RRBC – Long Term Flood Solutions

Comprehensive Basinwide Protection Recommendations

13 Primary Principals:

1. Serve as framework moving forward

2. Establish acceptable levels of protection

3. Basin approach – multiple measures to accomplish

4. Uniform flood regulations and zoning

5. Goals for the reduction in flood flows

6. Reduce runoff rate and volume

7. Incorporate multiple purposes (FDR/NRE…)

8. Avoid or minimize adverse impacts

9. Cost effectiveness

10.RRBC to facilitate implementation of cross-jurisdictional partnerships where possible

11.Evaluation and prioritization of plan recommendations

12.Measure and evaluate implementation of the LTFS

13.Requires a shared responsibility and commitment

• Part of Long Term Flood Solutions Report

• Reduce Red River main-stem flows by 20%

• Based on 1997 Spring Flood Event

• Applied to HEC-HMS Synthetic Hydrology

Red River Basin Commission – Basinwide Flow Reduction Strategy

RRBC-LTFS

Lidar/Enhanced Technology

RRWMB Distributed Detention Plans

Comprehensive Detention Planning…. Continued Progress

Red River Basin Tributary Detention Planning Efforts

• Large Scale Sites• Identification of all apparent sites• WRD Involvement• Multiple proposed conditions

scenarios• Multiple Runoff Events• Establish benefit within Tributaries• Establish reduction to Red River

main stem• Detailed reporting

• Large Scale Sites• Identification of sites required to

meet LTFS goals• Limited WD Involvement• One proposed condition• Standard melt progression event

only• Establish benefit within Tributaries• Establish reduction to Red River

main stem• Generalized reporting

ND Comprehensive Detention Plans

MN Expanded Distributed Detention Strategy

1. Guide WD project teams – Similar to BdSWD plan.

2. “Get FDR Projects in the Queue!” - State and Local Funding

3. Identify Project Concepts for Potential Federal Funding – Farm Bill

4. Consistency with On-going North Dakota Planning Effort

5. Potential Cost Share of FM Diversion Authority - $25 Million – Sites upstream of Halstad

6. Identify Sites for Halstad Upstream Retention Study (HUR) – RRBC

RRWMB… Why Develop Watershed Based Distributed Detention Plans?

Distributed Detention Planning – Level of Detail

• Project Planning Tool Incorporation• Watershed District/LGU Involvement• Upstream of local damage areas• Large Site Concepts (greater than 10 square miles – most in the

30 SM range)

Detention Site Identification

• LiDAR Derived Elevation/Storage Data• LiDAR Derived Contributing Watershed• Consider construction/environmental impacts of gated pool

elevations• Goal: 3” – 4” of gated storage per site (Meet LTFS Volume

and Peak Goals)

Detention Site Statistics

• Red River Basin HEC-HMS developed by the US Army Corps of Engineers

• Incorporate Identified Detention Sites• Assume all gates closed• 25, 50, 100-yr Rainfall (10-day) & 100-yr, 10-day Runoff (Snow melt

progression included)

Hydrologic Analysis - Benefits

• Existing conditions (Pre-1997) vs Proposed Conditions (Site Outlet, Damage areas, USGS Gages)

• Watershed scale mapping only• Report Summarizing Analysis

Reporting

MN Expanded Distributed Detention Scope

MN Expanded Distributed Detention Strategy – WRWD Example

Red River Basin CommissionBasinwide Flow Reduction Strategy

Peak Flow Goal: 35% ReductionPeak Flow Obtained: 36% Reduction