Search Results (5)

Wetlands play a crucial role in water purification, climate regulation, and biodiversity conservation. However, the Xianghai wetlands (situated in Tongyu County, Jilin Province, China) have experienced severe ecological degradation due to natural factors and unsustainable human activities, leading to declining groundwater levels and intensified salinity issues. To address these problems, this study aims to optimize ecological water replenishment strategies for the Xianghai nature reserve by integrating groundwater numerical simulation, surrogate modeling (convolutional neural network–long short-term memory neural network, CNN-LSTM), and intelligent optimization algorithms (Particle Swarm Optimization, PSO). During the design of the water replenishment scheme, the objective function maximizes the replenishment volume while considering the secondary salinization of soil in the reserve and its surrounding areas as a constraint. The results show that the surrogate model established using the convolutional neural network–long short-term memory neural network achieved high accuracy, with R² values of 0.9996 and 0.9962 and MREs of 0.0023 and 0.0089 for training and validation sets, respectively; Compared to the random replenishment scheme, the optimized water replenishment scheme significantly reduces secondary salinization. After 10 years water replenishment, the optimized scheme exhibited a 2 km² reduction in the salinized area compared to the randomized scheme, with the degree of salinization being reduced from moderate to mild. This method improves ecological sustainability and can be adapted to meet local water use demands. This simulation-optimization method provides an effective approach for designing water replenishment schemes that address secondary salinization. Full article

Drought is a major natural disaster that causes a reduction in rain-fed maize yield. Agricultural drought risk assessment is conducive to improving regional disaster management ability, thereby reducing food security risks and economic losses. Considering the complexity of risk assessment research, an increasing number of researchers are focusing on the multiple-criteria decision-making (MCDM) method. However, the applicability of the MCDM method to agro-meteorological disaster risk assessments is not clear. Therefore, this study comprehensively evaluated hazard, exposure, vulnerability, and emergency response and recovery capability using the TOPSIS and VIKOR models to generate a maize drought risk map in mid-western Jilin Province and ranked the drought risk of each county. The results showed that: (1) maize drought risk in the middle and west of Jilin province showed an increasing trend. Spatially, the risk diminished from west to east. The drought risks faced by Tongyu, Changchun, and Dehui were more severe; (2) the evaluation results of the two models were verified using the yield reduction rate. The VIKOR model was found to be more suitable for agrometeorological drought risk assessments; (3) according to the damage degree of drought disaster to maize, the cluster analysis method was used to divide the study area into three sub-regions: safe, moderate drought, and severe drought. Combined with the characteristics of different regions, suggestions on disaster prevention and mitigation are proposed. The results of this study can provide a basis for formulating strategies to alleviate drought, reduce losses, and ensure the sustainable development of agriculture. Full article

Land, nature, and the social environment in contiguous poor regions are harsh and difficult to change. The poor adaptive capacities of the socio-ecological systems of these regions are the main causes of deep, persistent poverty. In February 2016, the Chinese government issued a policy proposing to promote poverty alleviation by relocation (PAR) by means of the “Linking increases in urban construction land with decreases in rural construction land” policy (or simply, the “Link Policy” or LP), which intends to realize the sustainable social and economic development of local villages. Since then, many pilot projects have been carried out across the country based on local resources, environment, and economic development; however, few related studies on these cases have been conducted. After a review of poverty alleviation policies, this paper first introduces the unsustainable conditions of poor rural areas and the implications and advantages of PAR under the Link Policy; we then analyzed the complete PAR process, including formulation, implementation, and completion, by taking Tongyu County in Jilin Province as an example. The study found that the “whole village relocation” model practiced in Tongyu County was relatively successful in terms of improving the living environment, income, and public services of local villagers. On the other hand, there were three main problems: first, many follow-up industries were dominated by the village collectives and heavily dependent on government support or subsidies; second, the newly built village faced the dilemma of “re-hollowing” due to the out-migration of young people and the aging population; third, it was difficult to achieve a true requisition–compensation balance of farmland. Full article

General declines in ecosystem service values (ESV) are acknowledged worldwide; however, rather few studies have quantitatively analyzed the interrelationship between changing rural settlements and values of ecosystem services. This study used the county of Tongyu in West Jilin Province, China, as a case study to analyze how changing rural settlements impact the values of ecosystem services on surrounding land in the eco-fragile areas during 1997–2010. Quantitative analytical techniques mainly include the buffer analysis and an ecosystem services valuation. The results show that as the area of rural settlements increased in 1997–2010, the structure of land ecosystems had changed significantly during this time period, causing a change in ESV that was observed with a decline by 1.87 billion yuan and above 20%. The degradation of grasslands, wetlands, and water areas, as well as the farmland reclamation, were the main drivers of the decreases in ESV. The effects of the increased rural settlements on the distribution and variation of ESV were larger than the decreased rural settlements, especially the new rural settlements whose effect was largest, and the effect of changing rural settlements on the values of ecosystem services on the surrounding land was significant in proximity to these settlements. In conclusion, the effects of rural settlement evolution on the natural environment were obvious in the eco-fragile areas. Thus the encroachment of rural settlements still requires enhanced supervision in land management practices, and the scale and spatial distribution of rural settlements should be befittingly allocated in the eco-fragile areas to reduce the disturbance to the ecosystem. Full article

This paper introduces a surrogate model to identify an optimal exploitation scheme, while the western Jilin province was selected as the study area. A numerical simulation model of groundwater flow was established first, and four exploitation wells were set in the Tongyu county and Qian Gorlos county respectively so as to supply water to Daan county. Second, the Latin Hypercube Sampling (LHS) method was used to collect data in the feasible region for input variables. A surrogate model of the numerical simulation model of groundwater flow was developed using the regression kriging method. An optimization model was established to search an optimal groundwater exploitation scheme using the minimum average drawdown of groundwater table and the minimum cost of groundwater exploitation as multi-objective functions. Finally, the surrogate model was invoked by the optimization model in the process of solving the optimization problem. Results show that the relative error and root mean square error of the groundwater table drawdown between the simulation model and the surrogate model for 10 validation samples are both lower than 5%, which is a high approximation accuracy. The contrast between the surrogate-based simulation optimization model and the conventional simulation optimization model for solving the same optimization problem, shows the former only needs 5.5 hours, and the latter needs 25 days. The above results indicate that the surrogate model developed in this study could not only considerably reduce the computational burden of the simulation optimization process, but also maintain high computational accuracy. This can thus provide an effective method for identifying an optimal groundwater exploitation scheme quickly and accurately. Full article