I.2.3 - CRiSP.1 Submodels

Travel Time

The smolt migration submodel, which moves and spreads releases of fish down river, incorporates flow, river geometry, fish age and date of release. The arrival of fish at a given point in the river is expressed through a probability distribution. All travel time factors can be applied or they can be switched off individually, resulting in a simplified migration model.

The underlying fish migration theory was developed from ecological principles. Each fish stock travels at a particular velocity relative to the water velocity. The relative velocity can be set to vary with fish age. In addition, within a single release, fish spread as they move down the river.

Predation Rate

The predation rate submodel distinguishes mortality in the reservoir, and the forebay and tailrace of dams. The rate of predation can depend on temperature, diel distribution of light, smolt age, predator density, and reservoir elevation.

Gas Bubble Disease

A separate component of mortality from gas bubble disease produced by nitrogen supersaturation is incorporated into CRiSP.1. The mortality rate is species specific and is adjusted to reflect the effect of fish length and population depth distribution.

Dam Passage

Timing of fish passage at dams is developed in terms of a species dependent distribution factor and the distribution of fish in the forebay, which can change with daily and seasonal light levels. Fish guidance efficiency can be held constant over a season or it can vary with fish age and reservoir level.

Transportation Passage

Transportation of fish at collection dams is in accordance with the methods implemented by the U.S Army Corps of Engineers. The start and termination of transportation and separation of fish according to species can be determined for any dam under the same rules used to manage the transportation program. Time in transportation and transportation mortality can also be set.

Nitrogen Supersaturation

Nitrogen supersaturation, resulting from spill at dams, can be described with a mechanistic submodel that includes information of the geometry of the spill bay and physics of gas entrainment. Alternatively, supersaturation can be described by empirical models.

Flow

Flow is modeled in two ways: it can be specified at dams using results of system hydro-models or it can be described in terms of daily flows at system headwaters. When flow is described in headwater streams, the flow submodel generates a random set of seasonal flows that have statistical properties in accordance with the available water over a year. In this fashion, the model statistically reproduces flow for wet, average and dry years. The user controls the mainstem river flows by adjusting the outflow of the storage reservoirs within their volume constraints.

Water Velocity

Water velocity is used in CRiSP.1 as one of the elements defining fish migration. Velocity is determined from flow, reservoir geometry and reservoir elevation.

Reservoir Drawdown

Reservoir elevation is set on a daily basis from elevation information in the system hydro-models or from user specified files. As water levels drop, part of the reservoir may become a free-flowing stream.

Stochastic Processes

CRiSP.1 can be run in a Monte Carlo Mode in which flows and model parameters vary within prescribed limits. In this mode, survival to any point in the river can be determined as a probability distribution.

Geographical Extent

CRiSP.1 can describe a river to any desired level of detail by changing a single file containing the latitude and longitude of river segments, dams and release sites. In its present configuration, two river-description files are available. One file contains an abbreviated river map with the major tributaries. It contains three representative release sites, although more can be added easily. A second river descriptions file defines a more extensive river and tributary system and has upwards of 100 hatchery release sites.