### Abstract

Effective hydraulic conductivity (K(e)) is an important parameter for the prediction of infiltration and runoff volume from storms. The Water Erosion Prediction Project (WEPP) model, which uses a modified Green-Ampt equation, is sensitive to the hydraulic conductivity parameter in the prediction of runoff volume and peak discharge. Two sets of algorithms developed from cropland data to predict K(e) have previsouly been used in the WEPP model. When tested with data collected on rangelands, these equations resulted in low predictions of K(e) which significantly over-estimated runoff volume. The errors in runoff prediction were propagated through the model and resulted in poor predictions of peak discharge and sediment yield. The objective of this research was to develop a new predictive equation to calculate K(e) specifically for use on rangelands using field data collected in 8 western states on 15 different soil/vegetation complexes. A distinction was made between ground cover parameters located outside and underneath plant canopy in on effort to account for the significant spatial variability that occurs on most rangelands. Optimized K(e) values were determined using the WEPP model and observed runoff data. A regression model (r^{2}=0.60) was then developed to predict K(e) using measured soil, canopy cover, and spatially distributed ground cover data from 44 plots. Independent rangeland data sets are now required to test the new equation to determine how well the relationships developed from the data used in this study extend to other rangeland areas.

Original language | English (US) |
---|---|

Pages (from-to) | 290-299 |

Number of pages | 10 |

Journal | Journal of Range Management |

Volume | 50 |

Issue number | 3 |

State | Published - May 1997 |

### Fingerprint

### Keywords

- ground cover
- hydrologic modeling
- infiltration
- runoff
- spatial variability
- WEPP

### ASJC Scopus subject areas

- Animal Science and Zoology
- Ecology

### Cite this

*Journal of Range Management*,

*50*(3), 290-299.

**Estimation of Green-Ampt effective hydraulic conductivity for rangelands.** / Kidwell, Mary R.; Weltz, Mark A.; Guertin, Phillip.

Research output: Contribution to journal › Article

*Journal of Range Management*, vol. 50, no. 3, pp. 290-299.

}

TY - JOUR

T1 - Estimation of Green-Ampt effective hydraulic conductivity for rangelands

AU - Kidwell, Mary R.

AU - Weltz, Mark A.

AU - Guertin, Phillip

PY - 1997/5

Y1 - 1997/5

N2 - Effective hydraulic conductivity (K(e)) is an important parameter for the prediction of infiltration and runoff volume from storms. The Water Erosion Prediction Project (WEPP) model, which uses a modified Green-Ampt equation, is sensitive to the hydraulic conductivity parameter in the prediction of runoff volume and peak discharge. Two sets of algorithms developed from cropland data to predict K(e) have previsouly been used in the WEPP model. When tested with data collected on rangelands, these equations resulted in low predictions of K(e) which significantly over-estimated runoff volume. The errors in runoff prediction were propagated through the model and resulted in poor predictions of peak discharge and sediment yield. The objective of this research was to develop a new predictive equation to calculate K(e) specifically for use on rangelands using field data collected in 8 western states on 15 different soil/vegetation complexes. A distinction was made between ground cover parameters located outside and underneath plant canopy in on effort to account for the significant spatial variability that occurs on most rangelands. Optimized K(e) values were determined using the WEPP model and observed runoff data. A regression model (r2=0.60) was then developed to predict K(e) using measured soil, canopy cover, and spatially distributed ground cover data from 44 plots. Independent rangeland data sets are now required to test the new equation to determine how well the relationships developed from the data used in this study extend to other rangeland areas.

AB - Effective hydraulic conductivity (K(e)) is an important parameter for the prediction of infiltration and runoff volume from storms. The Water Erosion Prediction Project (WEPP) model, which uses a modified Green-Ampt equation, is sensitive to the hydraulic conductivity parameter in the prediction of runoff volume and peak discharge. Two sets of algorithms developed from cropland data to predict K(e) have previsouly been used in the WEPP model. When tested with data collected on rangelands, these equations resulted in low predictions of K(e) which significantly over-estimated runoff volume. The errors in runoff prediction were propagated through the model and resulted in poor predictions of peak discharge and sediment yield. The objective of this research was to develop a new predictive equation to calculate K(e) specifically for use on rangelands using field data collected in 8 western states on 15 different soil/vegetation complexes. A distinction was made between ground cover parameters located outside and underneath plant canopy in on effort to account for the significant spatial variability that occurs on most rangelands. Optimized K(e) values were determined using the WEPP model and observed runoff data. A regression model (r2=0.60) was then developed to predict K(e) using measured soil, canopy cover, and spatially distributed ground cover data from 44 plots. Independent rangeland data sets are now required to test the new equation to determine how well the relationships developed from the data used in this study extend to other rangeland areas.

KW - ground cover

KW - hydrologic modeling

KW - infiltration

KW - runoff

KW - spatial variability

KW - WEPP

UR - http://www.scopus.com/inward/record.url?scp=0030616430&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030616430&partnerID=8YFLogxK

M3 - Article

VL - 50

SP - 290

EP - 299

JO - Rangeland Ecology and Management

JF - Rangeland Ecology and Management

SN - 1550-7424

IS - 3

ER -