Designation of Nitrate Vulnerable Zones in Romania

Catalin SimotaResearch Institute for Soil Science and

AgrochemistryBucharest - Romania

OBJECTIVE

Use of existing databases linked with a simulation model for the evaluation of

nitrate leaching / runoff from agriculture sources and designation of

Nitrate Vulnerable Zones

METHOD

Overlapping three layers of information:

• Layer 1 : Soil transmission properties for nitrates below root front depth (leaching) and by surface runoff;

• Layer 2 : Groundwater;

• Layer 3 : Nitrogen balance at NUTS4 level (imports from local farmyard + livestock manure; export by crop yields).

Layer 1 : Soil transmission properties for nitrates below root front depth (leaching) and by surface runoff

METHOD

“Potential” vulnerability indexes for the water bodies pollution with nitrates distinct for groundwater / aquifers (by leaching below the root front depth) and surface waters (by runoff) were calculated using the pedotransfer functions derived from the soil attributes provided by Soil Database of Europe 1:1,000,000.

METHOD

To each soil attributes or derived pedotransfer functions is linked a “weight” (0-1 0: no impact, 1: maximum impact) related to the potential impact of the given soil property to leaching or runoff process. The potential vulnerability index is calculated by adding the weights for all the soil attributes contributing to leaching / runoff.

METHOD

The vulnerability index for pollution by leaching - Calculated only for slopes less than 8% (Dominant slope class: “Level”)

The vulnerability index for pollution by runoff - Calculated only for slopes greater than 8% (Dominant slope class: “Sloping”, “Moderately steep”, “Steep”)

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by leaching (groundwater / aquifers) are:

• Dominant limitation to agricultural use. If the codes for this attribute are: “Drained”, “Quasi permanently flooded” or “Phreatic phase” then the weight is ”1”.

• Secondary limitation to agricultural use. If the codes for this attribute are: “Drained”, “Quasi permanently flooded” or “Phreatic phase” then the weight is ”0.5”.

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by leaching (groundwater / aquifers) are:

• Wet front hydraulic conductivity (derived pedotransfer function). For values greater than 10 mm h-1 the corresponding weight is “1”, for values in the range 4 – 10 mm h-1 the weight is “0.5”.

• Maximum available water (derived pedo-transfer function). For values less than 10 cm the weight is “1”.

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by leaching (groundwater / aquifers) are:

• Dominant parent material. For “Sandy materials” the weight is 1, for “Organic materials” the weight is “0.8”, for “Sandy loam” , “Sandy loess” “River alluvium”, “Lacustrofluvial alluvium”, “Estuarine/Marine alluvium” the weight is “0.75”, for “Glaciofluvial deposits”, “Till”, “Glaciofluvial drift” and “Alluvial or glaciofluvial clay” the weight is “0.5”.

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by leaching (groundwater / aquifers) are:

• Dominant surface textural class and Dominant sub-surface textural class. If the codes for surface and sub-surface textural class are “Coarse” than the corresponding weight is “1”.

• Soil type. For “Gleysol”, “Fluvisol”, “Histosol” or “Arenosol” the weight is “1”

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by runoff (surface waters) are:

• Dominant limitation to agricultural use. If the codes for this attribute are: “Eroded phase, erosion”, “Lithic (coherent and hard rock within 50 cm)” or “Petrocalcic (cemented or indurated calcic horizon within 100 cm)” then the weight is ”1”.

• Secondary limitation to agricultural use. If the codes for this attribute are: “Eroded phase, erosion”, “Lithic (coherent and hard rock within 50 cm)” or “Petrocalcic (cemented or indurated calcic horizon within 100 cm)” then the weight is “0.5”

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by runoff (surface waters) are:

• Wet front hydraulic conductivity (derived pedotransfer function). For values less than 4 mm h-1 the corresponding weight is “1”

• Maximum available water (derived pedotransfer function). For values less than 10 cm and wet front hydraulic conductivity less than 5 mm h-1 the weight is “1”

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by runoff (surface waters) are:

• Dominant parent material. For “Detrital formations”, “Crystalline rocks and migmatites” and “Volcanic rocks” the weight is 1.

• Dominant surface textural class and Dominant sub-surface textural class. If the codes for surface and sub-surface textural class are “Fine” or “Very Fine” than the corresponding weight is “1”.

METHOD

The soil attributes and the corresponding weights used for calculating the vulnerability index for pollution by runoff (surface waters) are:

• Soil type. For “Lithosol”, “Andosol”, “Glacier”, “Rock Outcrop” the weight is “1”.

• Presence of an impermeable layer within the soil profile. If the impermeable layer is within 0-40 cm than the corresponding weight is “1”.

METHOD

For each polygon defining a Soil Mapping Unit (SMU) the sum of weights corresponding to vulnerability by leaching and by runoff are calculated for each soil type. Than, the vulnerability is evaluated considering the maximum sum of weights (corresponding to one of the soil types in the polygon).

METHOD

The sum of weights is translated into vulnerability classes:

• Very low : [0.0 – 0.5]• Low : (0.5 – 1.5]• Moderate : (1.5 – 2.5]• High : (2.5 – 3.5]• Very high : >3.5

LAYER 2. GROUNDWATER

METHOD

INDEX FOR NITROGEN POLLUTION RISK GROUNDWATER / AQUIFER using:

- Travel time to aquifer

- Aquifer position

- Aquifer vulnerability

METHODINDEX FOR NITROGEN POLLUTION RISK

GROUNDWATER / AQUIFER

Travel Time:

• Long ‑ means a travel time of more than 15 years. 

• Medium ‑ means a travel time of 5 to 15 years.

• Short ‑ means a travel time of less than 5 years.

METHODINDEX FOR NITROGEN POLLUTION RISK

GROUNDWATER / AQUIFER

Aquifer Position: • Shallow/Karst ‑ means that the aquifer is a shallow water table type with a

depth of less than 100 feet to the water table or that the local geology consists of a shallow karst (sink hole and solution tube) structure extending to the ground surface or bottom of the root zone.

• Intermediate ‑ means that the aquifer is a water table type (not confined),

and the depth to the water table Is at least 100 feet but less than 1000 feet. • Deep or Confined ‑ means that the aquifer is very deep (1000 feet or more

to water table) or that an aquiclude or aquitard is positioned between the aquifer and the ground surface such that the auifer is effectively Isolated from local percolation from the ground surface.

METHODINDEX FOR NITROGEN POLLUTION RISK

GROUNDWATER / AQUIFER

Aquifer Vulnerability:

• Class I and IIa ‑ Domestic water supply. An irreplaceable source of drinking water to substantial population or as ecologically vital.

• Class IIb ‑ Potential source of drinking water.• Class III ‑ Unlikely to be used as drinking water.

Potential vulnerable zones to nitrate pollution

(A) Potential vulnerable zones by runoff (surface water bodies)  : 5650 km2, i.e. 2.37% of country area, and 3.82% of agricultural area

(B) Potential vulnerable zones by leaching (groundwater / aquifers) – moderate risk: 13759 km2, i.e. 5.77% of country area, and 9.30% of agricultural area

(C) Potential vulnerable zones by leaching (groundwater / aquifers) high risk: 1200 km2, i.e. 0.50% of country area, and 0.81% of agricultural area

Potential vulnerable zones to nitrate pollution

Layer 3 : Nitrogen balance at NUTS4 level (imports from local farmyard + livestock manure; export by crop yields).

NUTS4-gate Nitrogen Balance

Evaluation of nitrogen balance at NUTS4 unit level (“Comuna”) considering uniform spreading of manure on the arable land (input) of the territorial unit and the export with crop yield

Agricultural Statistics – FARMYARD ANIMALS at NUTS4 level

LIVESTOCK

• Maximum & Actual Capacity of Livestock

• Manure & Waste waters management

Source of data: National Administration “Romanian Waters”

MANURE HANDLING AND STORAGE SYSTEMS

Excretion/transformation coefficients – animal dependent

List of sites having a nitrate import – export value over the threshold

Designation of Nitrate Vulnerable Zones

Overlapping Potential Nitrate Vulnerable Zones with NUTS4-units having a positive import – export value for Nitrogen

Vulnerable zones to nitrate pollution

(A) Vulnerable zones by runoff (surface water bodies)  : 474.685 Km2 (potential : 5650 km2)

(B) Potential vulnerable zones by leaching (groundwater / aquifers) – moderate risk: 2511.115 Km2 (Potential :13759 km2)

(C) Vulnerable zones by leaching (groundwater / aquifers) high risk: 158.94 km2 (Potential : 1200 km2)

Potential vulnerable zones to nitrate pollution + Sources exceeding threshold

Maximum amount of nitrogen (mineral + organic) for moderate aquifer vulnerability – Aquifer used

for domestic water supply

NEXT STEP….

More precise delimitation of the NUTS4 based Nitrate Vulnerable Zones according with the corresponding watersheds.