Estimation of lag time of water and nitrate flow through the vadose zone: Waikato and Waipa River catchments
TR 2018/31
Report: TR 2018/31
Author: Scott Wilson and Ali Shokri (Lincoln Agritech Ltd)
About this report
This report was commissioned by the Technical Leaders Group for the Healthy Rivers Wai Ora Project Report No. HR/TLG/2015-2016/1.3
This report presents a methodology and results for predicting the time taken for nitrate to travel from the land surface, though the unsaturated (vadose) zone and into shallow groundwater.
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| Contents | |
| 1 | Introduction |
| 1.1 | Study objectives |
| 1.2 | Scope and nature of the services |
| 1.3 | Introduction to time lags |
| 1.4 | Conceptual model |
| 2 | Soil moisture balance model |
| 2.1 | Methodology |
| 2.2 | Model inputs |
| 2.2.1 | Soil data |
| 2.3 | Model modifications |
| 2.3.1 | Runoff |
| 2.3.2 | Readily available water |
| 2.3.3 | Interception |
| 2.4 | Soil moisture balance results |
| 3 | Unsaturated zone model |
| 3.1 | Theoretical background |
| 3.2 | Unsaturated zone methodology |
| 3.2.1 | Assumptions |
| 3.2.2 | Numerical procedure |
| 3.3 | Vadose zone model parameterisation |
| 3.3.1 | Static water levels |
| 3.3.2 | Hydraulic properties |
| 3.4 | Vadose zone model results |
| 4 | Saturated zone model |
| 4.1 | Saturated zone model methodology |
| 5 | Comparison with tritium data |
| 6 | References |