User interface of the TARGETS-2D riparian seed model. The model represents river water surface elevations, groundwater elevations, and riparian plants from the time when they are deposited on the soil surface as seeds through sprouting, developing into seedlings, and winter dormancy.
What is TARGETS-2D?
TARGETS-2D is a new implementation of old concepts for how river flows affect the establishment, survival, and development of riparian tree seeds. It is designed to understand and predict how alternative river flow regimes and channel shapes affect where riparian tree species can grow. TARGETS-2D is the newest in a series of riparian plant models called TARGETS, the first to be fully two-dimensional and to explicitly represent individual habitat units, seeds, and plants. These models implement the concept of Mahoney and Rood (1998; Wetlands 18:634-645) that seeds can establish when and where flow recedes slowly enough so that roots can keep up with declining soil moisture levels. TARGETS-2D also explicitly represents seed and plant mortality due to inundation (when submerged), desiccation (when roots cannot reach moisture), and scour by high flows.
The model is designed especially for two kinds of river management applications: evaluating alternative flow regimes, and designing habitat restoration projects that re-contour riparian habitat. It uses the same river hydraulics simulation methods as InSTREAM and FYFAM, our river management models for salmonid fish and stream-breeding frogs.
TARGETS-2D was develop by Steve Railsback and John Bair (McBain Assoc., Arcata, CA), and funded by the Tuolumne River Conservancy and California Fish and Wildlife under grant agreement Q2140407 with McBain Associates.
Current version
The first release of TARGETS-2D was made in January 2023. The release of 6 March 2023 (a) Modified how water elevations are updated at cells where the hydraulic input says depth is zero but estimated groundwater elevation is above the ground surface. We set the depth to >0, which eliminates anomolous groundwater elevations at nearby cells. (b) Eliminated input and code to simulate water velocity, which has no effect on model results (it was previously included only for display).
The current release of 18 May 2023: (a) revises the root growth submodel and fits parameter values to published data, (b) revises the seedling desiccation submodel and parameters to fit published data, (c) adds an alternative way to represent how seedling scour varies with plant size, and (d) provides minor software and output improvements.
The current release is available by downloading this zip file (55 MB). The distribution includes:
- A complete model description and user manual,
- The model code, and
- Example input files for one site.
The TARGETS code uses the NetLogo modeling platform, which is available free from Northwestern University. Simply install NetLogo, then use it to open the TARGETS model file, which is named something like TARGETS-2D.nlogo. The model is compatible with versions 6.2.2 and later of NetLogo.
A large archive of code tests is available upon request.
Please feel free to use TARGETS-2D, but we ask that you contact Steve Railsback if you do, or if you need support.