Water Balance Analysis Research Articles

Influence of Infiltrations on the Recharge of the Nkoabang Aquifer Located in the Center Region, Cameroon

Due to the limited reach of the drinking-water delivery network, Yaoundé’s surrounding communities (such as Nkoabang) rely on well water, boreholes, and springs. This study conducted a Thornthwaite water-balance analysis in the watershed in order to understand its hydrology capability and investigated the influence of the flows and infiltrations on the recharge of the aquifer of Nkoabang (Centre Region, Cameroon). The methodology of this work consisted of updating the rainfall and temperature data of the Mvan meteorological station in Yaoundé to carry out the hydrological and water balances of the Nkoabang aquifer and performing the piezometric monitoring of seven wells and one spring in the dry season and the rainy season. The average rainfall height for the period between 1951–2017 was 1577 ± 222 mm, while the monthly temperatures ranged from 22.8 (July) to 25.4 °C (February) for an average of 24.1 °C ± 0.8 °C. The average interannual infiltration was 137 mm, corresponding to an infiltration coefficient of 8.68%. The value of the piezometric levering varies between 706 and 718 m for an average of 711.76 m during the dry season. It fluctuates between 706 and 719 m during the rainy season for an average of 712.95 ± 4.09 m. Irrespective of the season, the highest and lowest values are those of P6 and P3, respectively. Piezometric level values vary little from one season to another but are higher in the rainy season than in the dry season. Wells in the study area generally show small variations in piezometric level amplitude, ranging from 0.4 to 3.3 m with an average of 1.19 ± 1 m. The analysis of the piezometric map of the Nkoabang aquifer shows a flow in the NE-SW direction; storage areas south of the study areas and the water supply area in the peaks and NE of Nkoabang. The daily indicative flow rates of the spring (S) are 0.15 m3 (dry season), which can supply in the dry and rainy seasons 36 to 46 people, respectively, based on a ratio of 0.1 m3 per day per habitant.

Quantitative Effect Analysis of Rainwater Harvesting System based on Water Balance Analysis

The rainwater harvesting system (RHS) is a facility installed in accordance with the ｢Act on promotion and support of water reuse｣ and is currently installed in various buildings such as apartment houses, business facilities, schools, and sports facilities. Rainwater is used for various needs, such as toilet flushing water, tree irrigation, road cleaning water, and landscaped facilities. In this study, rainwater utilization was calculated by performing a water demand-supply time series analysis through a hydrological water balance analysis. The water supply-supply time series water balance analysis was performed based on the recent ten-year period, and the water balance analysis for RHS analyzed the supply satisfaction, rainwater utilization, and rainwater coverage rates according to the demand scenarios of each facility. Through this method, it is expected to become a support tool for planning and operating the storage tank capacity of the target facility by confirming the rainwater utilization for various RHSs with different building uses and demand sources.

기개발도시 물순환 체계구축을 위한 저영향개발기법 도입 개선방안 : 광주광역시 상무지구를 중심으로

LID techniques are being applied to build urban water circulation, but most of them are applied to basic urban plans such as the development of new cities and new development projects such as district unit planning. In this study, we derive LID application scenarios for establishing an appropriate water circulation system by selecting an old town. The applicability was reviewed through an effectiveness analysis. In addition, we identified problems in the LID introduction process and suggested ways to improve them, and conducted research with the following purposes.BR The target area was selected as the Gwangju Metropolitan City Sangmu District, which is an old town. The LID application scenarios were derived for establishing an appropriate water circulation system in the old town, and the effects of water balance analysis and non-point pollution sources were analyzed for each scenario. Finally, the problems of the LID introduction process were analyzed and an improvement method was proposed for establishment of the water circulation system.BR Urban environmental problems, such as urban development in an old town, are expected to be more diverse and increase, and one such problem will include environmental issues due to changes in water circulation. The need for LID techniques to solve these water circulation distortion problems will continue to increase. It is necessary to apply LID techniques to restore water circulation in the old town, as well as legal and institutional improvement methods that can support them.

Spatial-temporal heterogeneity analysis of blue and green water resources for Poyang Lake basin, China

Poyang Lake basin has drought-prone pattern and floods in recent decades, posing a serious threat to water security and human life. In this research, the Soil and Water Assessment Tool (SWAT) was applied to investigate hydrological parameters characteristics, simulating uncertainties as well as spatial and temporal patterns of both blue and green water resources for the whole basin. The results revealed a strong correlation between the observed and simulated streamflow at six hydrological stations. The overall hydrological water balance analysis showed that 58.1 % of annual water yield is contributed by surface runoff, while groundwater flow contributes 38.8 % of annual water yield. The annual average blue water resource was higher accounting for 65.1 % of the total water resources. Green water coefficient was 34.9 % for the entire basin, varying from 26 % to 50 %. The spatial distribution of blue water resource was uneven in the basin with higher value in parts of the Ganjiang, Xinjiang and Raohe subbasins. While distribution of green water resource was more homogeneous. Blue water resource decreased significantly in Raohe subbasin with −37.1 mm/a whereas having no significant variability in other river basins from 1992 to 2010. The change of green water resource is caused mainly by the increase of green water flow in most subbasins. The results provide insights into prediction uncertainty reduction of simulation as well as green and blue water endowments. This research is of great significance to improve water resources management in Poyang Lake basin.

A remote sensing-based method for daily evapotranspiration mapping and partitioning in a poorly gauged basin with arid ecosystems in the Qinghai-Tibet Plateau

Accurate estimation and partitioning of terrestrial evapotranspiration (ET) is essential for understanding the hydrological cycle and water use efficiency at different scales. Such knowledge is particularly important for sustainable water resources management in arid ecosystems. A daily scale framework for continuous ET mapping and partitioning was proposed in this study based on a universal solution of the traditional Ts-VI models. Its essence is to transform the Ts-VI feature space from regional to pixel scale on the basis of surface energy balance principle. Consequently, the ET estimation and partitioning was only related to the boundary conditions at pixel scale, regardless of the Ts-VI configuration over the spatial domain. We demonstrated the framework with MODIS (Moderate Resolution Imaging Spectroradiometer) products in Qaidam Basin, a poorly gauged basin with arid ecosystems in the Qinghai-Tibet Plateau in China. The scheme was performed pixel by pixel using as much of the remote sensing observations as possible, aiming at that it could be applied to other poorly gauged regions. The comparative analysis indicates that our ET estimates agreed well with three readily available ET products and those retrieved from water balance analysis. The advantages of our universal Ts-VI model mainly lie in its high spatial resolution and daily continuity, which enables it to capture the spatial details and temporal variations more accurately. The results show that our annual average ET estimation from 2001 to 2020 was around 179.20 mm/year, which was very close to its annual average precipitation. The annual average soil evaporation (E) and plant transpiration (T) was 168.77 and 10.43 mm/year, accounting for 94 % and 6 % of the total ET, respectively. ET in Qaidam Basin decreased generally from southeast to northwest and from surrounding mountains to the interior with significant vertical zonality. Consequently, ET of different landscapes followed the order: woodland > shrubland > alpine vegetation > alpine meadow > bare rock > alpine grassland > salt crust > desert grassland > bare soil > gobi > sandy land. As an arid basin, the spatial distribution of ET in Qaidam Basin was mainly controlled by precipitation. However, with the further decrease of temperature in high mountains, ET started to be controlled by energy availability rather than water availability. Accordingly, the variations of our ET estimates with altitude increased first and then decreased, with a peak value of 287.67 mm observed at altitudes of 4600–4800 m.

Analysis and Prediction of Water Balance Using Dynamic Modelling to Solve Water Scarcity in Cimahi

Cimahi is one of the most populated, fast-growing cities in Indonesia. Consequently, various environmental problems appear, primarily related to the sustainability of water resources. Exploitation and pollution of water, especially groundwater, are not accompanied by a good water conservation system that ensures proper water infiltration into the soil, causing several locations in the city to experience water deficits. The city may suffer a severe water shortage if this problem is unsolved. This study aims to predict and analyze the need and availability of water in Cimahi in the next few years to determine the right solution to deal with this problem. Analysis and prediction of water availability/needs were carried out by building a dynamic model using STELLA software for simulating the conditions in the next ten years. The results of the model were combined with the applicable spatial policies to formulate possible solutions. Results showed that Cimahi will experience a water crisis starting from 2029 with a total water deficit of 8.22 million M³. The model also predicted South Cimahi District is the area with the worst conditions where the water crisis has occurred since 2022 and peaked in 2029 with water sufficiency of only 59.83%. Based on local spatial planning laws and policies, the city's government is advised to improve its catchment area to protect its water resources. The vegetation cover area surrounding the catchment area can be improved, and water absorption capacity can be increased through civil technical actions such as building absorption wells. The model results showed that a proper solution could be done by expanding 142.8 Ha of green/vegetation cover, building 1576 units of absorption wells, and increasing the PDAM supply by 100 l/second.

Enhancing predictive skills in physically-consistent way: Physics Informed Machine Learning for hydrological processes

Current modeling approaches in hydrology often rely on either physics-based or data-science methods, including Machine Learning (ML) algorithms. While physics-based models tend to have rigid structures resulting in unrealistic parameter values in certain instances, ML algorithms establish the input–output relationship while ignoring the constraints imposed by well-known physical processes. While there is a notion that the physics-based model enables better process understanding and ML algorithms exhibit better predictive skills, scientific knowledge that does not add to predictive ability may be deceptive. Hence, there is a need for a hybrid modeling approach to couple ML algorithms and physics-based models in a synergistic manner. Here we develop the Physics Informed Machine Learning (PIML) model that combines the process understanding of conceptual hydrological model with predictive abilities of state-of-the-art ML models. We apply the proposed model to predict the monthly time series of the target (streamflow) and intermediate variables (actual evapotranspiration) in ten different subcatchments in peninsular India. Our results show the capability of the PIML model to outperform a purely conceptual model (abcd model) and ML algorithms while ensuring the physical consistency in outputs validated through water balance analysis. The systematic approach for combining conceptual model structure with ML algorithms could be used to improve the predictive accuracy of crucial hydrological processes important for flood risk assessment.

Climate fluctuation impacts in Astronium urundeuva (M. Allemão) Engl. silvicultural characters in the Brazilian Cerrado

Currently, mankind is responsible for changing our planet’s conditions. These changes are usually catastrophic, and yet, mankind does not develop preventative strategies to reduce their impacts. However, a species present in the Brazilian Cerrado, Astronium urundeuva, can be very economically logged and has a known landscape distribution, but lacks information regarding the impacts of climate change on its silviculture. This research aimed to verify A. urundeuva’s silvicultural behavior under current environmental conditions. Progenies from three populations (Cerrado and Atlantic Forest/Cerrado transition) were measured for silvicultural characters: height (HT) and diameter at breast height (DBH), in 2019. Climatic data (temperature, precipitation, evapotranspiration and soil available water, averages and accumulated) were also measured between 1996 and 2018. Descriptive and sequential water balance analysis, descriptive statistics, collinearity tests and a multiple linear regression were performed. There was water deficit in all years (−12.7 mm) researched, which showed an irregular rainfall distribution in Selvíria-MS, concentrated mostly in summer. Average HT ranged from 8.02 m to 10.69 m, while average DBH ranged from 0.10 m to 0.12 m, with high variability (CVs between 21.99% and 34.77%). There was significant correlation between HT, DBH, , and and between , and , which highlighted the importance of water availability . Multiple linear regression showed has a direct and negative relationship with silvicultural characters, implying productivity losses while evapotranspiration increases. Even though it is not a typical Cerrado species, A. urundeuva may have adapted to phytogeographic domain conditions, with slow growth due to water deficit for its survival, considering that, in Brazil, climate change has resulted from annual variations.

Analysis of Land Water Balance to Set The Planting Time of Upland Rice in Kampar District

Upland rice productivity in Kampar has decreased due to inappropriate planting time with rainfall. Plant water needs will not be met during the dry season and are at risk of crop failure. This study aims to determine the level of availability of groundwater based on land water balance analysis and determine the planting time of upland rice. The method used in this research was a survey method. Soil data of bulk density, field capacity water content, permanent wilting point moisture content, soil texture, and C-organic content were obtained with ring and composite soil samples. Soil sampling points were determined based on the results of overlaying the soil map and land use map using GIS techniques. Climate data for the period 1990–2019 was obtained from the Sumatra River Region III Center. Analysis of land water balance was carried out using the Thornthwaite-Matter method. The results showed that Kampar Regency was classified as a wet area with an annual rainfall of 2,508 mm (Oldemann D1). Soil water content was classified as a sufficient criterion every month, except for June–August. The planting of upland rice at SLH 1–SLH 7 (inpago variety) can be done in January, May, and September, while at SLH 8, it is done in January and September. Planting using local varieties at SLH 1–SLH 7 can be done in February and September, while at SLH 8, it is done in March and September. Alternatif planting can also be done by planting inpago varieties in February and local varieties in September.

Critical Role of Groundwater Inflow in Sustaining Lake Water Balance on the Western Tibetan Plateau

AbstractIt is difficult to quantify the amount of groundwater inflow on the Tibetan Plateau (TP), yet it can be critically important for sustaining lake water balance. Here we show that most endorheic lakes on the western TP exhibited considerable water level increase during the ice‐covered period, which contrasts with lakes in other regions of the TP. An analysis of lake water balance attributes this water surplus to significant groundwater inflow, which is estimated to be about 59%–66% of total inflow into lakes. The groundwater inflow occurred after the 2000s, which is consistent with the rapid lake expansion and significant increase in precipitation. We suggest that the groundwater inflow is mainly related to large‐scale active faults in the limestone bedrock and sufficient meltwater from high elevations. Our results imply that groundwater may be deeply involved in the water cycle and modify the seasonal and inter‐annual lake variations on the western TP.

Interaction Model of Rainfall, Lake, and Ground Waters

This research intends to build an interaction model between rainfall, lake water, and ground water. The location of research is in the Sentani Lake where is placed in the Jayapura Regency-Papua-Indonesia. Sentani Lake is a lake in the Sentani Watershed. Sentani Lake is located between Jayapura City and Jayapura Regency-Papua Province. The area of Sentani Lake is 9,630 ha with the depth is 75 m over the sea. In the northern of this lake are the Cyclops Mountains (Dafonsero) that separate the Sentani Lake and the Pacific Sea. The Sentani Lake functions as the track of transportation, food source, drinking water source, and tourism. Based on the bathymetry analysis result which is obtained from the River Region Institution of Papua, the Sentani Lake has the smallest elevation from 13.05 mdpl until 71.5 mdpl with a maximum storage capacity of 4.8 milliard m3. The methodology of this research consists of 1) To set and to simulate of Hydrology Model; 2) Analysis of water balance; 3) To set up the hydro-geology model; 4) To simulate the integration of rainfall-lake water- ground water. The interaction model between rainfall and lake waters is built based on the relation between the outlet discharge and the rainfall at 10 points and then is validated at the 5 points of observation data. This model produces the formulation as follows: inflow to the lake from rainfall = 0.067 x rainfall – 5. The interaction model between the lake water level and the ground water level is built based on the value of ground water-level fluctuation and the lake water level at the 10 points, and it is validated at the 6 points of observation data. This model produces the following formulation: fluctuation of ground water level = 0.1529 x fluctuation of lake water level. By combining the ground water and run-off in the Sentani Watershed, it is known as follows: inflow total of lake = base-flow + 0.067 x rainfall – 5.

Streamflow and Sediment Yield Analysis of Two Medium-Sized East-Flowing River Basins of India

With increased demand for water and soil in this Anthropocene era, it is necessary to understand the water balance components and critical source areas of land degradation that lead to soil erosion in agricultural dominant river basins. Two medium-sized east-flowing rivers in India, namely Nagavali and Vamsadhara, play a significant role in supporting water supply and agriculture demands in parts of the Odisha districts of Kalahandi, Koraput and Rayagada, as well as the Andhra Pradesh districts of Srikakulam and Vizianagaram. Floods are more likely in these basins as a result of cyclones and low-pressure depressions in the Bay of Bengal. The water balance components and sediment yield of the Nagavali and Vamsadhara river basins were assessed using a semi-distributed soil and water assessment tool (SWAT) model in this study. The calibrated model performance revealed a high degree of consistency between observed and predicted monthly streamflow and sediment load. The water balance analysis of Nagavali and Vamsadhara river basins showed the evapotranspiration accounted for 63% of the average annual rainfall. SWAT simulated evapotranspiration showed a correlation of 0.78 with FLDAS data. The calibrated SWAT model showed that 26.5% and 49% of watershed area falling under high soil erosion class over Nagavali and Vamsadhara river basins, respectively. These sub watersheds require immediate attention to management practices to improve the soil and water conservation measures.

Modelling LEAF stomatal resistance for common REED, peach‐leaf willow and cottonwood riparian plant communities

AbstractAccounting for the impact of riparian plant communities on water balances is usually ignored due to the lack of data and information on water use of these plant communities. This is especially important for areas with limited water resources and in areas where water resources are shared between different users (agriculture, riparian zones, other ecosystems/agro‐ecosystems, municipalities, recreational, mining, agro‐ecology, etc.). Modelling stomatal resistance (rL) of riparian vegetation species is a complex process, but is also one of the limited processes to estimate evaporative losses for these plant communities for more inclusive, complete and robust water balance and hydrologic analyses for forecasting, planning, allocating and managing surface and groundwater resources and for hydrologic modelling. The objectives of this research were to (i) modify Jarvis‐type model for estimating rL for three riparian plant species [Common reed (Phragmites australis), Peach‐leaf willow (Salix amygdaloides) and Cottonwood (Populus sect. Aigeiros)], (ii) investigate the rL response to microclimate/environmental variables, and (iii) evaluate the photosynthetic photon flux density (PPFD) versus rL response curves for estimating hourly rL. A Jarvis‐type model was modified by re‐parametrization using porometer‐measured data collected via extensive field campaigns in 2009 and 2010. Flooding in 2010 impacted the phenology and physiology of all species with increased rL and impedance in growth due to oxygen stress. While R2 values were generally low for both years for all species, the response of rL to the same climate variables under the same environmental conditions exhibited substantial variations between the species. Overall, the response of rL to climatic variables was species‐specific, complex and varied with surface and atmospheric conditions. For all species, stronger relationships between rL versus air temperature and net shortwave radiation were observed. The Jarvis‐type model underestimated rL for all species and hence required independent re‐parameterization for each specie independently. The model performance after re‐parameterization improved substantially during both calibration and validation. Validation of the new modified Jarvis‐type model (NMJ‐model) resulted in good estimates of rL with root‐mean‐squared difference (RMSD) and R2 values of 31 s m−1 and 0.51 for Common reed; 56 s m−1 and 0.81 for Peach‐leaf willow; and 237 s m−1 and 0.51 for Cottonwood, respectively. Strong agreements were found between measured and re‐parameterized NMJ‐model‐estimated rL values for all three species in both years, but the relationships improved significantly in 2009 with no flooding. The NMJ‐model‐estimated rL values were within 10, 7 and 11% of the measured values for Common reed, Peach‐leaf willow and Cottonwood, respectively. rL values estimated using PPFD versus rL response curves developed for individual species were used to estimate hourly rL and the response curves were able to effectively track the trends and magnitudes of rL. With re‐parameterization, the NMJ‐models developed and tested for each riparian vegetation specie provide robust estimates of rL that can be used to quantify evaporative losses of these riparian plant communities for more complete local and regional water balance analyses by accounting for riparian vegetation water use.

The influence of in vitro and ex vitro conditions cultivation on free proline contents in plants of some Gentiana L. species

Aim. To establish the dependence of free proline concentration in plant tissues of in vitro and ex vitro alpine species of Gentiana lutea L., Gentiana punctata L., Gentiana acaulis L. on light conditions of their cultivation and the source of carbon in the nutrient medium; to analyze expediency of free proline amino acid use as a biological marker of physiological adaptation of biotechnological plants of these species to water deficit of in vitro and ex vitro conditions. Methods. Methods of in vitro and ex vitro cultivation of plants, the method of free proline detection with the use of ninhydrin. Results. It is shown that under in vitro conditions of free proline content in plants is dependent on light regime of their cultivation and the source of carbon in the composition of nutrient medium. The increased intensity of luminous flux within the range of photosynthetically active radiation (PAR) from 85 W/m2 to 100 W/m2 and 1.92 times raised share of red range waves in the light spectral composition in variant 2.1 (intensity of the luminous flux in the PAR range is 100 W/m2, the waves correlation of blue (Eb): green (Eg): red (Er) ranges = 25 % : 27 % : 48 %) causes 11.5–37.1 % increased amount of free proline in plants in vitro cultivated on nutrient media supplemented with sucrose. Substitution of sucrose in the medium for mannitol is accompanied by 1.64–1.84 times increased concentration of free proline in plants of the investigated species under the light conditions of 1.1 variant (85 W/m2, spectral composition Eb : Eg : Er = 25 % : 27 % : 48 %= 33 % : 42 % : 25 %) and 1.3–2.57 times increased under light cultivation regime of 2.1 variant. The analysis of water balance of plants in vitro cultivated on mannitol under light conditions of 2.1 variant and the plants in conditions of natural growth doesn’t show any considerable distinctions in values of transpiration intensity, water deficit, general water content. The process of adaptation of plants in vitro to conditions ex vitro is accompanied by a change of proline content in leaves with dependence on water deficit in the substrate and light conditions of growing. Conclusions. The obtained results point to the expediency of using free proline content as a biochemical marker for assessing adaptive potential of plants in conditions in vitro and ex vitro.

Water Balance and Potency of the Duriangkang-Muka Kuning Reservoirs for Supporting the Raw Water Supply in Batam City, Indonesia

The Duriangkang and Muka Kuning reservoirs play an important role in supplying clean water to Batam City. The Duriangkang reservoir was built from 1992 until 1995 as the first estuary dam in Indonesia and the largest reservoir in Batam city. These two reservoirs are the cascade reservoirs. The dam with an effective storage capacity of 107 million m3 works to fulfill the water needs with a capacity of 2,500 l/s. However, the Muka Kuning reservoir was finished in 1990, but it was newly turned in 1992. At the beginning, the Muka Kuning WTP had a water production capacity of 310 l/s, but the capacity was increased to 600 l/s in 2015 along with the increasing water need in Batam. This research intends to analyze the water balance in the Duriangkang-Muka Kuning cascade reservoirs and to investigate the potency of the Duriangkang reservoir that can support the water availability in the Muka Kuning. The methodology uses water balance simulation in the Duriangkang-Muka Kuning reservoir to analyze the potency of the Duriangkang reservoir that can be used to support the water availability in the Muka Kuning reservoir. The catchment area of the Duriangkang reservoir now consists of residences, society plantations, forestry areas, empty land, and industry, which can decrease the amount of water availability to be stored every year. The results of the water balance analysis indicate that the water availability of the Duriangkang reservoir is in surplus conditions throughout the year in the wet, normal, and dry year conditions. Therefore, the Duriangkang reservoir has the potency to support the water availability in the Muka Kuning reservoir.

Hydrogeological processes and hydrochemical effects in the Manas river catchment, Northwest China, over the past 60 years

The arid inland regions around the world are suffering from extreme water shortages and ecological crises due to the impacts of climate change and enhanced human activities. This study used multiple methods including trend and abrupt analysis, correlation analysis, water-balance analysis, and hydrochemical analysis to evaluate the hydrogeological processes and hydrochemical effects in 5 periods in the Manas River catchment, a typical arid inland catchment in China. The results show that groundwater storage in the catchment decreased by 5.45 × 108 m3 over the past 60 years, while glacial melt, snowmelt, and precipitation showed an increasing trend since the 1980 s. A drop in the groundwater level in the alluvial fan and a 28 % reduction in spring discharge in the lower alluvial fan since 1959 were caused by reduced river infiltration owing to the water diversion projects. Meanwhile, the concentrations of SO42- and Cl- in the alluvial fan groundwater have more than doubled over the period 1957–2018 as a result of the decrease of both groundwater level and flow rate. Long-term over-exploitation of groundwater associated with irrigation after 1978 strongly depleted the groundwater storage and altered the flow path of groundwater in the oasis zone. In addition, the expansion of arable land and increased temperatures enhanced evapotranspiration and salinization of shallow groundwater in the oasis and desert zones. Based on the results, we propose making full use of natural underground reservoirs to increase infiltration of river water and flood water in the alluvial fan zone, and reducing the arable land area to ensure the sustainability of water resources and ecology in the middle and lower reaches of the catchment. The results will provide reference for the sustainable development of water resources and environmental protection in arid inland regions and similar catchments worldwide.

Multi-scale evaluation of global evapotranspiration products derived from remote sensing images: Accuracy and uncertainty

• Five global remote sensing-based evapotranspiration (ET) products are compared. • Their accuracy at point scale is evaluated based on 94 worldwide flux stations. • Accuracy at basin scale is assessed by water balance analysis across 414 basins. • ET uncertainty at pixel scale is quantified with three-cornered hat method. • ET quantity and trend at the global scale is assessed through comparison analysis. Advances in satellite remote sensing (RS) techniques have greatly prompted the development of large-scale evapotranspiration (ET) models, yielding several freely available global ET products. A comprehensive evaluation on these products is necessary for selecting the most suitable ET products and developing large-scale ET models step forward. In this study, the accuracy and uncertainty of five RS-based global ET products (MOD16, SSEBop, GLEAM, AVHRR, and BESS) were evaluated at multi scales. At point scale their accuracy was evaluated through a direct comparison with in-situ observations from 94 worldwide flux towers. Results indicate that accuracy differences of these five products vary with statistical metrics and land cover types. The combination of all statistics illustrates that GLEAM and AVHRR outperform three other products, which is consistent with the findings of most previous continental-scale studies. The accuracy at basin scale was assessed through water balance analysis across 19 big river basins. BESS is found to be the product that is superior to four other ET products at both monthly and multi-annual scale, which may be related with its low random error at point scale. The uncertainty of these five products at pixel scale was assessed by the three-cornered hat (TCH) method and comparison analysis. The TCH outputs reveal that BESS and SSEBop are the two products with the lowest and largest relative uncertainty, respectively. That explains the good performance of BESS at basin scale from another perspective. As for the two MODIS-based ET products (MOD16 and SSEBop), their accuracy at FLUXNET site scale is comparable in monthly ET estimation. However, SSEBop has special advantage in the capture of multiyear ET patterns. The comparison analysis indicates that SSEBop is the product that agrees best with the ensemble mean not only on a global scale but also in four of the six continents. Our results imply that it is difficult or even impossible to figure out the best ET product in all respects. The selection of ET products for scientific research should consider their performance difference in spatial scale as well as the influence of land cover and climate conditions.

Evaluation and Improvement Measures of the Runoff Coefficient of Urban Parks for Sustainable Water Balance

As the impermeable sidewalk area increases in urban areas, diverse problems related to water occur. The purposes of this research were to increase the rainwater infiltration rate through water balance analysis and estimate the runoff coefficient according to land cover types in urban parks. The regression equations and runoff coefficients relative to the rainwater infiltration rate were estimated according to the land cover types and applied to eight urban parks. In the results of the experiment, the runoff coefficient was 0.245 for vegetation areas, 0.583 for permeable sidewalks, 0.963 for sidewalk blocks, and 1.000 for impervious sidewalks, which had 100% outflow. The results show that the vegetation area in urban parks is significantly related to rainfall–runoff, infiltration, and evapotranspiration. The average of eight urban parks was 126.52 mm, indicating that 11.80% of the rainfall was recharged into groundwater. Additionally, the average runoff rate was 498.56 mm, indicating that 46.52% was leaked externally. Therefore, it is suggested to decrease the impermeable sidewalk areas in urban parks. Additionally, extending the waterway, swamp, and gravel sidewalk areas is suggested. Urban parks should be developed in order to contribute to hydrological control through the water balance in urban land use.

Spatial and temporal distribution of arsenic contamination in groundwater of Nawalparasi-West, Nepal: an investigation with suggested countermeasures for South Asian Region.

Nawalparasi-West/Parasi is one of the severely affected districts in the Terai lowlands of Nepal by arsenic (As) contamination in groundwater, exceeding standards of 10ppb (WHO) and 50ppb (Nepal Drinking Water Standard). This study presents the spatial and temporal distribution of As across 6km × 10km region in Parasi via meteorological, hydrogeological, physio-chemical, and sedimentological investigations in 31 communities for about 5years. In this study, water balance analysis was carried out for understanding the groundwater dynamics in the study area and its contribution to As elution. Gentle flow gradient and little to no infiltration was observed in the central region with relatively impervious silty clayey flood plain, where higher As concentrations were obtained compared to the northern Siwalik foothills and southern parts with coarser sediments. Similarly, higher As concentration (1048ppb) was recorded in the drier pre-monsoon season than the wet season (529ppb). The aquifer at 12 to 23m depth feeding 73% wells in the study area exhibited higher As concentration in reduced environment as opposed to the oxidizing state at 5- to 6-m and 30- to 50-m deep aquifers. Other constituents such as Fe, B, and Cr and their relation with As were analyzed. The results ofGERAS model analysis done for health risk assessment are also presented which show that under long-term exposure, the residents in Parasi were undertaking intolerable cancer risk of 1.1 to 6.4 × 10-3. This study further incorporates socio-economic sentimentsvital to analyze, and propose sustainable and cheap countermeasures for immediate implementation to reduce As exposure and health risk in Nepal, which is also highly applicable for other affected regions in South Asian Region.

Evaluating Inflow Result from SWAT Model at Singkarak Lake Under Limited Data

Sustained lake functioning requires proper management in the catchment area and the water body. To address this, information on lake water balance is crucial because it is the basis for many scientific investigations of processes that occur in lake ecosystems. In many lakes, inflow from catchment areas is dominated by river flow. The problem is that inflow measurement data on rivers into the lake are difficult to obtain. Several models are used for inflow estimation, but validation will undoubtedly be complex because there is no observational data. The approach taken is to analyze the model results’ inflow accuracy through water balance analysis based on observational data on water level, climatology, and outflow. This approach will be implemented on Singkarak Lake, 109.08 km2, which is a tectonic lake located in West Sumatra. The method used to calculate inflow uses the SWAT hydrological model based on land use data in 2014 and Chirps rainfall in the 2010-2019 period. Water balance analysis is used to evaluate the inflow of the model results based on observational data on water level and outflow. The results show that the monthly inflow is too high, with an average excess of 6.21cms, which causes the average water level to be 0.52 meters higher.