Subsurface Detection Drone Services — Sioux City & Tri-State Region
Multispectral cropmark and soil signature analysis reveals buried structures, drainage tile, foundations, and archaeological features through the differential stress patterns they create in vegetation and soil — without disturbing a single inch of ground.
What multispectral analysis reveals
- Buried drainage tile & subsurface water systems
- Buried foundations & historical structures
- Archaeological cropmarks & soil disturbance signatures
- Septic field footprints & utility corridors
- Ancient earthworks & burial mound complexes
- Pre-construction cultural resource screening
How Multispectral Imaging Reveals What's Below the Surface
Buried features don't disappear — they leave signatures in the vegetation and soil above them. Foundations, drainage tile, compacted fill, and disturbed soil all alter how plants grow and how bare soil reflects light. The DJI Mavic 3M captures five spectral bands — NIR, Red Edge, Red, Green, and RGB — that make these differences measurable and mappable.
Three indices form the core of the analysis. NDVI (Normalized Difference Vegetation Index) quantifies plant health; stressed vegetation above buried features shows reduced chlorophyll and shorter canopy height. NDRE (Normalized Difference Red Edge Index) is more sensitive to early-stage stress and penetrates deeper canopy, making it effective earlier in the growing season. GNDVI (Green NDVI) responds to nitrogen and water availability — useful for detecting buried disturbances that affect soil moisture differently from surrounding areas.
When all three indices are analyzed together against bare-soil reflectance data, the result is a spatial anomaly map that localizes subsurface disturbances with precision. Flight timing is critical: results are strongest during active crop stress periods (mid-season vegetative growth) or on bare soil in spring or post-harvest. We advise on optimal timing for each site.
Note: Multispectral cropmark and soilmark analysis is a remote sensing technique that identifies near-surface anomalies through differential vegetation stress and soil reflectance. It does not directly image below ground. For confirmed subsurface investigation, results should be followed up with qualified archaeologists, geophysicists, or ground-penetrating radar (GPR) specialists. We can recommend partner specialists in the Tri-State region.
Applications
Archaeological Prospection
Identify potential site locations before ground excavation. Multispectral cropmark analysis can screen large areas rapidly and non-destructively during the growing season, prioritizing where limited excavation resources should be focused. Earthwork mounds, buried pit features, and disturbed soils are all detectable via NDVI/NDRE anomaly patterns.
Pre-Construction Cultural Resource Survey
Section 106 compliance and Phase I archaeological assessments often require surface reconnaissance of project areas. Multispectral analysis provides a defensible, documented screening tool before ground disturbance begins on infrastructure or development projects, particularly effective in agricultural and pasture settings.
Historical Site Documentation
Document known or suspected historical sites — Civil War earthworks, Native American mound complexes, early settlement features — with precision spatial data for research, preservation planning, or interpretive display.
Subsidence & Sinkhole Risk Assessment
Ground subsidence and karst-related sinkhole development often show early topographic expression detectable in high-resolution terrain models. Useful for infrastructure siting, insurance assessments, and geohazard screening.
Agricultural Feature Mapping
Drainage tile systems, old field boundaries, buried infrastructure, and historic land use patterns all produce differential crop stress visible in NDVI and NDRE data. Particularly valuable for tile drainage planning, tile break location, septic field footprint identification, and precision agriculture applications.
How It Works
Every project begins with a consultation — scope and approach vary by site and objective
Initial Consultation
We discuss your project objectives, site location and size, existing knowledge of the area, and what you're hoping to find or rule out. This determines whether multispectral cropmark analysis, bare-soil reflectance imaging, photogrammetric DTM, or a combination is most appropriate. This step is required — subsurface detection is not a commodity service.
Desk Study & Site Research
Before flying, we review existing data — historical maps, USGS topographic surveys, county soil surveys, aerial photography archives, and any known site records. This informs what features to look for and helps calibrate interpretation of the resulting data products.
Aerial Data Capture
We fly the DJI Mavic 3M over the survey area in a systematic grid pattern, capturing all five spectral bands simultaneously. Flight altitude, overlap, and timing are set to achieve the spatial resolution required for the expected feature scale. Ground control points are established for georeferenced output.
Index Calculation & Anomaly Identification
NDVI, NDRE, and GNDVI indices are calculated from the calibrated multispectral imagery. Index maps are overlaid and cross-referenced to identify spatial anomalies that appear consistently across multiple indices. Anomalies are mapped, categorized by type, and rated by confidence level. This step requires expert interpretation — automated thresholding alone is insufficient.
Report & Recommendations
You receive a full report including the georeferenced terrain data, annotated anomaly map, feature descriptions and confidence ratings, and recommendations for follow-up investigation (ground truthing, GPR, archaeologist consultation). Data is delivered in formats compatible with GIS and CAD platforms.
What You Get
All deliverables include the spatial data and interpretive analysis
Multispectral Index Maps (GeoTIFF)
Calibrated NDVI, NDRE, and GNDVI rasters at full sensor resolution. The foundational datasets for all anomaly detection and interpretation work.
False-Color Composite Renders
Color-rendered index composites that visually highlight stress differentials and soil anomalies for client review, reporting, and presentation purposes.
Anomaly Map (Georeferenced)
GIS-compatible shapefile or KMZ with all identified anomalies mapped, attributed with type, dimensions, confidence level, and interpretation notes.
Raw Band Data (TIFF per band)
Individual calibrated reflectance images for each of the five Mavic 3M bands. Importable into QGIS, ArcGIS, and other GIS platforms for independent analysis or archiving.
Interpretive Report
Written analysis of identified anomalies, methodology, confidence assessments, and recommended next steps. Suitable for academic, regulatory, or planning purposes.
Specialist Referrals (If Needed)
Where follow-up ground investigation is warranted, we can connect you with qualified archaeologists, geophysicists, or GPR specialists in the Tri-State region.
Transparent Starting Prices
Tiers 1 and 2 have fixed entry rates based on acreage. Archaeological and regulatory scope is quoted per project after a free consultation.
Agricultural Tile & Drainage Screening
- ✓ NDVI, NDRE & GNDVI index maps
- ✓ Georeferenced anomaly overlay
- ✓ Digital delivery (GeoTIFF + PNG)
- ✓ Pre-flight consultation included
- +$12/acre over 40 acres
Property & Site Investigation
- ✓ Full multispectral capture
- ✓ NDVI, NDRE & GNDVI index maps
- ✓ Written interpretation report
- ✓ Anomaly map with confidence ratings (SHP/KMZ)
- ✓ Raw band data (TIFF per band)
- +$10/acre over 120 acres
Archaeological & Regulatory
- ✓ Everything in Site Investigation
- ✓ SHPO-ready documentation
- ✓ Archaeologist coordination available
- ✓ Section 106 compliance scope
- ✓ Confidentiality agreement available
Tier 1 and 2 prices are fixed entry rates — no hidden scope creep. Archaeological projects are quoted after a free 20-minute consultation. Schedule a free consultation →
What You're Comparing Against
- Trenching to locate drainage tile: $2,000–$15,000 depending on field size, plus crop damage and compaction from equipment. A $750 multispectral screening flight narrows the search to specific anomaly zones before a single shovel breaks ground.
- Ground-Penetrating Radar (GPR): $700–$2,500 per day for a trained operator and equipment — and GPR can only scan in narrow strips at walking pace. A drone covers 40 acres in a single flight. — Industry rate data
- Phase I CRM archaeological survey: $3,000–$20,000 depending on acreage and state requirements. Multispectral pre-screening at $1,750 can identify which portions of a project area warrant formal investigation, focusing Phase I costs where they're actually needed. — CRM industry benchmarks
- The U.S. experiences 400,000–800,000 utility strikes annually. Each strike averages $4,000 in direct repair costs — but indirect costs (downtime, delays, fines) add $29 for every $1 in direct damage, bringing the true average to approximately $116,000 per strike. — Common Ground Alliance 2024 DIRT Report
Have a Site You Need to Understand?
Subsurface detection projects start with a conversation. Tell us what you're looking for, where the site is, and what you already know — we'll advise on the right approach.
Subsurface Detection Questions
Can drones actually see underground?
Not directly. Multispectral imaging measures how vegetation and bare soil reflect light across five spectral bands, including near-infrared and red edge wavelengths invisible to the human eye. What makes it powerful for subsurface detection is that buried features — tile, foundations, compacted fill — alter soil moisture, drainage, and nutrient availability above them. Those differences appear as measurable anomalies in NDVI, NDRE, and GNDVI index maps. Think of it as the crop above a buried feature telling you something is underneath. Ground-penetrating radar (GPR) is required for direct subsurface imaging; we can refer you to GPR specialists if needed.
What kind of features have been detected with multispectral analysis?
In agricultural settings, drainage tile networks are among the most consistently detectable features — tile affects soil moisture and shows up clearly in NDRE and GNDVI data. Buried foundations, old road grades, and historic farmstead features produce soil disturbance signatures visible in both vegetated and bare-soil imagery. Archaeological earthworks — mounds, pit features, ditches — show differential crop stress in actively growing fields, particularly mid-season. Results are site-specific and season-dependent — we discuss realistic expectations during the consultation.
Do I need an archaeologist involved in this project?
It depends on your purpose. If you're doing informal research on your own property out of curiosity, no licensed archaeologist is required for the remote sensing phase. If you're conducting a Section 106 cultural resource survey for a federally-permitted project, or if you intend to publish or present findings, you will need a qualified archaeologist to supervise the investigation and sign off on reports. We can coordinate with or refer you to qualified Iowa, Nebraska, and South Dakota archaeologists as needed.
When is the best time to fly for subsurface detection?
Timing is critical and varies by feature type. Cropmark analysis is most effective during active vegetative growth — typically late May through July for row crops — when buried features are actively stressing the plants above them. Soilmark analysis (bare soil reflectance) works best on freshly tilled fields in spring or post-harvest in fall. For drainage tile specifically, flights during or immediately after a rain event can reveal tile networks through differential soil moisture. We advise on optimal timing for each project during consultation.