Combination of remote sensing and meteorological data for estimation of crop water requirements in the irrigated perimeter of Tadla in Morocco

Author(s):  
Jaouad El Hachimi ◽  
Abderrazak El Harti ◽  
Amine Jellouli

<p>In arid and semi-arid regions, agriculture is an important element of the national economy, but this sector is a large consumer of water. In a context of high pressure on water resources (climate change, population growth, desertification, etc.), an appropriate management is required. The development of remote sensing tools: temporal, spatial and spectral resolution offers a better opportunity for hydro-agricultural management. The main objective of this study is to combine climate data with that of optical remote sensing in order to estimate crop water requirements in the irrigated perimeter of Tadla. In semi-arid regions, such as Tadla Plain, a large quantity of water is lost by evapotranspiration (ET). The objective of this study is to use a scientific approach based on the modulation of evaporative demand for the estimation of crop water requirements. This approach is based on the FAO-56 method using image data from the Sentinel-2A and Landsat-8 satellites, and climate data: surface temperature, air humidity, wind speed, global solar radiation and precipitation. It also allowed the spatialization of crop water requirements on a large area of irrigated crops during the 2016–2017 agricultural season. Maps of water requirements have been developed. They show the variability over time of crop development and their estimated water requirements. The results obtained constitute an important indicator of how water should be distributed over the area in order to improve irrigation efficiency and protection of water resources.</p>


2015 ◽  
Author(s):  
Lampros Vasiliades ◽  
Marios Spiliotopoulos ◽  
John Tzabiras ◽  
Athanasios Loukas ◽  
Nikitas Mylopoulos


2020 ◽  
Vol 12 (16) ◽  
pp. 2587
Author(s):  
Yan Nie ◽  
Ying Tan ◽  
Yuqin Deng ◽  
Jing Yu

As a basic agricultural parameter in the formation, transformation, and consumption of surface water resources, soil moisture has a very important influence on the vegetation growth, agricultural production, and healthy operation of regional ecosystems. The Aksu river basin is a typical semi-arid agricultural area which seasonally suffers from water shortage. Due to the lack of knowledge on soil moisture change, the water management and decision-making processes have been a difficult issue for local government. Therefore, soil moisture monitoring by remote sensing became a reasonable way to schedule crop irrigation and evaluate the irrigation efficiency. Compared to in situ measurements, the use of remote sensing for the monitoring of soil water content is convenient and can be repetitively applied over a large area. To verify the applicability of the typical drought index to the rapid acquisition of soil moisture in arid and semi-arid regions, this study simulated, compared, and validated the effectiveness of soil moisture inversion. GF-1 WFV images, Landsat 8 OLI images, and the measured soil moisture data were used to determine the Perpendicular Drought Index (PDI), the Modified Perpendicular Drought Index (MPDI), and the Vegetation Adjusted Perpendicular Drought Index (VAPDI). First, the determination coefficients of the correlation analyses on the PDI, MPDI, VAPDI, and measured soil moisture in the 0–10, 10–20, and 20–30 cm depth layers based on the GF-1 WFV and Landsat 8 OLI images were good. Notably, in the 0–10 cm depth layers, the average determination coefficient was 0.68; all models met the accuracy requirements of soil moisture inversion. Both indicated that the drought indices based on the Near Infrared (NIR)-Red spectral space derived from the optical remote sensing images are more sensitive to soil moisture near the surface layer; however, the accuracy of retrieving the soil moisture in deep layers was slightly lower in the study area. Second, in areas of vegetation coverage, MPDI and VAPDI had a higher inversion accuracy than PDI. To a certain extent, they overcame the influence of mixed pixels on the soil moisture spectral information. VAPDI modified by Perpendicular Vegetation Index (PVI) was not susceptible to vegetation saturation and, thus, had a higher inversion accuracy, which makes it performs better than MPDI’s in vegetated areas. Third, the spatial heterogeneity of the soil moisture retrieved by the GF-1 WFV and Landsat 8 OLI image were similar. However, the GF-1 WFV images were more sensitive to changes in the soil moisture, which reflected the actual soil moisture level covered by different vegetation. These results provide a practical reference for the dynamic monitoring of surface soil moisture, obtaining agricultural information and agricultural condition parameters in arid and semi-arid regions.



Author(s):  
Alfonso Calera ◽  
Isidro Campos ◽  
Anna Osann ◽  
Guido D´Urso ◽  
Massimo Menenti

The experiences gathered during the past 30 years support the operational use of irrigation scheduling based on frequent multi-spectral image data. Currently, the operational use of dense time series of multispectral imagery at high spatial resolution makes monitoring of crop biophysical parameters feasible, capturing crop water use across the growing season, with suitable temporal and spatial resolutions. These achievements, and the availability of accurate forecasting of meteorological data, allow for precise predictions of crop water requirements with unprecedented spatial resolution. This information is greatly appreciated by the end users, i.e. professional farmers or decision-makers, and can be provided in an easy-to-use manner and in near-real-time by using the improvements achieved in web-GIS methodologies. This paper reviews the most operational and explored methods based on optical remote sensing for the assessment of crop water requirements, identifying strengths and weaknesses and proposing alternatives to advance towards full operational application of this methodology. In addition, we provide a general overview of the tools which facilitates co-creation and collaboration with stakeholders, paying special attention to these approaches based on web-GIS tools.



Author(s):  
Lisma Safitri

The accurate water use information at each stage of plant growth is important to better understand the efficient and precise crop water requirement for optimal plant productivity. Nurseries of palm oil are a phase where young palm oil requires extra maintenance, particularly in meeting the plant water needs. The palm oil in the nursery phase require the regular irrigation schedule due to the vulnerable root systems. The purpose of this study was to calculate the oil palm water requirement with Cropwat 8.0 toward the precise irrigation management and provide a scenario for irrigation scheduling in palm oil nursery. The study was conducted in palm oil main nurseries at KP2 Instiper Yogyakarta with site-specific climate data and soil properties. The method used is analyzing climate data and soil properties and simulating crop water requirements, actual water use and irrigation scheduling with Cropwat 8.0. Based on the results, the average of crop water requirement (ETP) of palm oil in main nursery is 3.4 mm / day. Based on the water deficit scenario from rainfall and crop water requirements, irrigation is scheduling in April for 1.4 mm, May for 18.3 mm, June for  3.5 mm, July for 44.1 mm and August for 42.8 mm. On a daily scale and taking into account the availability of soil moisture and the water retention of plant roots, the net irrigation scheduling is given at an average of 2.2 mm / day and gross irrigation of 6 mm / day which is given daily depending on rainfall and plant age.



Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 756 ◽  
Author(s):  
Ewaid ◽  
Abed ◽  
Al-Ansari

The climate of Iraq is of the subtropical semi-dry type; however, the country was rich in water resources until a few decades ago. Climate change and the construction of many dams on the Tigris and Euphrates rivers in the neighboring countries have caused water shortages and poor water quality. Now, there is a need to decrease consumption, improve management of water resources, and determine the water requirements of the major crops because agriculture is the first consumer of water in Iraq. The Food and Agriculture Organization (FAO) CROPWAT 8.0 simulation software and the CLIMWAT 2.0 tool attached to it have been used in this research for Dhi-Qar Province in southern Iraq to find the crop water requirements (CWRs) and irrigation schedules for some major crops. The CROPWAT Penman–Monteith method was used to calculate the reference crop evapotranspiration (ET0) and the United States Department of Agriculture (USDA) soil conservation (S.C.) method was used to estimate the effective rainfall. The study results showed that ET0 varied from 2.18 to 10.5 mm/day and the effective rainfall varied from 0.0 to 23.1 mm. The irrigation requirements were 1142, 203.2, 844.8, and 1180 mm/dec for wheat, barley, white corn, and tomatoes, respectively. There is a higher water demand for crops during the dry seasons (summer and autumn) and a lower demand during the wet seasons (winter and spring). The total gross irrigation and the total net irrigation were 343.8 mm and 240.7 mm for wheat, 175.2 mm and 122.6 mm for barley, 343.8 mm and 240.7 mm for white corn, and 203.3 mm and 142.3 mm for tomatoes. This study proved that the CROPWAT model is useful for calculating the crop irrigation needs for the proper management of water resources.



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