Catchments, flow routing, floods and surface water from DEMs and satellite imagery.
Build Voronoi (Thiessen) polygons in Python with shapely and GeoPandas, clipped to a real boundary. Compute Thiessen-weighted catchment rainfall for the River Eden from Environment Agency rain gauge readings, check the gauges, compare with the gauge average and IDW, then compare Voronoi 'nearest fire station' areas in Cumbria with drive-time service areas from OpenStreetMap.
Compute height above nearest drainage (HAND) from the Environment Agency LIDAR DTM at 5 m with pysheds, turn it into inundation extents for a range of stage heights on the River Severn between Shrewsbury and Buildwas, relate them to the Buildwas gauge, and score them honestly against the Environment Agency Flood Map for Planning with the hit rate, false-alarm ratio and critical success index.
Delineate a catchment and its stream network from a free DEM in Python with pysheds: fill pits and depressions, D8 flow direction, flow accumulation, snapping the pour point, catchment polygon and area, Strahler stream order and drainage density, all checked against the official NRFA boundary for the River Derwent at Yorkshire Bridge in the Peak District.
Track chlorophyll, turbidity and peat colour proxies in four Peak District reservoirs with free Sentinel-2 imagery: cloud and water masking for small, dark upland lakes, NDCI and NDTI time series from 2019 to 2026, anomaly ranking, maps, tidy CSVs and an honest check against Environment Agency samples.
Map the 2022 Sindh floods with free Sentinel-1 radar from the Microsoft Planetary Computer: convert backscatter to decibels, remove speckle with a Lee filter, pick a water threshold with Otsu's method, and measure the flood extent and how it receded over seven months.
Search seven summers of Sentinel-2 imagery with pystac-client, stream only the bands you need from Cloud Optimised GeoTIFFs, mask clouds, compute NDWI and MNDWI and measure how much of Lake Mead dried up between 2019 and 2025.
A look at the dramatic fall in Lake Mead's water level during the 2022 drought.