Ecological Water Requirement Research Articles

Agricultural water optimization coupling with a distributed ecohydrological model in a mountain-plain basin

Agricultural water optimization at the basin scale is critical for sustainable irrigated agriculture and water resources management. Crop Water Production Function (CWPF) and surface water are key components of agricultural water optimization. CWPF relates closely to crop yield/growth-related parameters, and surface water of sub-basins is often different and impacted by water withdrawals. However, CWPF accounting for the crop yield-related parameter and natural runoff of sub-basins were scarcely involved in agricultural water optimization at the basin scale. To fill this gap, CWPFs of different water units are estimated using a distributed ecohydrological model involving the spatial heterogeneity of crop photosynthetic capacity parameter, and the natural runoff of sub-basins is reproduced by this model. Integrating these functions and variables, and taking the agricultural benefit of the whole basin as the main objective, an agricultural water optimization model at the basin scale (AWOMB) is developed and applied to a mountain-plain basin in North China. The results showed that agricultural water optimization in a representative year would lead to 0.4% increase of crop production for the whole basin at the expense of certain urban ecological water and equity of agricultural water. In this scenario, the river ecological water requirements in all sub-basins would be satisfied. Assuming the domestic, industrial and river ecological water demand being fully satisfied in 2020s, water deficits will be 8% and 26% for the whole basin under the normal and dry year scenarios, respectively. Correspondingly, increments of 2% and 7% crop production are predicted in these two scenarios by agricultural water optimization. It is demonstrated that water resources utilization and agricultural production are effectively improved by coupling a distributed ecohydrological model with water resources optimization in the study basin. This research provides a methodology for integrative catchment water resources management.

Calculation of ecological water requirements of urban rivers using a hydrological model: A case study of Beiyun River

The impacts of human activity lead to uncertainty and ambiguity when ecological water requirements (EWRs) are calculated based entirely on the current hydrological conditions of urban rivers, and the requirements for meeting the rivers’ function will also be uncertain. Human activity and river function goals are important factors affecting EWRs. This paper discusses the definition of urban river EWRs and the uncertainties in the results of the calculation, and proposes a calculation method for urban river EWRs that is independent of human activity. The Beiyun River Basin, China, was selected for a case study. The EWRs of the Beiyun River were calculated by combining a precipitation frequency curve with a distributed hydrological model. The rationality of the calculated results was verified using the Tennant method and an evaporation plus seepage calculation for the river. The results of the calculation for the urban river EWRs method proposed in this paper are unique, and the total amount is not affected by human activities. With respect to wet, normal, and dry precipitation frequencies, the minimum, suitable, and ideal EWRs of the Beiyun River are 1.48 × 108 m3, 2.79 × 108 m3, and 3.57 × 108 m3, respectively. The research conclusions are of great significance for the objective determination of the EWRs of urban rivers, and for promoting the appropriate planning and development of urban water.

Lag in Hydrologic Recovery Following Extreme Meteorological Drought Events: Implications for Ecological Water Requirements

Hydrological regimes, being strongly impacted by climate change, play a vital role in maintaining the integrity of aquatic river habitats. We investigated lag in hydrologic recovery following extreme meteorological drought events, and we also discussed its implications in the assessment of ecological environment flow. We used monthly anomalies of three specific hydrometeorological variables (precipitation, streamflow, and baseflow) to identify drought, while we used the Chapman–Maxwell method (the CM filter) with recession constant calculated from Automatic Baseflow Identification Technique (ABIT) to separate baseflow. Results showed that: (i) Compared to the default recession parameter (α = 0.925), the CM filter with the ABIT estimate (α = 0.984) separated baseflow more accurately. (ii) Hydrological drought, resulting from meteorological drought, reflected the duration and intensity of meteorological drought; namely, longer meteorological drought periods resulted in longer hydrological drought periods. Interestingly, the time lag in streamflow and baseflow indicated that aquatic ecosystem habitat recovery also lagged behind meteorological drought. (iii) Assessing environmental flow by quantifying drought provided greater detail on hydrological regimes compared to abrupt changes, such as the increased hydrological periods and the different environment flows obtained. Taken together, our results indicated that the hydrological response in streamflow and baseflow (e.g., the time lag and the precipitation recovery rate (Pr)) played a vital role in the assessment of environmental flow.

A bi-level chance-constrained programming method for quantifying the effectiveness of water-trading to water-food-ecology nexus in Amu Darya River basin of Central Asia

Issues of water scarcity, food crisis, and ecological degradation pose great challenges to the sustainable development of Central Asia. In this study, a bi-level chance-constrained programming (BCCP) method is developed for planning water-food-ecology (WFE) nexus system of the Amu Darya River basin, where the efficiency of water-trading mechanism and the impact of uncertain water-availability are examined. This is the first attempt for planning WFE nexus system by incorporating chance-constrained programming (CCP) within a bi-level optimization framework. BCCP can reflect the risk of violating probabilistic constraint under uncertainty as well as balance the tradeoff between two-level decision makers in the WFE nexus system. Under trading scheme, multiple scenarios in association with different food demand, ecological-water requirement, and water availability are examined. Major findings are: (i) compared with that under non-trading, system benefits would increase [3.9, 20.4]% under trading scenarios, disclosing that water trading is an effective mechanism for the study basin; (ii) when food demand increases 10.5%, water allocated to ecological use would decrease [0.9, 2.7]% under all scenarios, revealing that agriculture can squeeze ecological water; (iii) both system benefit and water allocation would increase with p level, implying there is a tradeoff between system benefit and system-failure risk. These findings can gain insight into the interaction between two-level stakeholders and objectives as well as provide decision support for WFE nexus synergetic management.

PRESENT STATUS AND FUTURE PROSPECTS OF DRAINAGE IN RELATION TO THE ICID VISION 2030

AbstractThe International Commission on Irrigation and Drainage (ICID) regularly updates the areas drained and irrigated in the world based on information provided via their national committees (www.icid.org). Modern land drainage planning, design and implementation include making drainage environmentally sustainable and achieve this through enhanced water balance assessments at regional and field scale, prevent excess water except for leaching salts, support ecological water requirements, and then, if any excess water remains, design a drainage system. The less water mobilized through the root zone, the better the quality of drainage water. No matter how efficiently our crops are watered, sooner or later we need to have a well‐functioning drainage system for complete in‐field water management. Agricultural land drainage should include various approaches to assessment and prevention of waterlogging and salinity problems, consider the water–food–energy nexus approach and give due attention to social, environmental and financial considerations (triple bottom line, TBL) for the best sustainable results. The most important consideration to be included in drainage system planning and design is the consideration of cause and effect. Waterlogging and salinity problems are the effect of something that is occurring most likely upstream; the cause. © 2020 John Wiley & Sons, Ltd.

The dynamics of soil moisture balance components and their relations with the productivity of natural vegetation in an arid region of northwestern China

Precipitation and groundwater are important water source in soil and are vital for the survival and growth of natural vegetation in arid regions. Analyses on the dynamics of soil water balance components and their relations with plant growth are usually restricted by the lack of continuous measurement of deep soil moisture at a local or regional scale. By monitoring monthly soil water contents in the 0–3 m soil profiles, we analyzed the contributions of precipitation and groundwater to the growth of natural vegetation in an arid region of northwestern China from 2011 to 2013. The results showed that the 0–3 m desert soil and the 0–1.8 m grassland soil exhibited moderate spatial variability in the soil water contents (θ). Temporal variability of spatial mean θ decreased with depth in the soils of the desert and grassland. The profile-average of spatial mean θ maintained 0.11 cm3 cm−3 in the desert and varied from 0.37 to 0.44 cm3 cm−3 in the grassland over time. The evapotranspiration after calibration gave accurate estimation of water available for plants (402.0 and 532.4 mm year−1 in the desert and grassland, respectively). Annual mean net primary productivity of the grassland (233.4 g C m−2) was 3.8 times that of the desert. Water exchange in the desert soils was dominated by recharge into the 0–1 m soil from layers deeper than 3 m, with annual mean value of 303.4 mm. Recharge alternated with discharge events in grassland soils. Annual mean recharge and discharge amounts were 494.2 and 50.1 mm for the 0–1 m layer and 641.1 and 228.9 mm for the 0–3 m soil profile, respectively. Water supply into soil was totally consumed by evapotranspiration. Precipitation use efficiency increased when groundwater level became shallow (0.04 and 0.11 g C m−2 mm−1 in the desert and grassland, respectively). Groundwater supplied about 75% of water requirement for natural vegetation, and its use efficiencies were 0.12 and 0.33 g C m−2 mm−1 in the desert and grassland, respectively. Seedling of herbaceous species with trichomes at the interspace and under the canopy of shrubs can guarantee great utilization of precipitation in the desert. Transplanting of shrubs with large amounts of shallow lateral roots and shrubs with deep rooting systems can effectively utilize the shallow and deep soil water or groundwater. Reducing the irrigation consumption of groundwater and controlling the expansion of oasis cropland are foremost to guarantee the ecological water requirement and maintain the sustainability of natural ecosystems. Keep or increase current area and layout of the grassland may benefit the water cycle and carbon sequestration in the arid regions.

Analyzing the influence of landscape pattern change on ecological water requirements in an arid/semiarid region of China

With climate change and the intensification of human activities, landscape patterns have undergone important changes. These changes can have multiple impact on hydrology, nutrient transport between soil and vegetation and ecological function and health in vegetative ecosystems. Dynamic changes in landscape patterns may affect the ecological water requirements (EWRs) of vegetation. Based on meteorological data, soil data and 6 years of land use data (from 1990 to 2015), the EWRs were obtained through the Penman–Monteith formula. eight suitable landscape indices (Patch Density (PD), Connectivity Index (COHESION), Largest Patch Index (LPI), Aggregation Index (AI), Shannon Diversity Index (SHDI), Contagion Index (CONTAG), Separation Index (SPLIT), and Landscape Shape Index (LSI)) were used to explore the spatial and temporal characteristics of landscape patterns. Furthermore, the influences of landscape pattern changes on the EWRs of the middle main reaches of the Yellow River, China, were investigated. From 1990 to 2015, the total number of patches in the landscape pattern of the watershed increased, and the patch shape became more complex; the EWRs decreased from 392.7 mm to 276.5 mm, and the annual volume of the EWRs in the study area decreased from 124.8 × 108 m3 to 89.6 × 108 m3. The EWRs had a positive correlation with the LPI, indicating that the changes in the largest patch had a great impact on the EWRs. The EWRs also had a negative correlation with the SPLIT, showing that the more fragmented the landscape patches, the smaller the EWRs. With an increase in SHDI, the EWRs showed a downward trend. Furthermore, the EWRs showed a downward trend with decreasing CONTAG and COHESION. These results provide useful information for ecological restoration and provide an important reference for ecological environmental protection and the optimal allocation of water resources in arid/semiarid regions around the world. In the future, the EWRs can be regulated, and the utilization rate of water resources can be improved, by combining the current ecological environmental protection policies of the Yellow River Basin and managing future trends in landscape patterns.

Evaluation of water and land exploitation based on the ecosystem service value in a hyper‐arid region with intensifying basin management

AbstractEffective management is crucial for coordinating the conflict between environment protection and water and land exploitation. Changes in ecosystem service value (ESV) can be used to evaluate the gains and losses of the exploitation in a comprehensive way. Solutions to the following problems will facilitate the incorporating of ESV to the management of arid basin and improve the effectiveness. (a) How to improve the response sensitivity of ESV to the changes in water and land use, (b) how to determine the sustainable approach to land use/exploitation, and (c) how to ascertain the tipping point in the scale of water and land exploitation. In this research, key factors of vegetation cover, human disturbance, and soil drought were selected as the driving factors for the changes in ESV and incorporated in the ESV calculation. The approach enhanced the expression of the spatial heterogeneity in ESV as well as its response sensitivity to changes in the environment. As the management improved in the basin, the benefits of water and land exploitation increased gradually. An appropriate model of natural vegetation protection and exploitation was developed based on ESV produced by per cubic meter of ecological water requirement. Furthermore, the tipping point in the scale of water and land exploitation can be identified by the turning point in the fluctuations of the ESV. The results provide not only a new approach for formulating sustainable land development program in arid basins but also a scientific reference for making timely adjustments in land development strategies.

The multi-objective operation for cascade reservoirs using MMOSFLA with emphasis on power generation and ecological benefit

Abstract To efficiently develop power generation and solve downstream ecological health protection in Qingjiang basin, multi-objective ecological operation for cascade reservoirs (MOEOCR) model is established in contrast to conventional models that set ecological water requirement as constraint. The basic, suitable and ideal ecological water requirements in Geheyan and Gaobazhou sections are calculated using a requirement level index. Instead of the traditional evolution mode based on population, we introduce a shuffled frog leaping algorithm (SFLA) which evolves independently in sub-populations. Moreover, the SFLA is converted into a modified multi-objective algorithm (MMOSFLA) with strategies including chaotic population initialization, renewed frog grouping method and local search method, and elite frog set evolution based on cloud model. The water level corridor is used to help effectively handle complex constraints. The IGD and GD indexes are used to evaluate quality of solutions acquired by each method. In terms of normal year, the mean IGD and GD of MMOSFLA are 1.2 × 10–1 and 2.75 × 10–2, respectively. The scheduling results verify efficient search ability and convergence performance in solution diversity and distribution in comparison with other methods. Therefore, MMOSFLA is verified to provide an effective way to fulfill hydropower and ecological benefits facing the MOEOCR problem.

Intergenerational equity based optimal water allocation for sustainable development: A case study on the upper reaches of Minjiang River, China

For both physical and economic reasons, water scarcity has become a worldwide concern. To meet regional water demands and improve water resource optimization management, a multi-objective water resource allocation model was developed for a sustainable future, in which equity, efficiency, and sustainability were taken as the allocation principles to equitably maximize subarea economic and social welfare and coordinate social development and water management without compromising water ecosystem sustainability. To meet the water resource needs of both present and future generations, intra- and intergenerational equities were integrated using a Gini coefficient and a modified Bentham-Rawls criterion to allow for time and space social equity trade-offs for sustainable water allocation. To coordinate social development and water management for water sustainability, mean economic benefit efficiency was considered in the multi-objective water resource allocation model. By factoring in the competition between present and future generations, the ecological water requirements, and the fuzzy random water resource parameters, the optimal strategy better depicts a pattern of water inter-temporal configuration than current strategies. A case study from the upper reaches of the Minjiang River basin in China is given to demonstrate the practicality and rationality of the proposed model. Compared with previous models, the intergenerational allocation model was found to effectively consider sustainable water resource utilization, had a higher total social welfare value, and guaranteed equitable intra-generational water allocation. Based on the results and discussion, some management recommendations for water resource allocation strategies integrated intergenerational equity, and policy support are given.

Calculation of Comprehensive Ecological Flow with Weighted Multiple Methods Considering Hydrological Alteration

Instream ecological flow is an essential determinant of river health. Intra- and interannual distribution characteristics of runoff have been altered to different degrees by dam construction. Historical runoff series with alterations, as basic data for ecological flow calculation, provide minimal instream hydrological process information, which affects the credibility of calculation results. Considering the influence of the alterations in runoff series on ecological flow calculation, the Gini coefficient (GI) is introduced to study the evenness degrees of the intra-annual runoff distribution of four hydrological stations located in the Naolihe basin of the Sanjiang Plain. The hydrological alteration diagnosis system is used to examine the alteration points in the GI series of each hydrological station for selecting reasonable subsequences. Based on the selected subsequences, the ecological flow of each station is calculated using three hydrological methods, and the comprehensive ecological flow is calculated using weighted calculation results from the three hydrological methods. The study results show that ecological flow and natural flow have similar processes with two peaks occurring in the process in May and August, respectively. Also, dams decrease the ecological water requirement damage frequency in dry seasons, but overuse of water resources increases the ecological water requirement damage frequency in flood seasons.

Ecological water requirements of wetlands in the middle and lower reaches of the Naoli River

Abstract In the last few decades, the wetland area of the Sanjiang Plain in northeast China has shrunk severely. To provide a scientific basis for the protection and restoration of wetlands in the Sanjiang Plain, Landsat TM images of 13 typical years of four well-preserved and contiguous wetlands are interpreted by remote sensing technology in the Sanjiang Plain of the Naoli River Drainage Basin. According to the results of the interpretation, the calculation of the minimum and the optimal ecological water requirements of the four wetlands was carried out by combining ecology with remote sensing technology. At the same time, considering the rainfall and surface runoff at different guarantee rates, the artificial recharge of four wetlands was calculated according to the principle of water balance. The results indicate that the wetland area decreased significantly from 1984 to 2013, and natural inflow of water cannot meet the actual water requirements of wetlands. The calculated artificial recharge of the four reserves provides technical support for replenishment of wetlands in the Sanjiang Plain, and lays a good foundation for the restoration of wetland ecosystems in the Sanjiang Plain. At the same time, it also provides a good habitat for rare waterfowl.

Water use strategies of Populus euphratica seedlings under groundwater fluctuation in the Tarim River Basin of Central Asia

Riparian vegetation in arid regions is subject to frequent water environmental fluctuations and plays an important role in maintaining the riparian ecosystem. In recent decades, Populus euphratica (P. euphratica) has been threatened by decreasing groundwater levels, and large areas of P. euphratica seedlings are withered. To better understand the adaptive mechanism underlying hydrological process alterations, we designed an experiment to identify the water sources of P. euphratica seedlings using δ18O values (plant stem xylem, soil water and groundwater) under different groundwater scenarios by simulating the wild habitats conditions in the Tarim River bank of Central Asia. Seedlings were grown in lysimeters (2.0 m tall × 0.4 m inner diameter) under varying hydrological conditions. P. euphratica seedlings generally took up water from the shallow soil layer (0–80 cm). Under the T. ramosissima disturbance, the water source depths of the P. euphratica seedlings moved down as the groundwater depth increased. With increasing groundwater depth, the proportions of groundwater used by P. euphratica seedling monocultures (only P. euphratica seedlings) and P. euphratica seedling mixtures (P. euphratica and T. ramosissima seedlings) were reduced. Under shallow groundwater treatment (W1: 25 cm), the plant height growth of the P. euphratica seedlings slowed, and their biomass accumulation decreased. The aboveground and total biomasses of the non-coexistence seedlings under W2 (75 cm) treatment were maximized, while the maximum value for coexistence seedlings occurred under W3 (125 cm) treatment. Thus, we suggest that shallow groundwater depth is not beneficial to P. euphratica seedling growth, and appropriately decreasing the groundwater depth may promote their growth. Such information will be valuable to provide the configuration of water resources for a typical river basin in an arid region of Central Asia based on the ecological water requirements of desert riparian vegetation.

Eco-environmental water requirements in Shuangtaizi Estuary Wetland based on multi-source remote sensing data

Abstract With rapid economic development and expansion of urban boundaries, increasingly damaged wetland resources have seriously threatened the ecosystem. The study of eco-environmental requirements of wetlands is not only the basis of water resources allocation in development and utilization, but also for creating a sustainable system to maintain and improve the overall ecosystem. In this study, we used the Shuangtaizi Estuary Wetland as our study area. The breakdown of wetland cover types was extracted based on multi-source remote sensing data, providing the graphic database for ecological water requirement calculation. According to the characteristics of the Shuangtaizi Estuary Wetland ecosystem, the methods of quantifying the components of ecological water requirements were determined. The results showed that the optimum ecological water requirement of the total wetland was 239 million m3. The minimum, 75th percentile frequency, and 95th percentile frequency water requirements were 670 million m3, 921 million m3, and 1,078 million m3, respectively.

基于不同保护目标的河道内生态需水量分析——以琉璃河湿地为例

PDF HTML阅读 XML下载 导出引用 引用提醒 基于不同保护目标的河道内生态需水量分析——以琉璃河湿地为例 DOI: 10.5846/stxb201801300243 作者: 作者单位: 北京东方园林环境股份有限公司,北京东方园林环境股份有限公司,北京东方园林环境股份有限公司,中国科学院生态环境研究中心,北京东方园林环境股份有限公司,北京东方园林环境股份有限公司 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2016YFC0503000）；水体污染控制与治理科技重大专项（2017ZX07103） Analysis of ecological water requirement of rivers for different purposes: the case of Liuli River Author: Affiliation: Beijing Orient Landscape & Environment Co.,Ltd.,Beijing Orient Landscape DdDd Environment Co.,Ltd,Beijing Orient Landscape & Environment Co.,Ltd,,, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为探索不同阶段保护目标下的河道内生态需水量，以北京市房山区琉璃河为研究区域，基于琉璃河湿地工程的特殊性，在同一工程项目中不同阶段创新应用环境需水量和生态需水量两种方法，分别计算在截污工程完成前满足水质要求的河道内环境需水量和截污工程完成后满足以生态修复及维系为目标的河道内生态需水量。结果表明：①在考虑景观娱乐水量的情况下，二者一次生态需水量均为196.78万m3；②以消纳污水为目标的河道内，在考虑河道稀释及自净能力的情况下，利用水环境容量法计算净化需水量为30.39万m3/d，景观娱乐需水量为180.43万m3，河道内的土壤储水量为16.136万m3，水体年蒸发量为78.03万m3，日均0.21万m3，水体渗透量21.69万m3，日均渗漏量0.03万m3；③以生态修复及维系为目标的河道中，河道内的水生生物栖息地需水量为71.73万m3。④在截污工作未完成之前，琉璃河内需每日注入30.39万m3/d的湿地出水以保持水质。在不同保护目标下，如何依据河流实际情况，满足不同的需求，完善生态需水的计算方法，维持生态系统的稳定健康，将是未来关注的重点。 Abstract:In order to explore the ecological water requirement of rivers for different purposes, the case of Liuli River in Beijing Fangshan district was studied. The meaning and methods of calculation of environmental water requirement and ecological water requirement were defined. In this paper, environmental water requirement and ecological water requirement were calculated in the same project for the first time. Because the sewage treatment plant will be operated in 2021, sewage will continue to be discharged into Liuli River in 2019 and 2020. Before the operation of sewage treatment plant, the function of environmental water requirement is to eliminate sewage. However, after operation, the function of ecological water requirement would beto maintain the ecological balance. Both types of water requirement were calculated in this paper. The results indicated that both of the ecological and environmental water requirements were 1967800 m3. For eliminating sewage, the amount of purified water requirement was 303900 m3 considering water dilution and self-purification. The amount of landscape water demand was 1804300 m3. The amount of soil water storage was 161360 m3. The amount of annual evaporation from the river was 780300 m3. The amount of annual infiltration of the river was 216900 m3. For maintaining ecological balance, the water requirement for the habitat of aquatic organisms was 717300 m3. Future studies should be focused on the methods of coordinating the needs of different targets, refining the calculation methods of ecological water requirement, and maintaining a stable and healthy ecosystem under different situations. 参考文献 相似文献 引证文献

Hydraulic method to determine the ecological flow for fish

Social and economic development will influence the nature environment and lead to ecological problems, among which the ecological flow concerns the food chain and fish populations. Although there are many computation formulas for counting ecological flow, it is very difficult to unite and get reasonable values. According to the existing research of ecological flow, the concept and calculation method of ecological flow are analyzed, which shows that in a complex ecological system, ecological water requirement is difficult to meet the requirements of all the protection object of water requirement at the same time. Therefore, we should focus on the specific fish with reference value to build ecological protection object and determine the ecological flow. Furthermore, the ecological flow should be the regulation of water quality and water quantity in time and space. Using hydraulic method, the fish living space under different water flow environments can be determined, and specific time and space regulation schemes can be obtained.

基于生态需水量的湿地生态系统服务功能研究

湿地作为一种重要的生态系统，具有不可替代的生态功能，近年来天然湿地面积骤减，湿地生态系统服务功能严重降低，其保护工作紧迫而复杂。湿地作为一个复杂的自然生态系统，具有整体性，之前的研究仅局限于其某一或某几个功能是远远不够的。如何从湿地生态系统整体性探讨湿地的生态系统服务？本文以系统论为理论基础，从生态需水量角度出发，结合水文–生态法和生态功能法，建立湿地系统的各生态需水量之间的湿地生态需水量平衡方程，并基于此，建立湿地生态系统的理想状态模型，在不同管理目标下探索了实现湿地生态服务功能最优化的调控方式，同时，避免了以往生态需水量的重复计算问题。本文是对湿地生态系统服务功能的进一步探索，将丰富湿地保护和管理工作的理论基础。 Wetland, an important ecological system, has irreplaceable ecosystem service value. The area of natural wetland decreases rapidly in recent years ; the study on ecosystem service func-tion of wetland becomes a hot topic. Wetland system is a complicated natural system. However, in past several decades, people unilaterally emphasize the function and composition of wetland eco-system or studied as a whole. It becomes a question to study its ecological function with system theory. So, in this paper, the system theory is an integral theoretical basis to study water require-ment of wetland ecosystem. We build a dynamic balance with water requirement of ecology to get the balance equation about wetland system of the ecological water requirement. Then the ideal model is defined as the best function of wetland ecosystem based theory above. The model could avoid the repetition of the different water requirement. In the end, we discuss the application of the model under different management objectives and the best control model. The ideal model could be used for managers to estimate the health of wetland ecosystem, look for the reasons and restore them.

峰丛洼地植被生态需水定额及其影响因素

峰丛洼地植被生态需水定额及其影响因素

Ecological water requirement of plant–soil systems along the Silk Road Economic Belt: A case study of the Guanzhong–Tianshui region, China

“The Belt and Road” refers to the Silk Road Economic Belt and the 21st‐Century Maritime Silk Road. In this paper, the Guanzhong–Tianshui region is selected as a case study, which is located at the starting point of the Silk Road Economic Belt. First, the spatial distribution maps of plant and soil types are obtained based on the TM remote sensing images and the soil texture data. The boundaries of the third‐level watershed are extracted based on the digital elevation model data. Then the corresponding mathematical models are used to evaluate the ecological water requirements of the plant–soil systems. Also, the spatial distribution characteristics are analysed at the landscape scale and the third‐level watershed scale. The results show that the spatial differences of ecological water requirement in the Guanzhong–Tianshui are obvious. At the plant–soil landscape scale, the ecological water requirement per unit area of the woodland‐clay loam is the highest, about 0.4777 m3/m2, while that of the grassland‐gravel loam is the lowest, about 0.2813 m3/m2. At the third‐level watershed scale, the ecological water requirement per unit area in the Weihe watershed (Jinghezhangjiashan above) is the highest, about 0.4123 m3/m2, while that in the Weihe watershed (Longmen to Sanmenxia) is the lowest, about 0.3002 m3/m2. The study offers scientific references for the regional ecological environment protection and ecosystem management.

Estimation of the ecological water requirement for natural vegetation in the Ergune River basin in Northeastern China from 2001 to 2014

Vegetation is the most basic component of a basin. The ecological water requirement (EWR) of vegetation consequently has a direct impact on the judicious allocation of water resources in basin. In this paper, we combined the Penman–Monteith method with GIS and remote sensing techniques to dynamically calculate the vegetation coefficient and introduced the soil moisture limitation coefficient, which together provides a complete and accurate approach in calculating the EWR of natural vegetation. We then calculated the EWR and the ecological water deficit (EWD) of vegetation in the Ergune River basin and analyzed spatiotemporal variations. (1) The four main vegetation types were coniferous forest, broad-leaved forest, steppe, and meadow, which accounted for 87% of the basin’s total area. EWR were 2.11×1010m3, 0.76×1010m3, 3.39×1010m3, and 1010m3, respectively. (2) Evapotranspiration from coniferous and broad-leaved forests decreased by 7.93mma−1 and 6.88mma−1 from 2001 to 2014, respectively, while herbaceous vegetation exhibited a slightly increasing trend. Total EWR of vegetation in the Ergune River Basin remained almost unchanged. (3) The water deficit of vegetation in the Ergune River basin was widely distributed. This was due to the semi-arid and cold conditions of the study area, where precipitation could not meet the EWR of vegetation. Water deficit stresses on vegetation were more prominent in the northern Hulun Lake, the eastern Hailar River, and the western mainstream section of the Ergune River, which could be alleviated by rainwater harvesting measures. (4) We determined that the distribution of EWR and the time allocation of precipitation in growth season were incongruous. Water deficit stresses were high in both the initial and developing stages, while it was relatively low in the latter stage. We found it was in the Hulun Lake System (sub-region of the Ergune River basin) that vegetation experienced a significant water deficit during all stages. We recommend to store rainwater by constructing water storage repositories for use in dry seasons.