Hierarchical regulation of nitrogen export from urban catchments in central Arizona-Phoenix
Author(s):
- David Lewis, Arizona State University
- Nancy Grimm, Arizona State University
Abstract:
In urban catchments of arid central Arizona, we investigate how the export of mineral and organic nitrogen (N) in storm runoff is regulated by interactions between local landscape characteristics and broader scale storm features. First, we test whether N export is more a function of (1) processes that affect N concentration in runoff or (2) the propensity of the catchment to convey rainfall as runoff. With data pooled across catchments, the mass of N in export (load) is determined by processes regulating runoff N concentration. There are exceptions when catchments are examined individually, where N load from some catchments is determined by the hydrologic responsiveness of the catchment. Second, we investigate the relationship between N export and catchment features. Loads per catchment area were greater from more impervious catchments, probably because impervious catchments held more N in a mobilizable phase and conveyed more rainfall as overland flow. Loads per area were lower from larger catchments, possibly owing to more N-retention hot spots in larger catchments. Catchments with the greatest N exports were those with commercial land use, and loads decreased as development became less prevalent or as residential replaced industrial land use. Third, we investigated how catchment features moderated direct responses of N export to storms. Export was less correlated with storm features in catchments that were larger, more pervious, and less industrial. Results support an N build and flush hypothesis, which purports that there is little biotic processing of N deposited to arid, urban surfaces with little organic matter. The rate and duration of deposition determine the size of the mobile N pool. Any amount of rainfall capable of generating overland flow would entrain nearly all mobilizable N and export it from the catchment. Nonetheless, these results suggest that, even with daunting seasonal and interannual variability in storm conditions, material export can be reduced by managing intrinsic catchment features.
Keywords:
Temporal Coverage:
1991-01-01 to 2005-03-01Geographic Coverage:
Geographic Description: Phoenix metropolitan areaBounding Coordinates:
Longitude:-112.794316 to -111.566698
Latitude:33.838010 to 33.198342
Contact:
Information Manager, Global Institute of Sustainability, Arizona State University,POB 875402,TEMPE
caplter.data@asu.edu
Methods used in producing this dataset: Show
Data Files (2) :
Tabular: 74_sites_1.csv
Description: Descriptions of Catchments
Column | Description | Type | Units |
---|---|---|---|
id | record ID |
float | |
site_id | abbreviation of site name |
string | |
location | location within Phoenix metropolitan
area |
string | |
contrib_area_km2 | area contributing to runoff |
float | squareKilometers |
perc_residential | Residential landuse in catchment in percent
area |
float | dimensionless |
perc_industrial | Industrial landuse in catchment in percent
area |
float | dimensionless |
perc_commercial | Commercial landuse in catchment in percent
area |
float | dimensionless |
perc_developed | Developed landuse in catchment in percent
area |
float | dimensionless |
perc_undeveloped | Undeveloped landuse in catchment in percent
area |
float | dimensionless |
perc_impervious | Impervious ground cover in catchment in percent
area |
float | dimensionless |
landfac1 | Factor 1 factor scores from a factor analysis for data
reduction |
float | |
landfac2 | Factor 2 factor scores from a factor analysis for data
reduction |
float | |
landfac3 | Factor 3 factor scores from a factor analysis for data
reduction |
float |
Tabular: 74_storm_events_1.csv
Description: Nitrogen concentraitions in storm runoff events
Column | Description | Type | Units |
---|---|---|---|
ID | Automatically generated sequential ID
number |
integer | |
site_id | site ID as used in sites table |
string | |
month | Month of storm event |
float | nominalMonth |
year | Year of storm event |
float | nominalYear |
day | Day of storm event 1 is 1991-01-01 |
float | number |
discharge_l | Discharge during collection |
float | liter |
area_corr_discharge_megl_km2 | Discharge corrected for area |
float | megaLiterPerKilometerSquared |
season | Season during which the storm event occurred |
string | |
dry_days | Days without precipitation preceeding the storm
event |
float | number |
precipitation_cm | Total precipitation during the storm
event |
float | centimeter |
precip_intens_cm_5min | Precipitation intensity in cm per 5
minutes |
float | centimeterPerFiveMinute |
storm_duration_min | Storm duration in minutes |
float | nominalMinute |
no3_conc_mg_l | NO3 concentration in runoff Event-mean concentration of N
as NO2 and NO3 |
float | milligramsPerLiter |
nh4_conce_mg_l | NH4 concentration in runoff Event-mean concentration of N
as NH4 |
float | milligramsPerLiter |
organic_n_conc_mg_l | Organic N concentration in runoff Event-mean concentration
of N as organic N |
float | milligramsPerLiter |
tot_n_concentration_mg_l | Total N concentration in runoff Event-mean concentration of
N |
float | milligramsPerLiter |
no3_load_kg_km2 | Mass of N as NO2 and NO3 exported from the catchment during
the storm |
float | kilogramPerKilometerSquared |
nh4_load_kg_km2 | Mass of N as NH4 exported from the catchment during the
storm |
float | kilogramPerKilometerSquared |
org_n_load_kg_km2 | Mass of N as organic N exported from the catchment during
the storm |
float | kilogramPerKilometerSquared |
tot_n_load_kg_km2 | Mass of N (all forms) exported from the catchment during
the storm |
float | kilogramPerKilometerSquared |
landfac1_season | Landfactor 1 storm attribute interaction term
season |
float | dimensionless |
landfac1_dry_days | Landfactor 1 storm attribute interaction term
precipitation |
float | dimensionless |
landfac1_precip | Landfactor 1 storm attribute interaction term dry
days |
float | dimensionless |
landfac2_season | Landfactor 2 storm attribute interaction term
season |
float | dimensionless |
landfac2_dry_days | Landfactor 2 storm attribute interaction term dray
days |
float | dimensionless |
landfac2_precip | Landfactor 2 storm attribute interaction term
precipitation |
float | dimensionless |
Landfac3_season | Landfactor 3 storm attribute interaction term
season |
float | dimensionless |
Landfac3_dry_days | Landfactor 3 storm attribute interaction term dry
days |
float | dimensionless |
Landfac3_precip | Landfactor 3 storm attribute interaction term
precipitation |
float | dimensionless |