Land Use Tools

This grid‐based sediment tracing technique improves the precision of source contribution estimates and enhances the granularity of sediment source maps. This technique provides a greater spatial resolution of the sediment sources by assigning sediment contributions into grid sources rather than area‐specific source types.

Maps of the potential groundwater recharge zones across New Zealand (500m x 500m resolution), which can be used to identify areas of high nutrient leaching in zones where high groundwater recharge potential exists.

Soil conservation over large areas is expensive and needs to be targeted to obtain maximum benefit for the least cost. Cascade of Soil Erosion research has outlined an event-based model of soil erosion and sediment transport at the catchment scale.

This land-use assessment framework has been developed by Next Generation Systems to explore opportunities for adopting more suitable land use and to identify gaps in knowledge. It uses multi-criteria decision-making to simultaneously consider multiple domains, where selection of best alternatives is highly complex, context-specific and deeply personal. Please email Alan Renwick to discuss using the tool.

A model of soil erosion developed for the Manawatū-Wanganui by Cascade of Soil Erosion researchers can be parameterised with local data, then used in spreadsheet form to evaluate the impact of changes to land use and management on the sediment yield of catchments, and help regional councils plan cost-effective soil conservation work projects of varying size and complexity.

Cascade of Soil Erosion research developed a method for estimating the improvement in water clarity when soil conservation is practiced.

Land Use Suitability research has developed a method to identify the most appropriate management actions for aquatic ecosystems. This method provides a valuable decision support strategy to optimise catchment management actions toward a water quality objective.

Sources and Flows research modelled drought duration-severity distribution and frequency to generate SDF curves for six locations in different climatic regions. Modelling of soil drainage at these sites indicated 35% to 80% more drainage peaks than expected, suggesting better monitoring of soil moisture and scheduling of irrigation is required. The SDF curves provide a comprehensive understanding of occurrence and duration of dry conditions, and can be a useful tool for developing strategies for water management.

Measuring Groundwater Denitrification research has developed and proven a methodology for measuring dissolved neon which, in combination with argon and nitrogen measurements, can be to quantify excess nitrogen in groundwater. Measurement of ‘excess N2’ is the most promising method for directly measuring denitrification that has occurred in an aquifer.

Sources and Flows research identified 5 potential groundwater recharge zones across New Zealand. Knowledge of groundwater recharge potential is required for sustainable groundwater management, including the assessment of vulnerability to contamination. The maps can be used to identify areas of high nutrient leaching in zones where high groundwater recharge potential exists (regions with large lakes and in the lower elevation plains).

Physiographic Environments of New Zealand research is developing a cost-effective technique to measure and map (as an integrated physiographic layer) how features of the natural landscape lead to variation in water composition, and hence quality. A web-based map is being co-developed with a wide range of collaborators. So far 7 regional and district councils are sharing data and collaborating to develop and apply the physiographic approach to their regions. This document contains information for interested regional councils.

Phosphorus Best Practice research found that current practice and regional rules for the application of farm dairy effluent (FDE) to stony free-draining soil under irrigation were not sufficient to prevent phosphorus losses. Regional government and industry bodies can use these results to strengthen guidelines and regulations, particularly regarding the use of FDE on stony free-draining soils with low capacity to absorb P, such as those common in the Canterbury region, in order to meet community and government expectations.

Assessing Contaminants with Stream Order research discovered that fencing only large streams to exclude stock has less effect on freshwater quality than expected. Small, steeply sloping streams contribute, on average, 77% of the load of freshwater contaminants. To substantially reduce contaminant losses, stock should be excluded from small, steeply sloping streams. This research can be used by local government to determine policy to improve the quality of fresh water.