Watershed Modeling in Urban & Rural Landscapes

Andy Asell Andy.Asell@dnr.iowa.gov

515-727-8386

Annual Sponsored Project Workshop November 17, 2017

DNR Watershed Improvement Section • Funded by EPA Section 319 Program

• Since 1990, DNR-WIS “319” program has partnered with DSC, NRCS, and SWCDs to support over 100 watershed projects across Iowa

• Today the DNR 319 funds 13 active watershed projects primarily thru SWCDs

• Must have a 9 element watershed management plan (WMP) in order to implement a watershed project.

• DNR has cooperative agreement with IDALS to provide GIS services…GIS Project Library comprising >400 total projects

DNR 319 Goals • Show measureable improvement of water quality

• “Fix” impaired waters

• Remove waterbodies from the EPA’s Impaired water list

• Implementing Iowa’s Nonpoint Source Management Plan (reduce non-point pollution & improve water quality)

• Partner with SWCDs, IDALS, State Universities, NRCS, DNR Lake Restoration, Counties, Cities and others

Planning Similarities between DNR 319 WMPs and SRF

• Identify water quality concern; existing water quality condition

• Project goals/objectives to improve water quality

• Potential BMPs to improve water quality concern

• Local demographics, geography, partners

• Inventory and analyze watershed data…assessment and modeling

Watershed Modeling With the scope of SRF, full blown field assessments not absolutely necessary. Canned GIS datasets abound:

• Watershed Boundaries; HUC12 or a subset

• LiDAR Elevation

• Landuse/Zoning/Planimetric

• Existing BMPs

• Cadastral Boundaries; CLUs or Parcels

• Historic & Current Aerial Photography

• Administrative Boundaries

• USGS NHD Streams/Waterbodies, Stormwater Network

• Soils

GIS Data Sources

City & County Data

https://www.iowagisdata.org/

State GIS Data Repositories are Transitioning

Iowa Natural Resources Geographic Information Systems Library (a.k.a. NRGIS Library)

https://programs.iowadnr.gov/nrgislibx/

is in the process of moving to

Iowa GeoData

https://geodata.iowa.gov/

Urban Modeling

• LiDAR (high-res elevation)

• Planimetric or HRLC for determining impervious surfaces

• Stormwater network info

• Zoning

• Parcels

Determining Watershed Area/Infrastructure

Determining Watershed Area/Infrastructure

Breaking the Watershed into Subs by Outfalls

Urban Impervious Data Sources Are City Planimetrics available?

Urban Impervious Data Sources • If not…

• Iowa DNR’s 2010 State-wide High Resolution Land Cover (HRLC)

• Available by county mosaics at Iowa DNR Natural Resources GIS Library https://programs.iowadnr.gov/nrgislibx/ or Iowa Geodata Site https://geodata.iowa.gov/dataset/high-resolution-land-cover-iowa-2009

Buildings/Structures Roads/Impervious Surfaces

Maybe this approach doesn’t tell us much…

But this is much more helpful

What if there is no SWN Data Available?

Alternative Impervious Maps

Go Nuclear…ArcSLAMM

Looking at that Lake Right Outside of Town

How Protected are the Lakes, really?

Rural Modeling

• LiDAR (high-res elevation)

• USDA-NASS Cropland Data Layer (Landuse, 2000-2016)

• Soils

• Common Land Units (CLUs or field boundaries)

• High-Resolution RUSLE Data (sheet & rill erosion)

• Aerials

Watershed Modeling – Sheet & Rill Erosion Revised Universal Soil Loss Equation (RUSLE)

• “Old” NRCS erosion model; how much does soil move?

• A = C * P * K * R * L * S

• C = Cover Management Factor (Landuse)

• P = Practice Factor (Management BMPs)

• K = Soil Erodibility Factor

• R = Erosivity of the typical storms at given location

• L = Slope length Factor

• S = Slope Steepness Factor

• A = Average Annual Soil Loss

• ID where erosion may be most serious; where to concentrate conservation

Watershed Modeling – Sediment Delivery

• Multiply RUSLE outputs by a “Sediment Delivery Ratio” (SDR)

• SDR is used to express the efficiency of a watershed in moving soil particles from areas of erosion to the outlet of a watershed, usually expressed as a percentage

• Account for soil particles being trapped by existing structural BMPs in the watershed

RUSLE/Sediment Delivery using State-wide Dataset

Critical Areas with High RUSLE & Sed Del Rates

Modeling Shortcut - Existing Ag BMPs • Existing Agricultural “BMP Mapping Project”

• Funded by Iowa DNR, IDALS, ISU, USDA • Goal: Provide complete baseline dataset of Terraces, WASCOBs, Waterways, Pond

Dams, Contour Strip Cropping, & Contour Buffer Strips. • Baseline date starting 2007-2010. • https://www.gis.iastate.edu/gisf/projects/conservation-practices

Existing Ag BMPs Example

Ag BMPs Example – Protected Areas

Ag BMPs – Condition Assessment

Watershed Modeling – ACPF Model • Agricultural Conservation Planning Framework

• Developed by USDA ARS-NLAE (Ames) • Custom ArcGIS Toolbox that:

• Allows user to refine hydroconditioning of LiDAR DEMs () • Identifies potential locations to place BMPs such as:

• Ponds/Dry Sediment Basins • Wetlands • Terraces/Contour Buffer Strips • Riparian Buffers • Grassed Waterways • BASED UPON:

• Topography/Slopes (LiDAR) • Past 6 years of Landuse • Soils (hydricity, texture, etc) • Distance to streams (runoff risk)

• Homepage at http://northcentralwater.org/acpf/ • Preferred Hydroconditioned (S-Class) 2 meter DEMs available by

individual HUC12 watershed at https://www.gis.iastate.edu/gisf/projects/acpf

Hydroconditioning LiDAR

ACPF Model Outputs – WASCOBs & Wetlands

ACPF Model – Terraces & Ponds

Watershed Boundaries to Use Watershed Boundary Dataset

• Developed by USGS & USDA-NRCS

• Is a nationally consistent watershed dataset that is subdivided into 6 levels based on area

• Each subdivision has unique Hydrologic Unit Code (HUC) consisting of 2 to 12 digits. In watershed planning: • HUC 8 = 8 digit code, avg. size = 700 square miles

• HUC 10 = 10 digit code, avg. size = 227 square miles

• HUC 12 = 12 digit code, avg. size = 40 square miles

• Use the unique HUC codes in official documentation since watershed names are not unique. For Iowa HUC 12s: • 12 “Beaver Creeks”

• 11 “Otter Creeks”

• 9 “Bear, Elk, Rock and Walnut Creeks”

Illustrating Iowa’s HUCs & their codes 56 HUC 8s influenced by Iowa

HUC 10s within

the Boone HUC 8

HUC 12s within

the Boone River

HUC 10

GIS Data for Watersheds Iowa Natural Resources Geographic Information Systems Library (NRGIS Lib.) https://programs.iowadnr.gov/nrgislibx/

Web-based Watershed Viewer Iowa Geographic Map Server

• https://ortho.gis.iastate.edu/ ”Map Viewers” Menu select “ArcGIS app”)

LiDAR Viewer • LiDAR (continued)

• Web-viewer (Iowa Geographic Map ServerMap Viewers Menuselect ArcGIS app) • Pick “Iowa-LiDAR Hillshade” or “Iowa-LiDAR color Hillshade from “Layer List’ • https://isugisf.maps.arcgis.com/apps/webappviewer/index.html?id=47acfd9d3b6548d498b0ad2

604252a5c

GIS Data for Landuse • Landuse (low resolution)

• USDA Cropland Data Layer • For Iowa, 2000-2016 • Downloadable using “CropScape” at

https://nassgeodata.gmu.edu/CropScape/ • Upload shapefile or interactively define on screen “Area of Interest” to

generate exportable landuse statistics or perform change detection of a particular landuse through time.

Programs Supported – CWA, Section 319

• EPA funded

• DNR administered

• Goal of program to remove waters from impaired waters list

• BMP implementation to reduce non-point sediment, N, P, bacteria http://www.iowadnr.gov/Environmental-Protection/Water-

Quality/Watershed-Improvement

Programs Supported - WQI • State funded • IDALS

administered • Follows NRS

developed by IDALS/DNR/ISU, finalized in 2013 (reduce Gulf of Mexico hypoxia)

• Demo projects to implement BMPs to reduce N & P, erosion, change landuse mgmt

• Address point & non-point sources of pollution

https://www.cleanwateriowa.org/

Programs Supported – WMA Development • Created by 2010

Legislation • Formed by 28E

b/w cities, counties, SWCDs within HUC8 or smaller watershed area

• DNR gives tech assistance in planning

• Plan for flood risk, water quality

• Eventually secure funding after plan in place for implementation http://www.iowadnr.gov/Environmental-Protection/Water-

Quality/Watershed-Management-Authorities

Programs Supported – NDR-IWA

• CDBG National Disaster Recovery Program (HUD) Grant to Iowa for $96.9 million (2016)

• Goal: Flood resiliency/advancing water quality

• DNR/IIHR provide training/assistance in WMA development, watershed planning, and BMP implementation

http://www.iihr.uiowa.edu/iwa/

Program Questions Regarding 319/WMAs/NDR-IWA, contact

DNR 319 Staff

Kyle Ament

Western Basin Coordinator 502 E. Ninth St. Des Moines, IA 50319-0034 515-725-8389 or Kyle.Ament@dnr.iowa.gov

Mary Beth Stevenson Eastern Basin Coordinator 323 Stanley Hydraulics Laboratory Iowa City, Iowa 52242-1585 319-325-8593 or MaryBeth.Stevenson@dnr.iowa.gov

Andy Asell GIS Analyst Des Moines, IA 50319-0034 515-725-8386 or Andy.Asell@dnr.iowa.gov

Program Questions Regarding WQI, contact IDALS Staff

Watershed/Practice Demos

Derek Namanny Des Moines

(515)-725-0150

Jennifer Welch Ankeny

(515) 964-1883

Amy Bouska Iowa City

(319) 337-2322

Urban Demos