Vulnerability of shallow ground water and drinking-water wells to nitrate in the United States: Model of predicted nitrate concentration in U.S. ground water used for drinking (simulation depth 50 meters) -- Input data set for farmfertilizer (gwava-dw_ffer)

This data set represents the average annual nitrogen input from
commercial fertilizer applied to agricultural lands, 1992-2001,
in kilograms per hectare, in the conterminous United States.

The data set was used as an input data layer for a national
model to predict nitrate concentration in ground water used for
drinking.

Nolan and Hitt (2006) developed two national models to predict
contamination of ground water by nonpoint sources of
nitrate. The nonlinear approach to national-scale Ground-WAter
Vulnerability Assessment (GWAVA) uses components representing
nitrogen (N) sources, transport, and attenuation.

One model (GWAVA-S) predicts nitrate contamination of shallow
(typically less than 5 meters deep), recently recharged ground
water, which may or may not be used for drinking. The other
(GWAVA-DW) predicts ambient nitrate concentration in deeper
supplies used for drinking.

This data set is one of 14 data sets (1 output data set and 13
input data sets) associated with the GWAVA-DW model. Full details
of the model development are in Nolan and Hitt (2006).

For inputs to the model, spatial attributes representing 13
nitrogen loading and transport and attenuation factors were
compiled as raster data sets (1-km by 1-km grid cell size) for
the conterminous United States (see table 1).

>Table 1.-- Parameters of nonlinear regression model for
> nitrate in ground water used for drinking (GWAVA-DW)
> and corresponding input spatial data sets.
> [kg, kilograms; km2, square kilometers.]
>
>Nitrogen Source Factors Data Set Name
> 1 farm fertilizer (kg/hectare) gwava-dw_ffer
> 2 confined manure (kg/hectare) gwava-dw_conf
> 3 orchards/vineyards (percent) gwava-dw_orvi
> 4 population density (people/km2) gwava-dw_popd
>
>Transport to Aquifer Factors
> 5 water input (km2/cm) gwava-dw_wtin
> 6 glacial till (yes/no) gwava-dw_gtil
> 7 semiconsolidated sand aquifers gwava-dw_semc
> (yes/no)
> 8 sandstone and carbonate rocks gwava-dw_sscb
> (yes/no)
> 9 drainage ditch (km2) gwava-dw_ddit
> 10 Hortonian overland flow gwava-dw_hor
> (percent of streamflow)
>
>Attenuation Factors
> 11 fresh surface water withdrawal gwava-dw_swus
> for irrigation (megaliters/day)
> 12 irrigation tailwater recovery (km2) gwava-dw_twre
> 13 Dunne overland flow gwava-dw_dun
> (percent of streamflow)
> 14 well depth (meters) -

"Farm fertilizer" is the average annual nitrogen input from
commercial fertilizer applied to agricultural lands, 1992-2001, in
kilograms per hectare.

"Confined manure" is the average annual nitrogen input from
confined animal manure, 1992 and 1997, in kilograms per
hectare.

"Orchards/vineyards" is the percent of orchards/vineyards land
cover classification.

"Population density" is 1990 block group population density, in
people per square kilometer.

"Water input" is the ratio of the total area of irrigated land
to precipitation, in square kilometers per centimeter.

"Glacial till" is the presence or absence of poorly sorted
glacial till east of the Rocky Mountains.

"Semiconsolidated sand aquifers" is the presence or absence of
semiconsolidated sand aquifers.

"Sandstone and carbonate rocks" is the presence or absence of
sandstone and carbonate rock aquifers.

"Drainage ditch" is the area of National Resources Inventory surface
drainage, field ditch conservation practice, in square kilometers.

"Hortonian overland flow" is infiltration excess overland flow
estimated by TOPMODEL, in percent of streamflow.

"Fresh surface water withdrawal for irrigation" is the amount of
fresh surface water withdrawal for irrigation, in megaliters per day.

"Irrigation tailwater recovery" is the area of National
Resources Inventory irrigation system, tailwater recovery
conservation practice, in square kilometers.

"Dunne overland flow" is saturation overland flow estimated by
TOPMODEL, in percent of streamflow.

"Well depth" is the depth of the well, in meters. Well depth
was not compiled as a spatial data set. Well depth equals 50
meters for the model simulation being presented.

Reference cited:

Nolan, B.T. and Hitt, K.J., 2006, Vulnerability of shallow
ground water and drinking-water wells to nitrate in the United
States: Environmental Science and Technology, vol. 40, no. 24,
pages 7834-7840.

本数据集记录了1992-2001年间，美国本土48州农业用地施用商业化肥的年均氮输入量，单位为千克每公顷。

该数据集曾作为国家级模型的输入数据图层，用于预测饮用水地下水中的硝酸盐浓度。

Nolan与Hitt（2006）开发了两个国家级模型，用于预测非点源硝酸盐对地下水的污染。国家级尺度地下水脆弱性评价（Ground-WAter Vulnerability Assessment, GWAVA）的非线性方法采用了代表氮源、迁移与衰减的组分。

其中一个模型（GWAVA-S）可预测浅层（通常深度小于5米）、近期补给地下水的硝酸盐污染情况，这类地下水可能被用作饮用水，也可能不被用作饮用水。另一个模型（GWAVA-DW）则用于预测用作饮用水的深层地下水的环境硝酸盐浓度。

本数据集是与GWAVA-DW模型相关的14个数据集（1个输出数据集与13个输入数据集）之一，该模型的完整开发细节可参考Nolan与Hitt（2006）的研究。

针对该模型的输入数据，研究人员针对美国本土48州整合了代表13项氮负荷、迁移与衰减因子的空间属性数据，生成了栅格数据集（网格单元尺寸为1千米×1千米），详见表1。

>表1.-- 饮用水地下水硝酸盐非线性回归模型（GWAVA-DW）参数及对应输入空间数据集
> [kg，千克；km2，平方千米。]
>
>氮源因子 数据集名称
> 1 农用化肥（千克/公顷） gwava-dw_ffer
> 2 圈养畜禽粪便（千克/公顷） gwava-dw_conf
> 3 果园/葡萄园占比（百分比） gwava-dw_orvi
> 4 人口密度（人/平方千米） gwava-dw_popd
>
>含水层迁移因子
> 5 水分输入（平方千米/厘米） gwava-dw_wtin
> 6 冰碛物（有/无） gwava-dw_gtil
> 7 半固结砂质含水层（有/无） gwava-dw_semc
> 8 砂岩与碳酸盐岩含水层（有/无） gwava-dw_sscb
> 9 排水沟渠面积（平方千米） gwava-dw_ddit
> 10 霍顿坡面流（占径流量百分比） gwava-dw_hor
>
>衰减因子
> 11 灌溉淡水地表水取水量（兆升/天） gwava-dw_swus
> 12 灌溉尾水回收面积（平方千米） gwava-dw_twre
> 13 敦恩坡面流（占径流量百分比） gwava-dw_dun
> 14 井深（米） -

“农用化肥”指1992-2001年间农业用地施用商业化肥的年均氮输入量，单位为千克每公顷。
“圈养畜禽粪便”指1992年与1997年圈养畜禽粪便的年均氮输入量，单位为千克每公顷。
“果园/葡萄园占比”指土地覆盖分类中果园与葡萄园的占比百分比。
“人口密度”指1990年街区组人口密度，单位为人/平方千米。
“水分输入”指灌溉土地总面积与降水量的比值，单位为平方千米/厘米。
“冰碛物”指落基山脉东部是否存在分选性差的冰碛物。
“半固结砂质含水层”指是否存在半固结砂质含水层。
“砂岩与碳酸盐岩含水层”指是否存在砂岩与碳酸盐岩含水层。
“排水沟渠面积”指《国家资源清查（National Resources Inventory）》中地表排水、田间沟渠保护措施的面积，单位为平方千米。
“霍顿坡面流”指由TOPMODEL估算的超渗坡面流，以占径流量的百分比表示。
“灌溉淡水地表水取水量”指用于灌溉的淡水地表水取水量，单位为兆升/天。
“灌溉尾水回收面积”指《国家资源清查（National Resources Inventory）》中灌溉系统尾水回收保护措施的面积，单位为平方千米。
“敦恩坡面流”指由TOPMODEL估算的饱和坡面流，以占径流量的百分比表示。
“井深”指水井的深度，单位为米。井深未被整合为空间数据集，在本次展示的模型模拟中，井深统一取值为50米。

引用文献：
Nolan, B.T. 和 Hitt, K.J.，2006年，《美国浅层地下水与饮用水水井对硝酸盐的脆弱性》，《环境科学与技术（Environmental Science and Technology）》，第40卷，第24期，第7834-7840页。