Study on the Characteristics of Ecological Water Requirement in Maijishan Scenic Spot

[Objective] This study aimed to explore the characteristics of ecological water requirement in Maijishan Scenic Spot. [Methed] The characteristics of ecologi- cal water requirement in Maijishan Scenic Spot were analyzed based on,the data of soil humidity and meteorology of the spot. [Result] The result showed that the actual annual ecological water requirement in the spot was 678×10^6 m^3, and the proportion of soil water and evapotranspiration were 21% and 79%, respectively; the minimum annual ecological water requirement quota in the spot was 480.27×10^6 m^3, and the proportion of soil water and evapotranspiration were 16% and 84%, respectively; the minimum annual suitable ecological water requirement quota in the spot was 624.22×10^6 m^3, and the proportion of soil water and evapotranspiration were 18% and 82%, respectively. The precipitation was 614×10^6 m^3, and consumptive water surplus reached up to 78×10^6 m^3. The years when the precipitation was higher than the evapotranspiration accounted for 76%. Since 1980s, the evapotranspiration showed a linearly increasing trend. The precipitation was higher than the evapotranspiration from Jun. to Oct. and less than the evapotranspiration from Nov. to Dec. and Jan. to May. Evapotranspiration water requirement was regulated by soil water. The dis- parity between precipitation and evapotranspiration was huge in spring, thus having certain influence on waterfalls and streams in the spot. [Conclusion] The results of this study provided a basis for the rational use and long-term planning of the water sources in Maijishan Scenic Spot.

Estimation of Ecological Water Requirements Based on Habitat Response to Water Level in Huanghe River Delta,China

In recent years,wetland ecological water requirements (EWRs) have been estimated by using hydrological and functional approaches,but those approaches have not yet been integrated for a whole ecosystem.This paper presents a new method for calculating wetland EWRs,which is based on the response of habitats to water level,and determines water level threshold through the functional integrity of habitats.Results show that in the Huanghe (Yellow) River Delta water levels between 5.0 m and 5.5 m are required to maintain the functional integrity of the wetland at a value higher than 0.7.One of the dominant plants in the delta,Phragmites australis,tolerates water level fluctuation of about ± 0.25 m without the change in wetland functional integrity.The minimum,optimum and maximum EWRs for the Huanghe River Delta are 9.42×106 m3,15.56×106 m3 and 24.12×106 m3 with water levels of 5.0 m,5.2 m and 5.5 m,corresponding to functional integrity indices of 0.70,0.84 and 0.72,respectively.A wetland restoration program has been performed,which aims to meet these EWRs in attempt to recover from losses of up to 98% in the delta's former wetland area.

Environmental and ecological water requirement of river system: a case study of Haihe-Luanhe river system

In order to reduce the environmental and ecological problems induced by water resources development and utilization, this paper proposes a concept of environmental and ecological water requirement. It is defined as the minimum water amount to be consumed by the natural water bodies to conserve its environmental and ecological functions. Based on the definition, the methods on calculating the amount of environmental and ecological water requirement are determined. In the case study on Haihe-Luanhe river system, the water requirement is divided into three parts, i.e., the basic in-stream flow, water requirement for sediment transfer and water consumption by evaporation of the lakes or everglades. The results of the calculation show that the environmental and ecological water requirement in the river system is about 124×108 m3, including 57×108 m3 for basic in-stream flow, 63×108 m3 for sediment transfer and 4×108 m3 for net evaporation loss of lakes. The total amount of environmental and ecological water requirement accounts for 54% of the amount of runoff (228×108 m3). However, it should be realized that the amount of environmental and ecological water requirement must be more than that we have calculated. According to this result, we consider that the rational utilization rate of the runoff in the river systems must not be more than 40%. Since the current utilization rate of the river system, which is over 80%, has been far beyond the limitation, the problems of environment and ecology are quite serious. It is imperative to control and adjust water development and utilization to eliminate the existing problems and to avoid the potential ecological or environmental crisis.

Method for calculating ecological water storage and ecological water requirement of marsh

As one of the most typical wetlands,marsh plays an important role in hydrological and economic aspects,especially in keeping biological diversity.In this study,the definition and connotation of the ecological water storage of marsh is discussed for the first time,and its distinction and relationship with ecological water requirement are also analyzed.Furthermore,the gist and method of calculating ecological water storage and ecological water requirement have been provided,and Momoge wetland has been given as an example of calculation of the two variables.Ecological water use of marsh can be ascertained according to ecological water storage and ecological water requirement.For reasonably spatial and temporal variation of water storage and rational water resources planning,the suitable quantity of water supply to marsh can be calculated according to the hydrological conditions,ecological demand and actual water resources.

Study of Panjin Wetlands Along Bohai Coast(Ⅱ):Ecological Water Requirement of Shuangtaizi Estuarine Wetland

Shuangtaizi estuarine wetland along the Bohai Sea coast,the biggest bulrush wetland in the world,has been listed in 'The Record of Important International Wetland Conservation District'. Taking the year of 2 000 as an example,the minimum,the most suitable and the maximum ecological water requirement of Shuangtaizi estuarine wetland are calculated in this paper based on both ecological theory and Geological Information System technology. In addition,the remote sensing technique is adopted in the data acquisition process. Moreover,the total water requirement and the unit area water requirement for different wetland types are obtained. The result is very important for water resources planning,ecological conservation and regional agriculture structure adjustment in Shuangtaizi. Meanwhile,this study can serve as a useful example for calculating the ecological water requirement in other similar estuarine wetlands.

Ecological Water Requirement Estimates for Typical Areas in the Huaihe Basin

Aquatic ecosystems require ecological water allocation to prevent from being damaged by natural disasters and undue exploitation. This paper discusses and estimates the ecological water requirements （EWRs） of typical areas in the Huaihe Basin to determine rational allocations of water resources and pro- mote regional improvements of the ecological environment. The main river course, including Hongze Lake and Nansi Lake, was selected as the study subject. Calculational methods for the river and lake EWRs were based on the reasonableness of the results and data availability. The monthly guarantee rate method was used to calculate monthly, flood period, non-flood period, and annual EWRs for the main river course and the main tributaries at two different guarantee rates. The minimum water level method was used to calculate annual EWRs for Hongze Lake and the upper and lower Nansi Lake of 1.521×10^9 m^3, 0.637×10^9 m^3, and 0.306×10^9 m^3. The results were used to evaluate the rationality of the quantity of water resources allocated to ecological uses in the Huaihe Basin during 1998-2003. The result shows that the present water resource allocations in the Huaihe Basin cannot satisfy the basic ecological requirements for some years, especially years with less precipitation.

Calculation of instream ecological water requirements under runoff variation conditions:Taking Xitiaoxi River in Taihu Lake Basin as an example

Climate change and human activity can cause remarkable hydrological variation.Traits of hydrological series such as runoff before and after the change points could be significantly different,so the calculation of instream ecological water requirements(EWRs)is confronted with more challenges.Taking the Xitiaoxi River(XTXR)in the upper reach of the Taihu Lake Basin as an example,this paper investigates the calculation of EWRs using the range of variability approach(RVA)under changing environment.The change point diagnosis of the natural and observed runoff series are conducted for XTXR.Then,differences in the hydrological alternation indicators and instream EWRs processes obtained from various daily runoff series are compared.It was found that the natural and observed annual runoff series in XTXR from 1957 to 2018 both show significant variations,and the change points are in 2007 and 1999 respectively.If runoff data before the change points or all runoff data are used,the instream EWRs obtained from natural runoff are significantly lower than those obtained from the observed runoff.At the monthly time step,EWRs differences within a year mainly occurred from May to August.Also,calculation results of the instream EWRs are strongly related to the selected period of runoff series.The EWRs obtained using runoff series after the change points have rather acute fluctuation within a year.Therefore,when the RVA method is used under changing environment,the instream EWRs should be prudently determined by comparing different calculation results on the basis of river runoff restoration and variability analysis.To a certain extent,this paper enriches our understanding about the hydrological method for EWRs estimation,and proposes new ideas for future research on EWRs.

Determination of a Reasonable Percentage for Ecological Water-Use in the Haihe River Basin, China

An investigation was conducted to study problems of determining a reasonable percentage for ecological water-use in the Haihe River Basin of China. Three key aspects for the ecological water requirement （EWR） were analyzed, involving i） the EWR for river system, ii） the EWR for wetlands and lakes, and iii） the EWR for discharge into the sea to maintain the estuary ecological balance of the Haihe River. The Montana method and related water level-flow relationships, and the statistic approach based on hydrological records were applied to estimate different components of EWR. The results showed that the total ecological water demand in the region, was about 3.47-14.56 billion m^3. Considering flow regime change and uncertainty, the ecological water demand could be estimated by the hydrological frequency approach. Preliminary analysis showed that for different annual runoff under the frequencies of 20%, 50%, 75% and 95%, the ecological water demand approached 12%-50%, 18%-74%, 24%-103%, 35%-148% and 16%-66%, respectively. By further analysis to balance ecological water-use and socioeconomic water-use, the rational percentage of ecological water-use was estimated as 35%-74%, that provides useful information to judge whether the allocation of water resources is reasonable, and was proved to be satisfactory by comparing with the practical condition.

Estimating minimum ecological water required of the western route first stage project of China＇s south-to-north water transfer scheme for water exporting rivers

It is well known that there is abundant water resources in basin of the Yangtze River, the first largest river in China, which is mainly located in Southern China. However, water resources is very scarce in the basin of the Yellow River, which is mainly located in Northern China. So the western route project of south-north water transfer scheme （WRP-SNWTS） aims to transfer water from the Yangtze River to the Yellow River. The area of WRP-SNWT, located in the upper reaches of the Yangtze River and the main areas of Sichuan and the marginal areas of the Qinghai-Tibet Plateau, has sufficient water resources but fragile ecology and environment. Therefore, it is necessary for WRP-SNWT to analyze the ecology water required. Based on the planning principles of from low elevation to high elevation, from small to large, from short to long and from easy to difficulty, the WRP-SNWT will be constructed through three stage projects. The western route first stage project of the south-north water transfer scheme （WRFST-SNWTS） is planned to transfer 4×10^9m^3/a from six tributaries of the Yalong river and from Dadu river to Jiaqu of Yellow River.. Daqu river and Niqu river are the branches of Xianshui river. Sequ river, Duke river, Make river and Ake river are the branches of Dadu river, which account for 65-70% of the total river run-off. It need more research and the rest run-off can satisfy channel ecology water required. According to analysis ecological water required which mainly satisfy for aquicolous biology in water-exporting region, such as low air temperature. Fish and aquicolous biology main living from May to August, and rivers are iced up from December to March of next year, ecology water required mainly for fish and aquicolous biology. The flow criterion of Tennant method is modified. The ecology water required of WRFSP-SNWTS is estimated by the flow data of Zhuwo gauging station, Zhuba gauging station, Chuosijia gauging station and Zumuzu gauging station. The result show that the ecology water required calculated by modified Tennant less 1 l percent than that of Tennant. This estimating result can supply more water resources for transferring to Yellow River. Meanwhile, this can supply gist for research transferring water of WRFSP-SNWTS.

Effect of Groundwater Level Fluctuation on Phragmites australis Evapotranspiration in the Baiyangdian Lake

Abstract:Hydrological regimes influence ecological patterns and processes as well as alter rates of wetland evapotranspiration.This study aimed to investigate the impact of groundwater fluctuation on evapotranspiration of Phragmites australis.Supported by field data obtained from the Baiyangdian Lake in northern China,the variations in groundwater levels were explored,and the changes in soil water and evapotranspiration of reed were analyzed to investigate different groundwater level scenarios using HYDRUS-1D model.The results showed that soil water content,recharged by groundwater,remained stable in the lower soil layer but varied strongly in the upper layer of the soil profile;in comparison to evaporation,Phragmites australis transpiration contributed significantly more to the overall evapotranspiration rate;the high levels of evapotranspiration could be maintained when groundwater levels vary between 1.0 m and 1.8 m,while it was reduced with an increase in groundwater levels as a result of water stress conditions.The results also indicated that the evapotranspiration of Phragmites australis could maintain higher evapotranspiration rates under natural water levels.The evapotranspiration,in other words,might be the main water consumer,but it nevertheless has little effect on water levels during water shortages.The evapotranspiration of Phragmites australis responded to the changes in groundwater levels could help researchers understand water requirements of the wetlands and establish suitable water levels for the wetlands.