Fusion of high resolution orthophotos (0.4 m), Landsat imagery (30 m) and LiDAR based terrain indices (Topographic Wetness Index) were used to identify small-scale wetlands in the Waituna catchment in the Southland region, New Zealand. Suitability modelling approach was used to identify the spatial distribution of the sites most suited to wetland creation or restoration. We calculated the area, average depth, and water storage capacity for each modelled wetland based on the flooded area. The study showed that terrain analysis using high-resolution topographical data can produce suitability maps for wetlands that can be easily used by decision makers and planners in watershed management. The rapid methodology reveals potential wetland creation or restoration sites at a reasonable cost; with the resulting spatially explicit suitability map, managers can plan for wetland creation or restoration without having to wait for field-data collection.
On a the wetland level, a simple dynamic model operating on an hourly time step was used to explore potential wetland nitrogen removal performance of a wetland in Waikato region, New Zealand. Hourly measurements of inflow, outflow, rainfall and Penman evapotranspiration estimates were used to calculate a dynamic water balance for the wetland. In addition, nitrogen concentration measurements at inflow, outflow and piezometers installed in the wetland were used as input data for the model. A dynamic nitrogen-N mass balance was calculated by coupling influent concentrations to the dynamic water balance and applying a first order areal removal coefficient (k20) adjusted to the ambient temperature. Storm events above a certain threshold were assumed to always result in surface runoff or overland flow and were assigned higher nitrate based on surface run-off measurements. The removal efficiency was estimated for all nitrogen forms.
On catchment level, nitrogen and phosphorus losses were modelled 28-year period in the Porijõgi catchment, Estonia. An empirical model was used to model nutrient losses. Land use pattern, soil information, fertilization factor and hydrology factors were used as inputs for the model.The N and P runoffs declined following the post-Soviet collapse of agriculture, and stabilised at low output during the 1990s and early 2000s. Introduction of the European Union Common Agricultural Policy (CAP) reintensified the agriculture and somewhat rebounded the N and P discharges.
For spatial planning and implementation suitability modelling approach was used on spatial data to create a methodology for national-scale determination of Estonia’s green infrastructure and conflict hotspots between green infrastructure and human influenced areas to indicate the need for ecological engineering measures like the construction of buffer ecosystems, such as wetlands that are capable of capturing and treating wastewater, agricultural runoff, and stormwater.
Altogehter one book chapter and eight scientific papers in peer-reviewed journals were published. The results of this research have been presented in several local ( NZ Hydrological Society Conference and NZ Ecological Society Conference, Annual Conference of Estonian Geoinfinformatics Society) and international conferences (for example EGU and Ecosummit).
Two meetings with DairyNZ focusing on collaboration in modelling nutrient runoff and also possible use of current work on identifying wetlands using remote sensing in a practical tool for farmers. Several press releases and social media posts were made about the project progress and outcomes.
