# Presentation: 035009

## Floodplain Management Session 12Biology Effects of human disturbances on rivers and floodplains Prepared by Susan Bolton, PhD, PE

**Notes:**
Title slide for session 11

## Effects of human disturbances

**Objectives:**
**12.1   Identify changes in land cover/land use in ****	****watersheds and learn how to assess these   ****	****changes as they relate to river and ****	****floodplain ecology**
**12.2 ****	****Identify changes of concern in aquatic and ****	****floodplain communities due to changes in ****	****land use and land cover.**
**12.3****	****Identify additional sources of threats to**
**	****floodplain and river ecology**

**Notes:**
Slide outlines the objectives for session 11

## Land use/cover 

- and vegetation

- Modified from Roni et al. 2002.

**Notes:**
Slide depicts the interaction among landscape controls, habitat forming processes, stream morphology and biodiversity. Gray boxes at the landscape control level indicate things that humans have little to no control over.

## Land use and land cover

- Land use is technically the way humans employ the land and its resources
- Land cover is the physical state of the land surface and originally referred to vegetation (e.g., forest, grass)
- Land cover also included soils and water information (e.g., soil types, wetlands, streams)
- Land cover now includes human structures such as pavement and buildings

**Notes:**
Slide defining land use and land cover

## Land cover/use information

- Annual National Resource Inventory by the USDA-NRCS
- 8 categories
- Cropland, pastureland, grassland, forest land, other rural land, developed land, water bodies and land in conversion from cropland to vegetated land (CRP- conservation reserve program)
- Other agencies may use different categories

**Notes:**
Slide listing types of land cover

## Land cover/use information

- Ohio uses a number of subdivisions of the 8 USDA categories when data are available
- _      __[http://](http://www.dnr.state.oh.us/htdocs/realm/resanalysis/lumain.html#definitions)__[www.dnr.state.oh.us/htdocs/realm](http://www.dnr.state.oh.us/htdocs/realm/resanalysis/lumain.html#definitions)__[/](http://www.dnr.state.oh.us/htdocs/realm/resanalysis/lumain.html#definitions)_
- _[            ](http://www.dnr.state.oh.us/htdocs/realm/resanalysis/lumain.html#definitions)__[resanalysis/lumain.html#definitions](http://www.dnr.state.oh.us/htdocs/realm/resanalysis/lumain.html#definitions)__ _
- Other agencies may use different categories

**Notes:**
Slide listing types of land cover

## Watershed Assessment

-    step in determining the current and
-    potential condition of a watershed.
- Identify historic and current habitat types
- What is/were their size and distribution over
-     the watershed?
- How do the habitats relate to current or historic
-     distributions of species?

**Notes:**
Slide explaining the importance of watershed assessment. 

## Watershed Assessment

- Identify current and historical habitat distributions in the watershed
- Use air photos, old maps, General Land Office surveys, etc.
- Relate current and potential habitat to species distribution
- Identify habitat forming processes and any changes to their rates, frequency, magnitude or duration

**Notes:**
Slide of initial steps in watershed assessment

## Watershed AssessmentHabitat forming processes

**Sediment regime**
**Hydrologic regime**
**Nutrient inputs**
**Solar energy/light inputs**
**Organic matter inputs**

**Notes:**
Slide listing critical habitat forming processes to consider in watershed assessment

## Watershed assessment methodsHabitat forming processes

- Sediment regime
- Quantify landslides and estimate sediment budgets
- Assign landslide hazard ratings to roads and hillslopes
- Map surface erosion areas such as unpaved roads, bare areas, construction zones

**Notes:**
Slide showing how to assess sediment regimes in watersheds

## Watershed assessment methods Habitat forming processes

- Hydrologic regime
- Analyze flow records for changes in peak flows, flow durations, base flows, etc.
- Assess connectivity changes in watershed, e.g. dams, diversions, levees, impervious area

**Notes:**
Slide showing how to assess hydrologic regimes

## Watershed assessment methods Habitat forming processes

- Nutrient input regime
- Assess background inorganic inputs based on geologic and soils maps
- Assess inputs from anthropogenic sources such as:

**Notes:**
Slide showing how to assess nutrient regimes

## Watershed assessment methods Habitat forming processes

- Solar energy/light regime
- Assess current and historical shade/canopy conditions in stream and floodplain
- Assess current and historic turbidity levels in streams

**Notes:**
Slide showing how to assess light (solar energy) and heat regime

## Watershed assessment methods Habitat forming processes

- Organic matter input regime
- Assess riparian and floodplain forest/vegetation conditions
- Identify current and historic fire return patterns

**Notes:**
Slide showing how to assess organic regime.

## Watershed Assessmentfinal steps

- Identify which processes have been altered by changes in the watershed condition and the origin of the alterations.
- Identify the effects of the changes on stream ecology and decide whether to try and correct the changes.

**Notes:**
Slide listing final steps in watershed assessment

## Objective:

**12.2 ****	****Identify changes of concern in aquatic and floodplain communities due to changes in ****	****land use and land cover.**

**Notes:**
Slide outlines the objective 11.2

## Characteristics of disturbances

**Frequency** – number of times an event or disturbance occurs over a fixed time period, referred to more accurately as probability (e.g. probability of a flood of a given magnitude over some time period)
**Duration** – The time span over which the disturbance occurs (e.g., flooded time period)
**Magnitude** – this size of the disturbance, this may refer to the quantity of the disturbance (e.g., rainfall) or the area covered (e.g., acres burned)
- These concepts are evident in engineering design in the form of design limits (e.g., the use of ‘depth-duration-intensity’ charts for precipitation used for designing runoff storage)

**Notes:**
Slide describing characteristics of disturbances

## Changes of concern

- Alter ecosystem structure and function such that recovery from the disturbance is threatened
- Loss of watershed process or structure that persists beyond normal cyclical change (i.e., disturbances are more frequent, larger or of longer duration than expected)

**Notes:**
Slide discussing changes of concern

## Effects of human disturbances on rivers and floodplains

- Changes of concern generally permanently alter habitat forming processes

**Notes:**
Photos of human caused changes on the landscape. Upper slide is of drainage ditch in an agricultural field. Lower left slide shows timber harvest units. Center bottom slide shows in-channel gravel mining. Lower right slide shows an urban area. 

## Examples of changes of concern

- Changes in efficiency and pathways of nutrient cycling
- Alteration or cessation of vegetation successional sequences
- Pronounced changes in species diversity
- Increased incidence of diseases
- Abnormal population fluctuations
- Permanent shifts in energy sources
- Shifts in water temperature, light, and suspended sediment

**Notes:**
Slide of examples of changes of concern

## Human caused disturbances

- Agriculture
- Timber harvest
- Mining
- Urbanization
- Introduction of exotic species
- Harvesting of fish and wildlife

**Notes:**
Slide identifying human-caused disturbances in watersheds that affect rivers and floodplains. 

## Human caused disturbances

- Agriculture

**Notes:**
Photos showing agricultural activities. Upper left is terraced vineyard, upper right is drainage ditch in agricultural land, lower left is row crops, and lower right is cattle grazing.

## Human caused disturbances

- Timber harvest

**Notes:**
Slide with photos showing harvest in floodplain (left) and clearcuts on hillslopes (right)

## Human caused disturbances

- Mining

- M. Kondolf

**Notes:**
Slide with photos of in-channel gravel mining. Upper right shows a gravel dump truck in a river, lower right shows bank damage from mining and the left photo shows gravel mining adjacent to the river in the floodplain.

## Human caused disturbances

- Urbanization

**Notes:**
Slide of photos showing cities along rivers. 

## Human caused disturbances

- Introduction of exotic species

- Sea lamprey and trout damage

- Water hyacinth

- Whirling disease in trout

**Notes:**
Slide with photos of exotic species. Upper left is Eurasion watermilfoil, lower left is water hyacinth, upper right is whirling disease in trout, and lower right is sea lamprey and damage to trout.

## Human caused disturbances

- Harvesting of fish and wildlife

**Notes:**
Slide with photos of harvesting fish and wildlife. Left photo is of american bison, right photo is a salmon fishing boat. 

## Land Use and Vegetation

- The landscape control factor on which humans have the most influence
- Mining: extent of vegetation alteration depends on type of mining
- Forestry: tree removal and replacement over time
- Urbanization: tree removal and replacement with grass and impervious surfaces
- Agriculture: tree removal and replacement with pasture or crops, often non-perennial

**Notes:**
Slide describing the differences over time of vegetation changes by sector. 

## Common effects of human alterations to the landscape

- Vegetation removal or alteration
- Changes in soil characteristics (compaction, paving, roads and ditches)
- Changes in water and sediment storage (dams, retention ponds, stormwater)
- Changes affect the connectivity of the watershed by altering flow paths and flow timing

**Notes:**
Slide listing common effects of human disturbances on the environment

## Potential effects of human alterations to the landscape

- Changes in vegetation on streams and floodplains affects
-  Light and energy inputs to the aquatic ecosystem
- Organic matter inputs to the aquatic ecosystem
- Sediment inputs to the aquatic ecosystem
- Changes in light and flow pathways can alter water temperature
- Changes in organic matter can alter habitat complexity and food webs
- Changes in sediment production, transport and storage affects channel morphology, and substrate habitat

**Notes:**
Slide listing potential ecological effects of human alterations to the landscape

## How can streamflow be described 

- in a way that has
- ecological meaning?

**Notes:**
Slide introducing next section on streamflow characteristics that have ecological meaning.

## Flow characterization

- Magnitude  -  how much?
- Frequency  -   how often?
- Timing        -   when?
- Duration      -   how long?
- Rate of change – how fast?

**Notes:**
Slide of  ways to characterize flow

## Indicator of Hydrologic Alteration Model

- The IHA was developed by The Nature Conservancy
- Model available free from TNC web site
- Used to assess extent of change in streamflow from a dam or diversion
- Need pre- and post- disturbance flow data

**Notes:**
Slide describing the Indicator of Hydrologic Alteration Model.

## Ecological importance of hydrologic indices

- Skewness (mean daily flow/median daily flow) describes daily flow conditions for aquatic taxa and may be especially important below dams with variable releases compared to natural flows

**Notes:**
Slide defining skewness as an ecologically important element of hydrology

## Ecological importance of hydrologic indices

- Coefficient of variation of mean monthly flows in natural systems may indicate the importance of high and low flows for the distribution and propagation of riparian vegetation seeds and riparian vegetation density

**Notes:**
Slide defining the ecological importance of variability in mean monthly flows

## Ecological importance of hydrologic indices

- A flood duration measurement (e.g. monthly flow equaled or exceeded 95% of the time divided by mean monthly flow) can be important for determining the ability of floodplains to sustain a diverse riparian forest in snowmelt driven stream

**Notes:**
Slide defining flood duration as an ecologically important  hydrology variable.

## Ecological importance of hydrologic indices

- Indicators of flashiness (e.g. the coefficient of variation of the number of flows that exceed the 75th percentile of daily values) or the variability in changes of flow reversals (e.g. the coefficient of variation of the number of negative and positive changes in water level from one day to the next) may help identify the persistence of native and non-native stream organisms in intermittent streams

**Notes:**
Slide defining flashiness as an ecologically important hydrology variable.

## Ecological importance of hydrologic indices

- For more examples and more information see (Olden and Poff 2003) and other references cited within

**Notes:**
Slide showing a reference for more information on ecologically important hydrologic indices.

## Objectives:

**12.3****	****Identify sources of threats to ****	****floodplain and river ecology**

**Notes:**
Slide outlines objective 11.3

## Threats to Aquatic Species

- Aquatic species at higher risk of extinction in the U.S. than terrestrial species
- < 20% of terrestrial vertebrates are classified as at risk
- Estimates range from 35% to 70% of aquatic species at risk

**Notes:**
Slide comparing the threat to aquatic versus terrestrial species.

## Sources of major threats

- Habitat destruction and fragmentation
- Pollution
- Exotic species

**Notes:**
Slide of the three major threats to aquatic species

## River habitat destruction and fragmentation

- Dams, diversions and channelization disrupt the 4 dimensions of the river ecosystem, especially the lateral and longitudinal connectivity of rivers

**Notes:**
Slide discussing disruption of the 4 dimensions of rivers by dams, diversions, etc. 

- Brooks1988

**Notes:**
Diagram of how stream channelization leads to changes in habitat diversity and water quality. (Brooks 1988)

## Effects of dams

- Cold bottom release water can threaten native warm-water species
- Riparian vegetation survival and reproduction is affected by floods or the lack thereof
- Sediment and nutrient retention behind dams affects food webs, energy flow and nutrient cycling below dams

**Notes:**
Slide discussing the effects of dams on river ecology

## Pollution

- In 1994, EPA identified siltation/sediment as the leading cause of water quality impairment
- > 70% from agricultural practices
- 15% from municipal point sources
- 11% from urban runoff and sewer discharge
- Other sources include resource extraction, industrial point sources and silviculture

**Notes:**
Slide describing sources of river pollution

## Pollution

- Nutrient enhancement the second leading cause of water quality impairment
- 45% comes from agricultural practices
- 42%  comes from municipal land use
- Other sources of pollution include pathogens, pesticides, and organic enrichment which can lead to low dissolved oxygen levels

**Notes:**
Slide describing addition pollution sources

## Exotic Species

- Changes in floodplain vegetation can affect evapotranspiration rates, stream bank stability, food and nesting sites for animals, stream shade and organic inputs to streams
- Changes in aquatic species can alter food webs and nutrient and energy transfers in the stream

**Notes:**
Slide discussing effects of exotic species on riparian ecosystems

## Homework- Prepare for discussion at start of next session

- What are the major land use/land cover categories in your watershed?
- Are there any aquatic or riparian species at risk in your watershed? If so, what are the reasons for their imperiled status?
- Write a short essay on how sediment, hydrologic, nutrient, organic and solar energy/light regimes have changed since the pre-development state of your watershed.

**Notes:**
Homework slide