A rational water quality assessment program directly affects a success of a national socio-economic development strategy. This study was aimed to evaluate and classify surface water quality in Dong Thap province, Vietnam, using set pair analysis (SPA) and national water quality index (WQI_VN) methods. The water quality data was collected at 58 locations in 2019 by the Department of Natural Resources and Environment of Dong Thap province. Sixteen variables including temperature (°C), pH, turbidity (NTU), dissolved oxygen (DO, mg/L), biological oxygen demand (BOD, mg/L), chemical oxygen demand (COD, mg/L), total suspended solids (TSS, mg/L), ammonia (N-NH₄⁺, mg/L), nitrite (N-NO₂⁻), nitrate (N-NO₃⁻, mg/L), total nitrogen (TN, mg/L), orthophosphate (P-PO₄³⁻, mg/L), chloride (Cl⁻, mg/L), sulfate (SO₄²⁻, mg/L), coliform (MPN/100 mL), and Escherichia coli (MPN/100 mL) were monitored four times a year (58 water samples × 16 parameters × 4 monitoring times). The findings presented that TSS, BOD, COD, N-NH₄⁺, N-NO₂⁻, P-PO₄³⁻, coliform, and E. coli were the main constraints on water quality. The results of the entropy weight calculation indicated that deteriorated water quality was in the order of microbiological > nutrients > organic matters. Surface water quality was evaluated at medium (level III) and poor (level IV) by SPA and WQI_VN, respectively; however, the combination of SPA and entropy weight was considered more efficient in this classification and a positive spatial autocorrelation was also found through Moran’s I. The spatial distribution of water quality based on SPA classification revealed that better water quality was found in the inner parts of the study area. Due to its ease and effectiveness, set pair analysis should be considered for inclusion in the water quality assessment program of Vietnam.

合理的水质评估计划直接影响国家社会经济发展战略的成功。这项研究旨在使用集对分析（SPA）和国家水质指数（WQI_VN）方法对越南同塔省的地表水水质进行评估和分类。2019年，同塔省自然资源和环境部收集了58个地点的水质数据。16个变量包括温度（°C），pH，浊度（NTU），溶解氧（DO，mg / L），生物需氧量（BOD，mg / L），化学需氧量（COD，mg / L），总悬浮液固体（TSS，毫克/升），氨（N-NH ₄ ⁺，毫克/升），亚硝酸盐（N-NO ₂ ^- ），硝酸根（N-NO ₃ ^-，毫克/升），总氮（TN，毫克/升），磷酸（P-PO ₄ ^3-，毫克/升），氯（氯^- ，毫克/升），硫酸根（SO ₄ ^2-，毫克/升），大肠菌群（MPN / 100 mL）和大肠杆菌（MPN / 100 mL）一年进行四次监测（58个水样×16个参数×4次监测）。结果呈现该TSS，BOD，COD，N-NH ₄ ⁺，N-NO ₂ ^-，P-PO ₄ ^3-，大肠菌和大肠杆菌是水质的主要制约因素。熵权计算的结果表明，水质恶化的顺序为微生物>营养素>有机质。SPA和WQI_VN分别评估了中级（III级）和劣质（IV级）的地表水水质。然而，SPA和熵权的组合在这种分类中被认为是更有效的，并且通过Moran's I也发现了正的空间自相关。基于SPA分类的水质的空间分布表明，在SPA的内部发现了更好的水质。学习区。由于它的简便性和有效性，应该考虑将对分析纳入越南的水质评估计划中。