Purpose <p>The accumulation of high-water-content dredged material poses environmental and disposal challenges. This study aims to evaluate the influence of super absorbent polymer (SAP) on the settling behavior of dredged clay at elevated water contents, and to establish predictive models for settlement characteristics and dewatering efficiency under varying SAP dosages and initial conditions.</p> Methods <p>In this study, three dredged clay samples from distinct sources were prepared at varying initial water contents. Each sample underwent settling tests with SAP dosages of 0%, 0.5%, 1.0%, and 1.5% by weight. Settlement and settling rates were recorded over time to generate sedimentation curves. The end times of the flocculation stage (<i>t</i>_f) and the settling stage (<i>t</i>_s) were identified. A linear regression was applied to relate <i>t</i>_s to SAP dosage and initial water content. Additionally, the variation of settlement and rate with dosage was analyzed, and the slope (<i>λ</i>) of the log–log plot of settling rate versus elapsed time was determined. Post-test water contents were measured to assess dewatering efficiency.</p> Results and discussion <p>SAP-treated slurries exhibited increased settlement values and higher initial settling rates compared to untreated samples. Sedimentation curves demonstrated that <i>t</i>_f remained relatively constant across dosages, while <i>t</i>_s decreased linearly as SAP dosage increased. A predictive equation for <i>t</i>_s was validated under different water contents and dosages. At a fixed initial water content, settlement and settling rate peaked at 1.0% SAP and then declined at higher dosages. Dredged clay with higher initial water content showed greater treatment efficiency. In log–log plots, settling rate decreased linearly with time, characterized by slope <i>λ</i>. A quantitative expression for <i>λ</i> was derived for both untreated and SAP-treated samples. Post-test water content increased with initial water content but was substantially reduced by 1.0% SAP addition.</p> Conclusions <p>The addition of SAP markedly enhances dewatering of high-water-content dredged clay, with 1.0% dosage yielding optimal settlement and rate improvements. Predictive equations for <i>t</i>_s and <i>λ</i> reliably estimate settling behavior across varied initial water contents and dosages. A 1.0% SAP dose also significantly lowers post-test water content, demonstrating its effectiveness for sustainable dredged material management.</p>