Water Balance Principle Research Articles

Water-Use Efficiency of Potted Pakchoi in Yunnan Laterite with Root Infiltration Irrigation and Anticlogging Emitter

AbstractA method is developed to calculate crop water consumption based on the water balance principle. An independently designed emitter resistant to clogging caused by negative pressure (EK) is a...

Temporal Variations in the Quantity of Groundwater Flow in Nam Co Lake

This paper aims to calculate and analyze the spatial and temporal variations in the groundwater flow quantity in Nam Co Lake based on the water balance principle. The results show that a large amount of groundwater was gradually lost and that, groundwater loss decreased from 1.9 billion m3 to 1.5 billion m3 from the period of 1980–1984 to 1995–2009. The comparative analysis in the current study indicates that the decrease in the groundwater index has a strong linear relationship with the temperature of the ground surface on the Tibetan Plateau, with a correlation coefficient as high as 0.92. Moreover, environmental variations such as large-scale engineering construction projects and increases in water storage may have played dominant roles in the sudden changes in the water quantities of plateau lakes (e.g., Nam Co Lake) during the periods of 1990–1995 and 2000–2009. The increased water levels resulted in reduced groundwater losses, which may lead to the substantial expansion or gradual shrinkage of the Qinghai–Tibet Plateau lakes over short periods of time. The results of this study provide an important reference for studying the mechanisms of lake water level changes on the Qinghai–Tibet Plateau.

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.

Analysis on Spatial and Temporal Variations of Maize Irrigation Water Requirement in Jilin Province

Based on the location of meteorological stations in Jilin Province, seven meteorological stations were selected. They are Fuyu, Yanji, Linjiang, Ji’an, Meihekou, Tongyu and Changchun. These meteorological data are from the year of 1984 to 2012. The meteorological data are analyzed by using crop coefficient method and water balance principle. The irrigation water requirement during the growth period of Maize in Jilin province was analyzed. The results show that: the average irrigation water requirement is 166mm in the middle of the dry year (75%) and in the drought year (90%).The variation range of irrigation water demand in each weather station is from 0 mm to 375mm. Regional differences are obvious. There is no obvious difference in irrigation water requirement in time. The variation characteristics of irrigation water demand of maize are increasing from east to west.

Long-duration PMP and PMF estimation with SWAT model for the sparsely gauged Upper Nujiang River Basin

For large sparsely gauged basins, it is difficult to estimate long-duration probable maximum precipitation (PMP) and probable maximum flood (PMF) due to insufficient observed data and precipitation spatial distribution uncertainty. In this paper, a framework coupling the China Grid Daily Precipitation Datasets (CGDPDs) with Soil and Water Assessment Tool (SWAT) was proposed to estimate the 15-day PMP and PMF for the sparsely gauged Upper Nujiang River Basin (with a drainage area of 73,484 km2). CGDPD was tested against the observations and further corrected considering the error distribution characteristics. Results showed that 1-, 3-, 7- and 15-day maximum areal precipitations based on the corrected CGDPD were 17, 7, 4 and 18% larger than those calculated only by six observed stations’ precipitation. Then CGDPD was used as the precipitation data to estimate PMP. For the spatial distribution of PMP, the 15-day PMP process on the sub-basin scale (PMPsub-basin) could be obtained with the following procedure. First, the basin’s 15-day areal PMP was estimated. Among this estimation, the maximum 3-day PMP was estimated by moisture maximization, while the remaining 12-day PMP was estimated with the combined storm obtained by the similar process substitution method. Second, the model storm amplification approach based on water balance principle was used to distribute the areal PMP to each sub-basin to obtain the PMPsub-basin at all 27 sub-basins. The designed PMF could be finally estimated through inputting PMPsub-basin into SWAT. In comparison with PMF derived from PMP without spatial distribution, different duration PMFs could increase by 3–15% when considering PMP spatial distribution uncertainty. This study could provide a reasonable procedure to estimate long-duration PMP and PMF for similar basins.

Myths and methodologies: Making sense of exercise mass and water balance.

What is the topic of this review? There is a need to revisit the basic principles of exercise mass and water balance, the use of common equations and the practice of interpreting outcomes. What advances does it highlight? We propose use of the following equation as a way of simplifying exercise mass and water balance calculations in conditions where food is not consumed and waste is not excreted: ∆body mass-0.20g/kcal-1 =∆body water. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration=[(∆body mass-0.20gkcal-1 )/starting body mass]×100. Changes in body mass occur because of flux in liquids, solids and gases. This knowledge is crucial for understanding metabolism, health and human water needs. In exercise science, corrections to observed changes in body mass to estimate water balance are inconsistently applied and often misinterpreted, particularly after prolonged exercise. Although acute body mass losses in response to exercise can represent a close surrogate for body water losses, the discordance between mass and water balance equivalence becomes increasingly inaccurate as more and more energy is expended. The purpose of this paper is briefly to clarify the roles that respiratory water loss, gas exchange and metabolic water production play in the correction of body mass changes for fluid balance determinations during prolonged exercise. Computations do not include waters of association with glycogen because any movement of water among body water compartments contributes nothing to water or mass flux from the body. Estimates of sweat loss from changes in body mass should adjust for non-sweat losses when possible. We propose use of the following equation as a way of simplifying the study of exercise mass and water balance: ∆body mass-0.20gkcal-1 =∆body water. This equation directly controls for the influence of energy expenditure on body mass balance and the approximate offsetting equivalence of respiratory water loss and metabolic water production on body water balance. The relative efficacy of exercise drinking behaviours can be judged using the following equation: percentage dehydration=[(∆body mass-0.20gkcal-1 )/starting body mass]×100.

The central nervous system pressure histogram in hydrocephalus and hydromyelia

This work makes proposals on the relationship between intracranial pressure (ICP) and hydrocephalus that changes over time with the evolution of the disease. This includes the cerebrospinal fluid (CSF) filling mechanism that leads to an increase in mode pressure if excess fluid volume exacerbates the obstructive process. Elevation in mode occurs because pressure in the central nervous system (CNS) represents a state of reduced flow, rather than an abnormality of volume. Diseases that cause elevated mode pressure by means of a primary edema can lead to hydrocephalus if there is sufficient time and obstruction to flow for the filling mechanism to act. Hydrocephalus is driven primarily by labile pressure due to restricted compliance, it can expand skeletal compartments and deplete parenchyma volume as it advances. This hypothesis applies existing principles of water balance. It is part of a series of works that propose a spectrum of hydrocephalic disorders including developmental forms such as achondroplasia with other conditions such as functional trapped fourth ventricle, arachnoid cyst, syringomyelia and normal pressure hydrocephalus (NPH). Links between the conditions can be made by understanding the continuously variable pressure profile local to the cavity that is subject to filling. Fluid lesions of the brain or spine that arise from developmental malformations of the skull have a physiological component. Changes form part of the mechanisms that may compensate the disease process.

An innovative method to estimate regional-scale hydraulic diffusivity using GRACE data

ABSTRACTEstimation of hydraulic properties in the field is usually small-scale and not cost-effective. This paper proposes an innovative method for estimating hydraulic diffusivity at regional scale. Monthly groundwater storage change over the period from 2003 to 2013 is first estimated from GRACE-derived terrestrial water storage (TWS). Assuming that the aquifer system is unconfined and the hydraulic properties are uniform in a geographical cell, the water balance principle and Darcy’s law are used to establish a relation between groundwater storage and hydraulic diffusivity. The value of hydraulic diffusivity is then adjusted using the generalized least squares and linear correlation method. This GRACE-derived hydraulic diffusivity estimation method, or GHDE method for short, is first verified with a hypothetical case and then applied in the Beishan area with available field-measured hydraulic conductivity data. The hypothetical case study demonstrates that the method works perfectly if the TWS data are error free. The Beishan case study illustrates that the estimated hydraulic diffusivities using the GHDE method correlate reasonably well with field test results, suggesting that this method is applicable. The accuracy of this method is constrained by the resolution of the GRACE-derived TWS data and is most suitable for very large scale groundwater problems due to the current accuracy of the GRACE data.EDITOR A. Castellarin ASSOCIATE EDITOR N. Verhoest

Industrial water mass balance as a tool for water management in industrial parks

Industry is demanding ever-greater volumes of water, while at the same time producing wastes and effluents, which in many places taint and damage the quality of this precious resource on which all life depends. This article formalizes a systematic water mass balance framework to quantify all anthropogenic and natural water flows into, water flows inside and effluents out of the industrial parks. Quantitative performance indicators are derived, including management and operation indicators. The approach makes visible large flows of water that have previously been unaccounted and ignored. In 2012–2014, the water consumption, which made up 59.5–90.2% of industrial water withdrawal, was 8.5–51.2% higher than wastewater generation. The approach demonstrates how the principles of water balance can help robust water accounting, monitoring, optimum operating and management in industrial parks. Furthermore, performance indicators could evolve to a useful tool for leading to more systematic analysis of the impact of industrial design and management.

Study on the Model of Soil Water Resources Quantity in Baoding Plain

The soil water resources has special properties, independent of surface water resources and groundwater resources. The relationship between soil water resources and soil water, the concept and characteristics of soil water resources have been analyzed and the model calculating the soil water resources quantity under the natural condition has been put forward based on the principle of water balance principle in this study. The model parameters have been focused on. Firstly, the daily precipitation has been determined based on typical year. Secondly, the surface runoff has been applied on the basis of the hydrological model of runoff yield in excess of infiltration. Thirdly, canopy interception rainfall has been concluded according to canopy interception model. Fourthly, the water quantity of infiltrated out of the assessment layer has been calculated based on the hydrological model of runoff yield at natural storage. The model has been applied to the work of soil water resources assessment of Qingyuan county in Baoding plain and the result has showed that the soil water resources quantity in mean precipitation year is 301.1485 million m3 and its temporal distribution is consistent with the distribution of rainfall of the year.

A structure–efficiency based performance evaluation of the urban water cycle in northern China and its policy implications

Understanding the urban water cycle is critical, as the watershed water cycle is greatly influenced by cities under the processes of urbanization with problems of high frequency of water shortage, environment deterioration and ecological degradation. Different from traditional evaluation method which focuses on one or some component of the whole system, this research aims to propose an innovative framework to evaluate the performance of the urban water cycle by means of the structure–efficiency index (SE_index). This index aggregates key indicators from structure and efficiency aspects (i.e. S_index and E_index), based on the water balance principle (which considers a multi-source water distribution process, water consumption process, and the wastewater treatment and discharge process). An entropy weight method is used to determine the weights of different indicators in an objective way. The performance levels of the urban water cycle of case study cities in Haihe River basin are evaluated, and key indicators are identified by sensitivity analysis. Four city categories with different structures or efficiency characteristics are presented by cluster analysis technique and their associated policy implications are discussed. For cities with relatively low S_index and E_index values (such as Xingtai, Hebi, Shjiazhuang and Hebi), it is meaningful to both optimize their urban water cycle structure and improve the efficiency of the water supply and different water use sectors. Although cities such as Beijing and Tianjin have relatively high S_index and E_index values, there is still room for them to make structure optimization compared with other cities in the basin. The proposed SE_index and its application can help provide quantitative information on the urban water cycle performance status to promote sustainable urban water policy making and related infrastructure planning.

Using Bayesian model averaging to estimate terrestrial evapotranspiration in China

Summary Evapotranspiration (ET) is critical to terrestrial ecosystems as it links the water, carbon, and surface energy exchanges. Numerous ET models were developed for the ET estimations, but there are large model uncertainties. In this study, a Bayesian Model Averaging (BMA) method was used to merge eight satellite-based models, including five empirical and three process-based models, for improving the accuracy of ET estimates. At twenty-three eddy covariance flux towers, we examined the model performance on all possible combinations of eight models and found that an ensemble with four models (BMA_Best) showed the best model performance. The BMA_Best method can outperform the best of eight models, and the Kling–Gupta efficiency (KGE) value increased by 4% compared with the model with the highest KGE, and decreased RMSE by 4%. Although the correlation coefficient of BMA_Best is less than the best single model, the bias of BMA_Best is the smallest compared with the eight models. Moreover, based on the water balance principle over the river basin scale, the validation indicated the BMA_Best estimates can explain 86% variations. In general, the results showed BMA estimates will be very useful for future studies to characterize the regional water availability over long-time series.

Research on Infiltration Rate of Topsoil in Combination with Steady Infiltration Model and Penetration Resistance Test

In this study, infiltration experiment and survey on specific penetration resistance for the topsoil were conducted for five land use patterns at the Liudaogou Catchment on the northern Loess Plateau. A simple infiltration model has been developed based on water balance principle combined with theory of steady infiltration. The mean unsaturated infiltration rate of topsoil was estimated based on the results of infiltration experiment and survey on specific penetration resistance combined with model calculation. The results indicated that determination coefficient of relation curve between mean unsaturated infiltration rate and the topsoil specific penetration resistance is higher than 0.93; order of the mean unsaturated infiltration rate of topsoil was 10-5 m/s during the research period; sequence of the mean unsaturated infiltration rate of the five land use patterns is Alfalfa (on slope land) < Grassland (on slope land) < Grassland (on alluvial plain) < Farmland (on alluvial plain) < Sandy loess (bare land); mean unsaturated infiltration rate of alfalfa (on slope land) and grassland (on slope land) was obviously lower than that of the mean of the five land use patterns, and mean unsaturated infiltration rate of sandy loess (bare land) was significantly higher than that of the mean of the five land use patterns.

Configuration of water resources for a typical river basin in an arid region of China based on the ecological water requirements (EWRs) of desert riparian vegetation

Desert riparian vegetation is a natural cover promoting the stability and development of inland river ecosystems in arid regions. Calculating the ecological water requirements (EWRs) of desert riparian vegetation is an important step in achieving reasonable water utilization. Therefore, this study examined the Tarim River, located in an extremely arid region of China, and collected relevant data on hydrology, weather and vegetation using remote sensing. Subsequently, we analyzed the spatial distribution of the desert riparian vegetation in four sections of the Tarim River and calculated the EWR of the desert riparian vegetation using the phreatic evaporation model; additionally, we determined the required runoffs at five hydrologic stations based on the water balance principle. Ultimately, the necessary protection ranges and goals for desert riparian vegetation were established according to the water resource variations in the Tarim River. Our research showed that the total area of desert riparian vegetation along the Tarim River is 16,285.3km2; this distribution area gradually decreased as the distance from the river increased, and areas varied in the different river sections. The EWRs of desert riparian vegetation from Sections 1 to 5 are 5.698×108, 7.585×108, 4.900×108, 4.101×108m3 and 1.078×108m3, respectively. Therefore, the total EWR of the study region is 23.362×108m3. In terms of the transpiration law of the “unimodal type”, the peak value of EWR of natural vegetation occurs in July, and the decreasing trend appears in the other months. Based on the water balance principle, the required runoffs in Alar, Xinquman, Yingbaza, Wusiman and Qiala were determined to be 47.105×108, 35.174×108, 22.734×108, 15.775×108 and 7.707×108m3, respectively. According to the water resource frequency and the EWR of the desert riparian vegetation along the Tarim River, we divided the region into three protection ranges: key protection (8.9–11.8km from the river), basic protection (15.8–21.8km from the river) and influence protection (43.0km from the river). This research not only provides a reasonable calculation method for EWR on the scale of a river basin but also supports the healthy development of the desert riparian vegetation ecosystem and helps to achieve the optimal water allocation for this river.

Study on Wetland Connectivity Technology in the Urban Coalmine Subsidence Area of Huaibei, China—Hydrological Guarantee Analysis

A daily-process hydrological simulation model was developed according to the principles of water balance, with the requirements of navigation, flood control and water regulation of the planned connected wetlands. Four aspects of the wetlands were analyzed, namely the recharge-discharge relationship between surface water and groundwater, environmental water requirements, constructed wetland purification, and timely water diversion. The water sources of the connected wetlands in the subsidence area were also calculated. The daily-process model was used for different hydrological years to simulate the connected wetlands, including aspects such as navigation guarantee, flood control and available regulated water resources. Based on the study results, the following conclusions were made: (i) Water diversion from rivers may be used for water utilization, and navigation may be satisfied in normal years. (ii) A certain amount of water diversion is required to supply the wetlands and to maintain navigation in consecutive dry years. However, a small amount of water remains which may be utilized when the water originates from wetland purification and water diversion on appropriate occasions. (iii) The simulation of flood risk based on hourly analysis showed that the connected area is capable of preventing the threat of a 50-year flood.

Mapping groundwater recharge areas using CRD and RIB methods in the semi-arid Neishaboor Plain, Iran

Quantification of groundwater recharge is of fundamental importance for groundwater modeling, planning, management, and sustainable utilization of limited water resources, especially in arid and semi-arid environments such as the eastern part of Iran. Numerous techniques are used to quantify recharge rate based on certain hydro-geological conditions. In this study, based on available hydro-geological information, cumulative rainfall departure (CRD) and rainfall infiltration breakthrough (RIB) methods were selected to estimate the groundwater recharge. These methods are based on the water balance principle (rainfall–groundwater level relationship) and require few non-deterministic data such as groundwater level measurements, rainfall, aquifer properties, and groundwater extraction dataset. These methods were modified to provide the percentage of return flow and rainfall contributions to natural groundwater recharge. The study area was split to polygons based on the existing observation wells. The natural recharge rate was estimated for each Thiessen polygon on a monthly basis. Utilizing of these two methods, groundwater levels were simulated, and the optimization technique was also applied to minimize the root mean square error between the simulated and observed groundwater levels. The results were shown that the simulated groundwater levels were matched well with the observed values. The recharge areas were then mapped using these two methods. As an average 13 and 27 % of cumulative rainfall departure and return flow contributed to groundwater recharge for whole study area by applying CRD model, whereas by RIB these values were 11 and 19 %, respectively. The average annual recharge rate estimated for Neishaboor Plain, using RIB and CRD were 160 and 164 mm, respectively.

暴雨条件下绿化屋顶产流机制研究

绿化屋顶是减轻城市洪水灾害的一种有效手段，已被世界各国广泛使用。但是，对于绿化屋顶目前仍然缺乏一个简单的基于物理过程的模型来评价其雨洪蓄滞效果。本文首先基于水量平衡原理分析降雨量P与径流量R之间的关系，讨论绿化屋顶不同的产流机理，然后通过现场试验验证了此P-R关系。本文还使用HYDRUS-1D模拟绿化屋顶的产流机理以及评价方法的适用性。模拟结果显示绿化屋顶既会发生超渗产流，也会发生蓄满产流，但超渗产流的流量在总流量中所占比例很小。这表明虽然超渗产流存在，但之前本文提出的线性模型仍然可以用于模拟包括暴雨条件在内的绿化屋顶降雨径流关系。 Green roofs (GRs) are widely employed in urban areas to mitigate the detrimental impacts by stormwater flooding. However, a simple yet physical method for assessing the hydrological performance of GR is still lacking. In this study, we first perform an analysis on the relationship between rainfall depth P and runoff amount R based on the water balance principle and discuss the different runoff generation mechanisms on GR. A field experiment is then conducted to examine the P-R relationship constructed in the previous analysis, which demonstrates good validity in estimating runoff generated on our GR. Numeric simulations via HYDRUS-1D are then carried out to investigate the runoff generation mechanism on GR as well as to examine the applicability of the proposed assessment method. The simulation results indicate that both the saturation and infiltration excess processes occurred on our GR; nonetheless, the infiltration-excess runoff accounts for only a small portion of the total runoff. This implies that the proposed linear model is applicable for estimating the runoff from GR even under heavy rainfall condition where the infiltration-excess mecha- nism is supposedly active.

极端干旱区尾闾湖生态需水估算——以东居延海为例

PDF HTML阅读 XML下载 导出引用 引用提醒 极端干旱区尾闾湖生态需水估算——以东居延海为例 DOI: 10.5846/stxb201306171720 作者: 作者单位: 西北师范大学地环学院,西北师范大学地环学院,兰州大学 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目（91025015）；甘肃省青年科技基金计划（1107RJYA063）；西北师大青年教师科研能力提升计划骨干项目（NWNU-LKQN-11-12） Ecological water requirement estimation of the rump lake in an extreme arid region of East Juyanhai Author: Affiliation: College of Geography and Environment Science, Northwest Normal University,College of Geography and Environment Science, Northwest Normal University, 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:以东居延海为研究对象，利用遥感技术目视解译ETM影像，提取东居延海2002-2012年各月湖面面积。通过水文保证率法确定不同保证率下的湖面面积，结合额济纳旗气象站观测的风速、相对湿度、气温、水汽压、降水量等气象数据估算湖泊蒸发耗水量和湖泊降水补给量，根据湖泊渗漏系数估算湖泊渗漏量，最后运用水平衡原理构建湖泊生态需水模型，估算了东居延海在湖面面积保证率为50%、75%、95%时各月月均和年均生态需水量，其中年均生态需水量分别为1.78×108、1.60×108、1.03×108 m3，约占莺落峡年均径流量的9.66%、8.66%、5.59%，约占正义峡年均径流量的16.27%、14.60%、9.42%，约占狼心山年均径流量的30.81%、27.65%、17.84%。 Abstract:With population growth, industrialization and expansion of irrigated agriculture, in some areas over-exploitation of lake resources, and disruption of the balance of lake ecosystems, have caused problems within lakes such as drying, shrinkage and serious water pollution. This can lead to degradation of the ecological environment around the lake, land desertification, and salinity intensification. Therefore, it is critical to maintain the balance of lake ecosystems. In this paper taking East Juyanhai as the study area we use remote sensing technology and visual interpretation of ETM images of the lake area, and extract data for each month from 2002 to 2012. We determined the lake area using the hydrological guarantee rate method, and used meteorological data on wind speed, relative humidity, air temperature, vapor pressure, and precipitation from the Ejinaqi weather station. We determined the lake leakage coefficient, and constructed a lake ecological water requirement model by applying the water balance principle, conducting preliminary estimates for each month, and determining the annual average ecological water requirement for different guarantee rates in East Juyanhai.The results were as follows: in January to March each year, the lake area in East Juyanhai remained unchanged. In April, the lake area began to decrease. The lake area reached a minimum in July, and the lake area gradually increased in August. After October, the lake area remained stable. The evaporation water consumption of East Juyanhai was highest from May to August, and maximum evaporation was in June. The average annual evaporation of water consumption under the guarantee rates of 50%, 75%, 95% was 1.7910×108 m3, 1.6072×108 m3, and 1.0373×108 m3, respectively. The leakage of East Juyanhai was reasonably low; the average annual leakage under the guarantee rates of 50%, 75%, 95% was 15.0788×104 m3, 13.5314×104 m3, and 8.7334×104 m3, respectively. Precipitation was mainly concentrated in June to October, and the average annual precipitation recharge under the guarantee rates of 50%, 75%, 95% was 118.1083×104 m3, 105.9882×104 m3, 68.4062×104 m3, respectively. The average annual ecological water requirement of East Juyanhai under the guarantee rates of 50%, 75%, 95% was 1.7807×108 m3, 1.5980×108 m3, and 1.0314×108 m3, respectively; accounted for about 9.66%, 8.66, and 5.59%, respectively, of the average annual runoff of Yingluoxia; about 16.27%, 14.60%, and 9.42%, respectively, of the average annual runoff of Zhengyixia; and about 30.81%, 27.65%, 17.84%, respectively, of the average annual runoff of Langxinshan.The results showed that: under the minimum guaranteed rate, to maintain the East Juyanhai lake area (23.94 km2), prevent the lake from shrinking, and ensure the surrounding environment is not severely degraded, the minimum ecological water requirement is 1.03×108 m3; under the appropriate guaranteed rate, to maintain the East Juyanhai lake area (37.09 km2) and initially improve the surrounding ecological environment, the minimum ecological water requirement is 1.60×108 m3; under the ideal guaranteed rate, to maintain the East Juyanhai lake area (41.33 km2) and ensure that the surrounding ecological environment is greatly improved, the minimum ecological water requirement is 1.78×108 m3.This research can provide the basis for rational allocation of Heihe River Basin's water resources. According to the results on ecological water requirements at different guarantee rates, management schedules for East Juyanhai's water resources must account for the relative proportions of upper, middle and lower runoff to ensure the rational allocation of water resources in the Heihe River Basin. The results of the study are also a valuable reference for the restoration and reconstruction of East Juyanhai's surrounding vegetation. 参考文献 相似文献 引证文献

Estimation of maximum saturated depth in two-layered drainage blankets over the barrier in landfill cover system

For accurately calculating the maximum saturated depth over the landfill barrier and analyzing the variation of liquid head with inflow time, a new method is presented that considers the unsteady-state condition. Based on the principle of water balance and the extended Dupuit assumption, the solution of the new method can be calculated. Also, this method is capable of revealing the effect of the multilayered drainage media. One of the advantages of the method presented in this paper is that it can be used to draw a phreatic surface in layered drainage media under unsteady-state condition and estimate the location of the maximum liquid depth, for both homogeneous conditions and two-layered drainage conditions. Based on the developed analysis method, the effects of a parametric variation on the maximum saturated depth and the variation of saturated depth with time are presented. The calculated results show that with the increase of slope gradients of cover system, the saturated depth of cover system is easy to reach a stable value. Moreover, when the drainage layer consists of two layers with different thickness and hydraulic conductivity, the increase of hydraulic conductivity of the upper drainage layer will make it easier for the saturated depth of cover system to reach a stable and lower value.

Effects of soil moisture conditions on vegetative reconstruction with alfalfa on the northern Shaanxi Loess Plateau

Vegetative reconstruction using alfalfa (Medicago sativa) has been effective in many areas to combat desertification. In arid regions of the China Loess Plateau water availability limits alfalfa productivity. Precipitation, runoff, soil moisture, and alfalfa biomass data from 2008 to 2010 on four distinct slopes representative of the Northern Shaanxi Loess Region, were collected. Relationships between precipitation, water availability, water use, and biomass were evaluated. Two methods - the Penman-Monteith-56 method and the water balance method, were used to estimate soil water carrying capacity for alfalfa and were compared. For alfalfa land on steep slopes, the relationship between water availability (Ys) and precipitation (P) was Ys = 0.8003P + 2.8568. Available water and alfalfa biomass had a linear correlation and alfalfa biomass and water use had a quadratic correlation. The Penman-Monteith-56 method estimated average annual water use of alfalfa to be 446.6 mm and peak alfalfa production to be 3992.2 to 4173.7 kg ha-1. This method overestimated annual water use by 24.3 to 25.8% and biomass by 16.1 to 33.5%. Relationships between all measured parameters and recommendations for improving vegetative reconstruction are discussed. Key words: Penman-Monteith-56 method, soil and water balance principle, Medicago sativa, water availability, desertification.