The Sanjiang Plain stands as a pivotal grain-producing region in China. Faced with population growth and the imperative of ensuring food security, the rapid expansion of agricultural land in the Sanjiang Plain has led to escalating ecological and water-environmental challenges, hindering the sustainable development of regional agriculture. This research aims to explore and propose practical measures for utilizing agricultural drainage resources to address the ecological and water-environmental issues resulting from agricultural expansion in the Sanjiang Plain, striving to achieve harmonious and sustainable economic and environmental growth. The discussion revolves around the potential alleviation of water quality, water quantity, and ecological health issues in the Sanjiang Plain through the proposed approach. Considering regional characteristics, the focus is on potential environmental drawbacks resulting from the improper application of the method. Building on these findings, effective strategies are presented to enhance the systematic operation of agricultural drainage resource utilization in the region. In conclusion, addressing ecological and water-environmental challenges stemming from local agricultural development is imperative for the Sanjiang Plain to realize sustainable development for the economy and the environment.

As one of the artificial recharge technologies, the soil–aquifer treatment (SAT) system is used for the removal of nitrogen pollution from aquaculture wastewater. An adsorption-enhanced SAT system was designed to reduce the level of nitrogen pollution below the threshold stipulated by the standards. Adsorption kinetics experiments were used to measure the adsorption capacity of zeolite and activated carbon for ammonia nitrogen. Both adsorbents can be well described by the Lagergren pseudo-second-order model, and the adsorption rates of zeolite and activated carbon for ammonia nitrogen were 72.16% and 31.40%, respectively. Combining the experimental data and the actual situation, the medium-packing method was determined and the influence of wastewater characteristics and hydrodynamic conditions on the adsorption and retention capacity of the SAT system were considered. Finally, the feasibility of the adsorption-enhanced SAT site design scheme was verified by Hydrus-1D model simulation. The study found that the design scheme for the situation in the study area was feasible; however, the surrounding underground environment still had a risk of pollution during the operation of the site. Therefore, further research is needed for the nitrogen pollution to be completely removed within the scope of the SAT site.

The strategic reuse of agricultural drainage water presents a viable solution to address the growing disparity between water supply and demand in irrigated regions, with Soil Aquifer Treatment (SAT) systems demonstrating significant potential for water quality enhancement. However, the operational efficacy of SAT during drainage water recharge may be compromised by two principal factors stemming from compositional complexity: system clogging risks associated with improper management protocols or potential groundwater contamination through pollutant migration pathways. Through controlled laboratory experiments and systematic data analysis, this study revealed solute transport mechanisms in SAT simulated soil columns. Complementary HYDRUS-1D modeling further quantified the impacts of soil texture gradations and initial infiltration salinity on recharge system performance and subsurface environmental safety. The experimental results demonstrate that: (1) Media with fine-coarse particle gradation exhibited peak solute retention efficiency, and showed positive correlation with infiltration salinity. (2) Optimal gradation configuration requires salinity threshold control ≤ 1.3 g/L.

Existing assessments of geothermal water extraction suitability in sedimentary basins are often limited by subjective indicator selection, insufficient consideration of inter-indicator relationships, and weak adaptability to low- to medium-temperature geothermal systems. Taking Lindian County, a representative geothermal field in the northern Songnen Plain, as a case study, this work develops a process-based assessment framework integrating spatial zoning, key-factor identification, indicator quantification, and weighted evaluation. The study area was divided into 16 sub-regions using dominant-factor zoning and GIS-based overlay analysis. Five core driving indicators were then identified from 20 candidate indicators using DEMATEL, and their weights were determined using AHP after passing the consistency test. A four-level scoring scheme was established, and the linear weighted-sum method was used to generate quantitative suitability scores and spatial zoning maps. The results indicate that Lindian County has generally favorable conditions for geothermal water extraction, although clear spatial heterogeneity exists among the sub-regions. Overall, 87.5% of the sub-regions were classified as having good or relatively good suitability. WAI and WDI were identified as the optimal zones, whereas KAII and BEII showed relatively poor suitability. The spatial pattern supports the interpretation that geological structure controls both reservoir development and geothermal fluid occurrence, with hydrochemical properties and reservoir water-richness acting as secondary controlling factors. The proposed framework improves the transparency of indicator selection and provides a practical basis for zoning-based geothermal water extraction planning in similar sedimentary basins.

Due to the combined effects of many factors, flood disasters are becoming increasingly serious worldwide, resulting in increasingly frequent river floods. This situation has severely disrupted the ecological balance near riverbanks and has had a great negative impact on the normal production and life of residents. Therefore, certain solutions must be adopted to solve the problem of river floods. This study takes the section of the Erlongtao River in Heilongjiang Province, China, as the research object, presents detailed statistics on the occurrence of floods in this section in recent years, and conducts an in-depth investigation and research on the current status of various flood control projects. In view of the existing problems of the project and the root causes of floods, a comprehensive analysis of the necessity of governance is carried out, and corresponding governance countermeasures and scientific and reasonable design schemes are proposed to improve basic flood control construction and provide a reference case for flood control governance of rivers with the same type of flood control problems in the future.

The vadose zone is an important yet frequently understudied environment where bio‐clogging occurs during managed aquifer recharge. Understanding the synergistic effects of key hydrodynamic factors—water content ( θ ) and flow velocity (V)—on biofilm development and permeability reduction is essential for predicting and mitigating clogging. This study uses an effective microorganisms (EM) consortium to elucidate bio‐clogging mechanisms under variably saturated flow. Static batch experiments revealed that carbon source availability and temperature positively regulate EM growth and extracellular polymeric substance (EPS) secretion. Soil column experiments demonstrated that unsaturated conditions were found to promote higher microbial activity and organic accumulation compared to saturated groups, inducing more significant permeability decay. While high flow rates enhanced bacterial migration (84.3% breakthrough in saturated columns), unsaturated conditions effectively suppressed microbial mobility. The synergistic pore occlusion by EPS and bacterial cells was identified as the primary clogging mechanism. Permeability evolution exhibited distinct triphasic characteristics: a rapid initial decline, a mid‐term stabilization, and a long‐term dynamic equilibrium at approximately 4.3% of the initial conductivity. This quantitative threshold provides a core reference for clogging risk early warning, segmented hydrodynamic regulation strategy formulation, and operation cycle optimization of soil aquifer treatment (SAT) systems for agricultural drainage recharge in the Sanjiang Plain and similar rice‐growing areas. This study reveals a stratified clogging mechanism—bacteria‐dominated near the surface and EPS‐dominated in deeper layers—governed by θ ‐V synergism. Our findings offer a reference framework for optimizing the operation of recharge systems and developing targeted anti‐clogging strategies in the vadose zone.