Deep-learning + GIS pipeline detecting flood-driving drainage encroachment from 5 cm aerial imagery — U-Net semantic segmentation, multi-temporal change detection (Accra, Ghana)
# VISION — Geospatial Deep Learning for Flood-Driver Detection
> Computer vision on centimetre-scale aerial imagery to localise the *human* causes
> of urban flooding — drainage encroachment and obstructed waterways — that
> conventional satellite remote sensing cannot resolve.
**VISION** (*Vulnerability Inference for Submersion-prone Informal settlements via
Orthoimagery and Networks*) is an applied geospatial-AI system that couples
**deep-learning semantic segmentation** — a **U-Net convolutional neural network** —
with **multi-temporal change detection** and **topology-aware spatial reasoning** to
detect and quantify the anthropogenic drivers of pluvial flooding in Accra, Ghana,
at a resolution roughly two orders of magnitude finer than the satellite imagery on
which prior work has relied.
### Technical approach
- **Semantic segmentation (U-Net / CNN)** — pixel-wise extraction of buildings,
drainage, and encroachment from 5 cm RGB orthomosaics
- **Multi-temporal change detection** — 2020 vs 2024 epochs to quantify the
*growth* of encroachment onto watercourses
- **Topographic flood-susceptibility modelling** — gradient-boosted / random-forest
ensembles over terrain morphometrics (slope, flow accumulation, TWI)
- **Topology-aware geospatial overlay** — reconciling segmented structures against
the hydrographic network to rank hazard loci
- **Open-channel hydraulics** — Manning conveyance capacity of field-surveyed
drain cross-sections, and its collapse under progressive siltation
- **Corridor observation** — drain-aligned image chips cut at native 2–5 cm
along every surveyed segment, to observe channel condition rather than assume it
- **Reproducible by construction** — open data, scripted acquisition, and a
version-controlled methodology rather than committed binary payloads
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## Abstract
Recurrent and frequently catastrophic inundation in metropolitan Accra is, on the
preponderance of the evidence, an anthropogenic rather than a climatological
phen …