Flow Path Intervention for Water Quality

Client Name: Living Water - Waikato Peat Lake Catchments

Project Overview: This project, based in the Mangaotama catchment, Waikato, demonstrates one of the key principles in catchment management: how to prioritise effort and resources to make the biggest difference. Prioritisation at landscape scale can be driven by multiple outcomes. Outcomes can include social, cultural, economic, and environmental considerations. In this catchment the focus was on understanding the activity that would best improve water quality in the Mangaotama stream. 

To do this Element Environmental undertook 3 complimentary processes:

A) The first was to use a series of risk maps generated by overlapping soil and hydrological models. These models helped identify diversity across the land and soil and the potential impact on water quality.

B) The second was to understand the flows throughout the catchment. Contaminants only move to waterways when there is periods of rainfall and drainage, so knowing where water will flow through the landscape enables us to do something with that water before its flows into streams and rivers. 

C) The third was to understand what types of water treatment devices (in our case constructed wetlands, detention bunds, vegetated swales and sediment traps) we can install to treat the water before it enter streams. 

Key Insights: Catchments are not created equally and different parts of a catchment will need different management. 

Understanding the biophysical and geophysical make-up of a catchment will allow prioritised action and help reach water quality objectives faster and at a lower cost. 

Steps:

• Catchment modelling and understanding the current state. 
• Installation of interventions to improve water quality (edge of field mitigations).
• Flow path mapping to understand flows through a catchment.