AN INVESTIGATION INTO CAUSES OF RUNOFF FROM A CATCHMENT OF PUMICE LITHOLOGY,IN NEW ZEALAND |
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| Authors: | M J SELBY |
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| Institution: | Department of Earth Sciences , University of Waikato , Hamilton, New Zealand |
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| Abstract: | ABSTRACT Increased surface water runoff from about 3000 km2 of land converted to pasture from native forest and scrub, mostly in the last 20 years, in the central North Island of New Zealand has caused gully erosion. The causes of increased runoff were investigated by using 20 runoff plots and collecting data over a two-year period on climatic, soil, vegetation and runoff variables for 44 storms. Statistical analysis has shown that: runoff from pasture is greater than that from scrub or ungrazed grass; most of the intense runoff can be explained by intense rainfalls occuring on previously dry areas; 63 per cent of the runoff can be explained statistically in terms of three variables. Land use practices should be designed to reduce soil moisture depletion and to inhibit peak storm runoff, especially during intense summer rainstorms. |
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