Ephemeral water-harvesting ponds in drylands lose little of their water to evaporation

This record contains the data and code for the study “Ephemeral water-harvesting ponds in drylands lose little of their water to evaporation” (submitted to Nature Water). It provides event water budgets for 42,382 fill-and-drawdown events at 6,814 ponds in nine dryland regions: Oman, Saudi Arabia, the United Arab Emirates, Alwar and Udaipur (India), the Loess Plateau (China), Cyprus, Niger and the US Southern High Plains, from 2017 to 2025. The ponds include small dams, check dams, tanks, wadi pools and natural closed depressions. For each event, the data give: the water held at the peak, from Sentinel-2 water area and area–elevation–volume curves from three global elevation models (Copernicus GLO-30, NASADEM, AW3D30), with USGS 3DEP 1 m lidar for the US playas; the water evaporated until the pond emptied (Penman open-water evaporation from ERA5-Land); the remainder that infiltrated or was withdrawn. Flags identify the main sample used in the paper (11,186 events at 2,110 ponds). The record also includes: pond locations and outlines; floor-elevation percentiles for each pond and elevation model; the tables behind every result and sensitivity test; depth checks against airborne lidar and GEDI spaceborne lidar; the Google Earth Engine and Python code; the paper’s figures.