Search

Predicting flood event classes aids in the comprehensive investigation of flood behavior dynamics and supports flood early warning and emergency plan development. Existing studies have mainly focused on historical flood event classification and the prediction of flood hydrographs or certain metrics (e.g., magnitude and timing) but have not focused on predicting flood event classes. Our study proposes a new approach for predicting flood event classes based on the class membership functions of flood regime metrics and hydrological modeling. The approach is validated using 1446 unimpacted flood events in 68 headstream catchments widely distributed across China. The new approach performs well, with class hit rates of 68.3% ± 0.4% for all events; 65.8% ± 0.6%, 56.8% ± 0.9%, and 69.5% ± 0.9% for the small, moderate and high spike flood event classes, respectively; and 82.5% ± 1.2% and 75.4% ± 1.1% for the moderate and high dumpy flood event classes, respectively. Furthermore, it performs better in the basins of northern China than in those of southern China, particularly for the small spike flood event class in the Songliao and Yellow River Basins, with hit rates of 80.0% ± 3.2% and 78.8% ± 3.2%, respectively. Our results indicate that the new approach will help improve the prediction performance of flood events and their corresponding classes, and provide deep insights into the comprehensive dynamic patterns of flood events for early warning and control management. Plain Language Summary: The prediction of flood event classes is more effective and informative than that of individual events for obtaining comprehensive dynamic characteristics of flood events for early warning and development of emergency plans. However, this is challenging owing to massive flood events with remarkable spatiotemporal heterogeneity and unclear class membership functions. We propose a class prediction approach for flood events using the class membership functions of flood behavior metrics based on frequency analysis and catchment hydrological modeling. This approach deeply mines the behavior characteristics of historical flood events with a strong mathematical basis and cooperates with hydrological models to predict flood classes. Over thousand unimpacted flood events in 68 headstream catchments across China were selected to validate the robustness of the prediction scheme. Our results show that the proposed approach well predicts the flood class with class hit rates of 68.3% ± 0.4% for all events; 65.8% ± 0.6%, 56.8% ± 0.9%, and 69.5% ± 0.9% for the small, moderate and high spike flood event classes, respectively; and 82.5% ± 1.2% and 75.4% ± 1.1% for the moderate and high dumpy flood event classes, respectively. Our study has strong implications for scientific flood warning research and flood mitigation management. Key Points: A prediction approach for flood event classes is developed using class membership functions of flood regime metrics with hydrological modelClass membership degree is estimated using the frequency distribution function, which fits well with statistical significanceAverage class hit rates are 68.3% ± 0.4% for all the events and predictions of dumpy flood class are better than those of spike flood classes [ABSTRACT FROM AUTHOR]

Classification is beneficial for understanding flood variabilities and their formation mechanisms from massive flood event samples for both flood scientific research and management purposes. Our study investigates spatial and temporal variabilities of 1446 unregulated flood events in 68 headstream catchments in China at class scale using hierarchical and partitional clustering methods. Control mechanisms of meteorological and physio-geographical factors (e.g., meteorology, land cover and catchment attributes) are explored for individual flood event classes using constrained rank analysis and Monte Carlo permutation test. Results show that we identify five robust flood event classes, i.e., moderately, highly, and slightly fast floods, as well as moderately and highly slow floods, which accounts for 24.0 %, 21.2 %, 25.9 %, 13.5 % and 15.4 % of total events, respectively. All the classes are evenly distributed in the whole period, but the spatial distributions are quite distinct. The fast flood classes are mainly in the southern China, and the slow flood classes are mainly in the northern China and the transition region between southern and northern China. The meteorological category plays a dominant role in flood event variabilities, followed by catchment attributes and land covers. Precipitation factors, such as volume and intensity, and aridity index are the significant control factors. Our study provides insights into flood event variabilities and aids in flood prediction and control. [ABSTRACT FROM AUTHOR]

The soil water dynamic process is critical for the design, management, and evaluation of ridge-furrow tillage in the semi-arid region of the Loess Plateau. The aim of this study was to determine the effectual infiltration variables, to evaluate the performance of four classical infiltration models, and to investigate the effect of those variables on the infiltration characteristics in a ridge-furrow configuration. Sixteen experimental treatments with two replications were conducted to monitor furrow infiltration in four types of Loess Plateau soils. The path analysis method was applied to quantify the effects of variables--opportunity time (T), initial soil water content (Q), bulk density (P), flow section area (S), and wetted perimeter (Wp) as independent variables--on cumulative infiltration (I). The results revealed that the direct effects of variables Wp, P, T, Q, and S on I were 0.751, -0.649, 0.291, -0.251, and-0.123, respectively. Variables Wp and P were the effectual components of furrow infiltration. The direct effect and total effect of Q on I were relatively minor compared with the other variables. The performance of four infiltration models (Philip model, Kostiakov-Lewis model, Kostiakov model, and Horton model) was investigated on the basis of evaluation indices. The Kostiakov Lewis infiltration model with three parameters provided the best description of the relationship between cumulative infiltration and time. The influence of Wp on the constant coefficient k of the Kostiakov Lewis model was significant. A furrow infiltration model taking Wp into consideration was developed. Validations in different Wp of two other soil types indicated that the soil water infiltration characteristics could be effectively simulated by the effectual variable based model for an uncropped ridge-furrow system. The information obtained from this research is useful in designing irrigation schemes and field management for ridge furrow tillage. Additional keywords: furrow infiltration, infiltration model, path analysis, ridge-furrow configuration., Introduction Ridge furrow tillage with supplemental irrigation can effectively improve soil moisture storage and agricultural water-use efficiency in the semi-arid region of the Loess Plateau, where a shortage of water [...]