Environmental flow (e-flow) assessment is essential for the ecological protection and restoration of lake-marsh systems. Previous studies on e-flow assessment for lake-marsh systems focused on lake-marsh systems with natural seasonal hydrological patterns (i.e., low water level in winter and high water level in summer). However, they have not considered lake-marsh systems with reverse seasonal hydrological patterns (i.e., high water level in winter and low water level in summer). The reverse seasonal hydrological patterns impose seriously negative impacts on waterbirds, because the hydrological patterns could lead to limited plant germination in spring and massive plant death in summer, leaving few plants available as food for waterbirds in winter, and could consequently reduce the sheltering and forageable areas for waterbirds. This study took Hongze Lake Wetland National Nature Reserve in China as the study area. Based on the habitat requirements of waterbirds, the sheltering and forageable areas for waterbirds under different water-depth and aquatic plant distribution scenarios were calculated. By exploring the impacts of reverse seasonal hydrological processes on waterbird habitats, we determined the necessary e-flows for lake-marsh systems with reverse seasonal hydrological patterns to meet the needs of waterbird habitat. The results showed that the water level of Hongze Lake should be controlled to 13.0–13.1 m in March, 12.5–12.6 m in July, and 12.9–13.0 m in October, which can meet the needs of waterbirds for both shelter and foraging. 相似文献
The Paleogene upper Xiaganchaigou Formation (E32) is the most important source rock and reservoir in the Qaidam Basin. However, there are few studies on the processes of hydrocarbon accumulation in this formation; therefore, its hydrocarbon resource potential has not been estimated reasonably. This paper evaluates the hydrocarbon generation properties in light of an improved hydrocarbon generation and expulsion potential model. According to the geochemical characteristics of source rocks and the petrological features of reservoirs, the potentials of different resource types, including conventional oil, tight oil and shale oil, are quantified by combining the buoyancy-driven hydrocarbon accumulation depth (BHAD) and the lower limit for movable resource abundance. The results show that the source rocks are characterized by a large thickness (more than 1000 m), moderate organic matter content, high marginal maturity and a high conversion rate (50% hydrocarbons have been discharged before Ro?=?1%), which provide sufficient oil sources for reservoir formation. Moreover, the reservoirs in the Qaidam Basin consist mainly of low-porosity and low-permeability tight carbonates (porosity of 4.7% and permeability less than 1 mD). The maximum hydrocarbon generation, expulsion, retention and movable retention intensities at present are 350?×?104 t/km2, 250?×?104 t/km2, 130?×?104 t/km2 and 125?×?104 t/km2, respectively. The thresholds of hydrocarbon generation, expulsion and BHAD were 0.46% Ro, 0.67% Ro and 0.7% Ro, respectively. Moreover, the dynamic evolution process of hydrocarbon accumulation was divided into three evolution stages, namely, (a) initial hydrocarbon accumulation, (b) conventional hydrocarbon reservoir and shale oil accumulation and (c) unconventional tight oil accumulation. The conventional oil, tight oil and movable shale oil resource potentials were 10.44?×?108 t, 51.9?×?108 t and 390?×?108 t, respectively. This study demonstrates the good resource prospects of E32 in the Qaidam Basin. A comprehensive workflow for unconventional petroleum resource potential evaluation is provided, and it has certain reference significance for other petroliferous basins, especially those in the early unconventional hydrocarbon exploration stage.
To evaluate the ocean surface wind vector and the sea surface temperature obtained from Wind Sat, we compare these quantities over the time period from January 2004 to December 2013 with moored buoy measurements. The mean bias between the Wind Sat wind speed and the buoy wind speed is low for the low frequency wind speed product(WSPD_LF), ranging from –0.07 to 0.08 m/s in different selected areas. The overall RMS error is 0.98 m/s for WSPD_LF, ranging from 0.82 to 1.16 m/s in different selected regions. The wind speed retrieval result in the tropical Ocean is better than that of the coastal and offshore waters of the United States. In addition, the wind speed retrieval accuracy of WSPD_LF is better than that of the medium frequency wind speed product. The crosstalk analysis indicates that the Wind Sat wind speed retrieval contains some cross influences from the other geophysical parameters, such as sea surface temperature, water vapor and cloud liquid water. The mean bias between the Wind Sat wind direction and the buoy wind direction ranges from –0.46° to 1.19° in different selected regions. The overall RMS error is 19.59° when the wind speed is greater than 6 m/s. Measurements of the tropical ocean region have a better accuracy than those of the US west and east coasts. Very good agreement is obtained between sea surface temperatures of Wind Sat and buoy measurements in the tropical Pacific Ocean; the overall RMS error is only 0.36°C, and the retrieval accuracy of the low latitudes is better than that of the middle and high latitudes. 相似文献
In water-deficient rivers, environmental flows (e-flows) are usually sustained via inter-basin water transfer projects from water-sufficient rivers, but these projects incur tremendous costs and may lead to many negative ecological effects, such as ecological invasion. This research proposed to transfer hydropower instead of water from water-sufficient rivers, because hydropower could substitute for water to promote economic development and reduce water withdrawal from water-deficient rivers (conserved water). In addition, based on the analysis of eco-hydrological processes, the flow regime alteration plays an important role in restoring riverine ecosystem. With the goal of minimum flow regime alternation, we set up two scenarios to distribute the annual conserved water, and determined the optimal amount of transferred hydropower and the optimal use of conserved water, which could effectively sustain the e-flows. Accordingly, this paper established a computable general equilibrium model to analyse the substitution of hydropower for water in a water-deficient river basin, and determined the water withdrawal volume that could be reduced. We adopted a range-of-variability approach to measure the degree of flow regime alteration, and optimized the flow regime management scheme. The Luanhe River Basin was adopted as a study case. The results showed that: the water-hydropower equivalent decreased as the transferred hydropower into the Luanhe River Basin increased; a transferred hydropower amount of 22.46 kWh/s, equivalent to 18.30 m3/s conserved water, was optimal for the river basin; the conserved water should be distributed to the Luanhe River in the proportions of 0.55:0.1:0.35 during the wet, normal and dry seasons, respectively, which is the optimal scheme to sustain the hydrological processes of the river. 相似文献