Environmental Flows Strategic Allocation Platform (EFSAP)


EFSAP is designed to assist with quantifying instream (physical habitat for fish) and out-of-stream (reliability of supply) consequences of different minimum flow and allocation limits to inform water quantity limit setting.


EFSAP was developed by NIWA as a water allocation decision support tool. The main uses of this tool have been in response to the introduction of the National Policy Statement for Freshwater Management (NPSFM, 2011). EFSAP is used to address the requirement that water quantity limits be set for all freshwater rivers and streams in New Zealand under this recent policy change.

The model does this by describing the consequences of water resource planning scenarios (i.e., different options for managing water resources) on in stream and out of channel values across all parts of a catchment or region. It estimates how physical habitat for fish and the reliability of water supplies for out of channel users changes when different limits on water allocation are set.

EFSAP operates on a regional scale with the view of optimising water allocation limit-setting by evaluating the effects of allowable water take and minimum residual flows on in-stream values (such as ecological health and whitebait fisheries) and reliability of water-use (such as for irrigation). The model has the ability to explore the effects of multiple takes throughout a catchment on these values.

The model operates on a spatial framework known as the River Environment Classification (REC; Snelder & Biggs 2002) which is a digital representation of New Zealand’s river network contained within a Geographic Information System (GIS). Each river segment is associated with several attributes including the total catchment area and stream order, as well as the climatic, topographic, geological, and land-cover characteristics of the upstream catchment.

Several estimates of hydrological data are required on the use of EFSAP, while the exact inputs can be catchment sensitive given the goals of modelling examples could include; 1 in 5 year mean annual 7-day low flow (Q5), mean flow (Qbar), and the shape of the flow duration curve (FDC).                                      

Once EFSAP is set up for a region or catchment area it can be used to rapidly explore the effects of various water-use scenarios and proposed allocation limits. The outputs of this model include colour coded catchment or study area maps with supporting graphics. These effectively convey modelling results and allow community members and decision makers to visualise options and consequences of water use and allocation on both instream and out of stream values.                                                                 


State of Development Unknown

Development Contact

Jan Diettrich
10 Kyle Street,


Outcome Areas Environmental
Management Domains Freshwater, Biodiversity
Intended End Users
  • Regional Council Scientist
  • Researcher
Spatial Extents National, Local (i.e. Catchment or District)
Temporal Resolutions Months, Years
Steady State or Dynamic Unknown
Level of Integration Environmental

Input & Output Data

Key Input Data Hydrology, stream topology, habitat suitability curves
Output Data Formats MATLAB


Open/Closed Source Closed Source
Licence Type Unknown
Licence Cost
(Non Commercial)

User Information

Operating Systems MS Windows
User Interface Graphical desktop
Ease of Use Please Select
Use in Policy Process Plan (Policy Formulation), Review (Issue Identification)

Technical Considerations

Keywords Water allocation, stream habitat, scenarios
Linkages to other Models
Key References

Booker, D.J., 2016. Generalized models of riverine fish hydraulic habitat. Journal of Ecohydraulics 1, 31–49

Booker, D.J., Hicks, D.M. (2013) Estimating wetted width and fish habitat areas across New Zealand's rivers. NIWA Client Report, CHC2013-075: 33

Booker, D.J., Snelder, T.H. (2012) Comparing methods for estimating flow duration curves at ungauged sites. Journal of Hydrology, 434–435(0): 78-94. http://dx.doi.org/10.1016/j.jhydrol.2012.02.031

Booker, D.J., Woods, R.A. (2014) Comparing and combining physically-based and empirically-based approaches for estimating the hydrology of ungauged catchments. Journal of Hydrology, 508(0): 227-239. http://dx.doi.org/10.1016/j.jhydrol.2013.11.007

Snelder, T., Booker, D., Lamouroux, N. (2011) A method to assess and define environmental flow rules for large jurisdictional regions. Journal of the American Water Resources Association, 47(4): 828-840.

Snelder, T.H., Rouse, H.L., Franklin, P.A., Booker, D.J., Norton, N., Diettrich, J. (2014) The role of science in setting water resource use limits: case studies from New Zealand. Hydrological Sciences Journal, 59(3-4): 844-859. 10.1080/02626667.2013.793799

Associated Case Studies

EFSAP - Piako Catchment Waikato

This report evaluates the EFSAP using the Piako River catchment area as a case study.