Coastal Reclamation Area Research Articles

Assessment of Blue Carbon Storage Loss in Coastal Wetlands under Rapid Reclamation

Highly productive coastal wetlands play an essential role in storing blue carbon as one of their ecosystem services, but they are increasingly jeopardized by intensive reclamation activities to facilitate rapid population growth and urbanization. Coastal reclamation causes the destruction and severe degradation of wetland ecosystems, which may affect their abilities to store blue carbon. To assist with international accords on blue carbon, we evaluated the dynamics of blue carbon storage in coastal wetlands under coastal reclamation in China. By integrating carbon density data collected from field measurement experiments and from the literature, an InVEST model, Carbon Storage and Sequestration was used to estimate carbon storage across the reclamation area between 1990 and 2015. The result is the first map capable of informing about blue carbon storage in coastal reclamation areas on a national scale. We found that more than 380,000 hectares of coastal wetlands were affected by reclamation, which resulted in the release of ca. 20.7 Tg of blue carbon. The carbon loss from natural wetlands to artificial wetlands accounted for 72.5% of total carbon loss, which highlights the major task in managing coastal sustainability. In addition, the top 20% of coastal wetlands in carbon storage loss covered 4.2% of the total reclamation area, which can be applied as critical information for coastal redline planning. We conclude that the release of blue carbon due to the conversion of natural wetlands exceeded the total carbon emission from energy consumption within the reclamation area. Implementing the Redline policy could guide the management of coastal areas resulting in greater resiliency regarding carbon emission and sustained ecosystem services.

Efficiency Assessment of Existing Pumping/Hydraulic Network Systems to Mitigate Flooding in Low-Lying Coastal Regions under Different Scenarios of Sea Level Rise: The Mazzocchio Area Study Case

Rising of the sea level and/or heavy rainfall intensification significantly enhance the risk of flooding in low-lying coastal reclamation areas. Therefore, there is a necessity to assess whether channel hydraulic networks and pumping systems are still efficient and reliable in managing risks of flooding in such areas in the future. This study addresses these issues for the pumping system of the Mazzocchio area, which is the most depressed area within the Pontina plain, a large reclamation region in the south of Lazio (Italy). For this area, in order to assess climate change impact, a novel methodological approach is proposed, based on the development of a simulation–optimization model, which combines a multiobjective evolutionary algorithm and a hydraulic model. For assigned extreme rainfall events and sea levels, the model calculates sets of Pareto optimal solutions which are obtained by defining two optimality criteria: (a) to minimize the flooding surface in the considered area; (b) to minimize the pumping power necessary to mitigate the flooding. The application shows that the carrying capacity of the hydraulic network downstream of the pumping system is insufficient to cope with future sea level rise and intensification of rainfall.

Response of Soil Enzyme Activities and Their Relationships with Physicochemical Properties to Different Aged Coastal Reclamation Areas, Eastern China

Land reclamation transforms a tidal flat from a marine ecosystem to terrestrial ecosystem, which significantly changes the soil ecosystem process, affecting the soil enzyme activities. Soil enzyme is involved in almost all soil biochemical processes. Clarifying the relationship between soil physicochemical properties and soil enzyme activities can reveal the changes of soil quality after reclamation and provide a theoretical basis for the scientific regulation of the soil ecosystem. In this study, a total of 72 soil samples were collected from a coastal reclamation area with different years of reclamation (0, 7, 32, 40, and 63 a) in Rudong County. The changes in soil physicochemical properties and enzyme activities within different reclamation years were analyzed by classical statistical analysis, and the relationship between soil enzyme activities and physicochemical properties was analyzed using a redundancy analysis. The results showed that longterm land reclamation had significant effects on soil physicochemical properties and enzyme activities. pH and electrical conductivity showed a decreasing trend after reclamation, while the content of soil organic carbon, total nitrogen, and total phosphorus showed a trend of "rapidly accumulate-gradually consume-accumulate again" with increasing years of reclamation. Compared with the bare flat area (0 a), amylase, dehydrogenase, and acid phosphatase activity initially increased and then decreased with increasing years of reclamation, while urease and alkaline phosphatase activities were characterized by an increase-decrease-increase trend. Meanwhile, the enzyme activities within different reclamation ages were basically higher in surface soil than deep layers. Redundancy analysis revealed that the soil physicochemical properties explained 69.8% of the variation in soil enzyme activities, and an obvious relationship existed between pH, electronic conductivity, soil organic carbon, total nitrogen, total phosphorus, and soil enzyme activities (P<0.01). The order of importance of soil physicochemical properties to soil enzyme activities was as follows:total nitrogen > soil organic carbon > pH > total phosphorus > electronic conductivity.

Identifying the Main Factors Contributing to the Spatial Variability of Soil Saline–Sodic Properties in a Reclaimed Coastal Area

Core Ideas A spatial model was used for identifying the main factors affecting spatial variability of soil salt. Land‐use pattern was the most influential factor that affected spatial variation of soil salt. The generalized least squares model was suitable for soil salt content in Transect 2. This study is helpful for agronomic management practices in coastal reclamation areas. Studies on changes in soil saline–sodic characteristics have important reference value for reclamation planning and agricultural utilization of coastal regions. The objective of this study was to investigate the spatial distribution of the soil salt content (SSC) and sodium adsorption ratio (SAR) in two transects, which extended through different reclamation areas along a reclaimed coastal area of China. A total of 54 sampling points along Transect 1 were collected to study soil saline–sodic characteristics of a recently reclaimed farmland in 2007, and 50 sampling points were collected along Transect 2 that ran through six farmland areas reclaimed at different times (2007, 1981, 1960, 1950, 1940, and 1916). A spatial model, generalized least squares (GLS), was used to conduct multiple regression equations on SSC or SAR and explanatory variables. The results showed that land‐use pattern was the most influential factor that affected spatial variation of SSC and SAR. The parametric Levene's test and Moran's I test showed that heterogeneity and autocorrelated residuals could only be found for SSC in Transect 2, so the GLS model was suitable for SSC in Transect 2. The GLS method did not perform better than the nonspatial model (ordinary least squares) by incorporating exhaustive ancillary variables but was more suitable when autocorrelation and heteroscedasticity existed in the errors of a model. Using these methods, we obtained information on the spatial variation of soil saline–sodic characteristics and its controlling factors. This information is helpful for land‐use planning, soil partition management, and agronomic management practices in coastal reclamation areas.

MODEL REKLAMASI PANTAI SECARA BERKELANJUTAN KASUS : PANTAI KOTA MAKASSAR

Coastal urban phenomenon in the form of high population growth, rapid economic development and inadequate control of the sea, resulting in the use of the sea and coastal regions become more intensive in the last few years. This development led to the expansion of the city was further intensified by the coastal reclamation. Reclamation has been performed in many cities of the world and also in Indonesia, but many constraints. Research on model of sustainable Reclamation is still rare. The purpose of this paper is to formulate a model that could be applied on a coastal reclamation area using an index of sustainability. This research began with literature study of previous researches of developing sustainability index that not focusing yet on coastal reclamation area with the analytic hierarchy process (AHP) and expert choices. Reclamation sustainability index is used to as a tool to develop a sustainable reclamation model. This model will help project of reclamation activities and its relationship with suitable measures to manage the implementation of a sustainable reclamation. Formulation of the model is done by analysis of Structural Equatian Model (SEM) on the Makassar coastal zone and then tested the feasibility to found the appropriate reclamation model.

Response of soil physicochemical properties and enzyme activities to long-term reclamation of coastal saline soil, Eastern China

Soil enzyme activity during different years of reclamation and land use patterns could indicate changes in soil quality. The objective of this research is to explore the dynamics of 5 soil enzyme activities (dehydrogenase, amylase, urease, acid phosphatase and alkaline phosphatase) involved in C, N, and P cycling and their responses to changes in soil physicochemical properties resulting from long-term reclamation of coastal saline soil. Soil samples from a total of 55 sites were collected from a coastal reclamation area with different years of reclamation (0, 7, 32, 40, 63a) in this study. The results showed that both long-term reclamation and land use patterns have significant effects on soil physicochemical properties and enzyme activities. Compared with the bare flat, soil water content, soil bulk density, pH and electrical conductivity showed a decreasing trend after reclamation, whereas soil organic carbon, total nitrogen and total phosphorus tended to increase. Dehydrogenase, amylase and acid phosphatase activities initially increased and then decreased with increasing years of reclamation, whereas urease and alkaline phosphatase activities were characterized by an increase-decrease-increase trend. Moreover, urease, acid phosphatase and alkaline phosphatase activities exhibited significant differences between coastal saline soil with 63years of reclamation and bare flat, whereas dehydrogenase and amylase activities remained unchanged. Aquaculture ponds showed higher soil water content, pH and EC but lower soil organic carbon, total nitrogen and total phosphorus than rapeseed, broad bean and wheat fields. Rapeseed, broad bean and wheat fields displayed higher urease and alkaline phosphatase activities and lower dehydrogenase, amylase and acid phosphatase activities compared with aquaculture ponds. Redundancy analysis revealed that the soil physicochemical properties explained 74.5% of the variation in soil enzyme activities and that an obvious relationship existed between soil nutrients and soil enzyme activities. These results will assist governmental evaluation of the quality of reclaimed coastal soil.

Hierarchical Bayesian models for predicting soil salinity and sodicity characteristics in a coastal reclamation region

Knowledge of soil saline-alkaline distributions and salt migration mechanism is important when developing strategies that reduce soil salinity, improve soil fertility, and enhance soil management in coastal reclamation regions. Soil saline-alkaline characteristics are indicated by the soil salt content (SSC) and sodium adsorption ratio (SAR). However, direct measurements of these parameters are typically expensive, labor intensive and time consuming. Data that is more easily obtained for a property and that may already exist, such as soil organic matter (SOM), may be used to predict SSC and SAR if SOM contents are closely related to soil sodicity and salinity. Data collected in a coastal reclamation area in Rudong County, Jiangsu Province, China, was used to generate regression equations for the relationships between SSC and SOM and between SAR and SOM based on hierarchical Bayesian methods. Results showed that SSC and SAR both decreased with increases in SOM. The deviance information criterion (DIC) indicated that a modified power function model and a log-quadratic model could best describe the two relationships, respectively. Therefore, predicting SSC could be achieved from the relationship between ln[SSC] and a quadratic function of ln[SOM], while SAR used the relationship between ln[SAR] and a quadratic function of SOM. This further suggests that increasing SOM may enhance reductions in soil salinity and sodicity, which would improve soil structure and fertility in the study region and probably at other coastal reclamation sites.

Deformation Monitoring and Analysis of the Geological Environment of Pudong International Airport with Persistent Scatterer SAR Interferometry

Many coastal cities have undertaken reclamation projects to satisfy the land demands of rapid urbanization. However, the foundations of reclaimed land are susceptible to settlement and can have undesirable environmental impacts that could adversely affect these dense, populated areas. In the case of international airports built on reclaimed areas especially, regional-scale deformation must be monitored to ensure operational security for public safety. Persistent Scatterer SAR Interferometry (PSI) technology has proven to be an effective tool to detect ground deformation in urban areas. However, it is still a challenge to apply PSI to effectively monitor settlement at airports built on newly developed coastal reclamation areas because of the scarcity of identifiable targets. Moreover, additional issues arise as the complicated deformation patterns associated with the underlying geological conditions make it difficult to interpret InSAR-derived results. In this study, a time-series analysis of a high-resolution TerraSAR-X satellite image stack acquired from September 2011 to October 2012 was performed by employing a modified PSI technique to retrieve the mean deformation velocity and time series of surface deformation at Pudong International Airport. Qualitative evaluation of spatial distribution and temporal evolution of deformation was conducted by joint analyses of deformation measurements and local geological data. Detailed analysis of various driving forces for deformation patterns confirmed that the results of deformation monitoring obtained by PSI are reliable and consistent with that of local geological surveys. Since the factors responsible for the subsidence within the airport are still at play, ongoing and routine deformation monitoring is warranted.

Ecological Security and Ecosystem Services in Response to Land Use Change in the Coastal Area of Jiangsu, China

Urbanization, and the resulting land use/cover change, is a primary cause of the degradation of coastal wetland ecosystems. Reclamation projects are seen as a way to strike a balance between socioeconomic development and maintenance of coastal ecosystems. Our aim was to understand the ecological changes to Jiangsu’s coastal wetland resulting from land use change since 1977 by using remote sensing and spatial analyses. The results indicate that: (1) The area of artificial land use expanded while natural land use was reduced, which emphasized an increase in production-orientated land uses at the expense of ecologically important wetlands; (2) It took 34 years for landscape ecological security and 39 years for ecosystem services to regain equilibrium. The coastal reclamation area would recover ecological equilibrium only after a minimum of 30 years; (3) The total ecosystem service value decreased significantly from $2.98 billion per year to $2.31 billion per year from 1977 to 2014. Food production was the only one ecosystem service function that consistently increased, mainly because of government policy; (4) The relationship between landscape ecological security and ecosystem services is complicated, mainly because of the scale effect of landscape ecology. Spatial analysis of changing gravity centers showed that landscape ecological security and ecosystem service quality became better in the north than the south over the study period.

Hydrological responses on saline-sodic soil slopes in a coastal reclamation area of China

Evaluation of the effects of slope gradient and rainfall intensity on the hydrological responses on slopes can provide important information for soil and water conservation. We conducted simulated rainfall experiments to study the hydrological response of a saline-sodic soil on slopes with different gradients (6°, 11°, 22°, and 35°) and rainfall intensities (85, 95, 110, and 125mmh−1). Higher effective rainfall intensities significantly reduced the times to ponding and runoff. While the infiltration coefficient did not always increase with increasing slope gradient, it consistently increased with increasing rainfall intensity on slopes of 6°, 11°, or 22°. The mean flow velocities and stream power values tended to increase with increasing slope gradient but did not change consistently with changes in rainfall intensity. Hydraulic shear stress and its logarithm could predict sediment losses that were <20kgm−1h−1. However, stream power and its logarithm were better predictors of a wider range of sediment losses from slopes with saline-sodic soil. These results suggest that existing hydrological and erosion models should be adjusted to take into account the effects of salinity and sodicity.

Spatial scaling of soil salinity indices along a temporal coastal reclamation area transect in China using wavelet analysis

ABSTRACTHigh spatial variability of soil salinity in coastal reclamation regions makes it difficult to obtain accurate scale-dependent information. The objectives of this study were to describe the spatial patterns of saline-sodic soil properties (using soil pH, electrical conductivity (EC1:5) and sodium ion content (SIC) as indicators) and to gain knowledge of the scaling relationships between those variables. The soil pH, EC1:5 and SIC data were measured at intervals of 285 m along a 13,965-m temporal transect in a coastal region of China. The spatial variability of soil pH was weak but it was strong for soil EC1:5 and SIC at the measurement scale. There was a significant positive correlation between soil EC1:5 and SIC, while correlations between soil pH and either EC1:5 or SIC were weak and negative. For each saline-sodic soil parameter, the variability changed with the decomposition scales. The high-variance area at the larger scales (≥570 m) occupied less than 10% of the total area in the local wavelet spectrum, which meant that the spatial variations of the salinity indicators were insignificant at these scales. For local wavelet coherency, at a scale of 1500–2800 m and a sampling distance of 0–4500 m, the covariance was statistically significant between any two of the saline-sodic soil parameters.

Local Authority Empowerment towards Quality Living Environment for Coastal Reclamation Area

Good urban governance administration system is the key to a successful physical planning development. A local authority of a local government concentrates on planning administration and executes the policies and strategies either the federal or state, or even the local’s policies and strategies. Based on its characteristic as the lowest level of government, it becomes the best authority to regulate and monitor the development process within their territory. The significance of a local authority in providing quality living environment invites various academia and professionals to ponder the best urban governance system at a local level. However, there are issues with regards to financial and technical capacity of a local authority, its legal limitation and development instrument adopted in providing urban services for coastal reclamation area in Malaysia. The aim of this paper is to investigate the capability of local authorities in Malaysia in implementing their function as drawn by the legislation. Hence, this paper examines the roles and functions of a local authority as the lowest level of government administration agency in providing urban services; collecting revenue; safeguarding the physical environment in Malaysia, particularly when dealing with development in a coastal reclamation area. Primary data collection was gathered through face-to-face interview sessions involving government agencies and stakeholders. Legal documents, policies and development plans were then analysed to support the primary data for further understanding of the issues concerning the capacity of a local authority especially when providing urban services within its area. The study is expected to provide a new approach to local authorities in Malaysia in providing quality living environment in terms of development procedure, the role and function, legal empowerment, and decentralisation of function particularly in enhancing the current practices at local level.

Review on the Significance of Local Plan for Coastal Reclamation Development: The Case of Malacca, Malaysia

A Development Plan acts as a planning and controlling instrument that helps to guide in decision making of current and future development. Therefore, in the Malaysian Town and Country Planning Act 1976 (Act 172), the provision of development plan from each level of the planning administration is stated in the Act under Section 6B till Section 16B. In examining the significance of one of the many development plans in Malaysia, i.e. the local plan, this paper therefore, focuses on the provision of a local plan by the Local Planning Authority (LPA) of the said area. This paper, thus, aims to evaluate the Central Malacca Local Plan since Malacca is currently experiencing rapid growth in development along the coastal area. The primary data was obtained from interviews with the related planning authorities via face-to-face method. While, secondary data was gathered from related legal documents, policies and guidelines, as well as the existing development plan for the purpose of an in-depth data. Findings revealed incapability of the existing local plan to assist the development control in deciding the planning permission for reclaimed area. The existing local plan shows no zoning for coastal reclamation area because of the rapid growing development and time consuming procedure to amend the local plan according to the Act 172. In addition, the Act 172 and the process in amending the local plan should be more flexible and able to address the current issue efficiently. Finally, the paper concludes with a suggestion for further exploration in order to achieve an operative development process and functioning practice of the local plan.

Spatial and temporal variations of soil organic carbon and total nitrogen pools in the coastal reclamation area, eastern China

The spatial and temporal variation of soil organic carbon (SOC) and soil total nitrogen (STN) in a coastal reclamation area in eastern China were studied based on the ordinary kriging method. The 0–20 cm soil organic carbon pool (SOCP) and soil total nitrogen pool (STNP) ranged from 4.38 to 15.92 Mg/ha and from 0.24 to 2.37 Mg/ha, respectively, during the observed period. The results show there was a low level of spatial variation in both SOC and STN, which is to some extent the result of the same farmland management practiced in this region. The seasonal variation of SOC was attributed to plant growth and crop residue returning back to soil, while the spatial variation was mainly resulted from the fertilization practice. The average 0–20 cm SOCP and STNP were 10.38 ± 2.50 and 1.27 ± 0.38 Mg/ha, respectively, in the study region, both of which were much lower than in other ecosystems. Further analysis indicated that SOC was positively correlated with STN. This work revealed that the reclamation area from the tidal flat should be a potential sink for SOC and STN.

Analysis of Jiangsu tidal flats reclamation from 1974 to 2012 using remote sensing

Jiangsu has the most abundant tidal flat resources among China’s coastal provinces. To ease the conflict between the growing population and shrinking usable land and to promote regional sustainable development, large-scale coastal reclamation development activities have been performed in Jiangsu Province since 1949. The present study has integrated multi-source remote sensing images during 1974 to 2012 by using a Multi-point Fast Marching Method (MFMM) to extract the Jiangsu coastal reclamation areas for different time periods. The temporal and spatial patterns of the extent and elevation of the reclamation areas were analysed in order to determine the unused potential for future reclamation. It will provide information necessary to support the development and construction of tidal flats in Jiangsu. Results show that: (1) the reclaimed tidal flats along the Jiangsu coast cover more than 19.86×104 hm2, of which 13.97×104 hm2 is located in Yancheng, 4.84×104 hm2 in Nantong, and 1.05×104 hm2 in Lianyungang; (2) the average elevation of the reclaimed Jiangsu tidal flats has gradually decreased over the last 40 years, while those in Dongtai and Rudong have showed particularly accelerated decrease since the 1990s; and (3) in 2012, very few unused tidal flats two meters above the sea level are left along the Jiangsu coast, and mainly concentrated in Yancheng. As there are still reserving some coastal land resources between 0–2 m, providing us with a potential for future development. All of these findings may be useful for researchers and local authorities for the development and utilization of tidal flat resources in Jiangsu.

Numerical Analysis of the Soil Deformation Caused by Tunneling under Vehicle Loads in the Coastal Reclamation Area

Prediction of tunneling induced soil deformation is an important issue in the design of tunnels constructed in the densely populated urban areas. In this paper, commercial FEM software 3D ABAQUS is adopted to simulate the behavior of soil caused by tunneling under vehicle loads in the coastal reclamation area. A field case study was also carried out to verify the accuracy of the proposed model. A good agreement was achieved. It is also found from the studies that the areas affected by soil deformation can be classified into four zones: the key disturbed zone, the secondary disturbed zone, the general disturbed zone, and minor-disturbed zone. The maximum soil deformation occurs on side of the longitudinal medial axis of the tunnel. The shape of the settlement curve is almost the same as that of the normal distribution curve. The soil deformation in the action zone of vehicle load is greater than that of the nonaction zone of vehicle load.

Dynamic Compaction of Ultra-High Energy in Combination with Ground Replacement in Coastal Reclamation Areas

This paper presents a case study of dynamic compaction (DC) on backfill ground for planned oil tanks located at Nanjing Bay. The ultra-high energy DC level of 18,000 kN · m was applied in the area tamping phase of the dynamic compaction. In combination with ground replacement technique by forcing crushed stones into the underlain cohesive layer, the high-compressibility of this layer was properly tackled. The construction techniques and ground improvement mechanisms are introduced and discussed. Field evaluations before and after the dynamic compaction, including surface wave test, plate load test, and soil sampling, showed that the ultra-high energy dynamic compaction in combination with ground replacement achieved much greater improvement depth and ground bearing capacity than conventional DC. Results show that dynamic compaction of 18,000 kN · m combined with ground replacement is of great merit in dealing with backfill ground with weak cohesive content in harbor development.

Spatial Variation of Soil Salinity in the Coastal Reclamation Area, Eastern China

ABSTRACT Xu, Y.; Pu, L.; Zhu, M.; Li, J.; Zhang, M.; Li, P., and Zhang, J., 2014. Spatial variation of soil salinity in the coastal reclamation area, eastern China. Reclamation of coastal saline tidal flats has become a common practice for coastal countries faced with a decrease in cultivated land and an increase in population. Because the variability of soil salinity is considerable, understanding the spatial distribution of this salinity and its components is essential for land use planning. This study was conducted in a coastal area in eastern China that has been reclaimed under various land use types at different times. The objective of the work was to assess the effect of the reclamation time and land use types on soil salinity and spatial variation of soil salinity by using conventional statistics and geostatistical techniques. The results indicate that reclamation times and land use types significantly influence soil salinity in coastal areas. Cropland and aquaculture pond have same effect on soil ...

Micro Layout Research of Reclamation Area Based on Plane Grid Topology Formation

The micro-layout research of the reclamation area involves many other areas and disciplines, occupies an important position in the coastal economic study. On the base of geometry theory, this paper puts the micro-layout of the reclamation area under the economic analysis within the formation of two-dimensional plane of the grid point topology. Here we take the Heishijiao coastal areas of Dalian as the example for micro layout of the reclamation area research within the two-dimensional plane variable framework, which is calculated by the Ising lattice model. For the better macroeconomic development in the area as the objective function, the maximum economic value will determine the optimal layout. The results show that, in coastal reclamation area it should not be paid too much notation to the width of the extension in the sea, and more reclamation area should be gathered to the city's prosperity zone reflected in the overall layout of layering.

Determining minimum data set for soil quality assessment of typical salt-affected farmland in the coastal reclamation area

The need for understanding and assessing soil quality is getting increasingly important because of growing public interest in determining the effect of management practices on the sustainability of the soil resource base. Our objectives were to investigate the effect of consecutive cultivation and different rotation systems on potential soil quality indicators, to identify effective soil quality indicators and to establish a minimum data set that discriminate different rotation systems. This study was conducted in a typical coastal salt-affected farmland in north Jiangsu Province, China. A pool of 22 measured variables representing soil chemical and physical properties (0–10cm) and groundwater features at 60 sampling sites and 10 representative soil profiles were used. A specific emphasis was given to the impact of crop rotation systems on measured soil and groundwater properties because of the importance of cultivation to the sustainability of soil quality. One-way analysis of variance (ANOVA) showed that measured variables of SOM, SOCD, TN, AP, CEC, AK, ECe, Na and Cl were positively impacted by cultivation. In contrast to cotton–barley rotation, rice–rape rotation had significantly positive influence on SOM and SOCD, but adverse impact on AK, pH, ρb, Ks, WTg and ECg. Factor analysis grouped all measured variables into seven principal components explaining 78.5% of total variance: salinity (PC1), organic matter (PC2), water permeability (PC3), soil texture (PC4), ion exchange (PC5), soil alkalinity (PC6) and available nutrients (PC7). Discriminant analysis indicated that PC1 (Cl, Na and ECg), PC2 (SOM and SOCD) and PC7 (WTg) were the most powerful factors (indicators) to distinguish the two rotation systems. SOCD (SOM) and Cl offered the greatest potential for monitoring soil quality under different management practices. SOM not only had the strongest positive influence on crop biomass, but also contributed the greatest to distinguishing the effect of rotation systems on soil quality. Our study suggested that SOM may be considered as an indispensable factor to determine the sustainability of soil productivity for the salt-affected farmlands in coastal reclamation area.