Water Balance Method Research Articles

Soil Water Dynamics, Effective Rooting Zone, and Evapotranspiration of Sprinkler Irrigated Potato in a Sandy Loam Soil

Potato (Solanum tuberosum L.) is a very sensitive crop to water stress and timely irrigation water management improves tuber yield and quality. The objectives of this study were to (1) investigate soil water dynamics under potato crops across their root zone and (2) estimate potato crop evapotranspiration (ETa) under sprinkler irrigation on the sandy loam soil. The field experiment was conducted during the 2018 and 2019 growing seasons at the Navajo Farms within the Navajo Agricultural Products Industry, Farmington, NM. Two irrigation scheduling methods were evaluated as FAO-56 approach evapotranspiration-based scheduling and soil moisture sensing irrigation scheduling. Sentek capacitance soil moisture probe was used across four commercial potato fields in each year after calibration to the soil texture just after installation. Crop Evapotranspiration values estimated by the water balance method and the two-step approach were compared to the satellite-based models used in OpenET. The results showed that the potato’s effective rooting zone is the upper 40 cm soil layer. Potato plants extracted more than 50% of total water from the upper 15 cm of the soil profile and about 85% from the upper 40 cm of the soil profile. Little water amount was extracted from the 40–60 cm soil water. Potato crop seasonal evapotranspiration averaged 580 to 645 mm in 2018 and 2019, respectively. The Two-step approach ETa values of 795.5 and 832.7 mm in 2018 and 2019, respectively, were higher than the soil water balance estimated ETa. The satellite modeled ETa varied with field and years and ranged from 437 to 759 mm and averaged 570.4 mm for the 2016–2020 period. Soil moisture probe-based irrigation scheduling improved irrigation water management and the irrigation water use of potatoes in the semiarid climate.

Application of Budyko framework to irrigation districts in China under various climatic conditions

AbstractBudyko's framework has been widely used to study basin‐scale water balance. In this study, we focus on the extended application of Fu's equation (one formulation of the Budyko‐type curves) to 371 large irrigation districts in China over a period of 2010–2017. Water balance method was used to estimate actual evapotranspiration in the irrigated areas. Considering the contribution of shallow groundwater to , the water availability in the Budyko framework defined as equivalent precipitation for irrigation areas is the sum of irrigation water , precipitation and groundwater evaporation . Results showed that the relationships between evapotranspiration , water availability and energy supply can be accurately described by the Budyko's curves. The optimal values of Budyko parameter ω for each irrigation district was obtained with multi‐annual data using least square method. The Fu's equation performed better in humid and semi‐humid regions than arid and semi‐arid regions. The comparison between and confirmed the relative effect of water availability and energy supply on according to the variation of climatic conditions. Normalized difference vegetation index (NDVI) and soil properties (denoted by the proportion of clay and sand) were selected to develop empirical equation for parameter ω using multiple linear regression analysis method. This study shows that the Budyko framework can be extended to irrigation areas and provides useful information on evapotranspiration to assist in water management in irrigation areas.

Estimating surface flow based on the equation of heavy rain type LnLn / Estimativa do escoamento superficial baseado na equação de chuvas intensas do tipo LnLn

Runoff simulation is important in modeling various hydrological processes with application in agricultural engineering. The estimate of the surface runoff by the soil water balance method, developed by the Research Group on Water Resources at the Federal University of Viçosa, Brazil, is based on the IDF equation. This work aimed to adapt the methodology for use in locations with the LnLn-type equation. The equations for estimating the maximum instantaneous rainfall intensity and other adaptations for estimating the surface runoff were presented. Based on the intense rainfall equations of Piracicaba and Andradina, located in the state of São Paulo, Brazil, considering soils with a basic infiltration rate of 10, 25 and 50 mm.h-1, the values of the soil water balance method were presented. The results showed that the differences obtained are due only to errors in the estimation of rainfall intensity due to the method of adjusting the parameters of the intense rainfall equations and that the equations presented in this article allow the use of the maximum flow depth estimation method. surface water balance for sites with the LnLn type equation.

Comparisons of three scaling up methods to estimate stand transpiration of a xerophytic shrub (Salix psammophila) in northern China

Transpiration (T) is a key hydrological process, delivering water essential for plant metabolism and thus affecting productivity. A major challenge in estimating stand T is how to accurately scale sap flow data from individual trees to the stand. In shrub ecosystems, various scaling up methods have been used to extrapolate tree-level sap flow measurements to stand-level T, these include leaf area, cross-sectional area and number of branches. However, the performances of different scaling up methods have not been fully explored for shrubs. In this study, we measured sap flow of a xerophytic shrub (Salix psammophila) and scaled up using measures of leaf area, cross-sectional area and numbers of branches in order to estimate stand T during the rainy seasons in 2019 and 2020 on the northern Loess Plateau, China. In addition, we measured precipitation, throughfall, stemflow, soil evaporation, surface runoff and 0–200 cm soil water content to calculate actual stand T on the basis of soil water balance method. The results revealed that daily stand T differed according to the scaling up methods used for the estimation. Daily estimated stand T based on measures of leaf area (0.1–13.1 mm d−1) was consistently higher than those based on cross-sectional area (0.2–8.6 mm d−1) and number of branches (0.4–8.9 mm d−1) (p < 0.05). During the two rainy seasons, the actual daily mean stand T (2.5 ± 1.6 mm d−1) was significantly lower than the estimation by the three scaling up methods (p < 0.05). The method based on cross-sectional area appeared to be most suitable for scaling up because it had the lowest root mean square error and bias values (0.939 mm d−1 and 0.633 mm d−1, respectively). This study highlights the wide variations of stand T upon which scaling up method was chosen, and these differences need to be considered when converting tree-level sap flow to stand-level T in shrub and other ecosystems.

Evaluating the Potential of Different Evapotranspiration Datasets for Distributed Hydrological Model Calibration

Evapotranspiration (ET), a key component of the hydrological cycle, has a direct impact on runoff and water balance. Various global satellite-based and numerical datasets provide continuous and high spatiotemporal resolution data, which makes it possible to calibrate hydrological parameters against ET. However, the accuracy of ET datasets varies with region and algorithm, introducing uncertainties in hydrological parameter calibration. This study focused on evaluating the potential of different ET datasets in the calibration of distributed hydrological model parameters. Five different ET datasets (PML, SEBAL, EB-ET, GLASS, REA-ET) were evaluated using the water balance method to explore the effect of intrinsic dataset accuracy on applications. The benchmark calibration scheme calibrated parameters by using observed streamflow data from the outlet. Two calibration schemes were proposed to take advantage of the temporal dynamics and spatial patterns of the raw ET datasets. The results show that the model parameters calibrated by all selected ET datasets produced satisfactory results in streamflow simulations. These results were dependent on the calibration schemes and accuracy of ET datasets. Overall, the scheme calibrated by using temporal dynamics of ET at the grid scale provided better streamflow simulations at the basin outlet than the scheme calibrated by using spatial patterns of ET at the basin scale. Three metrics (bias, root mean square error [RMSE], and correlation coefficient [R]) showed that there is a high potential for selected ET datasets to improve soil moisture simulations, as compared to the benchmark scheme. Parameters calibrated by EB-ET and PML datasets provided the best performance in the simulation of streamflow at the outlet and the sub-basin scale. The calibration case with the SEBAL dataset showed the highest potential to improve soil moisture simulation. The annual average ET estimates of these three datasets were closest to the water balance-based ET values.

Remote sensing and soil moisture data for water productivity determination

This work was initiated in 2019 within the FAO WEPS project framework (2018–2022), aiming to determine the Water Productivity (WP) of the Tunisian olive orchards combining two scales of measurements for soil moisture determination: one for the global analysis (remote sensing) and the other for the field scale application. The experiment was made in 2019 and 2020 in the Centre of Tunisia (Kairouan city, locality of Elhouereb), which is one of the largest irrigation area of Tunisia. WP was computed regarding the actual crop evapotranspiration (ETa) which was determined following the water balance method as: ETa=R+I–ΔS, where ΔS is the amount of water stored in the soil (0–60 cm) and (R) and (I) are the amounts of the seasonal rainfall and the irrigation volume, respectively. The annual ETa reached 293 mm for the rainfed orchard, 823 mm for the semi-intensive irrigated plantation and 819 mm for the intensive fertigated orchard. The WP defined as being the ratio of Yield (kg olives/tree)/ETa ranged between 0.29 kg/m3 (rainfed) and 0.77 kg/m3 (fertigated) depending on the cultivation system. Soil moisture was found to be correlated to the average backscatter coefficient (r = −0.34 for the rainfed and 0.91 for the irrigated orchards) which was determined from the radar images which were treated by using different applications (SNAP, ODK, QGIS.), This result shows the performance of the remote sensing tools for such application. To conclude: WP is at least two times higher in the irrigated orchards than in the rainfed grove; this indicates a great potential of WP improvement if the horticultural practices are well applied in the orchad (pruning, irrigation); so that, the WP can be used as a decision-making-tool for farmers and makers in the future.

Evaluation of evapotranspiration estimation under cloud impacts over China using ground observations and multiple satellite optical and microwave measurements

Evapotranspiration (ET) is an important component of the hydrological cycle and energy balance in a land-atmosphere system. Satellite remote sensing has been widely used to estimate regional and global ET, but most previous methods depend on optical measurements that are limited to cloud-free conditions. This makes ET estimation challenging under cloudy sky. Currently, evaluations of satellite ET estimation under various cloud conditions remain lacking at the regional scale. Owing to the ability to penetrate clouds, satellite passive microwave measurements are powerful tools for retrieving ET under clouds. This study evaluated a satellite microwave-based daily ET method under all sky conditions over the part of China between 18°N and 50°N from 2003 to 2010, using microwave emissivity difference vegetation index (EDVI) as the proxy of vegetation water content (VWC). Validations using the surface water balance method found that the estimated ET (EDVI-ET) had an overall small bias (6.18%) in eight river basins. EDVI-ET displayed consistent spatiotemporal patterns with global MOD16 ET, with high spatial correlation (R>0.71) and monthly temporal correlation (R>0.82) throughout four seasons. Their differences were also small (<0.56mmday−1) in forests, savannas, grass/shrubs, and croplands. Furthermore, cloud impacts on the regional ET were found to be significant and spatiotemporally heterogeneous. Both EDVI-ET and in-situ observations at seven flux towers indicated that cloud-induced reduction in daily ET could exceed 30% when the cloud cover increased by 60% (R2 of 0.42, fitting line slope of 0.80, p<0.001). Under increased cloud conditions in summer, the changes in net radiation dominated the ET over dense vegetation in southern China, while the roles of air temperature and humidity increased over water-stressed barrens and short vegetation in northwest China. VWC affected EDVI-ET under clouds in temperate transitional zones from flatlands to highlands. This study highlighted the importance of cloud impacts in satellite ET estimation.

Водопотребление овощных культур в нечерноземной зоне России

The subject of research is the development of a method for calculating the total water consumpt ion of vegetable crops, aimed at increasing the accuracy of its determination, in the conditions of the Non-Chernozem zone of Russia, and saving water resources. The object of these studies are sod-podzolic soils and soil moisture, vegetable crops. Scientifi c research was carried out in lysimeters, on experimental plots and in the laboratory, in years with different meteorological conditions. Physical modeling, the method of water balance, the theory of groundwater fl ow and mathematical statistics were used in the processing and analysis of scientifi c research. Experiments in lysimeters in plots in 2010… 2015, served as the basis for the development of a formula for determining the total water consumption of vegetable crops. At the same time, empirical coeffi cients for this equation were obtained, characterizing the type of soils and the climatic zone. Biological coeffi cients for stem beets, potatoes, table carrots have been established, as well as coeffi cients depending on soil moisture when it decreases below the optimal values for these crops. A decrease in the total water consumption of vegetable crops at the beginning and end of the growing season was determined. A graph of the dependence of the actual total water consumption of the crops under consideration Ef (data from experimental plots) with the calculated Ep according to the formula is given, showing a close relationship between the considering features. A formula has been developed that we recommend using to determine the water consumption of vegetable crops in the Non-Chernozem zone of Russia.

Studies on Water Balance and Groundwater Budgeting in Godawari-Purna Sub-basin

The Godawari-Purna sub basin is located between 76°36' to 77°59' E and 19°07' to 19°17' N with an area of 34413.87 ha falls in assured rainfall region. The basin boundary was updated using the updated drainage and terrain information from high resolution satellite data of LISS-IV using GIS tool. Based on the last 30 years rainfall records, the runoff potential was estimated using SCS curve number method. Marathwada region of Maharashtra state has always been a water deficit area which calls for immediate remedial measures to address the critical water resources situation in the region. The entire Godawari-Purna sub basin (GP sub basin) is hard rock terrain. It suffers from growing water scarcity, which is aggravated by frequent droughts. The various water balance components viz. soil moisture storage, ground water recharge and surface storage were estimated for the GP basin. Similarly, the input from the rainfall was also worked out. The various losses such as runoff, evaporation from water bodies were estimated and accordingly the water available in the basin was estimated. The estimated values of ground water recharge were considered for water balance analysis. The surface water storage in each sub basin was estimated considering the water storage area as per satellite image and thus the storage volume was estimated. Combining the soil moisture storage, surface water storage and ground water recharge, water availability was estimated for each sub basin. The surface runoff was estimated by water balance method considering the rainfall volume and losses in each sub basin. Water balance study reflected that sub-catchment No. I, IV, VI and VIII of GP sub basin are under total water deficit and require urgent attention for water management to meet out the water deficit

Evaluation of soil moisture and evapotranspiration variation using water balance methods in Indian Mustard (Brassica juncea)

Evaluation of soil moisture and evapotranspiration variation using water balance methods in Indian Mustard (Brassica juncea)

Estimating Evapotranspiration of Maize under Different Management Practices in a Semiarid Tropical Area Using the Soil Water Balance Method

Smallholder farmers in semiarid areas face low and erratic rainfall and need field management practices that conserve water in the root zone. This work evaluated the effect of mulching and DD (deep tillage) practices as a way to conserve soil moisture and thus improve water availability and maize crop yield in this water-scarce environment. The field experiment was carried out in which the soil moisture content (SMC) was monitored and the other water balance components were measured to quantify the crop ET with the soil water balance (SWB) method. The components of the SWB (rainfall, supplemental irrigation, runoff, deep percolation and change of soil moisture content) were measured for three consecutive seasons of 2018-2019, i.e. two long rain seasons (Masika 2018 and 2019) and one short-rains season (Vuli 2018). The estimation of the deep percolation (DP) involved calculating water fluxes from hydraulic properties measured in the laboratory and from hydraulic gradients measured with tensiometers in the field plots. Treatments significantly affected ET (p ’ cultivation, FC), mulching (FCM) reduced evapotranspiration by 14% and 18% during more water-stressed seasons of Vuli 2018 and Masika 2019. The ET reduction among the treatments was in line with the reduction in soil evaporation, as reflected in the results (of the other article of the same work). The crop transpiration was observed higher, which was consistent with the higher canopy cover observations for the two treatments relative to the FC treatment. Also, while the mulch practice did not affect ET during the first and less water-stressed season of Masika 2018, DD reduced it by 9% and showed no effect during other seasons.

基于水源涵养参照系的中国生态系统水源涵养功能优劣评估

PDF HTML阅读 XML下载 导出引用 引用提醒 基于水源涵养参照系的中国生态系统水源涵养功能优劣评估 DOI: 10.5846/stxb202107161912 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研究计划（2016YFC0500204）；中国科学院战略性先导专项（XDA20010202）；广西科技重大专项（桂科AA20161002-3） Evaluation of water conservation of China's ecosystems based on benchmark Author: Affiliation: Fund Project: the National Key Research & Development Program of China (2016YFC0500204) 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:为解决水源涵养优劣评估结果空间可比性差的问题，在拟合1990-2018年中国生态系统水源涵养动态数据基础上，构建基于参照系的水源涵养功能优劣等级评估方法体系，从全国和分区尺度揭示中国生态系统水源涵养功能优劣格局与演变规律，阐明该方法的优越性。结果表明：（1）2015年中国全国生态系统水源涵养功能以差级别占主导，约占总面积的44.8%，主要分布于西北、青藏高原、华北平原和东北平原。1990-2018年中国生态系统水源涵养功能中等级面积极显著降低，差等级面积显著增加，其余类型呈波动变化。（2）各气候区生态系统水源涵养优劣等级构成因气候、生态系统构成等差异而不同，一般为气候区愈湿润，其优良等级比重愈高。1990-2018年，共有10个气候区的优、良、中、低或差等级面积发生了显著变化，主要为优、良、中等级以显著降低为主，差等级全显著增加。（3）与其他方法相比，基于参照系的生态系统水源涵养功能优劣评估法因引入分区分类评估思想，评估结果更科学，空间可比性显著提高。 Abstract:Water conservation was one of the important ecological service function of terrestrial ecosystems, which covered the hydrological processes of water in vegetation, soil, atmosphere and animal systems. the change in water conservation of ecosystems was not only directly affected the regional ecosystem status (e.g., regional climate hydrology, vegetation and soil conditions), but also restricted the regional social, economic and ecological sustainable development. Therefore, the evaluation of regional ecosystem water conservation function has become an important part of ecological services research. Although there were many achievements in the researches on the conception, calculation of function and value, and transfer of of ecosystem water conservation, and its ecological compensation across regions. There was still no recognized method to evaluate the level of ecosystem water conservation function, therefore, there were no comparison between most of the previous studies on the level of water conservation function. Because the water conservation calculated based on water balance method was mainly restricted by meteorological conditions, the comparability of the level of water conservation function in different periods were also lower, all those factors greatly reduced the application value of the previous evaluation on the level of regional ecosytem water conservation function. In order to solve the problem of poor comparison in the pros and cons evaluation of water conservation, the evaluation method system of grade of water resource conservation function was constructed based on the water conservation benchmark after fitting the dynamic data of China's ecosystem water conservation from 1990 to 2018, and determining the water conservation benchmark of each evaluation unit. Then the pattern and evolution of the grade of water conservation function in the Chinese ecosystems were revealed on the national and regional scales, and its advantages and disadvantages were also illustrated. The main results were as follows:(1) the grade of water conservation of China's national ecosystem was dominated by poor grade, accounting for 44.8% of the total area, and mainly distributed in northwestern China, Qinghai-Tibet Plateau, North China Plain and Northeast China Plain in 2015. The area of the medium grade of water conservation in China's ecosystem decreased significantly from 1990 to 2018, while the area of poor grade of water conservation in China's ecosystem increased significantly, and the areas of the others grades showed no significant regular fluctuations. (2) The grade composition of ecosystem water conservation was different between climate zones because of the differences in climate, ecosystem composition, human disturbance, and so on. Generally, the wetter the climate zone was, the higher proportion of the excellent grades was. There were 10 climate zones which area of the excellent, good, low, or poor grade of water conservation significantly changed from 1990 to 2018. The main performances were that the areas of excellent, good, and medium grades of ecosystem water conservation were significantly reduced, while the areas of poor grade were all increased. (3) Compared with the other two methods, the evaluation method of the ecosystem water conservation based of water conservation benchmark was more comparable and scientific due to the introduction of the research idea of subarea and classification. 参考文献 相似文献 引证文献

Surface flow of melted snow water on the central Russian upland

In areas with a pronounced relief, water erosion causes great harm to agriculture and other sectors of the national economy. It leads to the destruction of the soil cover, a reduction in the area of arable land, a decrease in fertility, the removal of erosion products into floodplains, the siltation of ponds and rivers and the destruction of the road network. The scientific goal was to identify the influence of the main natural factors (snow reserves, freezing and soil moisture) on the formation of the spring melt water runoff on the plow. To study the questions raised, the water-balance method was used with the use of runoff sites. Observations showed that the formation of the melt water runoff depended on the depth of soil freezing. With shallow soil freezing up to 50 cm, there was no runoff. All the melt water was absorbed by the soil. As a result of 30 years of research (1991-2020), it was found that the average annual runoff on the plow was very weak - 3.8 mm on the scale of Surmach, the runoff coefficient is 0.05, shallow soil freezing - 19-28 cm, duration of snow melting - 16 days.

Зависимость комплексной гарантированной водоотдачи от регулирующего объема водохранилища

The purpose of the study is to generalize the methodology for solving one of the common engineering problems solved in the development of basin schemes and water management projects, assessment of the parameters of reservoirs of complex purpose. The article analyzes the methodology of construction and practical use ofthe dependence of the complex reservoir guaranteed output onthecalculated hydrological characteristics, the reservoir usable storageand water resourcesprovision for requirements coverage. The role of reservoirs for the development of the integrated use schemesand reservoir water resources using rules to solve the most important water management problems is shown. The engineering and mathematical statement of the problem is formulated. The representativeness of long-term hydrological series by their duration is analyzed, when the relative errors of parameters are put in accordance with the serieslength. It is shown that consideration of the in-series connection (coeffi cient of autocorrelation) and an increase in changeability by 30% leadto the increase in the minimum required duration by several times. On the example of specifi c water objects, the Tsimlyanskiy hydroelectric complex and the cascade of reservoirs of the upper Tobol, the practical application of the generalized method and simulation modeling of the long-term water balance is considered. A variant of water supply scheme to the defi cient areas of Donbass with the involvement of the Severskiy Donets resources for their long-term regulation in the Krasnopavlovsky reservoir (currently not used as a regulating capacity) is presented. Based on the analyzing dependence «capacity-yield», an assessment of additional guaranteed water resources was obtained. With regard to the transboundary section line on the Tobol River, the assessment of the real water yield was obtained by simulation modeling according to the authors’ methodology. The expediency of using simulation and optimization modeling is discussed. The relevance of the topic is noted in connection with the cross-sections topologyand the reservoirsregulating capacity that have been changing for decades. It is rec ommended to discuss the raised issues at conferences and in publications.

Analysis of the availability of water resources using the Thornthwaite-Matter water balance method with dual reservoir development in residential locations in Tangerang regency

Many settlements still use groundwater sources and this can cause a decrease in the ground water level. There is a need for alternative sources of water to meet the water needs of settlements. The purpose of this study was to determine the magnitude of the surplus or deficit of water in Tangerang Regency, Indonesia and also to determine the amount of water demand for the population in the region. Therefore, it is necessary to analyze the planning of dual reservoirs in providing groundwater for residential areas in overcoming the problem of drought in the dry season. This research method uses Thornthwaite-Matter water balance analysis and multiple reservoir design planning. The results showed that the estimated water surplus occurred from January to April with a magnitude between 25.07 mm to 186.09 mm. The water deficit occurs from July to October with a magnitude between 127 mm to 219 mm. The pattern of water consumption in the household is used as a reference for making reservoirs to maintain the availability of air in residential areas. The dual reservoir will be equipped with sensors that can help determine the water level so that it is easy to detect water needs and can prevent water wastage.

The State-of-the-Art Estimation of Groundwater Recharge and Water Balance with a Special Emphasis on India: A Critical Review

Groundwater recharge estimation is essential for sustainable water management and water supply schemes. In this paper, we review groundwater recharge estimation techniques and identify the appropriate methods by considering India’s hydrological and climatic conditions. Significant components of recharge, factors affecting groundwater recharge, aquifer systems of India, and historical groundwater recharge estimation practices are reviewed. Currently used recharge estimation methods are assessed based on case studies. The most popular estimation methods are studied and compared based on their application in various regions. It is observed that the accuracy of the recharge estimates is largely influenced by false assumptions, the possibility of erroneous measurements, a potential lack of reliable data, and a variety of problems associated with parameter estimation. The suitability of different methods for a region is found to depend on time and space considerations, the objective of the study, hydrogeological condition, and availability of data. In Indian conditions, it is suggested to use water table fluctuation and water balance methods for the recharge estimation, provided that accurate water level measurements are assured.

Analysis of the additional cost of addressing per- and polyfluoroalkyl substance contamination from landfill leachate by reverse osmosis membranes in Thailand

Per- and polyfluoroalkyl substances (PFAS), persistent organic pollutants, have been found in landfill leachate (LL) and can lead to environmental contamination. Recently, more stringent global regulations to control the maximum levels of PFAS have forced landfill authorities to improve treatment technologies to meet higher effluent quality standards. This study analyzed the additional cost of the treatment process to remediate PFAS contamination from LL in Thailand using a two-pass reverse osmosis (RO) system, including pretreatment and the use of evaporation ponds. The total estimated LL volume from 111 sites of sanitary landfills was ascertained using the water balance method, and then the overall project cost in the form of the net present cost (NPC) was evaluated. The capital investment, expense, and related operating and maintenance costs over the project lifetime were taken into account. The results showed that the total estimated LL volume was 17.5 m3/yr. To handle this amount of LL, the NPCs of the RO system were found to be 577.9 mil. USD for the system with an evaporation pond and 391.9 mil. USD for the system without an evaporation pond. The treatment unit costs ranged from 1.72–2.71 USD/m3 for the system with an evaporation pond and ranged from 1.06 to 2.09 USD/m3 for the system without an evaporation pond, depending on the size of the landfills. Based on these results, technological, operational, financial, and regulatory policy recommendations are presented.

Evaluations of Remote Sensing-Based Global Evapotranspiration Datasets at Catchment Scale in Mountain Regions

Evapotranspiration (ET) is essential for connecting ecosystems and directly affects the water consumption of forests, grasslands, and farmlands. Eight global remote sensing-based ET (RS_ET) datasets generated using satellite imagery and ground-based observations were comprehensively assessed using monthly ET time series simulated by the water balance (WB) method at the catchment scale in the Hengduan Mountain (HDM) region, including the Nu River, Lancang River, and Jinsha River basins. The complementary relationship (CR) model, which derives ET from meteorological data, was also evaluated against WB-based ET (WB_ET). In addition, WB_ET, RS_ET, and CR-based ET (CR_ET) data were used to investigate ET spatial and temporal variations at the catchment, grid, and site scale, respectively. Most RS_ET datasets accurately simulated monthly ET with an average index of agreement ranging from 0.71–0.91. The Operational Simplified Surface Energy Balance dataset outperformed other RS_ET datasets, with Nash–Sutcliffe efficiency coefficient (NSE) and Kling–Gupta efficiency values of 0.80 and 0.90, respectively. RS_ET datasets generally performed better in northern semiarid areas than in humid southern areas. The monthly ET simulation by the CR model was consistent with that of the WB_ET in the HDM region, with mean values of correlation coefficient (cc) and NSE at each site of 0.89 and 0.68, respectively. The model showed better performance in simulating monthly ET in the Lancang River Basin than in the Nu River and Lancang River basins, with mean cc and NSE of 0.92 and 0.83, respectively. Generally, annual ET trends were consistent at the catchment, grid, and site scale, as estimated by the WB method, RS_ET datasets, and CR model. It showed a significant decreasing trend in the northern semiarid region of the HDM while exhibiting an increasing trend in the humid southern region.

Impact of active night population and leakage exponent on leakage estimation in developing countries

Abstract Methods for network leakage estimation include water balance, component analysis and minimum night flow (MNF) methods, the latter of which involves subtracting the customer night use (QCNU) from night leakage and multiplying by the hour day factor (HDF). QCNU and HDF respectively depend on Active Night Population (ANP) and leakage exponent (N1). In most developing countries, these parameters are assumed in the MNF method, thus introducing errors which makes setting realistic leakage reduction targets and key performance indicators (KPI) problematic. In this study, QCNU and HDF were evaluated by determining the relative error associated with ANP and N1 to establish localized rates for accurately estimating leakage in water networks. Between 7 and 11% relative error was associated with every 1% higher or lower ANP while up to 4% relative error was observed for every step considered. A linear relationship exists between the relative error associated with both and ANP although that of ANP is twice as high as This has technical implications for setting water loss reduction targets and investing in the water infrastructure. It is recommended that water utilities must establish localized ANP and values for accurate leakage estimation in water networks.

Determining water use and crop coefficients of drip-irrigated cotton in south Xinjiang of China under various irrigation amounts

Crop evapotranspiration (ETc) and crop coefficient (Kc) can vary among various geographical locations and cultivated species. Therefore, determining regional- and species-specific crop coefficients is fundamental for rational irrigation water management. A two-year field study was conducted in south Xinjiang of northwest China to estimate periodic ETc and reference evapotranspiration (ET0), and thus develop the regional crop coefficient (Kc) at various growth stages of fertigated cotton (Gossypium hirstum L. Xinluzhong No 67) under various irrigation amounts. ETc was determined by the soil water balance method, while ET0 was obtained using the FAO (Food and Agriculture Organization of the United Nations) Penman-Monteith model. The results indicated that increasing irrigation amounts resulted in increased seed cotton yields, but reduced crop water productivity (WP). The water consumption at flowering and boll setting stages accounted approximately for 60% of the seasonal water use of cotton under various irrigation amounts. The average locally developed Kc (Kc-local) values over two seasons were 0.38, 1.30 and 1.09 for initial, mid-season, and end-season stages, respectively. The locally developed initial Kc (Kc-local-ini) (0.38) was higher than the optimized initial-stage Kc (Kc-opt-ini) (0.23) and similar to the FAO recommended Kc (Kc-FAO) (0.35). The optimized Kc (Kc-opt) did not significantly differ from Kc-FAO at mid-season and end-season stages. The locally developed middle-stage Kc (Kc-local-mid) was 10% higher than the optimized middle-stage Kc (Kc-opt-mid) and the FAO recommended middle-stage Kc (Kc-FAO-mid), and the locally developed end-stage Kc (Kc-local-end) was approximately 82% higher than the optimized end-stage Kc (Kc-opt-end) and the FAO recommended end-stage Kc (Kc-FAO-end). The difference between Kc-local, Kc-opt and Kc-FAO was attributed to the variations of climate condition, cultivated variety and field management. Kc-local determined by the soil water balance method in the present study fully considered the regional conditions including weather, species and management practices, which can be adopted to guide the irrigation management in this region. This study provided credible cotton periodic Kc in the arid and semiarid regions of northwest China. A second-order polynomial relationship between cotton Kc and t/T (the days after emergence/the days of total cotton growth period) was established, which can provide a reference for the determination of local cotton Kc and irrigation management.