Freshwater bodies cannot be viewed in isolation because they are strongly interconnected with land (rock and soils), coast, atmosphere, and living things (plants and animals, including humans). These connections mean what happens in one can have flow-on effects in another.
Māori have emphasised the need to consider the environment in its entirety through a concept referred to as ki uta ki tai (Tipa et al, 2016). Māori use this concept to describe their holistic understanding of freshwater ecosystems and how the health and well-being of the people are intrinsically linked to the natural environment.
Ki uta ki tai (from the mountains to the sea) recognises the movement of water through the landscape and the numerous interactions it may have on its journey (see figure 1). Ki uta ki tai acknowledges the connections between the atmosphere, surface water, groundwater, land use, water quality, water quantity, and the coast. It also acknowledges the connections between people and communities, people and the land, and people and water.
The ki uta ki tai journey begins with precipitation falling on land, where the water flows over the ground as surface water. A portion of surface water enters rivers and streams and flows towards the oceans. Water emerging from the ground (groundwater) and some surface water may be stored as fresh water in lakes. Some surface water will also soak into the ground where it replenishes deep and shallow aquifers and seeps back into water bodies (and the ocean). Along the way, water can be modified through human activities, such as when we take water for power generation and irrigation, discharge contaminants to water bodies, and channelize rivers. Surface water in rivers, along with the material it carries, eventually flows into estuaries and the ocean. The journey ends with the water returning to the atmosphere through evaporation and transpiration (moisture carried through plants from roots and then evaporated from leaves).
This illustration shows the movement and interactions of water through the landscape.