Abstract
Dissolved oxygen (DO) is a direct indicator of water pollution and an important water quality parameter that affects aquatic life. Based on the fundamental theorem of surfaces in differential geometry, the present study proposes a new modeling approach to estimate DO concentrations with high accuracy by assessing the spatial correlation and heterogeneity of DO with respect to explanatory variables. Specifically, a regularization penalty term is integrated into the high-accuracy surface modeling (HASM) method by applying geographically weighted regression (GWR) with some covariates. A modified version of HASM, namely HASM_MOD, is illustrated through a case study of Poyang Lake, China, by comparing the results of HASM, a support vector machine (SVM), and cokriging. The results indicate that HASM_MOD yields the best performance, with a mean absolute error (MAE) that is 38%, 45%, and 42% lower than those of HASM, the SVM, and cokriging, respectively, by using the cross-validation method. The introduction of a regularization penalty term by using GWR with respect to covariates can effectively improve the quality of the DO estimates. The results also suggest that HASM_MOD is able to effectively estimate nonlinear and nonstationary time series and outperforms three other methods using cross-validation, with a root-mean-square error (RMSE) of 0.20 mg/L and R2 of 0.93 for the two study sites (Sanshan and Outlet_A stations). The proposed method, HASM_MOD, provides a new way to estimate the DO concentration with high accuracy.
Highlights
As a health indicator for water bodies, the dissolved oxygen (DO) concentration plays important roles in maintaining microbial diversity and various ecosystem and biogeochemical processes in lake ecosystems [1,2,3]
In August, the candidate factors water temperature (WT), Chl-a, atmospheric pressure (AP), and Pre were strongly correlated with DO, and the corresponding
According to the results of Spearman’s rank method among the candidate factors, the explanatory variables related to the DO concentration in July included WT, PH, Chl-a, and Pre, and the most relevant environmental variables for DO in August included WT, Chl-a, AP, and Pre
Summary
As a health indicator for water bodies, the dissolved oxygen (DO) concentration plays important roles in maintaining microbial diversity and various ecosystem and biogeochemical processes in lake ecosystems [1,2,3]. Sufficient levels of DO in water are essential for the survival of various aquatic organisms, such as algae, zooplankton, and aquatic plants. The DO concentration in a healthy water body ranges from 8 to 12 mg/L, and concentrations below 8 mg/L can adversely affect the survival of aquatic species [4,5]. Reliable estimates of DO concentrations enable us to identify future contaminant problems and provide a basis for taking effective countermeasures to prevent water pollution
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have