Pajaro River Watershed Study

Pajaro River Watershed Map

Sunday, 08 March 2009 03:21 |

Click for larger image

Last Updated (Sunday, 08 March 2009 03:31)

Sediment Model

Sunday, 08 March 2009 03:14 |

Sediment Model Conditions

Source: County of Santa Clara

Additional scenarios were developed for the sediment model to expand the understanding of the sediment characteristics of the Pajaro River. The sediment model used the hydrology model results as one of several variables. Other variables included stream flow data, hydraulic roughness of the channel, and sediment data. Comparison between the current peak discharges shows the effects of varying stream flow. Increasing the channel hydraulic roughness simulates additional vegetation and impacts the velocity and water depth in the channel, which increases sediment deposition. The other conditions are developed based on an increase or decrease in actual sediment load which could result from changes in upstream land use, in stream gravel mining, incision and erosion of upstream channels, and reservoir construction.

Last Updated (Tuesday, 17 March 2009 05:03)

Four Watershed Conditions

Sunday, 08 March 2009 01:50 |

Source: County of Santa Clara

Land use is one of the factors that affect flood frequency and magnitude. One of the major goals of Phase 1 of the study was to understand the potential flooding affects of land use changes over time. Four different land use conditions were chosen to span the extent of the reasonable land use changes and associated flooding affects. Modeling the watershed in different conditions gives insight into potential future flooding problems and allows the impacts of development trends to be identified.

Last Updated (Tuesday, 17 March 2009 05:04)

Pajaro River Watershed Study

Sunday, 08 March 2009 01:17 |

Source: County of Santa Clara

Hydrology

Since 1947, the addition of three reservoirs significantly reduced the probability of flooding in the lower Pajaro River.
Neither current agriculture conditions nor potential agricultural changes have a significant effect on design discharge or flood impacts.
Urbanization increases the runoff from frequent events (2-years to 25-year) but has little impact on runoff from large storms (50-year to 200-year).
Soap Lake provides significant flow attenuation and flood storage benefits for the upper Pajaro River and is key to flood protection.

Last Updated (Tuesday, 17 March 2009 05:05)