Managing catchments for water yield : a project [dissertation] presented in partial fulfilment of the requirements of a Diploma in Natural Resources from Lincoln College

The management of stream catchments for water yield is a topic that is receiving some attention at present in New Zealand. The hypothesis under scrutiny is that a change in the vegetative cover of a catchment may significantly alter the volume of water yielded by the catchment. A significant increase in water yield would be one that would be utilised for downstream purposes such as electricity generation, irrigation supply, domestic or industrial water supply or recreation, and that would make an appreciable impact on these uses. Apart from a few studies on small catchments which yielded fairly predictable results, research on this topic in New Zealand has not provided catchment managers with much in the way of definite guidelines by which to make decisions. But perhaps this is a function of the nature of the problem as much as of the nature of the research. The importance and number of limiting conditions for such management indicate that an approach to investigating the potential for management of a catchment must recognise the unique situation and hydrologic response of each catchment to a change in vegetative cover. The second part of this report, therefore, will investigate a possible approach to the determination of the potential of a given catchment for management