Method Development for Including Environmental Water Requirement in the Water Stress Index

2018 ◽  
Vol 32 (5) ◽  
pp. 1585-1598 ◽  
Author(s):  
Pariyapat Nilsalab ◽  
Shabbir H. Gheewala ◽  
Stephan Pfister
2018 ◽  
Vol 11 (1) ◽  
pp. 152
Author(s):  
Pariyapat Nilsalab ◽  
Shabbir Gheewala

Human and environmental demands for water are both important; therefore, two approaches are proposed for assessing water scarcity using the water stress index. In one of them, the human demand for water explicitly includes environmental water as one of the components (WSIe1), whereas in the other, environmental water is explicitly reserved by subtracting it from the water availability (WSIe2). The results obtained from using the two approaches in the case of Bang Pakong watershed correspondingly contribute to the explanation of the existing stress situation, especially in the dry season. The stressful results were noticed during December to February for both approaches as a result of less available water and higher environmental water requirement. The assessment of environmental water requirement (EWR) in this study was quantified according to low and high flow periods. The two approaches perform well for assessing water scarcity in the Bang Pakong watershed; however, the result interpretation using the WSIe1 approach is more serious than the WSIe2 approach in terms of water scarcity potential beyond the critical threshold. In conclusion, priority of water allocation is the key consideration for selecting the approach. Higher priority for the environment favors the use of WSIe2 for policy making whereas for a lower priority, the use of WSIe1. In case of Thailand, the WSIe2 approach would be recommended in order to put the EWR as the first priority. Then, water allocation priorities can be rearranged only for human demands for water while the EWR is already safeguarded by setting it aside.


HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 905D-905
Author(s):  
Thomas R. Clarke ◽  
M. Susan Moran

Water application efficiency can be improved by directly monitoring plant water status rather than depending on soil moisture measurements or modeled ET estimates. Plants receiving sufficient water through their roots have cooler leaves than those that are water-stressed, leading to the development of the Crop Water Stress Index based on hand-held infrared thermometry. Substantial error can occur in partial canopies, however, as exposed hot soil contributes to deceptively warm temperature readings. Mathematically comparing red and near-infrared reflectances provides a measure of vegetative cover, and this information was combined with thermal radiance to give a two-dimensional index capable of detecting water stress even with a low percentage of canopy cover. Thermal, red, and near-infrared images acquired over subsurface drip-irrigated cantaloupe fields demonstrated the method's ability to detect areas with clogged emitters, insufficient irrigation rate, and system water leaks.


2013 ◽  
Vol 118 ◽  
pp. 79-86 ◽  
Author(s):  
N. Agam ◽  
Y. Cohen ◽  
J.A.J. Berni ◽  
V. Alchanatis ◽  
D. Kool ◽  
...  

Agriculture ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 116 ◽  
Author(s):  
Alessandro Matese ◽  
Salvatore Di Gennaro

High spatial ground resolution and highly flexible and timely control due to reduced planning time are the strengths of unmanned aerial vehicle (UAV) platforms for remote sensing applications. These characteristics make them ideal especially in the medium–small agricultural systems typical of many Italian viticulture areas of excellence. UAV can be equipped with a wide range of sensors useful for several applications. Numerous assessments have been made using several imaging sensors with different flight times. This paper describes the implementation of a multisensor UAV system capable of flying with three sensors simultaneously to perform different monitoring options. The intra-vineyard variability was assessed in terms of characterization of the state of vines vigor using a multispectral camera, leaf temperature with a thermal camera and an innovative approach of missing plants analysis with a high spatial resolution RGB camera. The normalized difference vegetation index (NDVI) values detected in different vigor blocks were compared with shoot weights, obtaining a good regression (R2 = 0.69). The crop water stress index (CWSI) map, produced after canopy pure pixel filtering, highlighted the homogeneous water stress areas. The performance index developed from RGB images shows that the method identified 80% of total missing plants. The applicability of a UAV platform to use RGB, multispectral and thermal sensors was tested for specific purposes in precision viticulture and was demonstrated to be a valuable tool for fast multipurpose monitoring in a vineyard.


Author(s):  
Rodrigo G. Brunini ◽  
José E. P. Turco

ABSTRACT Sugarcane (Saccharum officinarum L.) is a crop of vital importance to Brazil, in the production of sugar and ethanol, power generation and raw materials for various purposes. Strategic information such as topography and canopy temperature can provide management technologies accessible to farmers. The objective of this study was to determine water stress indices for sugarcane in irrigated areas, with different exposures and slopes. The daily water stress index of the plants and the water potential in the soil were evaluated and the production system was analyzed. The experiment was carried out in an “Experimental Watershed”, using six surfaces, two horizontal and the other ones with 20 and 40% North and South exposure slopes. Water stress level was determined by measuring the temperatures of the vegetation cover and the ambient air. Watering was carried out using a drip irrigation system. The results showed that water stress index of sugarcane varies according to exposure and slope of the terrain, while areas whose water stress index was above 5.0 oC had lower yield values.


Author(s):  
Jian Peng ◽  
Yuanbo Liu ◽  
Xiaosong Zhao ◽  
Chun Ye ◽  
Ping Song ◽  
...  

1994 ◽  
Vol 86 (3) ◽  
pp. 574-581 ◽  
Author(s):  
H. R. Jalali‐Farahani ◽  
D. C. Slack ◽  
D. M. Kopec ◽  
A. D. Matthias ◽  
P. W. Brown

1994 ◽  
Vol 86 (1) ◽  
pp. 195-199 ◽  
Author(s):  
Donald J. Garrot ◽  
Michael J. Ottman ◽  
D.D. Fangmeier ◽  
Stephen H. Husman

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