Quantify Water Use Research Articles

Deep Infiltration Model to Quantify Water Use Efficiency of Center-Pivot Irrigated Alfalfa

Deep Infiltration Model to Quantify Water Use Efficiency of Center-Pivot Irrigated Alfalfa

Quantifying the water use efficiency of karst ecosystems and response to environmental factors

Study regionThe study area is located in Guizhou province, the centre of the karst region in southwest China. Study focusAs a typical karst region, Guizhou has long faced challenges with water scarcity. Quantifying water use efficiency (WUE) is crucial for the efficient use of water resources and sustainable management. This study examined the spatio-temporal evolution patterns and its driving factors on WUE in Guizhou using Theil-Sen's slope, partial correlation methods, and the geographic detector model. New hydrological insights for the region(1) The multi-annual mean WUE of non-karst region (NKR, 2.75 gC kg−1 H2O yr−1) is higher than that of karst region (KR, 2.10 gC kg−1 H2O yr−1) during 2001–2020. (2) The rate of increase of WUE was three times higher in KR than in NKR. (3) Precipitation and temperature were identified as the key factors influencing WUE. Interactions between each environmental factors were observed to have both bi-variate and non-linear enhancement effects. Notably, in the NKR, soil moisture, vegetation type and leaf area index were the dominant factors influencing WUE, with interactions between environmental factors had both enhanced and weakened effect on WUE. (4) The synergistic effects of these interactions exceeded the individual or cumulative effects of the two environmental factors. These findings contribute to our understanding of the environmental factors driving changes in WUE in the KR.

The slope of assimilation rate against stomatal conductance should not be used as a measure of water use efficiency or stomatal control over assimilation

Quantifying water use efficiency, and the impact of stomata on CO2 uptake are pivotal in physiology and efforts to improve crop yields. Although tempting, relying on regression slopes from assimilation-stomatal conductance plots to estimate water use efficiency or stomatal control over assimilation is erroneous. Through numerical simulations, I substantiate this assertion. I propose the term ‘instantaneous transpiration efficiency’ for the assimilation-to-transpiration ratio to avoid confusion with ‘intrinsic water use efficiency’ which refers to the assimilation-to-stomatal conductance ratio, and recommend to compute both metrics for each gas exchange data point.

Exploring Water Use in Mildly Water-Scarce Regions: A Structural Decomposition Analysis for Anhui Province in China

Because of severe water scarcity, it is crucial to quantify water use in China’s water-scarce regions and to analyze the factors driving its use. In this paper, we analyze the driving factors behind the water footprint from 2007 to 2017 in the mildly water-scarce region of Anhui Province, using regional input–output models and structural decomposition analysis. The results show the following: (1) Although the average virtual water intensity of Anhui Province decreased by 52.58% from 2007 to 2017, the water-use efficiency was still low; (2) During the study period, the total water footprint of Anhui Province increased by 25.06%, with an obvious upward trend; (3) From 2012 to 2017, the net export volume of virtual water in Anhui Province was positive, and the flow volume decreased by 78.87%; (4) Technological progress contributed the most to reducing the water footprint of Anhui Province, followed by the increased counter-urbanization rate as the second-largest driving force. The expansion of the scale effect, including the size of the economy and the size of the population, was the main negative driving force for the increase in Anhui’s water footprint. However, the proportion of economic scale in the water footprint drivers gradually decreased.

Sap flow and transpiration of young Brazilian mahogany plants submitted to soil water potential variation

Brazilian mahogany (Swietenia macrophylla King) is a forest species of economic and environmental interest due to its wood’s great finish and its use in recovering and recomposing ecosystems. However, clarification on how this species uses water resources is still necessary. This study proposes to evaluate sap flow and transpiration behavior in young Brazilian mahogany plants under variable conditions of soil water potential. We conducted the study in a protected environment and cultivated the plants in weighing lysimeters wherein the soil underwent potential variations between -10 kPa and -35 kPa during periods of water restriction, rehydration, and full irrigation. To quantify water use in the mahogany plants, we measured sap flow through heat pulses, transpiration through the weighing lysimeters, and evapotranspiration by weather variables. Sap flow and transpiration are affected negatively by soil water potential variation. The leaves lost water to the atmosphere under water deficit conditions, even with the absence of upward sap flow. Sap flow was restored four days after irrigation had resumed.

Handily measuring sensible and latent heat exchanges at a bargain: A test of the variance-Bowen ratio approach

Eddy covariance has been the gold standard used to quantify on-farm crop water use and validate evapotranspiration and remote sensing models, but it comes with a high cost. Development of surface renewal allowed cheaper implementations, but it still requires complex data processing. Additionally, the thermocouple used in this method is vulnerable to breakage. With the depleting water resources in the western U.S., there needs to be a method that is cost-effective and simple to quantify water use across wide range of crops. Here, we employed the variance-Bowen ratio approach at an alfalfa site to measure sensible and latent heat flux (λE) using 1) a sonic anemometer and 2) an air temperature and relative humidity sensor (T-RH). The variance-based sensible heat flux, using a sonic anemometer and a T-RH sensor, agreed strongly (slope = 0.98, R2 = 0.96, n = 3726) with eddy covariance. The modified-Bowen-based latent heat flux (λEβ) also showed very good results (slope = 0.89, R2 = 0.91, n = 3773) with some uncertainty. We then assessed cases where λEβ performed lesser based on heat advection measurements and remote sensing observations from ECOSTRESS. The problematic λEβ was attributed as a product of the advection of heat and moisture from upwind fields because the assumed equal diffusion of heat and water no longer stands under advection. Overall, our results suggest that the variance-Bowen ratio is a robust, inexpensive, yet user-friendly approach to measure sensible and latent heat flux. Given its reduced cost, this approach also has the potential for measuring horizontal heat advection and validating remote sensing models across many different crop types and ecosystems. Furthermore, the inclusion of advection measurement could be crucial in addressing certain remote sensing models (i.e. DisALEXI and PT-JPL) as they systematically omit any advection components.

Evaluation of Sustainable Water Resource Use in the Tarim River Basin Based on Water Footprint

Quantifying water use for agricultural production and accurate evaluation is important for achieving a balance between water supply and demand and sustainable use, especially in arid regions. This study quantifies the water footprint of food production in the Tarim River Basin (TRB) from 2000 to 2019 by conducting a sustainability evaluation using both the water footprint and DPSIR model as a theoretical framework, and by analyzing spatial and temporal changes. The results show that the water footprint of the TRB increased from 2.15 m3/kg to 2.86 m3/kg per unit during the study period. The average annual weighted water footprint of the basin is 2.59 m3/kg, of which 2.41 m3/kg is blue water and 0.18 m3/kg is green water. Blue water inputs contribute more than 94% to food production annually. Furthermore, although the level of sustainable water use increased, its score is low, with the most prominent stress assessment value indicating poor regional water use. Prior to 2010, the Tarim River Basin region’s sustainability was less than 0.4, indicating that water resources were at or below the level of basic unsustainability. By 2019, however, the sustainability of areas with better water use was greater than 0.4., and the sustainability of 80% of the region was above 0.2. In the future, we need to reduce the crop water footprint and improve water use efficiency to ensure the sustainable use of water resources and avoid further pressure on water use.

Quantifying Water Use Efficiency in Paddy Production for Different Regions of Thenpennaiyaru River Basin (TRB) of Tamil Nadu

Agriculture is the world's greatest user and consumer of water. Crop irrigation accounts for two-thirds of all world water withdrawals and 85 per cent of total global water consumption. Today we face major issues on water scarcity which is closely related to “water stress” or “water crisis” is the lack of fresh water resources to meet the standard water demand. Irrigated cropping faces some issues on, decreasing water supply owing to increasing extraction and fewer inflows, as well as increased competition from other users in this context the current study focused on the estimation of crop water use efficiency and irrigation efficiency in the different regions of Thenpennaiyaru river basin (TRB) of Tamil Nadu. As per the Central Water Commission’s Basin Report, Thenpennaiyar Basin is the second largest interstate flowing river basin among the 12 basins lying between pennar and Cauvery basins. The river is the main source for irrigating over 38,000 acres in Krishnagiri district; 6250 acres in Dharmapuri district; 17,980 acres in Tiruvannamalai district and 25000 acres in Villupuram district and majority of population depend on this river for agricultural and allied activities. So, this river basin was purposefully selected for the present study to access the efficiency in water usage with the sample size of (320). As per the result CWUE is better in the head region (12.34 quintals/ha/mm) due to consistent water supply, which is directly dependent on effective management practices, which ultimately have higher efficiency and higher yield. Irrigation efficiency is most similarly in all three regions. The CWUE is a better indicator when quantifying the efficiency of a crop production system because it directly reflects the amount of grain yield produced per amount of water used rather than per depth of water applied, which is the case with the IWUE.

Quantifying Water Consumption through the Satellite Estimation of Land Use/Land Cover and Groundwater Storage Changes in a Hyper-Arid Region of Egypt

One of the areas that show the most visible effects of human-induced land alterations is also the world’s most essential resource: water. Decision-makers in arid regions face considerable difficulties in providing and maintaining sustainable water resource management. However, developing appropriate and straightforward approaches for quantifying water use in arid/hyper-arid regions is still a formidable challenge. Meanwhile, a better knowledge of the effects of land use land cover (LULC) changes on natural resources and environmental systems is required. The purpose of this study was to quantify the water consumption in a hyper-arid region (New Valley, Egypt) using two different approaches—LULC based on optical remote sensing data and groundwater storage changes based on Gravity Recovery Climate Experiment (GRACE) satellite data—and to compare and contrast the quantitative results of the two approaches. The LULC of the study area was constructed from 1986 to 2021 to identify the land cover changes and investigate the primary water consumption patterns. The analysis of groundwater storage changes utilized two GRACE mascon solutions from 2002 to 2021 in New Valley. The results showed an increase in agricultural areas in New Valley’s oases. They also showed an increased in irrigation water usage and a continuous decrease in the groundwater storage of New Valley. The overall water usage in New Valley for domestic and irrigation was calculated as 18.62 km3 (0.93 km3/yr) based on the LULC estimates. Moreover, the groundwater storage changes of New Valley were extracted using GRACE and calculated to be 19.36 ± 7.96 km3 (0.97 ± 0.39 km3/yr). The results indicated that the water use calculated from LULC was consistent with the depletion in groundwater storage calculated by applying GRACE. This study provides an essential reference for regional sustainability and water resource management in arid/hyper-arid regions.

Water for energy: Characterizing co‐evolving energy and water systems under twin climate and energy system nonstationarities

AbstractThe energy system is a major water user, but understanding how much water is consumed and withdrawn for energy is a challenging empirical task: nonevaporative volumetric water use is not easily calculated from first principles. Water use also has impacts that differ in important ways depending on where water is abstracted and used, timing of use, and socioenvironmental context. Moreover, different decarbonization pathways and policy environments have very different water use implications. We currently face a crisis of twin nonstationarities in hydrology and energy systems that make understanding water use for energy critical for decision support as hydroclimate and energy systems change. Currently, water‐for‐energy data are highly uncertain and not centrally collected, which means researchers spend substantial effort collecting inventory data. Recent advances in impact assessment methods for water volumes focus largely on spatially resolved water scarcity evaluations, but robust conclusions can be elusive due to uncertain and low‐metadata inventory information. As water‐for‐energy quantification efforts progress, research should emphasize decision support for energy system design, incorporating crucial hydrologic dynamics. Beyond the location of water use, relative scarcity, and potential competing uses, these include sub‐daily to interannual temporal dynamics, the impacts of climate change on these dimensions, potential feedbacks between energy and water systems, and the impacts of hydrologic variability or change on policy‐based incentive structures. This article reviews prior US‐focused efforts to quantify water use for energy, highlights why these nonstationarities are analytically relevant with a brief policy case study, and highlights research needs for decision support under twin nonstationarities.This article is categorized under: Engineering Water > Sustainable Engineering of Water Engineering Water > Planning Water Engineering Water > Methods

Assessing local impacts of water use on human health: evaluation of water footprint models in the Province Punjab, Pakistan

PurposeThe water footprint (WF) method is widely applied to quantify water use along the life cycle of products and organizations and to evaluate the resulting impacts on human health. This study analyzes the cause-effect chains for the human health damage related to the water use on a local scale in the Province Punjab of Pakistan, evaluates their consistency with existing WF models, and provides recommendations for future model development.MethodLocally occurring cause-effect chains are analyzed based on site observations in Punjab and a literature review. Then, existing WF models are compared to the findings in the study area including their comprehensiveness (covered cause-effect chains), relevance (contribution of the modeled cause-effect chain to the total health damage), and representativeness (correspondence with the local cause-effect chain). Finally, recommendations for the development of new characterization models describing the local cause-effect chains are provided.Results and discussionThe cause-effect chains for the agricultural water deprivation include malnutrition due to reduced food availability and income loss as well as diseases resulting from the use of wastewater for irrigation, out of which only the first one is addressed by existing WF models. The cause-effect chain for the infectious diseases due to domestic water deprivation is associated primarily with the absence of water supply systems, while the linkage to the water consumption of a product system was not identified. The cause-effect chains related to the water pollution include the exposure via agricultural products, fish, and drinking water, all of which are reflected in existing impact assessment models. Including the groundwater compartment may increase the relevance of the model for the study area.ConclusionsMost cause-effect chains identified on the local scale are consistent with existing WF models. Modeling currently missing cause-effect chains for the impacts related to the income loss and wastewater usage for irrigation can enhance the assessment of the human health damage in water footprinting.

High-Resolution Spatiotemporal Water Use Mapping of Surface and Direct-Root-Zone Drip-Irrigated Grapevines Using UAS-Based Thermal and Multispectral Remote Sensing

Site-specific irrigation management for perennial crops such as grape requires water use assessments at high spatiotemporal resolution. In this study, small unmanned-aerial-system (UAS)-based imaging was used with a modified mapping evapotranspiration at high resolution with internalized calibration (METRIC) energy balance model to map water use (UASM-ET approach) of a commercial, surface, and direct-root-zone (DRZ) drip-irrigated vineyard. Four irrigation treatments, 100%, 80%, 60%, and 40%, of commercial rate (CR) were also applied, with the CR estimated using soil moisture data and a non-stressed average crop coefficient of 0.5. Fourteen campaigns were conducted in the 2018 and 2019 seasons to collect multispectral (ground sampling distance (GSD): 7 cm/pixel) and thermal imaging (GSD: 13 cm/pixel) data. Six of those campaigns were near Landsat 7/8 satellite overpass of the field site. Weather inputs were obtained from a nearby WSU-AgWeatherNet station (1 km). First, UASM-ET estimates were compared to those derived from soil water balance (SWB) and conventional Landsat-METRIC (LM) approaches. Overall, UASM-ET (2.70 ± 1.03 mm day−1 [mean ± std. dev.]) was higher than SWB-ET (1.80 ± 0.98 mm day−1). However, both estimates had a significant linear correlation (r = 0.64–0.81, p < 0.01). For the days of satellite overpass, UASM-ET was statistically similar to LM-ET, with mean absolute normalized ET departures (ETd,MAN) of 4.30% and a mean r of 0.83 (p < 0.01). The study also extracted spatial canopy transpiration (UASM-T) maps by segmenting the soil background from the UASM-ET, which had strong correlation with the estimates derived by the standard basal crop coefficient approach (Td,MAN = 14%, r = 0.95, p < 0.01). The UASM-T maps were then used to quantify water use differences in the DRZ-irrigated grapevines. Canopy transpiration (T) was statistically significant among the irrigation treatments and was highest for grapevines irrigated at 100% or 80% of the CR, followed by 60% and 40% of the CR (p < 0.01). Reference T fraction (TrF) curves established from the UASM-T maps showed a notable effect of irrigation treatment rates. The total water use of grapevines estimated using interpolated TrF curves was highest for treatments of 100% (425 and 320 mm for the 2018 and 2019 seasons, respectively), followed by 80% (420 and 317 mm), 60% (391 and 318 mm), and 40% (370 and 304 mm) of the CR. Such estimates were within 5% to 11% of the SWB-based water use calculations. The UASM-T-estimated water use was not the same as the actual amount of water applied in the two seasons, probably because DRZ-irrigated vines might have developed deeper or lateral roots to fulfill water requirements outside the irrigated soil volume. Overall, results highlight the usefulness of high-resolution imagery toward site-specific water use management of grapevines.

Exploring the Influence of Biological Traits and Environmental Drivers on Water Use Variations across Contrasting Forests

Understanding species-specific water use patterns across contrasting sites and how sensitivity of responses to environmental variables changes for different species is critical for evaluating potential forest dynamics and land use changes under global change. To quantify water use patterns and the sensitivity of tree transpiration to environmental drivers among sites and species, sap flow and meteorological data sets from three contrasting climatic zones were combined and compared in this analysis. Agathis australis from NZHP site, Schima wallichii Choisy (native) and Acacia mangium Willd (exotic) from CHS site, Liquidamber formosana Hance, Quercus variabilis Blume and Quercus acutissima Carruth from CJGS site were the dominant trees chosen as our study species. Biological traits were collected to explain the underlying physiological mechanisms for water use variation. Results showed that the strongest environmental drivers of sap flow were photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and temperature across sites, indicating that the response of water use to abiotic drivers converged across sites. Water use magnitude was site specific, which was controlled by site characteristics, species composition and local weather conditions. The species with higher sap flow density (Fd) generally had greater stomatal conductance. Native deciduous broadleaved species had a higher Fd and faster response to stomatal regulation than that of native evergreen broadleaved species (S. wallichii) and conifer species A. australis. The analysis also showed that exotic species (A. mangium) consumed more water than native species (S. wallichii). Trees with diffuse porous and lower wood density had relatively higher Fd for angiosperms, suggesting that water use was regulated by physiological differences. Water use characteristics across sites are controlled by both external factors such as site-specific characteristics (local environmental conditions and species composition) and internal factors such as biological traits (xylem anatomy, root biomass and leaf area), which highlights the complexity of quantifying land water budgets for areas covered by different species.

Sectoral water footprint dynamics: An input-output structural decomposition analysis for Morocco

Over the last decades, Morocco has been facing increasingly severe water scarcity. To quantify water use in Morocco, we refer to the water footprint (WF) concept, including both direct and indirect water use. WF considered covers internal WF and exported virtual water (VW). We used the input-output structural decomposition analysis (SDA) to quantitatively analyze the drivers of changes in Morocco’s sectoral WF from 1995 to 2015. The considered mechanisms governing WF changes are the technological, economic system efficiency, and structural effects. The WF growth experienced in Morocco primarily resulted from final demand changes. The technological effect acted as an additional increase factor. Nevertheless, the economic system efficiency effect contributed to the water conservation process. Unfortunately, it was not sufficient to reverse the expansion of Morocco’s WF resulted from other driving factors. Agriculture is the dominant economic sector in WF changes, regardless of any driving factor and any period considered. The study provides insight into Morocco’s water policy limits and helps develop policies towards sustainable water resources planning and management. That is by suggesting that final demand structure adjustment and technological innovation in the agricultural sector should be at the center of Morocco’s strategies in addressing water scarcity.

Quantifying water use and groundwater recharge under flood irrigation in an arid oasis of northwestern China

Accurate knowledge of evapotranspiration (ET) and irrigation return flow is critical for the sustainable management of water resources in arid inland river basins. Flood irrigation with large amounts of groundwater and resulting return flow may be not suitable for cropland with long cultivation history. In the midstream of the Heihe River Basin of northwestern China, flood-irrigated cropland with rotation of spring wheat and spring maize from 2005 to 2014 was selected as study area. Deep percolation fluxes below the 1.5 m, 3.0 m and 5.0 m layers were determined based on soil water balance, for which, soil evaporation, transpiration and soil water content (SWC) dynamics during the growing seasons were calibrated and validated by the HYDRUS-1D simulation. Mean annual soil evaporation and transpiration were 64.11 mm and 352.36 mm for spring wheat and 84.03 mm and 447.43 mm for spring maize, respectively. Large amounts of water discharged within the first few days after irrigation from the second to the last irrigation events. Deep percolation below the 1.5 m soil were 841.87 mm and 973.73 mm, occupying 67.10 % and 68.00 % of applied water during the growing seasons of spring wheat and spring maize, respectively. About 108.86 mm and 70.72 mm water percolated from the 0–1.5 m soil were stored in the 1.5–3.0 m layer, respectively. Groundwater recharge (the amount of deep percolation below 5.0 m) amounted to 734.03 mm and 1002.10 mm, occupying 58.86 % and 70.20 % of applied irrigation during the growing seasons of spring wheat and spring maize, respectively. Mean water productivity were 4.24 kg ha−1 mm−1 for spring wheat and 5.86 kg ha−1 mm−1 for spring maize. The impact of decreasing irrigation amount on deep percolation was assessed by assuming 80 % (80 % I), 60 % (60 % I), 50 % (50 % I) and 40 % (40 % I) of current irrigation quota (I) of each event throughout the growing seasons from 2005 to 2014. Even the 40 % I treatment would satisfy water demand of spring wheat and spring maize, and deep percolation would decrease remarkably. The percentage of percolated water from the 0–1.5 m soil to irrigation would decrease on average by 8.31 %, 22.43 %, 33.88 % and 49.78 % under the treatments of 80 % I, 60 % I, 50 % I and 40 % I, respectively. Groundwater recharge would occupy 48.90 %, 34.20 %, 24.45 % and 21.79 % of irrigated water for spring wheat and 62.32 %, 50.21 %, 42.68 % and 40.44 % of irrigated water for spring maize, respectively. The 50 % I treatment would improve water productivity by at least 2.52 kg ha-1 mm-1 for spring wheat and 5.26 kg ha-1 mm-1 for spring maize. The hypothesized irrigation schedule with current frequency and 50 % quota of each event is promising to improve crop water utilization and protect groundwater resources. Optimized irrigation strategy for irrigated agriculture in the midstream will aid the comprehensive management of water resources at a watershed scale in the arid inland river basins.

Groundwater use of a small Eucalyptus patch during the dry monsoon phase

Given the critical role of water in rural development, it is essential to quantify water use by various sectors. Reportedly, a significant water loss during the dry monsoon phase is by Eucalyptus trees in the Ethiopian highlands but few quantitative studies have been carried out. In our study in the Fogera plain near Lake Tana, consumptive water use of a small Eucalyptus patch was calculated from the fluctuating diurnal water table observations for two dry monsoon phases. During the dry monsoon phase in 2014, the groundwater table declined linearly at a rate of 2.6 cm d−1 and in 2015 the decline was 2.5 cm d−1. Daily fluctuations in groundwater were around 20 cm. Translating changing groundwater levels in precise evapotranspiration rates was cumbersome because of uncertainty in the value of drainable porosity. We concluded that the evapotranspiration over the small Eucalyptus patch was at a minimum 3.4 mm d−1 but more likely around 10 mm d−1 at the end of the dry phase. The 10 mm d−1 is twice the reference evaporation rate. This is in accordance with advection aridity approach where the actual evaporation of isolated patches with access to groundwater in dry environments can evaporate at twice the reference rate. The current and future extent of Eucalyptus patches and forests need, therefore, be considered in the management of the groundwater resource.

Efficiency of water use in a dairy industry: a case study from Campo Largo, Brazil

Abstract This paper aims to (i) quantify water use during the milk production process in a farm in southern Brazil, (ii) propose measures to reduce it, and (iii) elaborate and subsequently implement educational and structural measures promoting water-use efficiency and final disposal of the manure produced. The research was conducted during 6 months and it was divided into three field stages. The first stage identified and quantified the multiple uses of water during milk production, using water meters. In the second stage, reduction measures were implemented to reduce the water use. Finally, in the third stage, a series of educational and structural measures were elaborated with the validated measures. The average water disappearance (intake + waste) measured was 98 L·cow−1·d−1, decreasing to 83 L·cow−1·d−1 and 91 L·cow−1·d−1 at the second and third stages, respectively. The modification of the cleaning and disinfection process was the most efficient measure, saving 8.5 litres per day. The potential saving of all the measures combined was 17 L·cow−1·d−1. Seeking to increase even more the water economy, the resulting series of recommended measures covered the whole cycle of water disappearance in the milking process.

Estimation and analysis of the ratio of transpiration to evapotranspiration in forest ecosystems along the North-South Transect of East China

The ratio of transpiration to evapotranspiration (T/ET) is a key parameter for quantifying water use efficiency of ecosystems and understanding the interaction between ecosystem carbon uptake and water cycling in the context of global change. The estimation of T/ET has been paid increasing attention from the scientific community in recent years globally. In this paper, we used the Priestly-Taylor Jet Propulsion Laboratory Model (PT-JPL) driven by regional remote sensing data and gridded meteorological data, to simulate the T/ET in forest ecosystems along the North-South Transect of East China (NSTEC) during 2001–2010, and to analyze the spatial distribution and temporal variation of T/ET, as well as the factors influencing the variation in T/ET. The results showed that: (1) The PT-JPL model is suitable for the simulation of evapotranspiration and its components of forest ecosystems in Eastern China, and has relatively good stability and reliability. (2) Spatial distribution of T/ET in forest ecosystems along NSTEC was heterogeneous, i.e., T/ET was higher in the north and lower in the south, with an averaged value of 0.69; and the inter-annual variation of T/ET showed a significantly increasing trend, with an increment of 0.007/yr (p<0.01). (3) Seasonal and inter-annual variations of T/ET had different dominant factors. Temperature and EVI can explain around 90% (p<0.01) of the seasonal variation in T/ET, while the inter-annual variation in T/ET was mainly controlled by EVI (53%, p<0.05).

INDO-FRENCH HIGH-RESOLUTION THERMAL INFRARED SPACE MISSION FOR EARTH NATURAL RESOURCES ASSESSMENT AND MONITORING – CONCEPT AND DEFINITION OF TRISHNA

Abstract. The Indian and French Space Agencies, ISRO and CNES, have conceptualized a space-borne Thermal Infrared Reflectance (TIR) mission, TRISHNA (Thermal infRared Imaging Satellite for High-resolution Natural Resource Assessment). The primary design drivers of TRISHNA are the monitoring of (i) terrestrial water stress and use, and of (ii) coastal and continental water. A suit of four TIR bands and six optical bands is planned. The TIR bands will be centred at 8.6 μm, 9.1 μm, 10.3 μm and 11.5 μm to provide noon-night global observations at 57m nadir resolution over land and coastal regions. The field of view (FOV) is ±34° and the orbit of 761 km altitude was designed to allow 3 sub-cycle acquisitions during the 8-day cycle. The optical bands correspond to blue, green, red, and NIR plus two SWIR bands at 1.38 μm and 1.61 μm. The green, red, NIR and the 1.61 μm SWIR bands will have better radiometry quality than those of AWiFS. ISRO and CNES will develop optical and TIR payloads, respectively. Assessing evapotranspiration and furthermore Gross and Net Primary Productivity (GPP and NPP) will in turn assist in quantifying water use in rainfed and irrigated agriculture, water stress and water use efficiency, with expected applications to agricultural drought and early warning, crop yield prediction, water allocation, implementation of water rights, crop insurance business and agro-advisories to farmers. The other scientific objectives of TRISHNA are also briefly described. TRISHNA instrument will fly aboard a ISRO spacecraft scheduled to be launched from 2024 for a minimum period of 5 years’ mission lifetime.

Using Plant Phenology and Landsat-8 Satellite Data to Quantify Water Use by Onion Crop in the Mesilla Valley, New Mexico

Using Plant Phenology and Landsat-8 Satellite Data to Quantify Water Use by Onion Crop in the Mesilla Valley, New MexicoCantekin KIVRAK1*, A. Salim BAWAZIR2, Zohrab SAMANI3, Caiti STEELE4, and Bülent SÖNMEZ51. Graduate Student, Dept. of Civil Engineering, New Mexico State University, MSC 3CE, PO Box 30001, Las Cruces, NM 88003, E-mail: cantekin@nmsu.edu , Corresponding author2. Associate Professor, Dept. of Civil Engineering, New Mexico State University, MSC 3CE, PO Box 30001, Las Cruces, NM 88003, E-mail: abawazir@nmsu.edu3. Professor, Dept. of Civil Engineering, New Mexico State University, MSC 3CE, PO Box 30001, Las Cruces, NM 88003, E-mail: zsamani@nmsu.edu4. Assistant Professor, Dept. of Plant and Environmental Science Jornada Experimental Range Station, USDA-ARS-Jornada Experimental Range, P.O. Box 30003, MSC 3JER, NMSU, Las Cruces, NM 88003, E-mail: caiti@nmsu.edu5. Dept. Chair of Soil and Water Resources, MFAL, General Directorate of Agricultural Research and Policies, Ankara, TURKEY, E-mail: bulent.sonmez@tarim.gov.tr ABSTRACT Non-storage summer dry onion crop is among the top 10 agricultural commodities in New Mexico (NM), USA. In 2000, NM was ranked the second in the nation as the leading state in growing summer dry onion. According to USDA statistical records, onion production or sales in NM was valued at $91.4 million. Mesilla Valley is one of the major onion-producing regions of NM. Due to many years of drought in the region and the concern for climate change, irrigation managers and decision makers are interested in quantifying water use or evapotranspiration (ET) and the number of acreage of onion crop grown in the Valley. This information can then be used for managing the scarce water resources of the region. Plant phenology, Landsat-8 satellite data, and USDA crop data were used to identify onion crops in the Valley (area of about 47,000 ha) and to determine their consumptive water use or ET using remote sensing Regional ET Estimation Model (REEM) from 2014 through 2016. Time series of NDVI clearly identified Fall and Spring-season onion crops in the Valley. REEM estimated Spring-season onion crop maximum ET of 973 mm in 2015 and 975 mm in 2016 during the growing season. These values compared reasonably well to ET estimates of 894 and 955 mm for the same periods (i.e. 2015 and 2016) using FAO-56 crop coefficient based method. The methodology presented could be used in other regions to identify onion crops and their consumptive water use.Key words:Onion, NDVI, Evapotranspiration, Landsat-8, Remote Sensing [*] Corresponding author: cantekin@nmsu.edu