Landcare Research - Manaaki Whenua

Landcare-Research -Manaaki Whenua


The survey was completed by a range of researchers and consultants, half of whom are active modellers, while the others are users of established models. This demonstrates the importance of the proposed hydrological model platform being made accessible to users with a limited knowledge of programming.

There is a current interest in modelling river dynamics, saturated flow and plant growth. The outputs that rely on hydrological data are nitrogen and phosphorous dynamics, phosphate dynamics, plant growth and sediment transport. There was less interest in bypass flow, macroporosity and aeration, which nevertheless are important parameters in nitrate leaching.

The main focus is at catchment scale, on terrain <15°, and having a daily time step. The most commonly used models are one-dimensional. Nevertheless, a great number of users believe that the accuracy of their model output could be improved if they had available more accurate spatial time series hydrological data at the scale of interest where one can plug-and-play their module of interest. A means of improving their models would be to model and incorporate lateral flow.

S-map and the Fundamental Soil Layers are the most widely used soil databases. Nevertheless, these databases are used by only 60% of participants, and 18% of users do not incorporate any soil information into their hydrological models. The most important derived hydraulic parameters from the soil databases were field capacity and saturated hydraulic conductivity, of which the latter is the most variable. Users showed less interest in macroporosity, which is an important parameter to accurately compute drainage and nitrate leaching, especially in stony soils. A significant number of participants would be interested in obtaining effective soil parameters that can be derived at their scale of interest in POLYGON or RASTER format.

A majority of participants are interested in having a powerful calibration tool, such as PEST, and there is an interest in future use of the Bayesian tool box.

Forty percent of the participants responded that they would like to contribute to the development of a ‘new’ hydrological platform. More research needs to be performed to determine the suitability of PCRASTER as a suitable platform for such a development.