Please click on the tutorial most fitting of your expertise in order to learn about the features of the visualization tool.

Transcription

1 Introduction Welcome to the Indian Creek Conservation Reserve Program (CRP) visualization tool. This tool was developed by the University of Iowa - Institute for Hydroscience and Research (IIHR) as part of a pilot between the US Army Corps of Engineers and the USDA Farm Service Agency. The purpose of this pilot effort was to explore the flood reduction benefits that upstream CRP lands provide to downstream urban areas. This pilot used a physically-based hydrologic model to investigate the importance of physical location on specific CRP practices. This pilot concluded that existing CRP lands are providing urban communities in Indian Creek economic benefits due to their flood damage reduction properties. This pilot also concluded that targeted implementation of additional CRP practices may provide greater economic benefits to downstream urban communities. The type and location of the CRP practice is an important factor in the cost-effectiveness. A combination of grass-based riparian buffers and wetlands provide the greatest economic benefits due to flood damage reduction potential but require a relatively large amount of land conversion to realize the benefits. Grass-based riparian buffers were identified as having the greatest potential for realizing economic benefits associated with flood damage reduction for a relatively small amount of land conversion. This study concluded that targeted grass-based riparian buffers are the most cost effective CRP practice in providing economic flood damage reduction benefits versus their CRP rental costs. This visualization tool has been developed to help communicate the results of this study in an interactive way so that individuals and water resources managers can better understand the implications of CRP policy and landuse actions on the resilience of the communities in Indian Creek. Please click on the tutorial most fitting of your expertise in order to learn about the features of the visualization tool. How do CRP practices effect flooding Different vegetation types common to CRP practices have an impact on soil structure and soil health which are directly related to a soil s ability to take in water from rainfall, called infiltration. Vegetation also has potential to slow down water that flows over it based on how dense the vegetation is. This pilot project used a state of the art hydrologic model that is able to account for these processes based on their physical location. This physically-based hydrologic model is able to track rainfall as it runs across the surface of the earth, through the soil and to the groundwater. This model also includes a hydraulic routing component which helps highlight how vegetative cover may slow water and allow time for infiltration of water to the soil or groundwater. How the landscape manages the rainfall is based in part on the timing of rainfall and runoff. CRP practices that provide dense vegetative cover which slows water, and may allow for more water to infiltrate, change the

2 timing of runoff. In most cases this change in runoff volume results in lower flood peaks and consequently less damages resulting from flooding. However, because vegetation changes impact the timing of runoff there can be locations that will experience higher flood stages and more damages due to the timing. The following graphics depicts how grass-based riparian buffers: 1. Increase the soils ability to infiltrate water when they are saturated (saturated hydraulic conductivity) 2. Increase the resistance on water flowing over the ground (overland flow roughness) due to dense vegetation. 3. Decrease the maximum amount of water (peak discharge) flowing over the ground. 4. Decrease (and in some cases increase) the velocity of the water flowing over the ground due to changes in the timing of the overland flow.

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