Land Management Impacts on Water Quality in New Zealand Across Political Boundaries

The most immediate and widespread driver of land cover change is land management, such as forest clearing for livestock farming or grassland conversion to plantation forests for timber production. These land management decisions are heavily influenced by regional policies, and thus analyses of the socioeconomic drivers for land cover change need to occur at these regional levels. Evaluation of environmental impacts of land management is difficult because regional political boundaries rarely coincide with environmental boundaries such as catchments (aka watersheds). One nation has recognized this disconnect between political boundaries and environmental sustainability. In 1991, New Zealand (NZ) adopted the Resource Management Act, which among other policies related to sustainable development, redefined the political boundaries of the nation to coincide with catchment boundaries so that each Regional Council would be solely responsible for the health of their ecosystems, particularly water quality of their rivers, lakes, and coastal environments. The goal of this proposal is to use NZ as a case study where land use change analyses at fine spatial and temporal resolutions are used to understand how Regional land management impacts water quality. In order to assess the effectiveness of regional policies in improving or preserving water quality, we will create high-resolution (8-day, 30 meter) land use and water quality time series and then overlay them onto socioeconomic timelines for the period 1990 - 2014. The key products of this research will be: (1) a fused 30m land use time series for all of NZ and one of the most comprehensive spatiotemporal analyses of strip grazing and plantation forestry land uses (2) empirical models, based on hundreds of catchments with 24 years of monthly data, that quantify relationships between land use, weather, and water quality (turbidity, dissolved organic matter, total and dissolved forms of nitrogen and phosphorous, and E. coli) and (3) an assessment of the effectiveness of catchment scale land management in terms of water quality. Because NZ is the first nation to redefine its political boundaries to coincide with environmental boundaries (i.e. catchments) this project will set a precedent for future considerations of catchment-based governance. The objectives and expected products of this proposal contribute to the mission of the NASA LCLUC Program by using interdisciplinary science (Remote Sensing, Geomorphology, Hydrology, Socioeconomics) to address the management of a natural resource (water quality) with multidimensional societal relevance (water treatment, recreation, safety, tourism, ecosystem health), starting with agricultural land use change. The proposed research will investigate Vulnerability of agricultural land uses to climate changes, particularly the Impact of severe droughts in NZ from intensifying ENSO phenomena (e.g. 1998 and 2008) on livestock grazing pressures and how Regional governments are Adapting to these interdependent climate and land use changes. Indeed, NZ Regional Council policy statements are currently being modified to address predicted regional climate changes. The other agricultural land use that will be assessed with fine spatial and temporal resolution – plantation forestry – will also be of broad interest to NASA’s Carbon Cycle and Ecosystems focus research area, as well as GOFC-GOLD and GLP. The project’s focus on differences in land use across political Regions within NZ, along with the goal of explaining these differences using socio-political-economic factors and feedbacks, is directly related to this ROSES solicitation. An essential element of this international project is collaboration with regional scientists from NIWA, LCR, and the Regional Councils. and the use of local socioeconomic and geophysical data, some of which is proprietary to these institutions. Remote sensing and data fusion are essential components of this proposal.