The frequent occurrence of drought–flood abrupt alternation (DFAA) in Huaibei Plain has shown a great impact on local rice production. Pot experiments were performed in 2016–2018 to investigate the effects of co-occurring drought and flooding stresses on dry weight (DW), grain yield, nitrogen (N), phosphorus (P) and potassium (K) uptake and use efficiencies (NUE, PUE and KUE) in rice. The results showed that DFAA changed the accumulation of biomass and nutrients among different organs in rice. Compared with control, DFAA significantly reduced the grain yield (−29.8%) and root DW (−30.0%), but increased the DW in stem and leaf (10.2% and 9.7%). The root/shoot ratio and morphological size of the root system in DFAA-treated plants was smaller than those of drought alone and flooding alone. Under DFAA stresses, the specific absorption rate of N, P and K increased significantly (47.9%, 31.8% and 32.8%, respectively), while NUE, PUE and KUE decreased significantly (−27.9%, −10.8% and −19.7%, respectively). The decrease of nutrient use efficiencies was mainly due to the redundant growth of branches and leaves, and the key factor limiting grain yield under DFAA conditions was the effective utilization of N. Compared with the earlier drought, the subsequent flooding might have more influence on rice growth, nutrient utilization and yield formation, but the interaction of the two weakened the cumulative effect of drought and flooding. These findings provide a scientific basis for establishing a nutrient and water management system of rice cultivation under transient soil moisture conditions.

Cooperative and self-enforceable water allocation is a key instrument to manage geopolitical conflict induced by water scarcity, which necessitates the cooperative willingness of the agents and considers their heterogeneity in geography, climate, hydrology, environment and social economy. Based on a multi-indicator system that contains asymmetric information on water volume contribution, current water consumption, water economic efficiency and efforts for eco-environmental protection, this study proposed a water allocation framework by combining the asymmetric power index approach with bankruptcy theory for solving the transboundary water allocation problem under scarcity. The proposed method was applied to the Yellow River Basin in northern China, which is mainly shared by nine provincial districts and frequently suffers from severe water shortages, and its results were compared with six alternative methods. The results highlight the necessity of quantifying agents’ willingness to cooperate under the condition of asymmetric negotiation power when making decisions on transboundary water allocations. The proposed method allows for transboundary water allocations through simultaneous consideration of the agent’s willingness to cooperate and asymmetric negotiation power, as well as disagreement allocation points, which ensure the stability, fairness and self-enforceability of allocation results. Therefore, it can offer practical and valuable decision-making insights for transboundary water management under water scarcity.

The development of an accurate root water-uptake model is pivotal for evaluating crop evapotranspiration; understanding the combined effect of drought and waterlogging stresses; and optimizing water use efficiency, namely, crop yield [kg/ha] per unit of ET [mm]. Existing models often lack quantitative approaches to depicting crop root water uptake in scenarios of concurrent drought and waterlogging moisture stresses. Addressing this as our objective; we modified the Feddes root water-uptake model by revising the soil water potential response threshold and by introducing a novel method to calculate root water-uptake rates under simultaneous drought and waterlogging stresses. Then, we incorporated a water stress lag effect coefficient, $\phi \left(W_s\right)$, that investigated the combined effect of historical drought and waterlogging stress events based on the assumption that the normalized influence weight of each past stress event decreases with an increase in the time interval before simulation as an exponential function of the decay rate. Further, we tested the model parameters and validated the results obtained with the modified model using data from three years (2016–2018) of rice (Oryza sativa, L) trails with pots in Bengbu, China. The modified Feddes model significantly improved precision by 9.6% on average when calculating relative transpiration rates, particularly post-stress recovery, and by 5.8% on average when simulating soil moisture fluctuations during drought periods. The root mean square error of relative transpiration was reduced by 60.8%, and soil water was reduced by 55.1%. By accounting for both the accumulated impact of past moisture stress and current moisture conditions in rice fields, the modified model will be useful in quantifying rice transpiration and rice water use efficiency in drought–waterlogging-prone areas in southern China.

Managing trans-jurisdictional water scarcity conflicts is a thorny task, as it is usually challenged by multiple institutionally independent decision-making agents, which requires developing cooperative and self-enforcing solutions. This study proposed a decision-making method that combines fairness and stability concerns to solve trans-jurisdictional water allocation conflicts under scarcity. Based on the water allocation alternatives yielded by seven bankruptcy rules, the Gini coefficient and Shapley–Shubik power index were used to separately quantify their fairness and stability criteria from distributive justice and individual-level acceptability, and then game theory was employed to integrate the quantitative results of the two criteria to make final water allocation decisions. The decision-making method was applied to the Hanjiang River Basin of Hubei Province in China under two water scarcity scenarios, which is shared by ten city-level jurisdictions. Numerical results indicate that bankruptcy rules are considered practical for performing trans-jurisdictional water allocations under scarcity, but their realistic eligibility should be investigated before implementation. An apparent trade-off between fairness and stability exists among the water allocation alternatives, and there exists room for identifying compromise alternatives; the constrained equal losses and adjusted proportional rules are identified as the preferred rule by the proposed decision-making method for allocating water resources in the Hanjiang River Basin of Hubei Province, respectively, in dry and extremely dry years. The findings highlight the necessity and significance of balancing fairness and stability criteria in managing trans-jurisdictional water scarcity conflicts, and the proposed method has proved to be an effective decision-making tool to facilitate negotiation over trans-jurisdictional water allocations under scarcity.