Dhaka, home to more than 22.4 million residents, delivers a wide spectrum of ecosystem services through its green spaces and water bodies, yet these systems are being converted to built-up land at an accelerating rate. This study maps, monitors, and values those services using primary and secondary data. Primary data came from a field-based observation protocol, transect assessment, a questionnaire survey of visitors and adjacent residents, key informant interviews, and geospatial recording. Secondary data came from published land cover, remote sensing, water quality, and
valuation studies. Surface water fell from 11.82 percent of the city area in 1990 to 5.16 percent in 2021. Water bodies declined by 32.57 percent and lowlands by 52.58 percent between 1960 and 2008, while rivers and canals contracted by 64.55 percent between 1978 and 2009. Built-up land expanded by 188.35 percent between 1990 and 2020, driving a 59.55 percent decline in ecosystem service value, a loss of 85 million US dollars. Residual green and blue spaces still perform critical cooling, air purification, drainage, recharge, and cultural functions, but supply is spatially unequal and
institutionally unprotected.