Bangladesh has a subtropical monsoon driven climate with diverse seasonal variations. These variations are primarily influenced by atmospheric heat-flux, local hydrodynamics, and geomorphological features. The present study describes the seasonal temperature-salinity profile of a tidal river Halda considering two distinct seasons (monsoon and winter). Surface and bottom temperature and salinity varied from 22.1–28.6 °C and 0.4–1.2 psu respectively. Overall temperature variation followed isothermal characteristics in both seasons, while winter was significantly colder than monsoon (p < 0.05). The temperature gradient was almost similar during 2011–12 and 2012–13 but comparatively higher in 2013–14 (0.12 °C/m). Salinity concentration found 3–4 folds higher in winter than monsoon without any strong gradient between surface and bottom. As a typical river estuary, salinity decreased upstream. The Halda mouth was remarkably (p < 0.05) salty than upstream sites with 0.04–0.05 psu throughout monsoon and 0.91–1.0 psu amid winters. Three-year trends of salinity have coincided with sea surface elevation with a positive non-significant correlation. The saltwater intrudes about 6 km upstream with sea surface elevation of 0.12 m from 1993 to 2013. Over the years, the rainfall pattern has also been marked as one of the influential factors controlling the temperature-salinity profile. Moreover, the sequential plotting model described the trend of salinity at the river mouth. This initial study depicts a clear view of seasonal variability and recent saltwater incursion with sea-level rise and possible alterations in local ecology, geomorphology, and coastal processes.

孟加拉国属亚热带季风气候，季节性变化多样。这些变化主要受大气热通量、局部流体动力学和地貌特征的影响。本研究描述了考虑到两个不同季节（季风和冬季）的潮汐河 Halda 的季节性温度 - 盐度分布。地表和底部温度和盐度分别在 22.1–28.6 °C 和 0.4–1.2 psu 之间变化。两个季节的总体温度变化遵循等温特征，而冬季明显比季风冷（p < 0.05)。2011-12 年和 2012-13 年的温度梯度几乎相似，但 2013-14 年的温度梯度相对较高（0.12 °C/m）。冬季盐度浓度比季风高 3-4 倍，表面和底部之间没有任何强梯度。作为典型的河口，上游盐度下降。哈尔达的嘴巴很明显（p < 0.05) 比上游站点咸，整个季风为 0.04–0.05 psu，冬季为 0.91–1.0 psu。三年的盐度趋势与海面海拔高度一致，呈非显着正相关。1993年至2013年，海水侵入上游约6km，海面高程0.12m。多年来，降雨模式也被标记为控制温度-盐度剖面的影响因素之一。此外，序贯绘图模型描述了河口盐度的变化趋势。这项初步研究清楚地描述了季节性变化和近期随着海平面上升以及当地生态、地貌和海岸过程可能发生的变化的咸水入侵。