NCEES PE Agricultural and Biological Engineering · USA · NCEES (ASABE is the content partner)
Original practice questions written to the published syllabus · not past papersNCEES PE Agricultural and Biological Engineering is a licensing and registration exam run by NCEES (ASABE is the content partner), for candidates in USA. Computer-based, 85 questions, 9.5-hour appointment (8.5 hours of exam). Once a year (next: 28 Oct 2026). Closed book with the electronic NCEES handbook and supplied searchable ASABE standards; SI and US customary units.
Source: ncees.org.
Checked against the exam body's published information. Formats and fees change; confirm the current edition there before you book.
Natural Resources and Environmental Systems: RUSLE-based soil loss, vegetative filter strips, runoff and open-channel design for waterways and terraces, small dams and reservoirs, using supplied standards and handbooks rather than memorised tables.
Estimating erosion and designing the bunds, terraces, waterways, spillways, ponds and dams that control it.
Our 19 NCEES PE Agricultural and Biological Engineering questions in this subject: 3 easy, 10 medium, 6 hard, across 8 units.
Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.
These 10 were written to NCEES PE Agricultural and Biological Engineering and are not shown on any other exam's page.
Shallow overland flow has a hydraulic radius of 0.05 m on a 4% slope. The mean bed shear stress (γ = 9.81 kN/m³) is closest to:
D. 19.6 Pa
τ = γRS = 9810 × 0.05 × 0.04 = 19.6 N/m² (Pa). Using ρ (1000) instead of γ gives 2.0; using the slope as 4 rather than 0.04 gives 1,962; using γ in kN/m³ without converting gives 0.020 (which is kPa, not Pa).
For a field, R = 4,000 MJ·mm/(ha·h·yr), K = 0.02 t·ha·h/(ha·MJ·mm) and LS = 2.0. The soil loss tolerance is 11.2 t/ha/yr and the planned rotation has C = 0.2. The largest P value that keeps loss within tolerance is:
A. 0.35
Allowable C × P = T/(R K LS) = 11.2 / (4000 × 0.02 × 2.0) = 0.070. With C = 0.2, P ≤ 0.070/0.2 = 0.35, which contouring or strip cropping can achieve on moderate slopes. 0.07 is the product CP, not P; omitting LS gives 0.70. 2.86 inverts the ratio (0.2/0.070).
MUSLE differs from the USLE chiefly in that it:
C. replaces rainfall erosivity with a runoff factor and predicts sediment yield from single storms
Williams replaced R with 11.8(Q qp)^0.56, so the equation reflects runoff energy and deposition and gives storm sediment yield at a watershed outlet. It still has no gully term and has nothing to do with wind erosion.
US NRCS soil loss tolerance (T) values, converted to SI, range from about:
C. 2 to 11 t/ha/yr
NRCS assigns 1 to 5 tons per acre per year, about 2.2 to 11.2 t/ha/yr, with the lowest values for shallow soils. Other countries set their own values. 20 to 110 and 0.2 to 1.1 t/ha/yr are factor-of-10 slips in the tons-per-acre conversion.
Soil loss from a 6% field farmed on the contour (P = 0.5) is 18 t/ha/yr. If contour strip cropping with P = 0.25 is adopted and nothing else changes, the new soil loss is:
B. 9.0 t/ha/yr
The loss is proportional to P: 18 × 0.25/0.5 = 9.0 t/ha/yr. Multiplying the present loss by 0.25 applies the new P on top of the old one (giving 4.5); reading P = 0.25 as a 25% reduction gives 13.5. 2.25 multiplies by both P values (18 × 0.25 × 0.5).
Level (ridge-type) broad-base terraces are best suited to:
D. areas of moderate to low rainfall with permeable soils, where runoff is held to infiltrate
Level terraces hold water for infiltration, so the soil must take it in reasonably quickly and the rainfall must not overwhelm storage. Graded (channel-type) terraces are used in wetter areas or on slowly permeable soils.
Flow in a grassed channel has hydraulic radius 0.25 m on a slope of 2%. With Manning's n = 0.04, the mean velocity is closest to:
C. 1.40 m/s
V = (1/n) R^(2/3) S^(1/2) = 25 × 0.25^(2/3) × 0.02^0.5 = 25 × 0.3969 × 0.1414 = 1.40 m/s. Using S = 2 instead of 0.02 gives 14.0 m/s; using R^0.5 gives 1.77 m/s; multiplying by n gives 0.0022 m/s.
In grassed waterway design, the stability (maximum permissible velocity) check is made using:
B. a low vegetal retardance, representing short or newly mown grass
Short grass gives the lowest n and therefore the highest velocity, the critical case for scour. Tall grass (high retardance) gives the greatest depth and is used for the capacity check.
A 0.3 m diameter pipe spillway flows full under an effective head of 3 m. The entrance loss coefficient is 0.5, bend losses are negligible and the friction term K_c L is 1.2. Its discharge is closest to:
C. 0.330 m³/s
a = π × 0.3²/4 = 0.0707 m². Q = a √(2gH/(1 + Ke + Kb + KcL)) = 0.0707 × √(58.86/2.7) = 0.0707 × 4.669 = 0.330 m³/s. Ignoring losses gives 0.542; leaving out the 1 (velocity head at exit) gives 0.416; using πd² for area quadruples the answer. πd² as the area gives 1.320 m³/s.
For an earthen dam, the upstream slope is most likely to fail:
A. after a sudden drawdown of the reservoir
Rapid drawdown removes the stabilising water load on the upstream face while pore pressures inside the slope remain high. The downstream slope is critical under steady seepage with a full reservoir.
This plan follows where our questions actually fall, so the time goes where the marks are likely to be. It is our reading of the syllabus, not the exam body's weighting.
Read the manual chapters for these first and do every worked question you can find on them.
Aim for one sitting per unit, then mixed questions across them.
Learn the definitions, classifications and standard numbers; these units are more often recalled than worked.
Come back to these after a first pass, untimed, and read every explanation, including for the options you rejected.
Do these early in revision so they are fast on the day.
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