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  • Rights: The University of Waikato Te Whare Wānanga o Waikato and Waikato Regional Council
    Published 13 March 2020 Referencing Hub media
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    Ki uta ki tai refers to the concept of mountains to the sea – a whole-systems approach to the sustainable management of water. The water catchment influences the biodiversity and ecology of stream and river systems.

    The following resources explore what water catchments are and why they are important.

    Transcript

    ALICE TREVELYAN

    A catchment is shaped by topography. So imagine a basin, and it’s everything that falls within that basin, that steep sides that flows towards that water body. But it’s not just necessarily rainfall. A catchment will have groundwater and surface water sources.

    DR ELOISE RYAN

    Groundwater is the water that exists underground in the spaces of soils and rocks. It’s much like water fills a sponge, it’s the water that exists in the pores. And some groundwater is pumped above ground for irrigation or drinking water. Everything that happens on the ground can impact the groundwater.

    ALICE TREVELYAN

    The easiest way to define a catchment is an area where any rainfall in that area all flows into a water source, so whether that be a river, a stream, a lake or a wetland. So catchments can be really variable in size. They can be massive, for example, the Waikato River catchment, or they can be really small, for example, a small wetland on someone’s property. There’ll be hundreds or thousands of catchments across the Waikato region.

    DR ELOISE RYAN

    To map catchments, you can start at the mouth where your stream discharges and work your way back up by looking on a map. And catchments tend to be bounded by things like mountain ridges or forests. So you can actually look on a map and trace your streams from the mouth up to the source. So a headwater is the source of the stream. That is where the stream starts from and then the water flows down the river and ends up in the lowlands – and that’s low-elevation waterways, and those waters tend to be warmer, slow flowing and more full of nutrients or sediment because they’ve flown quite a long distance through the land, whereas headwaters at the source tend to be more clearer, cooler and faster flowing.

    ALICE TREVELYAN

    Catchments are really important for water quality. Every activity that’s happening in that area – whether it be related to water, soil or air – is going to impact upon the water quality further downstream, whether that’s good or bad.

    Acknowledgements

    Alice Trevelyan
    Dr Eloise Ryan
    Waikato Regional Council
    Catchment diagram by Phil Jones, New Zealand Landcare Trust
    Stream footage: Dairy NZ
    Healthy Farms Healthy Rivers and Waikato Regional Council

    Acknowledgement

    This video has been developed in partnership with the Waikato Regional Council as part of the Rivers and Us resource.

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