2) is usually impossible because C(t), the continuous time trace of concentration, is known only at those times when concentrations were measured.

• Method 1: Estimate a Continuous Concentration Trace
  • The Worked Record
  • Rating Curves
  • Modification 1: Retransformation and Bias Correction Factors
  • Modification 2: Bias and Variance of Long-term Transport Estimates
  • Modification 3: ``Less-than'' Values
  • Modification 4: Time Series and Transfer Function Models
• Method 2: Direct Estimation
  • Stratified Sampling
  • A Modification: Statistically-Based Sampling
• Other Methods for Estimating Transport
  • Ratio Estimators
  • Bivariate Lognormal Load Estimator