『Abstract
A method for computing loads of total phosphorus and nitrate
from a small catchment in the Czech Republic has been presented,
given continuous measurements of water levels, turbidity and an
ion-specific NO3--N probe together
with a limited number of discharge measurements and analyses of
grab samples. Given the observed variability in the observations,
log-log regressions are used to convert water levels to discharge
and to derive continuous estimates of total phosphorus and nitrate.
Integrations to estimate loads using predicted values of the true
discharges and concentrations are then carried out by a Monte
Carlo method to avoid strong assumptions of independence and distribution.
Coefficients of variation for the estimated monthly loads range
from 5% to 23% for TP and 12-36% for NO3--N.
At the annual time scales, coefficients of variation are of the
order of 5% for both TP and NO3--N.
The variability in the estimated annual loads between the years
was, however, significantly larger than the uncertainties estimated
within each year.
Keywords: Uncertainty estimation; Rating curve; Monte Carlo sampling;
Nutrient loads』
1. Introduction
1.1. Uncertainty in load estimation
2. The catchment
3. Evaluating the load
3.1. Predicting the instantaneous load
4. Results
4.1. Modelling discharge
4.2. Modelling phosphorus
4.3. Modelling nitrate
4.4. Load predictions
5. Conclusions
Acknowledgement
References