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Hydrologic modeling - Landuse & Runoff


Landuse & Runoff Coefficients


Table 1. Original land-use categories as determined by this study and the broad landuse categories used in the to compair to previous years.
See interactive maps for illustrations.

2005 NCRCPD landuse

1994 ODNR data (Erie County only)

1983 ODNR data (Sandusky County only)

1976 ODNR data (Medina & Lorain Counties only)

Broad Landuse

Two (2) coverages showing land use in the study watersheds were collected. Earilest landuse studies for the areas were
obtained from O.D.N.R. (Ohio Department of Natural Resources) and the 2005 landuse was created by digitizing landuse
from aerial photography (see Metadata information).

The original 42 classified land-use types in the 2005 landuse classification and 57 to 7 landuse classifications from previous years,
were reduced to 7 primary land-use types for the purposes of this study. The table below indicates the categories that were lumped.


2005 NCRCPD landuse 1994 ODNR Data Erie County 1983 ODNR Data Sandusky County 1976 ODNR Data Medina & Lorain Counties Broad Landuse
111 High density residential*  Apparent lot sizes less than 1 acre.  May be single or multi-family housing. 1 URBAN   (open impervious surfaces: roads, buildings, parking lots and similar hard surface areas which are not obstructed from areal view by tree cover.) See 7. BARREN 5 Multi-unit apartment 1129                    6 Mobile home, Trailer parks 0113 25 Residential - High density 20 d. u./acre              22  Residential - Single family 1-4 d. u./acre          23 Residential - Single - Two family 4 d. u./acre     24  Residential - Multi-family 20 d. u./acre 1  Urban or built-up land
112 Large lot residential*  Apparent lot sizes greater than 2 acres. Single family units generally set well back from streets and roads, but contained within apparent subdivisions. 2 Residential 0011 21  Residential - Rural 1 d. u./acre
113 Rural residential*  Large or small lot sizes, single family units generally found in adjacent to agriculture. The sense is just a few houses along a road, adjacent to ag and apparently sub-divided from the ag land. 63 Farmstead 0241 21  Residential - Rural 1 d. u./acre
121 Retail trade/office  Retail stores, shopping centers and offices. 7 Commercial and services 0012          10 Shopping centers 1212                     9 Junk yards 1211                               19 Drive - in movies 1232 62  Business/offices - Option                                63  Business/offices - All other retail
122 Institutions  Educational, government buildings and complexes, religious and health care facilities. 50 Campgrounds 0178                        12 Institutions 0122                              13 Religious 1222                                14 Health care 1223                            46 Cemeteries 0174 35 Public/private - Institutional, municipal
123 Recreation  Parks, golf courses, sports facilities, marinas, amusement parks, race tracks. 2  AGRICULTURE/OPEN URBAN AREAS (cropland and pasture; parks, golf courses, lawns and similar grassy areas not obstructed from view by tree cover) 17 Recreation 0123                             23 Fairgrounds 1236                           45 Golf courses 0173                           47 Parks 0175 32 Public/private - Parks                                      33 Public/private - Outdoor recreation                   34 Public/private - Indoor recreation 2  Agriculture
131 Light industry  Smaller industrial sites that generally have pre-fabricated appearing buildings and lack large smokestacks and other signs of heavy industry. 1 URBAN   (open impervious surfaces: roads, buildings, parking lots and similar hard surface areas which are not obstructed from areal view by tree cover.) See 7. BARREN 24Industrial 0013 42 Industry - Wholesale and storage 1  Urban or built-up land
132 Heavy industry  Large industrial sites may have outdoor material handling areas, smokestacks and other evidence of major manufacturing areas. 41 Mixed urban or built up land 0016 45 Industry - Industry                                           
141 Transportation  Airports, rail yards, port facilities.  We will not map roads and rail lines. 30 Airports 1411                                 31 Rail 1412                                       32 Highways 1413 44 Industry - Transportation and terminals             53 Other - Utility/R.O.W. Rail                                 55 Other - R.O.W. street  
142 Utilities  Electric generating facilities,  switchyards and substations, natural gas substations.  34 Communications 0142                     37 Gas utilities 1432                            36 Electric utilities 1431                         38 Water utilities 1433                          39 Sewage utilities 1434                      49 Water control 0177 43 Industry - Utilities and communications
15  Industrial and Commercial Complexes  Generally dense urban areas where it is not possible to identify individual industrial or commercial parcels. 40 Industrial & Commercial complex 0015 45 Industry - Industry                                            64 Business/offices - Regional Shopping 710 acres 65 Business/offices - Central business district
16 Mixed urban or built-up land  Dense urban areas where a mix of urban residential, commercial and other land uses predominate.  Many "downtown" areas would be mapped in this category. 41 Mixed urban or built up land 0016 62  Business/offices - Option                                
171 Vacant undeveloped  Vacant or obviously abandoned urban lots. 43 Undeveloped 0171 13 Vacant - Urban vacant, abandoned                   15 Vacant - Under construction
172  Landfills Landfills of any type. 48 Landfills wastedumps 0176 54 Other - Mining, quarries
211 Row crops  Corn, soybeans or other row crop ag. 2  AGRICULTURE/OPEN URBAN AREAS (cropland and pasture; parks, golf courses, lawns and similar grassy areas not obstructed from view by tree cover) 53 Cropland 0211 12 Vacant - Agriculture 2  Agriculture
212 Pastures  Self-explanatory. 56 Pastures 0212 14 Vacant - Intensive livestock
221 Orchards and groves  Self-explanatory. 58 Orchards, Groves 0221 12 Vacant - Agriculture
222 Vineyards  Self-explanatory.   12 Vacant - Agriculture
223 Nurseries and horticultural areas Self-explanatory. 60Nurseries and ornamental horticultural areas 0223 61 Business/offices - Greenhouses
24  Other Agricultural Lands 61Confined feeding operations 0023     62 Other agricultural land 0024 12 Vacant - Agriculture
31 Herbaceous rangeland  Early successional old fields dominated by herbaceous plants.  Clear evidence that the field is abandoned from a previous land use.   3 SHRUB/SCRUB (young, sparse, woody vegetation; typically areas of scattered young tree saplings) 65 Shrub and brush rangeland 0032 11 Vacant - Grass land 3  Rangeland
32  Shrub and brush rangeland  Later successional odlfields dominated by a mix of herbaceous plants and shrubs. 65 Shrub and brush rangeland 0032 11 Vacant - Grass land
41 Deciduous forest  Self-explanatory. 4 WOODED (deciduous and coniferous) 67 Deciduous forest land 0041 16 Vacant - Forest land 4  Forest land
42 Evergreen forest  Self-explanatory. 68 Evergreen forest land 0042 16 Vacant - Forest land
43 Mixed forest  Mixed deciduous and evergreen stands.   16 Vacant - Forest land
51 Streams and canals These will be extracted from the hydrology layer and not mapped as part of land use. 5 OPEN WATER 71 Streams and canals 0051 51 Other - Water/marsh 5 Water
52 Lakes  Non-flowing, enclosed bodies of water greater than 20 acres. 72 Lakes 0052 51 Other - Water/marsh
53 Reservoir  Non-flowing, enclosed bodies of water greater than 20 acres, obviously impounded and apparently constructed for water supply. 73 Reservoirs 0053 51 Other - Water/marsh
54 Bays and estuaries  Areas where rivers open to Lake Erie.  Simple river mouths are not mapped here, rather drowned mouths such as Old Woman Creek and bays such as Muddy Creek and Sandusky Bay. 74 Bays and estuaries 0054 51 Other - Water/marsh
55 Ponds  Non-flowing, enclosed bodies of water less than 20 acres. 72 Lakes 0052 51 Other - Water/marsh
61 Forested wetlands  Palustrine wetlands dominated by tree species. 6 NON-FORESTED WETLANDS (includes wetlands identified from 1994 Thematic Mapper data as well as from the Ohio Wetlands Inventory) 76 Forested wetlands 0061 51 Other - Water/marsh 6 Wetlands
621 Emergent wetland*  Palustrine or lacustrine wetlands dominated by emergent species 77 Non-forested wetlands 0062 51 Other - Water/marsh
622 Scrub-shrub wetland*  Palustrine wetlands dominated by shrub species 72 Lakes 0052 51 Other - Water/marsh
623  Floating-leaved wetland*  Palustrine or lacustrine wetlands dominated by floating-leaved species 72 Lakes 0052 51 Other - Water/marsh
624 Diked/impounded wetland*  Palustrine or lacustrine wetlands dominated by emergent, shrubby or tree species and showing obvious evidence of impoundment. 72 Lakes 0052 51 Other - Water/marsh
72 Beaches  Self-explanatory. 7  BARREN (strip mines, quarries, sand and gravel pits, beaches) Many of the URBAN features identified in this inventory are constructed from materials obtained from the BARREN features. Because of this, there will on occasion be URBAN areas identified as BARREN as well as BARREN areas identified as URBAN. 79 Beaches 0072   7 Barren
73 Other exposed sands  Exposed sand areas not located in a beach. 89 Sand and gravel pits 7522 54 Other - Mining, quarries
74 Exposed rock  Self-explanatory. 88 Quarries 7521 54 Other - Mining, quarries
751 Strip Mine  Active or recently abandoned strip mines.  Little or no signs of reclamation. 88 Quarries 7521 54 Other - Mining, quarries
752 other surface extraction  Quarries, sand pits, marl mines. 88 Quarries 7521 54 Other - Mining, quarries
76 Transitional areas  Abandoned mines and quarries that show signs of reclamation but have not progressed to the point where they appear to be odlfields, pastures or some other land use.  Bare areas and equipment trails are often present. 91 Transitional areas 0076 52 Other - Abandoned mines and quarries
Runoff coefficients and loading factors were assigned to various land-use types within the study areas.
The following table provides the runoff coefficients and bacterial loading factors assigned to the land-use categories. Low density residential areas are assumed to be using
on-site sewage disposal systems.
Table 2. Land-use types that correspond to land-use codes. Also shown are the corresponding runoff coefficients and bacterial loading factors for each land-use type.
Land use CODE Land use - Description Storm Runoff coefficient
1 Urban or Built-up Land 0.6
2 Aggricultural 0.3
3 Range 0.25
4 Forest 0.15
5 Water 0
6 Wetland 0.05
7 Barren 0.8
The following is a list of the individual watersheds studied in Phase 1. Click onto the link to see their individual runoff tables and area calculations.
Sandusky County      
Little Muddy Creek      
Erie County      
Huron River (at Mouth) Old Woman Creek (at Mouth) Old Woman Creek Chappel Creek
Old Woman Creek above Norfolk Western Huron River above Mason Rd. north of Milan Mud Brook Unnamed Creek "C" (Tributary to Huron River at Milan State Wildlife Area)
Huron River above Mud Creek Others    
Lorain County      
Buck Creek (above Charlemont Creek) South of Oberlin (below Rt 303) South of Oberlin (near Oberlin) Wellington Creek
Charlemont Creek Buck Creek (above Buck Creek)    
Medina County      
Coon Creek Mallet Creek (at Mouth) E. Branch Black River (above Coon Creek)  

URBAN RUNOFF

Past concerns with urban runoff have primarily dealt with the prevention of localized flooding. Only recently has urban runoff been considered as a significant contributor to the degradation of the quality of receiving waters. Water quality problems are not always immediately obvious and are less dramatic than floods. The major problem created by urban stormwater runoff is degradation of the quality of receiving waters. In some cases, the load applied to neighboring water bodies by stormwater runoff can be greater than point source loads.

Recent water quality monitoring studies in urban areas have shown that the highest pollutant loadings and concentrations usually occur during rainfall events in the first runoff of rain, commonly referred to as the "first flush." In urbanizing an area, impervious surface area such as streets, parking lots, and rooftops, is increased. These smooth, impenetrable surfaces allow little or no detention or infiltration of stormwater. Pollutants that are present between rainfall events in the atmosphere prior to a storm and which accumulate on impervious surfaces are generally carried away in the first 0 to 1 inch of rainfall in moderate to heavy storms. Urban nonpoint source pollution is the result of precipitation washing the surfaces of urbanized areas. As precipitation falls on urban areas, it picks up contaminants from the air, littered and dirtied streets and sidewalks; petroleum residues from automobiles, exhaust products, heavy metals and tar residuals from the roads; chemicals applied for fertilization, weed and insect control; and, sediments from construction sites. The dumping of chemicals such as used motor oil and antifreeze into storm sewers is another source of urban NPS pollution. Illegal hookups of storm drains to sanitary sewers can result in increased volumes of flow to waste water treatment plants causing more frequent overflows of sewage into receiving waters. Sources of urban NPS pollution are extremely variable. Some of the more common runoff pollutants include:

(1) Sediment pollution is a result of excessive soil erosion. The primary source of sediment in urban areas is construction activities. The volume of sediment decreases flow capacity in drainageways and blankets the bottom of receiving water bodies, killing oxygen-producing plants, smothering spawning grounds and juvenile aquatic organisms, and altering benthic communities. Soil in runoff may also have other pollutants attached to it such as pesticides, nutrients, or oxygen-demanding substances. These pollutants may produce an impact on the receiving waters immediately or they may settle out and slowly produce an impact on the receiving waters over a period of time.

(2) Nutrients can pollute urban runoff from a variety of sources including washoff from excessive fertilizer application, and the decomposition of fallen leaves and other organic materials. Nutrients causing the greatest concern are forms of phosphorous and nitrogen, which in high concentrations can lead to large algal blooms in still waters. As the algae die off and are oxidized, severe depletion of dissolved oxygen and subsequent fish kills can occur.

(3) Toxic substances including heavy metals (especially copper, lead, and zinc), pesticides, herbicides, and other chemicals are often found in significant concentrations in urban runoff.

(4) Oxygen-demanding substances include all organic materials which consume oxygen as they decompose. Excessive quantities of organic materials result in oxygen depletion in receiving waters. This can cause a balanced aquatic population of fish and other aquatic organisms in the food chain to be adversely affected, resulting in fish kills and nuisance conditions. Animal droppings, sewage overflows, fallen leaves, and grass clippings are a few examples of oxygen-demanding substances.

(5) Petroleum products such as gasoline, oil and grease are found in high concentrations in runoff from streets, highways, parking lots, and other motor vehicle traffic areas. These substances destroy aquatic life by adhering to them or by coating aquatic organisms thereby cutting off their oxygen supply. Petroleum products also exert an oxygen demand and destroy the aesthetic quality of receiving waters.

(6) Pathogenic Microorganisms from animal (animal and bird droppings) and human (sewage overflows) fecal wastes are a frequent pollutant in urban runoff. This type of contamination can present a health hazard if water contact activities or water supply operations occur before natural purification takes place.

Urbanization has a profound impact not only on water quality, but on the hydrologic characteristics of watersheds as well. In undeveloped natural drainage areas, the volume and rate of stormwater runoff from a particular rainfall event is primarily determined by the natural detention and infiltration characteristics of the land, and is related to topography, soil types, and vegetative cover. In urbanizing an area, the dominating factor of impervious surface is added. With less detention and infiltration due to impervious surfaces, runoff volume increases, as well as, the rate of stormwater runoff. Flooding and stream channel degradation in urbanizing watersheds have obvious adverse impacts upon public convenience, safety, and aesthetics, but there are some significant adverse impacts on water quality as well. When streams overflow their banks, there is an increased opportunity for pollutants including trash and debris to enter the flow of water. Erosion of the stream channel represents a significant source of sediment pollution, and the loss of vegetation along stream banks reduces the pollutant assimilation capacity of a stream.

The effects of urban runoff on receiving water quality are extremely complex. There are many highly variable factors involved including: the type, size, and hydrological characteristics of the receiving waters; the urban runoff quality and quantity characteristics; the designated beneficial uses; and behavioral characteristics and concentration levels of the specific pollutants that affect those uses.

Citations

Landscape Architecture Foundation, Handbook of Landscape Architectural Construction, Second Edition Volume 1, Landscape Architecture Foundation 1993 .

Indiana Geological Survey, LakeRim GIS; http://igs.indiana.edu/survey/projects,Hydrolic Modeling, Indiana Geological Survey 2003.

Ohio Department of Natural Resources, GIMS Project; www.dnr.state.oh.us, ODNR, 2005