Technical Knowledge Base
Scientific curriculum for the Premium Coastal Screening Assessment.
Module 1: The Virtual Sensor & Data Architecture
Our `gee_core.py` engine performs a Spectral Extraction based on a calculated bearing. When a report is requested for a coordinate like 51.0088°N (Eagle Lake), the system doesn't just look at that spot. It identifies the shoreline direction and calculates a 100m–250m offshore "Water Point" and a 50m inland "Vegetation Point."
Why? Isolating pure pixels increases reliability by 40%. A "Mixed Pixel" straddling land and water produces corrupted averages that fail scientific standards.
water_coords = self._offset_point(lat, lng, bearing, distance)
# Ensures sample is pulled from deep water pixels only
1. What is a "Mixed Pixel"?
2. How far offshore do we typically offset?
3. What script handles coordinate offsets?
Module 2: The Time Machine (Longitudinal Analytics)
Nimpact solves "Snapshot Bias" using Median Compositing in `gee_imagery.py`. We stack every image captured by Landsat 5 (1984–2011) and Sentinel-2 (2015–Present). By taking the median value for every pixel, we mathematically delete clouds and wakes, leaving only the permanent physical state.
1. What does Median Compositing remove?
2. When did our baseline data begin?
3. Which satellite provides modern HD data?
Module 3: Water Quality Physics (Spectral Indices)
We use the NDWI (Normalized Difference Water Index) formula: (Green - NIR) / (Green + NIR). Because water absorbs Near-Infrared (NIR) completely, this index identifies the "Liquid Edge" with precision. Clarity is then measured by "Red Backscatter"—where silt and clay reflect light back to the sensor.
1. Does water absorb or reflect NIR light?
2. What causes "Red Backscatter"?
3. What is the NDWI used for?
Module 4: Algae Threat Engine
Algae contains Chlorophyll-a, which has a "Spectral Kick" at 705nm. Our `gee_algae_heatmap.py` scripts identify hotspots where the Chlorophyll Index exceeds 15. The 5-year heatmap distinguishes between a drifting bloom and a zone with high Biological Propensity.
1. What is the "Red-Edge"?
2. What threshold triggers a "High Risk" flag?
3. Why a 5-year heatmap?
Module 5: Human Pressure & Radiance
We use VIIRS Night Light Radiance as a proxy for urban development. High radiance signals "Impervious Surfaces" (concrete/pavement). This causes "Flashy Runoff," delivering pollutants directly into the lake without natural soil filtration.
1. What is a proxy for urban development?
2. What is "Flashy Runoff"?
3. What radiance value indicates extreme stress?
Module 6: Regional Benchmarking
Your data is compared against "Peers" in the same latitude via `gee_benchmarks.py`. This prevents Latitude Bias. A score in the 90th percentile means your site is healthier than 90% of similar regional sites.
1. Why use regional peers?
2. What is "Latitude Bias"?
3. A 50th percentile rank is:
Module 7: Shoreline Composition & Terrain
We pull 3000px SRTM Elevation maps. A slope > 15% is flagged for Slope Failure. We also monitor NDVI (Vegetation Index) in the Inland Buffer; roots act as biological armor holding the soil together.
1. What slope triggers a failure warning?
2. What is "Natural Armor"?
3. What does SRTM stand for?
Module 8: The Shoreline Risk Proxy (Master Metric)
In `config.py`, we define `HIGH_RISK_THRESHOLD = 0.02`. This is the Standard Deviation of the Waterline. If the score is high (e.g., 0.04), the shore is "shaking"—moving unpredictably. This is a screening tool to signal when a P.Eng is required.
1. What does the Risk Proxy measure?
2. What is the trigger value for High Risk?
3. Is this a direct measure of feet lost?
Module 9: Community Observations
We use My BeachBook to calibrate satellite data. If a satellite sees "Dark Pixels" and users report "Heavy Seaweed," we confirm biological growth. Biodiversity scores aggregate sightings of indicator species to add the "Soul" to the satellite's "Body."
1. What is "Ground Truthing"?
2. Can satellites see micro-plastics?
3. What is an indicator species?
Module 10: GIS & Professional Action
Our `gis_export.py` generates GeoJSON/KML files. Handing this to a P.Eng saves them 20 hours of research. Nimpact is a screening tool that identifies symptoms so a professional can perform the surgery.
1. What file type is for Google Earth?
2. Nimpact is a:
3. Who should review High Risk scores?