Minimum Water Requirement Research Articles

Socio-Spatial Analysis of Water Affordability at Small Scales: A Needs-Based Approach

Water affordability as a dimension of water poverty is becoming an increasing source of concern in cities of the Global North. Studies on water affordability are either based on water wants and not needs or tend to use spatial scales too large for effective analyses of local inequities that can truly guide policy actions. In this contribution, we calculate and map a Water Affordability Index (WAI) based on the minimum water requirement of 100 litres/person/day at the scale of the census tract for the Metropolitan Area of Barcelona. We also apply global and local spatial autocorrelation analyses to investigate spatial relationships between the WAI and poverty-related sociodemographic variables. Results show that, even though average WAI values are moderate, the distribution pattern of higher and lower values tends to be clustered in some districts and neighbourhoods of the study area. Bivariate correlations indicate that water affordability is not only related to poverty variables but also to the diversity of water prices. Findings exemplify how the constructed index can complement existing affordability indicators, revealing and mapping important risk groups struggling to meet the costs of essential water needs. Water affordability could be mitigated by supportive water pricing policies for vulnerable households in water poverty hotspots.

Study on Ecological Water Demand Pressure of Forest and Grass Vegetation Construction in Northwest Loess Plateau Based on Fitting Verification

In this paper, the minimum ecological water requirement of forest and grass vegetation in different types and regions and small basins in Pingliang City was analyzed and evaluated by using the quota of water consumption for ecological construction. The actual evapotranspiration water consumption of different types of vegetation was used as the quota to calculate the appropriate ecological water demand of vegetation, and the actual evapotranspiration water consumption of vegetation was used as the quota to calculate the appropriate ecological water consumption of vegetation in this region. At the same time, in order to make the calculation result more accurate, the water consumption per unit area after the actual evapotranspiration of different regions and different types of vegetation is used as the calculation quota. In addition, according to the principles of similar vegetation types, similar site conditions and similar climate environment, the research results of He Wentao et al., Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, on the ecological water requirement of forest in the whole Jinghe River basin (He Wentao et al. Determination and calculation of ecological water requirement of forest vegetation, Journal of Soil and Water Conservation, 2004, 18(6)) were selected and compared with this study. This study verifies the reliability of the calculation results of evapotranspiration water consumption of vegetation in this area. It should be noted that He Wentao et al. also evaluated the ecological water requirement of vegetation in the whole Jinghe River basin by calculating the evapotranspiration water consumption of vegetation, and analyzed the vegetation ecological water requirement deficit in 2020 by comparing the calculated minimum ecological water requirement of vegetation in the region, so as to reflect the ecological water demand pressure faced by vegetation construction in the region. It provides a basic basis for coordinating the relationship between vegetation construction and water resources in this region.

Optimization of Cascade Small Hydropower Station Operation in the Jianhe River Basin Using a One-Dimensional Hydrodynamic Model

Hydropower development brings benefits in terms of power generation and flood control, but it also has inevitable ecological impacts. These impacts must be considered and addressed in order to ensure sustainable development and minimize harm to the environment. This study utilized the MIKE 11 HD modeling system to construct a hydrological and hydrodynamic model of the Jianhe River basin. The model incorporates the flow demand of ecologically sensitive targets for scheduling purposes and was calibrated and validated using hydrological data from 2014 to 2022. The hydrodynamic model was then applied to analyze the evolution characteristics of the water level in the main stream of the Jianhe River, identify key areas and periods for hydropower station operation, and calculate the minimum ecological water requirement using verification and estimation methods. Based on these findings, an ecological dispatching scheme for the cascade hydropower stations in the Jianhe River basin was developed. The results demonstrate satisfactory performance of the constructed NAM model for rainfall runoff and the 1D hydrodynamic MIKE 11 HD model for the Jianhe River basin. The deterministic coefficients exceed 0.8, and the relative errors in the total water volume are below 5.5%. The critical time and space interval for hydropower station operation in the main stream of the Jianhe River is identified as December to February of the following year, with the highest risk of flow interruption occurring in January, primarily concentrated between the Duoluo II and Huahai hydropower stations. If the appropriate dispatching scheme is not implemented in the areas prone to flow interruption during critical periods, it will have a negative impact on the ecological environment. These findings provide a scientific basis and decision support for developing multi-objective ecological flow guarantee schemes for rivers.

Emerging Issues and Problems of Soil Salinity and Water Logging

Soil salinity negatively affects plant growth and induces soil degradation. Saline soils indicate lower agricultural productivity and their impact on the livelihood security of farmers and the socio-economic status of the Indira Gandhi Canal region, Rajasthan. In the context of irrigation development, problems of rising groundwater levels and the development of salinity have arisen in the Indira Gandhi Nahar Priyojana (IGNP) area. The irrigation has recently decreased to about 1 meter, much higher than the specified value of 0.51 m in phase I. In phase I, severe inundation was observed. found in a variety of locations. It is anticipated that by the end of this century, roughly 49.6 percent of the region being studied will be at risk of experiencing flooding. The waterlogging, soil salinity, and alkalinity that plague India's agricultural landscape pose a challenge to the viability of irrigated farming. It has been determined that the most effective technique for halting the reduction in agricultural output is to use enhanced irrigation management in conjunction with a combination of surface and subsurface drainage. The method of reclaiming waterlogged lands by bio drainage is one that is efficient and economical. For the objectives of rehabilitation, species such as Salvador, Tamarix, Eucalyptus, and Prosopis Juliflora are among those that are recommended for planting in afflicted regions. The bio-drainage system helped in reducing the waterlogged areas and soil salinity by lowering the water table in the study area. Traditional knowledge and modern agricultural management good practices should be adopted for efficient and optimal use of water resources. This can be achieved by maintaining irrigation through the minimum pumping hours according to the minimum water requirements of the crop, as well as choosing more cost-effective planting methods. This research paper recommends policies to improve traditional and scientific knowledge into policies and improve mutual understanding, cooperation, and collaboration for better policy results for sustainable development and mitigate the emerging Issues and problems of soil Salinity and water logging in the area of Indira Gandhi Canal, Rajasthan.

Determination of ecological flow thresholds for rainfall-recharging rivers based on multiple hydrological methods

Given the threats to the regional river ecological flow, including the sharp increase in per capita water demand, the increase in the number of hydraulic engineering, and the strong seasonal runoff of rainfall recharge channels, we clarified the appropriate ecological flow thresholds for the middle reaches of Bailong River of northwest China. Based on the monthly runoff data in the Wudu Hydrological Station of Bailong River from 1990 to 2020, seven suitable hydrological methods were used to couple the estimation of the ecological flow in the middle reaches of Bailong River, which were tested by runoff satisfaction level analysis, using quadratic fit and 95% confidence interval to determine the monthly ecological flow and threshold of the river in the study area. The results by using the single hydrological methods showed that the calculation results from the monthly minimum ecological runoff calculation method, the improved RVA method, the Tennant method, and the DC method were four better estimation methods, which had a satisfaction level of more than 90% in the whole year. The improved RVA method and the Tennant method were more suitable for the diversion power station whose main task aimed at power generation. Although the economic benefits of hydropower stations were better when the improved RVA method was used to calculate ecological flow, the calculation results from the improved RVA method were tested and analyzed by the Tennant method, which were extremely poor from November to April in the following year, and could not meet the minimum ecological water requirements for the biological community in the river channel. While the other five methods all meet this requirement. We suggest that the minimum ecological flow in the middle reaches of the Bailong River maintained at 27.28 m3⁄s, and the maximum retained at 116.33 m3⁄s. The calculation results were in line with the dynamics of runoff in the study area, which could improve the accuracy of water ecological protection. The calculation results of this study could be used for the middle reaches of the Bailong River and may provide a reference for follow-up ecological restoration research and management in similar ecological zones.

Analysis of Irrigated Crops in Regions with Overexploited Water Sources: Case Aguascalientes, Ags, Mexico

There are few crop options for arid and semi-arid soils with annual rainfall of less than five hundred millimeters. Irrigated crops are supplied by rivers, dams, and aquifers. Due to climate change, rainfall has significantly changed its start of the season, frequency, and intensity. This causes problems in the recharge of aquifers and intensive extraction of water, putting the availability of the liquid in check to ensure the total development of the crop. What are the crops that should be replaced by more suitable ones? Which plants should no longer be cultivated? To answer these questions, optimization techniques and cross elasticities were applied, maximizing the value of production subject to the minimum water requirements that ensure the total development of the crop. Some perennial crops showed that they could be replaced, and other seasonal ones should not be cultivated in the coming years. The study was done at the regional level given the access to public and free information.

Development of mobile billing application system for PAMDES water meter data logging

Along with the growth of Sindangsari's population, the water requirement in this village has increased. So, the drinking water company (PAMDES) in this village must be able to manage the available water to meet the necessities of public life. Now, the water company is still collecting and recording water meters manually. It is very risky to consider the water condition in the village because an officer can make a human error while recording the water meter's value. When the water meter recorder is damaged, the officer estimates the water meter's value. An application is needed to manage bills and record water meters to avoid this in previous studies using the Internet of Things (IoT) or mobile applications that must be sent online to the server in real-time. This solution is not suitable for the internet condition in Indonesia, which is not evenly distributed to remote villages. This study proposes to use a mobile application that can store data on mobile devices. When the internet connection is unavailable, it can be sent later when it is available again. In this study, data obtained that the condition of the meter recorder from 672 customers, 37 water meters recorder is damaged. In addition, water meter data is also obtained for the following month's bill and data on average water usage of 10,661m3 per month. With these data, it is found that the minimum water requirement is 10,661 m3 per month. It is hoped that the application for billing management and recording of PAMDES water meters in Sindangsari village, Cikoneng sub-district, Ciamis district can help increase PAMDES management capacity.

Water optimization technique for precision irrigation system using IoT and machine learning

Water management system and energy optimization are most important for today’s agriculture. Precision irrigation manages the water utilization and reduces the utilization of energy. The irrigation system consists of observation system, storing, processing and it helps in decision making as well. Internet of Things (IoT) components is used to observe the various information’s, such as soil moisture, soil temperature, weather conditions, and environmental conditions from the fields. With the help of various information, the proposed work optimizes the requirements and thus reduces energy. The cloud environment is used to store the observed parameters from the IoT components. The machine learning algorithm is useful in taking the process of data, from the cloud environments, and do forecasting on the irrigation system. In this work, proposed a hybrid model for irrigation system and do the decision making using, different observation of parameters. This work consists of K-Nearest Neighbors (KNN), Gradient Boosting-based Tree (GBT), Long Short-Term Memory (LSTM) and Spearman's rank correlation. The KNN is used to gather the nearest sensing information, with the help of various parameters. The GBT is used to predict the real values based on the observations. The LSTM is used to predict, time series prediction using different observations of the surrounding. The Spearman's rank correlation is used to receive the correlated values of real, and time series prediction. Using the GBT, LSTM and spearman rank correlation, the consolidated time series forecasting values are predicted in irrigation. The implementation of proposed work is done with the help of banana species in the time period, between Feb 2020, Dec 2020 and 2021. The duration of the cultivation, minimum and maximum water requirements and other supporting parameters are calculated using various sensors. The real and time series water requirements are calculated in the time interval of 12, 24, 36 and 48 etc. With the help of this time series data, month-wise prediction is performed. The implementations were performed in single and group of banana tree water requirements. After implementation of proposed work, for single banana tree 31.4 % of the water requirement has been optimized in 2020 time period. Due to this optimized irrigation, heavy usage of fresh water usage and energy wastage is also reduced.

Photosynthetic and water-related physiological characteristics of Periploca sepium in response to changing soil water conditions in a shell sand habitat

This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats. Four-year-old Periploca sepium seedlings were used as model species. A gradient of 12 water levels was established by artificially supplying the shell sand with water up to saturation and then allowing natural evapotranspiration to occur. The photosynthetic, chlorophyll fluorescence and stem sap flow parameters of P. sepium were measured under a range of water conditions. The different soil water conditions were classified according to the responses of these parameters. (1) With the increase in the relative water content (RWC) of the shell sand, the parameters of leaf photosynthesis, chlorophyll fluorescence and water-related physiology in P. sepium showed significant critical responses. The net photosynthetic rate (Pn), transpiration rate (Tr), instantaneous water use efficiency (WUE), potential water use efficiency (WUEi), maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSII) and daily accumulation of stem sap flow all increased first and then decreased with increasing RWC, but the corresponding water conditions associated with their maximum values were not the same. An RWC of 69.40% was determined to be the optimal water condition for photosynthesis and water-related physiological activity in P. sepium. At an RWC of 36.61%, the mechanism of photosynthetic inhibition in P. sepium changed from stomatal limitation to nonstomatal limitation; this was also the minimum water requirement for maintaining normal photosynthetic processes. An RWC of 50.27% resulted in the highest WUE in P. sepium, indicating that moderate drought stress increased WUE. (2) Based on the quantitative relationship between the photosynthetic parameters of P. sepium and the shell sand water gradient, the soil water availability was classified into 6 water grades. The RWC range for maintaining strong photosynthesis and high WUE in P. sepium was 63.22–69.98%. (3) Gas exchange in P. sepium was inhibited under drought and waterlogging stresses. Under these conditions, the photosynthetic electron transport chain was blocked, and the dissipation of light energy as heat increased, which ultimately led to a decline in photosynthetic productivity; moreover, transpiration and dissipation were aggravated, and water transmission and utilization processes in P. sepium were hindered. A significant negative feedback regulation mechanism in the photosynthetic and water-related physiological processes of P. sepium was observed; this mechanism allowed P. sepium growing in shell sand to be highly adaptable to water stress.

Estimation of crop water requirement for Bargi left bank canal command area-Jabalpur M.P. India

Effective water management methods are needed to maximize crop yield that required calculating crop water requirement correctly. Evapotranspiration is the main component of hydrological cycle, so it is important to estimate this component in an accurate manner which is necessary for many hydrological studies. The water requirement of any crop can be estimated by multiplying reference crop evapotranspiration with crop coefficient values. Various method of estimation evapotranspiration is available at present. However, in this paper the best method is focused to compute evapotranspiration for crop water requirement. It was found that the wheat has the highest water requirement whereas maize has the minimum water requirement throughout the periods and the February month requires the maximum supply of water. The Gross water requirement is found out to be 16,082,177.24 m3 per year and 5,064,098.5 m3 per year by Blaney Criddle Method and modified Penman method respectively.

The Ecological Water Demand of Different Vegetation Types in the Bashang Area, Northwest Hebei Province

In order to construct stable vegetation for reducing wind and sand disasters and soil erosion in the Bashang Area of Northwest Hebei Province in China, it is very important to understand the ecological water demand of different vegetation types in this area. Based on observed data and the Irmak-Allen formula, we investigated the ecological water demand and ecological water shortage of arbor, shrub and grassland in Bashang Area of northwestern Hebei province. The results showed that the actual evapotranspiration values of the three vegetation types in the growing seasons in the study area from high to low were arbor forest (401.81 mm), shrub (358.78 mm) and grassland (346.02 mm). The minimum ecological water requirements of arbor forest, shrub and grassland in the growing season were 243.96 mm, 218.35 mm and 211.36 mm, respectively, and the optimal ecological water requirements were 472.99 mm, 423.34 mm and 409.77 mm, respectively. In addition, the optimal ecological water shortage values were 198.56 mm for arbor forest, 148.91 mm for shrub and 135.34 mm for grassland. The ecological water shortage of vegetation has obvious seasonality, with the largest water shortage in May and June, and a lower and steady water surplus in July to October. Therefore, an artificial water supplementation in May and June would alleviate the drought stress of the vegetation. The rainfall in Bashang Area of Northwest Hebei Province can meet the requirements of minimum ecological water demand for arbor forest, but the gap between the rainfall and the optimal ecological water requirement is too large to support good growth of an arbor forest, which could explain why the degradation of poplar protective forests has occurred in Bashang Area.

Precipitation patterns in the Gambia from 1981 to 2020

The present study used composite analysis and rainy season definition to investigate rainfall patterns in The Gambia from 1981 to 2020. Rainfall dataset as observed by 10 meteorological stations scattered across The Gambia was used. Results showed that the highest single month rainfall ever recorded in The Gambia during the study period was observed in Sapu, in the eastern sector of the country. The station recorded a total rainfall amount of 767 mm in August, 1999, while the lowest single month rainfall ever recorded was 463 mm in September 2012. It was observed in Jenoi, a station situated in the western sector of the country. Climatological results showed that the study area experienced monomodal rainfall regime during the West African Monsoon, and that the southern part of the western sector region such as Sibanor tend to receive more rainfall compared to other regions of the study area. Part of the central region receives the least annual rainfall. The eastern sector of The Gambia received much of its rain from May to October with July - September as the peak of the rain season. During May - October, Sapu received the heaviest rainfall while Fatoto received the least amount. Results also show that July - September is the period when significant amounts of rainfall are received over the eastern sector of the study area. While May and October are both transitional months, the eastern sector of the study area receives more rains in October than in May. The western sector of the study area, on the other hand, received much of its rain from June to October with July - September as the peak of the rain season. During June - October, Sibanor received the heaviest rainfall while Jenoi received the least amount. The results also show that July - September is the period when significant amounts of rainfall are received over the western sector of the study area. Although June and October are both transitional months, the western sector receives more or less the same rain amounts in June and October. Results further found that, to avert losses associated with excess or deficit in crop water requirement, in the eastern sector, crops with high water requirement should be grown before August as maximum rainfall is observed in August, whereas crops with minimum water requirement should be grown in May or October, that is when minimum rainfall is experienced. In the western sector, on the other hand, crops requiring high water amount should be grown before August or September when maximum rainfall is recorded in the sector, whereas crops with minimum water requirement should be grown in June or October. This study will help create awareness on the erratic rain seasons due to Climate Change, and to provide farmers with information on rainfall distribution in The Gambia to avert losses and impacts associated with water deficit or excess on society, agriculture, and the environment.

Influence of water and nutrients on cork oak radial growth – looking for an efficient fertirrigation regime

The widespread cork oak (Quercus suber L.) mortality and reduced afforestation /regeneration are causing an overall reduction in cork production. To enhance trees’ growth and vitality, afforestation techniques using fertirrigation were tested. The main objective was the promotion of trees’ growth on new dense plantations using minimum water requirements until reaching productive forests. The experimental plot – Irricork – was installed in 2017 in a ≈1 ha stand with 14 years’ age cork oaks summer-fertirrigated since plantation. Four fertirrigation treatments were applied during fertirrigation campaigns. Radial growth, meteorological parameters and fertirrigation volume were measured every 15–30 days over four years. It was observed that weather, tree size, debarking and trees’ intra-competition had a significant effect on radial increments. Fertirrigation significantly enhanced growth during summer drought and decoupled increments from air vapor pressure deficit constraints. There was a linear relationship between trees’ radial increments and fertirrigation volume up to 140 m3 week–1. Above this value, increments were smoother. In conclusion, summer fertirrigation of 140 m3 week–1 efficiently enhanced the radial growth of trees with 50–75 circumference at breast height, under the particular edaphoclimatic conditions of the stand. This study showed to be, therefore, promising in the use of efficient fertirrigation the enhance cork oaks’ radial growth.

Ecological Water Requirement in Upper and Middle Reaches of the Yellow River Based on Flow Components and Hydraulic Index.

Deterioration of the ecological environment in the upper and middle reaches of the Yellow River in China substantially impacts the growth and development of aquatic organisms in the drainage basin. This paper builds a conceptual model by applying flow components and fish ecological requirements relation with a relevant object of main fish in the upper and middle reaches of the Yellow River. The paper utilized the flow restoration method by employing the River2D model (two-dimensional model of river hydrodynamics and fish habitat), and a one-dimensional hydrodynamics HEC-RAS (hydrologic engineering center’s-river analysis system). The calculation result showed that the runoff condition required for Silurus lanzhouensis survival is that the monthly lowest flow in a year is 150 m3·s−1, and the lowest flow for suitable flow from April to October is 150 m3·s−1, and 300 m3·s−1 from November to March. The research result is closer to the actual condition and has more outstanding operability. Meanwhile, the results proposed the coupling method of ecological water requirement for the mainstream of the Yellow River. Moreover, the results portrayed the ecological flow process according to the upper envelope of minimum and maximum ecological water requirements of each fracture surface. It is regarded that the ecological flow process is deemed as the initial value of the reservoir regulation model.

An Environmental Flow Framework for Riverine Macroinvertebrates During Dry and Wet Seasons Through Non-linear Ecological Modeling

A suitable environmental flow is critical for the functional maintenance of riverine ecosystems. Hydropower plants alter the flow regime by decreasing or even drying up the streamflow downstream of the dams, thereby affecting ecosystem sustainability. In this study, we aimed to develop a robust environmental flow framework that can provide scientific evidence for sustainable water resource management. Using ecological niche modeling based on non-linear responses of species to habitat factors, we assessed the environmental flow in the Xiangxi River Basin of Central China during dry and wet seasons from a multi-year perspective. The most abundant macroinvertebrate taxon (i.e.,Baetis) was selected for model testing. The results showed seasonal differences in the minimum ecological water requirements and optimal environmental flow. These two hydrological metrics were higher during the wet season than during the dry season. During the dry season, the minimum ecological water requirement ofBaetiswas 1.3 m3·s−1, and the optimal environmental flow was 1.6 m3·s−1. During the wet season, the minimum ecological water requirement ofBaetiswas 2.5 m3·s−1, and the optimal environmental flow was 2.6 m3·s−1. This study provides a theoretical basis for the robust management of water resources in river basins.

Yield Comparisons between Cotton Variety Xin Nong Mian 1 and Its Transgenic ScALDH21 Lines under Different Water Deficiencies in a Desert-Oasis Ecotone

Water scarcity is the major limiting factor for oasis-desert agricultural production of cotton. It is necessary to improve cotton for drought tolerance and minimize drought-related crop losses, and the transgenic approach is efficient for cotton improvement. In order to evaluate the value of ScALDH21 transgenic cotton (G. hirsutum L.), it was tested in the main cotton region of south Xinjiang, in an environment of extreme drought around the desert. Transgenic cotton, overexpressing aldehyde dehydrogenase gene (ScALDH21) from the desiccation-tolerant moss Syntrichia caninervis in cotton variety Xin Nong Mian 1, was field-tested under six treatments based on three irrigation schedules and two irrigation levels (full (FI) and deficit (DI) irrigation) as follows: root zone model-simulated forecast irrigation (F) (FFI and FDI), soil moisture sensor-based irrigation (S) (SFI and SDI), and flood irrigation based on experience estimates (E) (EFI and EDI) to evaluate growth and yield performances. The results revealed that plant height and leaf area increased significantly in ScALDH21-transgenic cotton genotypes under all treatments. Physiological parameters such as chlorophyll content, net photosynthesis rate, and instantaneous water use efficiency were not significantly highly in transgenic lines compared to non-transgenic plants (NT). However, transgenic lines showed significantly improved yield and superior fiber quality than NT plants regardless of irrigation. The results demonstrate that ScALDH21-transgenic lines were excellent compared to NT plants under different water deficiency conditions. The study also provides guidelines for optimal irrigation protocol and minimum water requirements for the use of the ScALDH21-transgenic cotton lines in arid zones.

Stability evaluation and formula optimization of cellulose-based scaffold for the air-liquid interface cultivation of Navicula incerta

Culture scaffolds allow microalgae cultivation with minimum water requirement using the air-liquid interface approach. However, the stability of cellulose-based scaffolds in microalgae cultivation remains questionable. In this study, the stability of regenerated cellulose culture scaffolds was enhanced by adjusting TiO2 loading and casting gap. The membrane scaffolds were synthesized using cellulose dissolved in NaOH/urea aqueous solution with various loading of TiO2 nanoparticles. The TiO2 nanoparticles were embedded into the porous membrane scaffolds as proven by Fourier transform infrared spectra, scanning electron microscopic images, and energy-dispersive X-ray spectra. Although surface hydrophilicity and porosity were enhanced by increasing TiO2 and casting gap, the scaffold pore size was reduced. Cellulose membrane scaffold with 0.05 wt% of TiO2 concentration and thickness of 100 μm attained the highest percentage of Navicula incerta growth rate, up to 37.4%. The membrane scaffolds remained stable in terms of weight, porosity and pore size even they were immersed in acidic solution, hydrogen peroxide or autoclaved at 121 °C for 15 min. The optimal cellulose membrane scaffold is with TiO2 loading of 0.5 wt% and thickness of 100 μm, resulting in supporting the highest N. incerta growth rate and and exhibits good membrane stability.

Quantitative calculation and optimized applications of ecological flow based on nature-based solutions

The current difficulties in determining the ecological flow of rivers in northern China are the poor pertinence of methods and insufficient consideration of ecological factors. On the basis of systematic analysis of river hydrological situations and ecological protection objectives, the existing water ecological problems in river reaches were identified, a nested calculation framework for ecological flow of rivers was given based on Nature-based Solutions (NbS), considering the ecological integrity, biological diversity, morphological diversity and ecological service functions. With help of physical habitat simulation and the Penman-Monteith formula, indicator species were selected to research the natural process of restoring river function and realizing river runoff. To meet the water requirements of riparian vegetation during the growth period of the indicated species, the water demand law of typical vegetation changing with the growth time was studied, the upper and lower water levels were set, and the ecological water requirements of vegetation at each growth stage were determined. The results showed that the ecological basic flows required for the spawning period (April-June), the juvenile period (July-November) and the growth period (December-March) of Pseudorasbora parva in the Long River (typical section) were 3.14 m3/s, 4.32 m3/s and 2.16 m3/s, respectively. At the end of the spawning period, a 7-day (90% guarantee rate) pulse flow with a peak flow of 11.31 m3/s, a small flood process with a peak flow of 24.95 m3/s and a small flood process in the flood season lasting for 3 days provided effective external stimulation for the spawning of Pseudorasbora parva. The minimum annual ecological water requirement of reed was 15,100 m3. The current ecological flow of the Long River can meet the water requirements of most aquatic organisms and plants in the river ecosystem. The ecological flow calculation method based on NbS is widely applicable, and the results are representative. The method can be used to calculate the ecological flow of small and medium-sized northern rivers with a small flow and low flow rate.

Minimum water requirements of cool‐season turfgrasses for survival and recovery after prolonged drought

AbstractWater restrictions may be imposed on irrigation during drought with little regard for damage to turfgrass. Minimal irrigation that may result in dormancy during prolonged drought but allows for recovery thereafter may save water and prevent expensive reestablishment. Our objectives were (a) to determine minimum water amounts in turfgrass during drought that allow for acceptable recovery, and (b) to evaluate turfgrass quality and performance during drought and recovery among irrigation levels. Sodded ‘Seed Research 8650’ tall fescue (TF, Schedonorus arundinaceus Schreb.) and a ‘Mallard’ and ‘Ridgeline’ Kentucky bluegrass blend (KB, Poa pratensis L.) were watered weekly with 0–50% reference evapotranspiration (ETo) replacement during two summers under rainout shelters near Manhattan, KS. Soil moisture, percentage green cover, normalized difference vegetation index, and turfgrass quality were measured weekly. After fall sodding, TF recovered fully after 60–83 d dry downs in both years even without water inputs. However, KB in all ETo treatments did not recover in either year. Irrigation at 50% ETo maintained TF above minimally acceptable quality 15–43 d longer than 0% ETo during drought, recovered 17–18 d faster, and reduced water inputs by 38% compared with 80% ETo, which is usually recommended for well‐watered cool‐season turfgrass. Results indicate TF is better adapted than KB to prolonged drought in the first summer after fall sodding.

Exploration Testing on High-Performance Cement-Based Materials Using Granulated Blast Furnace Slag as Fine Aggregates

This study investigates the feasibility of using granulated blast furnace slag (GBFS) as fine aggregates for high-performance cement-based (HPCB) materials. The mixture ratio of HPCB materials using GBFS as fine aggregates is calculated based on the dense packing theory of aggregates and the minimum water requirement. A series of cement-based material mixes are prepared with three water binder ratios (0.16, 0.18, and 0.2) and three GBFS replacement ratios (0%, 50%, and 100%). Various properties of the cement-based materials, such as the compressive strength, flexural strength, splitting tensile strength, and elastic modulus, are studied. The research on the selected HPCB material compositions using scanning electronic microscopy (SEM), hardened concrete pore structure determination (HCPD), and mercury intrusion porosimetry (MIP) enables a further understanding of the relationship between the mechanical properties and microstructures. The test results show that it is feasible to produce HPCB materials using GBFS as fine aggregates. Despite its large crushing value index and irregular particle shape, GBFS has hydraulic properties that can make up for these disadvantages. GBFS and mixed fine aggregate cement-based materials with good properties can be prepared with a reasonable mix design. The strength of such cement-based materials is consistent with that of ordinary quartz sand (QS) fine aggregate cement-based materials. The compressive, flexural, and splitting tensile strengths of GBFS and mixed fine aggregate cement-based materials may be higher than those of ordinary QS fine aggregate HPCB materials. The relationship between the compressive strength and porosity is in agreement with the formulas proposed by Powers, Ryshkevitch, Schiller, and Hasselman.