Introduction: The Open Data Revolution in Engineering
A generation ago, an engineer designing a dam in West Africa or a road corridor in Southeast Asia could expect to spend weeks trying to obtain basic topographic maps, and to pay significant fees for rainfall records of uncertain quality. Hydrological analysis was often limited to a handful of gauging stations with incomplete records. Ground investigations were expensive and slow. The data foundation for design was frequently thin.
The open data revolution, driven by space agencies, climate research institutions, and international development organisations, has fundamentally changed this situation. Today, free global datasets cover topography at 10–30m resolution, daily satellite rainfall at 5–10km going back 40 years, river discharge at thousands of gauging stations, soil properties at 250m resolution globally, and land cover at 10m. Cloud platforms allow these datasets to be processed and analysed without downloading raw files.
This article provides a curated reference guide to the most useful free data sources for civil and water resources engineering, organised by data type. Each entry includes the data coverage, resolution, access point, and notes on engineering applications and limitations.
1. Topography and Digital Elevation Models
Elevation data underpins nearly every civil and water resources analysis — catchment delineation, site selection, road alignment, flood routing, and reservoir planning all require a reliable DEM.
NASA/NGA radar survey from 2000. Global coverage from 56°S to 60°N at 1 arc-second (~30m). The most widely used DEM globally. Available via USGS Earth Explorer, OpenTopography, and directly within QGIS.
ESA's global DEM derived from TanDEM-X data. Currently among the most accurate freely available global DEMs. GLO-30 (30m) freely available via AWS S3 or Copernicus Data Space Ecosystem. Superior to SRTM in most terrain types.
Copernicus DEM corrected to remove tree canopy and building heights using machine learning. Critical for flood hydraulic modelling in vegetated or urban areas. Free for non-commercial use; academic and NGO licences available.
JAXA optical stereo DEM at 30m. Generally good accuracy; particularly valuable in forested areas where SAR (SRTM) performance degrades. Free for research and non-commercial use; available at 5m resolution commercially.
For hydraulic modelling in low-gradient floodplains (common in West and Central Africa), the difference between DEM products can be significant. Always validate your DEM against available survey benchmarks before building a hydraulic model. FABDEM typically outperforms raw SRTM by 30–50% RMSE in vegetated areas.
2. Rainfall and Climate Data
Rainfall is the primary driver of most hydrological analyses. The following sources cover the spectrum from near-real-time satellite estimates to century-long reanalysis records.
Daily and monthly rainfall at 0.05° (~5km) from 1981 to present. Blends satellite and gauge data. Particularly well-validated in Africa. Excellent for long-term trend analysis, design flood estimation, and drought indices. Available at UCSB and Google Earth Engine.
NASA's flagship satellite rainfall product. Near-global coverage, 30-minute and daily data at 10km from 2000 to present (TRMM extends back to 1998). Near-real-time availability makes it suitable for flood early warning. Accessed via NASA GES DISC or Google Earth Engine.
Copernicus Climate Data Store. Global climate reanalysis at ~31km (0.25°), hourly, from 1940 to present. Provides rainfall, temperature, wind, humidity, evapotranspiration, and soil moisture. The gold standard for long-term climate data where gauge records are absent. Python API via cdsapi.
Africa-only rainfall product calibrated specifically for sub-Saharan Africa. Daily data at ~4km from 1983 to present. Developed by University of Reading. Particularly useful for agricultural water management and drought monitoring in West and East Africa.
Climate projections for design
For climate change impact assessment and climate-resilient design:
- CORDEX — Coordinated Regional Climate Downscaling Experiment. RCM outputs at 25–50km for all global domains including Africa (CORDEX-Africa), available via ESGF data nodes.
- IPCC Interactive Atlas — Pre-computed CMIP6 climate change projections visualised by region and scenario. Useful for rapid screening and client communication.
- World Bank Climate Knowledge Portal — Country-level climate data, projections, and risk indices from the World Bank. No login required; good entry point for project-level climate screening.
3. Streamflow and Hydrological Data
German Federal Institute of Hydrology maintains the world's largest archive of river discharge data — over 10,000 stations globally, many with daily records spanning 50+ years. Free for research and non-commercial use after registration.
Copernicus Emergency Management Service. Provides modelled river discharge, flood forecasts, and historical reanalysis for the global river network. GloFAS-ERA5 reanalysis provides a consistent 40-year simulated discharge record. Accessed via Copernicus Climate Data Store.
WWF/USGS global hydrographic dataset derived from SRTM. Provides river network, sub-basin delineations (at multiple scales), and flow accumulation grids. Essential for global and regional hydrological studies. HydroRIVERS includes river attributes for ~8.5 million river segments.
USA-focused but globally valuable reference. Real-time and historical streamflow, groundwater levels, and water quality at ~1.5 million sites. Excellent calibration dataset for hydrological modellers. Fully open API access.
4. Soil and Geological Data
Soil properties control infiltration, runoff generation, and foundation conditions. The following sources cover the main soil datasets used in engineering analysis.
Global 250m gridded predictions of soil properties — texture, bulk density, organic carbon, cation exchange capacity, pH, and more — at 6 standard depths. Machine-learning based, using over 150,000 soil profiles. Freely downloadable via REST API or ISRIC data portal.
FAO-IIASA-ISRIC global soil map at 1km. Provides soil taxonomy, texture class, organic carbon, and drainage class. Version 2.0 released in 2023. Widely used for catchment-scale hydrological modelling parameter estimation and SCS-CN land classification.
Global geology at 1:5,000,000 scale. Provides lithology, age, and structure. Useful for regional hydrogeological assessments, borehole siting, and preliminary site characterisation. Available as shapefile download or WMS.
BGR/UNESCO global groundwater resources map. Identifies major aquifer systems, groundwater recharge zones, and hydrogeological provinces. Useful for preliminary groundwater feasibility assessments and water supply planning at regional scale.
5. Land Use and Land Cover
| Dataset | Resolution | Year(s) | Access | Cost |
|---|---|---|---|---|
| ESA WorldCover | 10m | 2020, 2021 | worldcover2021.esa.int | Free |
| MODIS MCD12Q1 | 500m | 2001–present annual | LP DAAC | Free |
| Copernicus Global Land Service | 100m | 2015–2019 annual | VITO | Free |
| Dynamic World (Google) | 10m | 2015–present (near-real-time) | Earth Engine | Free |
| Global Forest Watch | 30m | 2000–present annual | globalforestwatch.org | Free |
6. Flood Hazard and Infrastructure Data
Satellite-observed flood extents for 913 flood events globally from 2000 to 2018, derived from Landsat and MODIS. Useful for flood frequency analysis calibration and historical impact assessment.
Landsat-based mapping of surface water occurrence, seasonality, and change from 1984 to present at 30m. Identifies permanent water bodies, seasonal flooding zones, and historical water extent. Available in Google Earth Engine.
Crowd-sourced global infrastructure map. Roads, buildings, land use, waterways, and utilities. Quality varies by region but coverage is extensive. Download via Geofabrik or use via Overpass API. JOSM and QGIS plugins available.
High-resolution population distribution at 100m globally, disaggregated by age and sex. Essential for flood risk and dam break inundation consequence assessments. Updated annually. Freely available via WorldPop Hub.
7. Satellite Imagery Platforms
Direct access to satellite imagery is essential for site investigation, land use classification, and change detection.
- USGS Earth Explorer — Access to Landsat archive (1972–present) and SRTM DEM. Best starting point for historical imagery.
- Copernicus Open Access Hub / Dataspace — Sentinel-1 (SAR), Sentinel-2 (multispectral), Sentinel-3, and Sentinel-5P. Free, 5–10 day revisit globally.
- Google Earth Engine — Cloud analysis of the full Landsat and Sentinel archives plus hundreds of other datasets. Free for non-commercial use; Python and JavaScript APIs. Transforms what would take weeks of processing into hours of cloud computation.
- Copernicus Browser — Web-based viewer and download portal for Sentinel imagery with pre-built analysis visualisations (NDVI, false colour, flood mapping, fire detection).
- Planet Education & Research Programme — Free 3–5m daily imagery access for academic researchers and non-profits. Application-based.
8. Engineering Standards and Reference Data
Beyond spatial datasets, engineers need access to standards, reference values, and technical guidance. Several sources provide free access to materials that would otherwise require institutional subscriptions.
- FAO AQUASTAT — Global water resources statistics, country profiles, dam databases, and irrigation area data. Essential reference for water resources planning at national and regional scale.
- ICOLD World Register of Dams — Database of large dams worldwide. Useful for regional hydrological studies and precedent research for dam design parameters.
- USDA-NRCS Engineering Handbooks — National Engineering Handbook (NEH) Parts 630 (Hydrology) and 654 (Stream Restoration). Authoritative free reference for SCS Curve Number, TR-55, and channel design methods.
- WHO Guidelines for Drinking Water Quality — The authoritative global reference for water quality standards and treatment design.
- Open Library / Internet Archive — Freely accessible engineering textbooks (many older editions) including classics like Chow's Open Channel Hydraulics, Linsley's Hydrology for Engineers, and Terzaghi's Soil Mechanics.
A practical tip: before beginning any project desk study, build a data inventory checklist specific to your project type and region. Systematically query each source in this guide before concluding that data is unavailable. In our experience, the answer is almost always "more data exists than the project team initially realised."
Summary Table: Key Free Data Sources at a Glance
| Category | Top Free Source | Key Use Case | Link |
|---|---|---|---|
| DEM / Topography | Copernicus DEM GLO-30 | Catchment delineation, hydraulic modelling | Copernicus |
| Rainfall (historical) | CHIRPS / ERA5 | Design rainfall, water balance | CDS |
| Rainfall (near-real-time) | IMERG (GPM) | Flood monitoring, event analysis | NASA |
| River discharge | GRDC | Flood frequency, calibration | BafG |
| Soil properties | SoilGrids 2.0 | Infiltration, SCS-CN, foundation screening | ISRIC |
| Land use | ESA WorldCover | SCS-CN, runoff coefficients | ESA |
| Satellite imagery | Google Earth Engine | Site investigation, change detection | GEE |
| Flood hazard | JRC Global Surface Water | Flood zone delineation | JRC |
| Infrastructure / Roads | OpenStreetMap | Base mapping, access routes | OSM |
| Population | WorldPop | Flood risk, dam break consequence | WorldPop |
| Climate projections | CORDEX / IPCC Atlas | Climate-resilient design | IPCC |
| Groundwater | GRACE-FO via NASA | Aquifer storage trends | NASA/JPL |
Conclusion: The Informed Engineer in the Data Age
The availability of free, high-quality engineering data has reduced — but not eliminated — the data constraints on infrastructure design in data-scarce regions. The difference between an engineer who produces a thin, assumption-heavy feasibility study and one who delivers a rigorous, data-grounded analysis often comes down to data literacy: knowing what exists, where to find it, how to access it, and critically, how to interpret its limitations.
Every dataset in this guide has limitations. Resolution affects accuracy. Coverage has gaps. Algorithms have biases. Satellite estimates are not the same as gauge measurements. The goal is not to use all of these sources on every project — it is to build the habit of systematic data discovery before resorting to assumptions, and to apply the appropriate critical lens when interpreting the data you find.
Mastering the sources catalogued here, and staying current as new datasets emerge — particularly from the rapidly evolving landscape of commercial smallsat constellations and AI-driven data products — is a meaningful competitive advantage for any civil or water resources engineering practice.