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. Click any card to open the resource directly.
⚠️ Note on link validity: The web addresses in this article were verified at time of publication (April 2026). Data portals and agency websites occasionally restructure their URLs or migrate to new platforms. If a link does not resolve, search for the dataset name directly — the data almost certainly still exists at an updated address.
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.
SRTM — Shuttle Radar Topography Mission
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.
Visit →Copernicus DEM (GLO-30 / GLO-90)
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.
Visit →FABDEM — Forest And Buildings Removed DEM
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.
Visit →ALOS World 3D (AW3D30)
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.
Visit →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.
CHIRPS — Climate Hazards Group InfraRed Precipitation with Stations
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.
Visit →IMERG — Integrated Multi-satellitE Retrievals for GPM
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.
Visit →ERA5 — ECMWF Reanalysis v5
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.
Visit →TAMSAT — Tropical Applications of Meteorology using SATellite data
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.
Visit →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 CORDEX-Africa. Provides scenario-based projections (SSP1–SSP5) downscaled to regional scale. Accessed via ESGF data nodes. Essential for climate-resilient infrastructure design across Africa.
Visit →IPCC AR6 Interactive Atlas
Pre-computed CMIP6 climate change projections visualised by region and scenario. Displays changes in temperature, precipitation, and extremes for all global regions under SSP1-1.9 through SSP5-8.5. Useful for rapid screening and client communication.
Visit →World Bank Climate Knowledge Portal
Country-level climate data, projections, and risk indices. Covers historical climate statistics, future projections, and climate risk profiles. No login required; a strong entry point for project-level climate screening and feasibility documentation.
Visit →3. Streamflow and Hydrological Data
GRDC — Global Runoff Data Centre
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.
Visit →GloFAS — Global Flood Awareness System
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.
Visit →HydroSHEDS / HydroBASINS
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.
Visit →USGS National Water Information System
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 and benchmark reference for method validation. Fully open API access.
Visit →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.
SoilGrids 2.0 — ISRIC World Soil Information
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.
Visit →HWSD — Harmonized World Soil Database v2.0
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.
Visit →USGS Global Geological Map
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 service.
Visit →WHYMAP — World-wide Hydrogeological Mapping and Assessment
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.
Visit →5. Land Use and Land Cover
Land cover data is essential for SCS Curve Number assignments, runoff coefficient estimation, environmental impact assessments, and change detection studies.
ESA WorldCover
Global land cover at 10m resolution for 2020 and 2021, produced from Sentinel-1 and Sentinel-2 data. 11 classes including trees, cropland, built-up, water, and bare ground. Currently the highest-resolution freely available global land cover product.
Visit →MODIS MCD12Q1 — Annual Land Cover
Annual global land cover at 500m from 2001 to present, derived from MODIS satellite data. Multiple classification schemes available (IGBP, UMD). Long time series makes it valuable for deforestation analysis and multi-year hydrological studies. Access via LP DAAC or AppEEARS.
Visit →Copernicus Global Land Service
Annual land cover at 100m from 2015–2019, plus biophysical variables (NDVI, LAI, FAPAR) at 300m. Produced from PROBA-V and Sentinel data. Freely available via the VITO viewer and Copernicus Land Service portal.
Visit →Dynamic World — Google / WRI
Near-real-time global land cover at 10m, updated continuously from Sentinel-2 imagery since 2015. Probability-based output for 9 classes. Particularly useful for project sites undergoing active land use change. Access via Google Earth Engine.
Visit →Global Forest Watch — WRI
Annual tree cover, deforestation, and forest gain data at 30m from 2000 to present, derived from Landsat by Hansen et al. (UMD). Includes fire alerts and plantation layers. Critical for environmental impact assessments in forested catchments.
Visit →6. Flood Hazard and Infrastructure Data
Global Flood Database — Cloud to Street
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 flood impact assessment.
Visit →JRC Global Surface Water Explorer
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 and as direct download.
Visit →OpenStreetMap (OSM)
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.
Visit →WorldPop — Population and Demographics
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.
Visit →7. Satellite Imagery Platforms
Direct access to satellite imagery is essential for site investigation, land use classification, and change detection.
USGS Earth Explorer
The primary portal for the full Landsat archive (1972–present) plus SRTM DEM, ASTER, and aerial photography. Best starting point for historical imagery analysis. Account registration required for download; browsing is open.
Visit →Copernicus Data Space Ecosystem
ESA's unified portal for Sentinel-1 (SAR), Sentinel-2 (multispectral), Sentinel-3, and Sentinel-5P data. Free global coverage with 5–10 day revisit. Replaces the legacy scihub.copernicus.eu. Includes a JupyterLab environment for cloud processing.
Visit →Google Earth Engine
Cloud analysis platform providing access to the full Landsat and Sentinel archives plus hundreds of other datasets. Free for non-commercial use via Python and JavaScript APIs. Transforms weeks of local processing into hours of cloud computation.
Visit →Copernicus Browser
Web-based viewer and download portal for Sentinel imagery with pre-built analysis visualisations — NDVI, false colour, flood mapping, and fire detection. No coding required. Suitable for quick visual assessment and small-area downloads during site investigations.
Visit →Planet Education & Research Programme
Free access to 3–5m daily imagery from Planet's smallsat constellation for academic researchers and registered non-profits. Application-based approval required. Exceptional temporal resolution for monitoring construction, flooding, and land cover change.
Visit →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 from the UN Food and Agriculture Organization. Essential reference for water resources planning at national and regional scale. Includes basin-level water balance data for major river systems.
Visit →ICOLD — World Register of Dams
International Commission on Large Dams database of over 60,000 large dams worldwide. Covers dam height, reservoir capacity, purpose, and design parameters. Valuable for regional hydrological studies and precedent research for dam design parameter estimation.
Visit →USDA-NRCS National Engineering Handbook
Authoritative free reference for hydrological and hydraulic design methods. NEH Part 630 (Hydrology) covers SCS Curve Number and TR-55. Part 654 covers stream channel stability and restoration design. Downloadable chapter by chapter at no cost.
Visit →WHO Guidelines for Drinking Water Quality
The authoritative global reference for water quality standards and treatment design, published by the World Health Organization. Covers chemical, microbiological, and radiological parameters. The fourth edition is freely downloadable as PDF.
Visit →Open Library / Internet Archive
Freely accessible engineering textbooks including older editions of classics: Chow's Open Channel Hydraulics, Linsley's Hydrology for Engineers, and Terzaghi's Soil Mechanics. Also hosts scanned versions of older Nigerian and African engineering standards.
Visit →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.