Development of a New Zealand SedNet model for assessment of catchment-wide soil-conservation works

摘要: Abstract Much hill country in New Zealand has been converted from indigenous forest to pastoral agriculture, resulting increased soil erosion. Following a severe storm that hit the Manawatu–Wanaganui region 2004 and caused 62,000 landslides, Horizons Regional Council have implemented Sustainable Land Use Initiative (SLUI), programme of widespread conservation. We developed version (SedNetNZ) Australian SedNet model evaluate impact SLUI 5850 km2 Manawatu catchment. SedNetNZ spatially distributes budgets fine sediment landscape. It incorporates landslide, gully, earthflow erosion, surficial bank flood-plain deposition, important forms erosion Zealand. Modelled suspended loads compared well with measured an R2 value 0.85 after log transformation. A sensitivity analysis gave uncertainty estimated be approximately plus or minus 50% (at 95% confidence level). is expected by 2040, targeted water management zones will decrease about 40%. The for whole catchment 34%. reduction due maturity tree planting on land at risk 34% represents annual rate return 20% 20 million NZ$ investment conservation works through avoided damage property infrastructure clean-up costs.