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Wetlands are sensitive, easily disturbed, and globally important ecosystems which face lots of threats, such as global climate change and local human activities. Those might result in the degradation of wetlands. The relationship between hydrological connectivity and the degradation of wetlands has gained prominence among researchers as a simple way to quickly evaluate the degradation of wetlands. This metric is responsive to preferential flow, which can, to some extent, indicate hydrological connectivity. To quantify hydrological connectivity at soil column scales, we explored the relationships between soil properties and the strength of preferential flow in samples from a degrading wetland in which Chinese tamarisk (Tamarix chinensis Lour.) grow in the Yellow River Delta. We conducted laboratory solute penetration tests through the undisturbed soil sample columns and analyzed the relationship between the solute penetration test results and preferential flow. We then verified the applicability of the dual-permeability model to predict the results of the solute penetration test. Our results revealed that the discharge rate from the soil columns was the highest in samples from 20 to 40 cm soil depth and that the flow of discharge concentration remained stable for a long time before increasing rapidly, which exhibited rich medium porosity and macroporosity. We associated this with some improvement in hydrological connectivity, which was also consistent with our dual-permeability simulation results. In the future experimental operation, we can preliminarily predict the hydrological connectivity and preferential flow intensity of soil column by using the dual-permeability model with the discharge data of solute penetration test, which can help us know quickly to what extent are wetlands degraded.

Under the condition of rainstorm, the underlying surface is an important factor of erosion and sediment yield, and an important embodiment of the process of soil erosion and the law of sediment deposition. This paper analyzes the soil erosion of warping dams with different underlying surface characteristics based on the data of typical warping dams, such as sedimentation amount, sediment retention modulus and underlying surface. The results show that: (1) the average slope of dam55, dam97 and dam011 is 27.55°, 30.79° and 34.68° respectively, and the erosion modulus is 11020t/km2, 15204 t/km2 and 22579 t/km2 respectively; the average slope of dam55, dam97 and dam011 is positively correlated with the erosion modulus, and the correlation coefficient is 0.9889. (2) The sedimentation depth and erosion modulus of dam011 are significantly higher than those of dam55 and dam97. Under the condition of rainstorm, the average slope of watershed is an important factor of soil erosion, which can better reflect and predict the comprehensive intensity of soil erosion.

It is the premise and foundation of the study on the laws of sediment transport and deposition to deeply analyze the sedimentary characteristics of warping dams in different siltation states under rainstorm conditions. Taking Chabagou basin as the research area, based on the sediment deposition information of different types of warping dams in the basin, linear regression and correlation analysis were used to analyze the characteristics of dam deposition under different silting conditions in Chabagou basin. The results show that: (1) The maximum sediment depth and average sediment depth of warping dams under different sediment conditions are as follows: blocking dam > waterlogging dam > intact dam > full dam; (2) The sediment depth of warping dams under different sediment conditions has an exponential negative correlation with the ratio of dam field to dam-controlled watershed area, and the correlation coefficient of blocking dam is best(0.7267); (3) Warping dams average modulus of intercepting sediment with different siltation types is as follows: blocking dam 14274 t/km2, intact dam 12480 t/km2, waterlogging dam 11725 t/km2, full dam 3350 t/km2.

In order to provide useful and effective reference indicators for wetland protection and restoration, we are trying to understand the role of hydrological processes in wetlands with hydrological connectivity. To quantify hydrological connectivity at soil-profile scale with the soil-profile indexes, dye-tracing field tests were conducted in Yellow River Delta to determine the size and distribution of soil pores, as well as the trail of waterflow. After data analyses, the results showed: (1) where preferential pathways were rich, that is, where hydrological connectivity was strong, the dye coverage was larger (the dye coverage of CLa1 was 0.20 ± 0.08, when CLa2 was 0.22 ± 0.05 and CLa3 was 0.13 ± 0.02), and the dye coverage of preferential pathway was larger (the dye coverage of preferential pathway of CLa1 was 0.16 ± 0.07, when CLa2 was 0.19 ± 0.04 and CLa3 was 0.11 ± 0.02). (2) hydrological connectivity weakens non-linearly from about 30 cm deep. (3) hydrological barrier in soil made dye coverage increase at 10–20 cm deep and it would weaken the vertical hydrological connectivity and strengthen the horizontal hydrological connectivity by preventing the flow from infiltrating further down.

Forest-sediment relationship is a hot and important issue in Ecohydrology studies. China has implemented many large-scale reforestation programmes in the last decades to address the growing soil erosion and desertification. In this study, we made statistical and graphic analyses on the long-term hydrological data of the 39 watersheds in the rocky mountain area of the North China, and then we were able to analyze the effect of forest on sediment yield. Our results show that the effect is weak in the lees-precipitation regions (when MAP < 500 mm). And in the more-precipitation regions(when MAP >500 mm), the impact of forest on reducing sediment yield is different with the varied forest coverage (f), the relationship between the sediment yield and forest coverage show a quadratic polynomial.