[This dataset is embargoed until January 4, 2027]. This dataset contains water quality data across rivers and ponds in the Vietnamese Mekong River Delta (MRD), Vietnamese Red River Delta (RRD) and Bangladeshi and Indian Ganges Brahmaputra Meghna (GBM) Delta. The main objective of this work was to establish a baseline database for water quality, covering a wide range of water quality parameters to address emerging environmental concerns, such as anti-microbial resistance for the Bangladeshi Ganges Brahmaputra Meghna Delta. The available data are separated by delta, and are listed below. Bangladeshi GBM Three datasets are available: river water quality, pond water quality, and phytoplankton biomonitoring. One river water quality dataset is available, containing point measurements from February 2022 to February 2024 at 11 pre-selected locations of four rivers in the coastal areas of the Bangladeshi GBM. Each of the 4 rivers were sampled 5 times over different seasons. Daily measurements (during each of the 5 sampling periods) include 6-7 samples per site (from morning until 19.00). Two separate pond water quality datasets are available: (1) The first ponds dataset contains point measurements of 40 ponds in September 2023 and March 2024. Available data and information include the site location and context - including user and use information (occupation, water source, etc.), physical properties (surface area, depth, etc.), context (region, adjacent buildings, urban setting), and treatment regimes. Available water chemistry data include temperature, pH, total suspended solids, total phosphorus, soluble reactive phosphorus, phosphate, ammonium, nitrate, silia, Δ13c, particulate organic carbon, total dissolved nitrogen, C:N, chloride, sulphate, sodium, potassium, calcium, magnesium, dissolved oxygen, SPC, alkalinity, rugged dissolved oxygen, electrical conductivity, turbidity, total coliforms, E. Coli, algal pigments, and sediment chemistry. Additionally, pond depth water chemistry profiles - including water body stratification depths and pycnoclines - are available for 39/40 ponds in September 2023. (2) The second ponds dataset contains point measurements of 20 ponds and groundwater tubewells from Gabura, Satkhira and South Bedkashi, Khulna from February 2022 to February 2024. Tubewells were sampled 5 times (once per day) during the same sampling period as the river water quality dataset. Parameters here include water quality variables (pH, conductivity, turbidity), microbial indicators, and selected emerging contaminants. One phytoplankton biomonitoring dataset is available for 8 pond and stream sites from February-March 2022. Each sampling site has a variable number of diatom species. Measurements include concentration (number per ml), biovolume and mean cell biovolume. Indian GBM Three datasets are available: river water quality, pond water quality, and phytoplankton biomonitoring. One river water quality monitoring dataset seasonal water quality measurements collected from multiple sampling stations across the Indian Sundarbans region. The dataset includes physicochemical, biological, and bacteriological parameters, measured under high tide and low tide conditions across nine seasonal campaigns (2021-2024). The data support environmental monitoring, estuarine studies, and biogeochemical assessments. One pond water quality dataset includes point measurements from 29 ponds in the Indian GBM in three sampling periods: July 2024, December 2023 and March 2024. Data include details of the site location, context (i.e. region), user and use information, water chemistry (salinity, temperature, pH, total alkalinity, oxidation-reduction potential, dissolved oxygen, secchi depth, total dissolved solids, total phosphorus, phosphate anions, soluble reactive phosphorus, nitrate anions, total Kjedahl nitrogen, ammoniacal nitrogen, silicate, total suspended solids, conductivity, absolute conductivity, chloride anions, sodium cations, potassium cations, calcium cations, magnesium cations, sulphate anions, dissolved silica, Chl A, Chl B, Chl C, total Chl, carotenoid, total coliform and E Coli. One phytoplankton biomonitoring dataset is available for 20 sites in 3 time periods - both low and high tide for December 2021, July 2022, and March 2023. Data include concentration and biovolumes, concentrations per 1 mL, concentrations per 10 mL, biovolume per 1 mL, and biovolume per 10 mL for 48 diatom species. RRD Three datasets are available for the Vietnamese Red River Delta: two river surface water quality datasets, and one surface pond water quality datasets. The first dataset contains monthly water chemistry data in the RRD from March 2018 to February 2022. The data include pH, TDS, Ca2+, Mg2+, Na+, K+, HCO3-, SiO2, Cl-, and SO42-. Data collected at five stations namely Yen Bai, Vu Quang, Hoa Binh, Gian Khau, and Quyet Chien. The Red River Delta is both a densely populated region and an area of intensive agricultural activity, implying significant potential for pollution. To provide a comprehensive assessment of water quality across the delta and evaluate the impacts of different human activities, we conducted monthly sampling at 22 sites throughout the region. These sites are strategically located across diverse land-use types and at the confluences of major rivers-including the Red, Day, and Nhue rivers-and their tributaries, enabling us to trace potential sources of pollution within the area. Within the second dataset, the following data are available: - Stable isotopes (July 2019-March 2024) - Organic content - dissolved organic carbon, dissolved inorganic carbon & particulate organic carbon (July 2019-March 2024) - Physiochemistry - temperature, dissolved oxygen, salinity, oxidation reduction potential, pH, turbidity, conductivity, total dissolved solid and total suspended solids (July 2019-March 2024) - Major ions (Na, Mg, K, Ca, Cl, SO4, B; July 2019-March 2024) - Nutrients (NO3-N, NO2-N, NH4-N, total nitrogen, soluble reactive phosphorus, TSP, total phosphorus, SIO2 & alkalinity; July 2019-March 2024) - Water discharge (01-01-2014 to 31-12-2023) - Quantitative phytoplankton for (1) the Red River (December 2019-March 2024) and (2) the Day River (July 2019-March 2024). Lastly, one dataset containing water and sediment chemistry of 37 ponds in March 2023 is available. This includes pond user and use information, and water and sediment quality parameters for 37 sampling locations in 36 ponds in the Red River Delta taken in March 2023. The data include details of the site location, pond physical properties (i.e. age, surface area, depth), context (i.e. region, adjacent buildings, urban setting), use information (i.e. agricultural, water source), treatment regimes, water chemistry (i.e. Temp, pH, Secchi depth, Total Suspended Solids, Total Phosphorus, Soluble Reactive Phosphorus, Total Nitrogen, Nitrite, Nitrate, Ammonium, Nitrate δ15N/ δ18O, Aquatic Si, Δ13C, Particulate Organic Carbon, Dissolved Organic Carbon, Total Dissolved Nitrogen, C:N, Chloride anions, Sulphate anion, dissolved oxygen, SPC), algal pigments, and sediment chemistry. MRD Two datasets are available for the Vietnamese Mekong River Delta. The first includes water quality monitoring of surface water in October 2021 in three provinces: Ca Mau, Soc Trang and Kien Giang. Parameters include physiochemical and microbiological water quality measurements, including Ammonium (NH4+), BOD5, COD, Chloride (Cl-), DO, E. coli, Nitrate (NO3-), Nitrite (NO2-), pH, Phosphate (PO43-), Temperature (°C), Total Coliform, Total Iron (Fe), TSS, Turbidity (NTU). The total number of sampling sites is 126 across Soc Trang (N = 35), Kien Giang (N = 49) and Ca Mau (N = 42). The second dataset includes further surface water quality monitoring and water quality index metric in Soc Trang and Ca Mau provinces. Cà Mau includes data from 52 stations (NM-01 to NM-52) sampled during dry and wet seasons (coded as Season 1 and Season 2) from 2015 to 2020. Sóc Trăng includes data from 21 stations (coded M1 to M21) sampled annually from 2014 to 2018. The stations cover diverse water environments including freshwater and brackish water systems. Parameters measured include field parameters (pH, temperature, dissolved oxygen, electrical conductivity), organic pollution indicators (BOD5, COD), nutrients (N-NH4, P-PO4), solids (TSS, Turbidity), metals (Fe, Hg, As, Cu etc.), anions (Cl-, SO4-), salinity, total coliform, and petroleum hydrocarbons. A Water Quality Index (WQI) derived from an Artificial Neural Network (ANN), is also calculated for most samples. Full details about this dataset can be found at https://doi.org/10.5285/f311f69d-ecd2-4505-9882-e59d9b56852d
