| 1.
Model identification |
Soil
Erosion Network - Model |
|
1.1
Model name |
|
|
1.2
Most recent version |
ACRU
3.0 |
|
1.3
Date of release |
February
1995. |
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|
|
| 2.
Water erosion |
|
|
|
| 3.
Contact person |
|
|
3.1
Name |
Simon
A Lorentz |
|
3.2
Address |
Dept
Agricultural Engineering, University of Natal, Box X01, Scottsville,
South Africa |
|
3.3
Tel |
+27
331 2605701 |
|
3.4
Fax |
+27
331 2605818 |
|
3.5
Email |
lorentz@aqua.ccwr.ac.za
|
|
|
| 4.
Model Author(s) |
Professor
Roland Schulze, Hydrology
Dr Simon Lorentz (et al) Sediment Yield. |
|
|
| 5.
Model components |
|
|
5.1
Water erosion: |
Modified
universal soil loss equation with RUSLE parameters. K factor
moisture content dependant. GIS based evaluation of parameters. |
|
5.2
Wind erosion: |
None |
|
5.3
Hydrology: . |
Daily
soil water budget. SCS with updated soil water redistribution |
|
5.4
Site/topography: |
Latitude
and longitude. Slope |
|
5.5
Plant growth: |
Maize
model. |
|
5.6
Management: |
Simulates
surface roughness |
|
5.7
Soil: |
Mode
1 ® A and B horizon
Mode 2 ® 20 user defined layers |
|
5.8
Chemistry: |
P
and E-Coli considered. |
|
5.9
Weather: |
Daily
weather data |
|
|
| 6.
Model characteristics |
|
|
6.1
Spatial |
|
|
6.1.1
Class of area: |
Catchment:
Mode 1.
Point or Field: Mode 2 |
|
6.1.2
Flow routing system: |
Muskingum
routing between sub-catchments |
|
6.1.3
Minimum area: |
Point. |
|
6.1.4
Maximum area: |
Not
advised for > 50 km2 |
|
6.2.
Temporal |
|
|
6.2.1
Timestep: . |
Mode
1: Daily.
Mode 2: Break point or 1 minute. |
|
6.2.2
Single or multiple event? |
Multiple |
|
6.2.3
Maximum simulation duration: |
System
limitation is 150 years (daily) |
|
|
| 7
Model's representation of processes |
|
|
7.1
Water erosion processes |
|
|
7.1.1
Interrill: |
Lumped
with rill using. RUSLE |
|
7.1.2
Rill: |
Lumped |
|
7.1.3
Gully: |
Not
modelled separately. Subject of current study |
|
7.1.4
Streambank: |
- |
|
7.1.5
Deposition: |
Only
in terms of RUSLE LS factor |
|
7.2
Wind erosion processes: |
|
|
7.2.1
Creep/surface roll: |
None |
|
7.2.2
Saltation: |
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|
7.2.3
Suspension: |
|
|
7.3
Hydrological processes: |
|
|
7.3.1
Evaporation/transpiration: |
Selection
of: Expert system. A - pan, Penman, Margreaves, Limacre, Blaney-Criddle,
Thoruthwaite |
|
7.3.2
Runoff: |
Mode
1. Daily water budget.
SCS with updated soil water content and redistribution.
Mode 2. Excess from Green - Ampt. |
|
7.3.3
Infiltration: |
Mode
1. Difference between effective rain and runoff. Unsaturated
redistribution
Mode 2. Green - Ampt and Richards equ. redistribution.
|
|
7.3.4
Subsurface flow: |
Mode
1. Cascading layers with user define response parameters.
Mode 2. Richards equ with constant head boundary. |
|
7.3.5
Return flow: |
Mode
1. User defined response rate |
|
7.4
Plant processes: |
|
|
7.4.1
Light interception and photosynthesis: |
Through
crop coefficient. Leaf area index and degree day |
|
7.4.2
Dry matter and residue: |
Specified
in RUSLE C factor. |
|
7.4.3
Root growth: |
Specified
in RUSLE C factor. Growth in irrigation routine. |
|
7.4.4
Pests: |
None |
|
7.4.5
CO2 sensitivity: |
Through
sensitivity of transpiration suppression. Select C3 or C4 plant. |
|
7.5
Soil: |
Mode
1. A and B horizon + baseflow response - cascading layers.
Mode 2. 20 layers retention + hydraulic characteristics green
- ampt and Richards equ |
|
7.5.1
Crust development: |
Mode
2: Exponential equ. |
|
7.5.2
Aggregate properties: |
Used
in specification option for defining hydraulic properties. Used
in specifying RUSLE K factor in sediment yield. |
|
7.6
Chemistry: |
|
|
7.6.1
Nutrients: |
In
irrigation option. Nitrate and phosphorus in water quality option. |
|
7.6.2
Carbon: |
None |
|
7.6.3
Pesticides: |
None |
|
7.6.4
Other contaminants: |
Phosphorus
and e-coli |
|
7.7
Weather: |
On-line
real time mode is planned |
|
|
| 8.
Input Data (* = Mandatory) |
|
|
8.1
Weather: |
Daily
precipitation*, Max*, Min* temperature, Relative humidity, wind
speed, a pan data, radiation. |
|
8.2
Soil: |
Physical
characteristics* of each layer - Texture, porosity, WP, FC -
or soil form and series* mandatory or A-B horizon response,
B-T horizon response - HC for each layer. Surface K* factor
for sediment yield. |
|
8.3
Hydrology |
Coefficient
of baseflow response*. Coefficient of quickflow response*. Impervious
area*. Coefficient of initial abstraction*. Critical depth of
soil from which stormflow takes place* |
|
8.4
Plant cover: |
Crop
coefficient* - Leaf area index*. C factor for sediment yield.
Interception loss* - Fraction of root in topsoil*, effective
root depth* orcrop/type vegetation. |
|
8.5
Soil surface cover: |
Depth
of A & B horizons. Cracking soil (clay content class). |
|
8.6
Management: |
P
factor for sediment yield. Mode 2: Soil roughness |
|
8.7
Topography/site characteristics: |
Time
of concentration (*for sediment yield). Slope (for peak flow).
Hydraulic length - altitude, lat, long catchment area* |
|
8.8
Micro-topography: |
Mode
2: Soil roughness - decrease of roughness with rainfall after
tillage. |
|
|
| 9.
Output data: |
Daily,
monthly or annual values of any variable calculated in the program.
Specified in output option program. Typically: rainfall, effective
rain, evap (pot & actual) soil water content, quickflow,
total runoff, peakflow, sediment yield. |
|
|
| 10
Programming Language: |
PC
: Fortran or Unix : Fortran 77 |
|
|
| 11
Computer requirement: |
PC
: 560KB RAM 20 mb disk space. Storage of output (daily) 98kb
per subcatchment (all variables) per year. 16kb/sc/ (10 variables
per year. Unix enquire CCWR. |
|
|
| 12
Documentation |
|
|
12.1
Scientific Documentation |
Hydrology
and Agrohydrology: A text to accompany the ACRU 3.00 Agrohydrological
Modelling System. Schulze, R. 1995. WRC report II |
|
12.2
User's guide |
ACRU
- Agrohydrological Modelling System. User Manual v3.00. Smithers,
J. and Schulze, R. 1995. Water Research Commission (WRC) Report
II 70/95, Pretoria, South Africa. |
|
12.3
Technical Documentation |
None |
|
|
| 13
Availability |
On
Request |
|
|
| 14
Other Relevant Information |
Future
planning. GIS-model direct link. Real time modelling. Enhancement
of soil water & sediment yield processes. |
