# Presentation: 851650

## What tidal creeks say about land use changes: the interface between hydrology and ecology

Guy DiDonato and Anne Blair
Hollings Marine Laboratory

Turkey Creek Watershed Meeting
Sept 12, 2007

**Guy DiDonato and Anne Blair**
**Hollings Marine Laboratory**
**Turkey Creek Watershed Meeting**
**Sept 12, 2007**

## Collaborators

- Field and Lab Crew (A. Rourk, P. Biondo, G. Riekerk, M. Levisen, M. Dunlap, L. Forbes, K. Seals, J. Siewicki, J. Richardson, A. Coghill L. Hayes, M. Messersmith, C. Buzzelli, C. Battey, R. Garner, E. McDonald, D. Couillard, B. Robinson, B. Thompson, J. Gooch, L. Webster, M. Fulton, E. Wirth, Y. Sapozhnikova)
- Data Management Team (D. White, D. Wolf, D. Dabney)

**Collaborators**

**Notes:**
The model previously discussed is specific only to the headwater creeks. A more complete conceptual model must account for changes along the creek length. To explore this, we implemented a creek classification system. The current model is only a strawman model, and will likely be revised in the future. 

## Changing Land Use

**Changing Land Use**

**Allen and Lu 2003**

## Why Tidal Creeks?

**Primary hydrologic link to uplands**
**Preferred sites for development**

**Why Tidal Creeks?**

**Complex ecosystems and dynamics**
**Critical refuge and nursery habitat**

**Notes:**
1. Tidal creeks and expansive salt marshes are a dominant feature of the coastal zone.  
2. These highly productive habitats are critical to the State’s fisheries by providing refuge and nursery habitat for fish, shrimp, and crabs. 
3. These habitats are known for their complex food webs.
4. Due to their close proximity to land, tidal creeks and associated salt marshes are the primary link between upland areas and the larger estuary. These habitats often receive storm-water runoff and serve as a repository for many toxic pollutants.

## Research Questions

**What are the impacts of changing land use on tidal creeks?                                                ****	****	****Comparative Ecosystem Approach**
**How do these impacts change along the longitudinal gradient of tidal creeks (i.e., headwaters to larger tidal rivers)?           ****	****	****      ****Classification**

## Conceptual Model of Creek-Watershed Linkages

**Physical-**
**Chemical Changes**

- Altered Land Cover

- Increased Impervious Cover

**Living Resources**

**Coastal Development**
**Activities**

- Impaired Water Quality & Hydrography

- Reduced Biological Productivity

- Altered Food Webs

- Chemical Contamination

- Impaired Animal Health

- Microbial and Pathogen Contamination

- Increased Population Density

**Conceptual Model of Creek-Watershed Linkages**

**Stressor**

**Exposure**

**Ecological**
**Response**

## Classification—means to stratify creeks

**Order 1—headwaters, intertidal**
**Order 2—below confluence of Order 1s, subtidal**
**Order 3—below confluence of Order 2s, subtidal**
**“****Straw Man” model**
**Classification****—****means to stratify creeks**

**Tidal Creek Classification**

**Notes:**
The model previously discussed is specific only to the headwater creeks. A more complete conceptual model must account for changes along the creek length. To explore this, we implemented a creek classification system. The current model is only a strawman model, and will likely be revised in the future. 

## Creeks Sampled

** ****2005 (South Carolina)**
**3 forested creeks**
**5 suburban creeks**
**3 urban creeks**
** ****2006 (NC, SC, GA)**
**5 forested/salt marsh creeks**
**3 suburban creeks**
**3 urban/industrial creeks**

## Pathogens, 2005

**Winter**

**Summer**

**Fecal Coliforms (Log****10**** (CFU / 100mL))**

**Forested**

**Suburban**

**Urban**

**Notes:**
This slide shows the results of enumerating fecal coliforms, a bacterial indicator. In both summer and winter, there is a significant effect of land use class. FC increases with increasing urbanization. Also, there were significantly more coliforms in the headwater Order 1 creeks than in either 2 or 3, which never differed from each other. 

## Pathogens, 2006

**Notes:**
This slide shows the results of enumerating fecal coliforms, a bacterial indicator. In both summer and winter, there is a significant effect of land use class. FC increases with increasing urbanization. Also, there were significantly more coliforms in the headwater Order 1 creeks than in either 2 or 3, which never differed from each other. 

## Nutrients, 2005

**Winter**

**Summer**

**PO****4**** (mg/L)**

**Forested**

**Suburban**

**Urban**

**Notes:**
Land use effect in both winter and summer (F<S=U in winter, F<U=S in summer). Effect of creek order in summer. 

## Nutrients, 2006

**PO4 (mg/L)**

**SC**

**NC**

**GA**

**Notes:**
This slide shows the results of enumerating fecal coliforms, a bacterial indicator. In both summer and winter, there is a significant effect of land use class. FC increases with increasing urbanization. Also, there were significantly more coliforms in the headwater Order 1 creeks than in either 2 or 3, which never differed from each other. 

## Sediment Contaminants, 2005

**Sediment Contaminants, 2005**

## Sediment Contaminants, 2005

**North Inlet**

**Guerin**

**Village**

**Okatee**

**Albergottie**

**James Island**

**Parrot**

**Orange Grove**

**Bulls**

**Murrells Inlet**

**Shem**

**New Market**

**Forested****                     ****Suburban****                           ****Urban**

**Sediment Contaminants, 2005**

## Conclusions

**Data from 2005 shows consistent effects of land use changes on tidal creeks, across season.**
**Creek classification explains much of the variance in measured parameters (2005) and appears regionally valid (2006). **
**Hydrology provides link between land use changes and impacts to creeks.**

## Hydrology Objectives

**Develop non-field-based method for quantifying stormwater runoff in watersheds of headwater (i.e., first order) streams and tidal creeks.**
**Provide non-field-based method to forecast changes in stormwater runoff with increasing urbanization in headwater stream/creek watersheds. **

## Hydrology Methods

**NRCS TR20 with modifications**
**         ****	****➣ ****Peak rate factor = 200 (Sheridan et al. 2002; USDA, NRCS 2007)**
**	****➣**** ****Temporal rain distribution – NOAA Atlas 14, 1****st**** quartile, 30% distribution  ****	****(****http://hdsc.nws.noaa.gov)**
**        ****	****➣**** ****λ**** = 5% (Hawkins et al. 2002; Lim et al. 2006) **
**	****➣**** ****Developed landuse soils reclassified (Lim et al. 2006)**
**	****➣**** ****Revised sheet flow equation (Zomorodi 2005)**
**Geographic Information System ****(ArcGIS 9.0)**
**  ****	****➣**** ****USGS NLCD 2001 – Land cover **
**	****➣**** ****SCDNR GIS Data Clearinghouse: digital raster graphic (scanned USGS topo maps) ****	****soil survey geographic data, digital orthophoto quarter quadrangles**
- 		(**https://www.dnr.sc.gov/pls/gisdata)**
** ****	****➣**** ****NOAA Oceans and Human Health Initiative watershed shapes and channel lines**

## Slide 18

**Notes:**
Describe graph
Uses TR20 with its assumptions that 
	rain evenly distributed
	antecedent moisture conditions average
some modifications – prf, lambda, rain distribution, sheet flow

##                         Area     Imperv.      Peak flow    Volume    Runoff 

**                        ****Area     ****Imperv.      Peak flow    Volume    Runoff **
_**Watershed     (mi**__**-2**__**)      cover            (cfs)            (in.)   **__**      **__**ratio**_**  ****  **
**Forested          0.77         3%               14             0.64         0.14****            **
**Suburban        1.14        21%              49             1.12         0.25****            **
**Urban              0.71        70%             125             2.85        0.63****            **

**Notes:**
Describe graph
Uses TR20 with its assumptions that 
	rain evenly distributed
	antecedent moisture conditions average
some modifications – prf, lambda, rain distribution, sheet flow

## 24-hour 4.5" Storm Event 

**                        ****Impervious      Peak flow   Volume    Runoff **
_**Watershed         cover           (cfs mi**__**-2**__**)        (in.)   **__**      **__**ratio**_**  ****  **
**Forested                3%                 19              0.64          0.14****            **
**Suburban             21%                42              1.12          0.25****            **
**Urban                   70%               163              2.85         0.63****            **

**24-hour 4.5" Storm Event**** **

## Slide 21

**Notes:**
Discharge rate triples
Volume doubles

## Slide 22

**Notes:**
Discharge rate triples
Volume doubles

## Slide 23

**Notes:**
Discharge rate triples
Volume doubles

## Slide 24

## Slide 25

## Hydrology Conclusions

**Stormwater runoff increases with urbanization.**
**Impact of urbanization on stormwater runoff is more pronounced with smaller storms.**
**The method presented appears to be a reasonable non-field-based approach to quantifying and forecasting stormwater runoff in headwater stream/creek watersheds.**