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Irrigation and drainage performance assessment: practical guidelines
Effective irrigation and drainage systems are essential if growing demands for water resources are to be met. For the use of water for irrigation to be improved we must understand current levels of performance. This book draws together the growing body of knowledge on irrigation and drainage performance assessment that has been gained over the last twenty years. It provides guidelines for practitioners to enable them to design and carry out performance assessment and implement performance-based management. Developed by a working group of the International Commission on Irrigation and Drainage (ICID) it provides a generic framework for performance assessment with guidance on the theory and practice of how to audit and assess the performance of irrigation and drainage schemes.
eBook
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.
Journal Article
Mapping water status based on aerial thermal imagery: comparison of methodologies for upscaling from a single leaf to commercial fields
Aerial thermal remote sensing can provide a means for collecting spatial plant water status data. Many studies have shown their potential in irrigation management but the adaptation of this technology is not straight forward. In this paper, knowledge accumulated in recent years on thermal imagery analysis methodology for water status mapping is summarized aiming at indicating alternatives to calculate the Crop Water Stress Index (CWSI) for commercial scale water status mapping. Based on literature overview, four forms of wet-baselines to calculate CWSI were selected, namely: artificial wet reference surface, two theoretical calculations and a statistical bio-indicator. These baselines were used to calculate CWSI based on multi-temporal aerial thermal images of cotton fields. CWSI based on a statistical bio-indicator and one of the theoretical wet-baselines provided the best correlations. It is argued though that the statistical one is preferable since it includes the plant characteristics and it is farmer-friendly. Based on bio-indicators, leaf water potential maps of three commercial fields were produced on several dates through the season. Water status spatial patterns were not static and the effect of static factors like sandy soil patches also changed through the season. The maps show the importance of in-season variability mapping for rational irrigation management. To improve current variable-rate irrigation, the concept of in-season irrigation management zones (IMZ) based on thermal-images should be considered and integrated with the delineation of static irrigation IMZ.
Journal Article
Major crops and water scarcity in Egypt : irrigation water management under changing climate
Including multi-disciplinary quantifications of the effect of climate change on the water requirements of wheat, maize, rice and sugarcane, this text provides on-farm management that faces water scarcity under current situations and under climate change.
Book
EFFECT OF LENGTHANDDEPTHOF THEDRIPTAPEON WETTING FRONT ADVANCE IN THE ROOT ZONE OF SUNFLOWR USING HYDRUS 2D/3D PROGRAM
A field experiment was carried out during the spring season 2020 at the University of Baghdad to study the effect of the length and depth of the drip tape on wetting advance ofsubsurface drip irrigation system using Hydrus 2D/3D program. The site was planted with sunflower in a clay loam texture. The drip tape was installed at 0.3m below soil surfacein two lengths; 20m and 40m. The experiment was designed according to the arrangement of split plotsdesign and with three replications. The treatments were randomly distributed and planted with sunflower crop. The results showed that the moisture contents of the 20 mlength drip tape was higher compared with the 40 m drip tape length. Also, the length of the tape was superior in some components of the yield if the length of the drip tape exceeded 20 m in the character of the number of seeds in one disc, and the result was a significant superiority.
Journal Article
Soil moisture retrieval from dual-polarized Sentinel-1 SAR data over agricultural regions using a water cloud model
The accurate retrieval of soil moisture plays a pivotal role in agriculture, particularly in effective irrigation water management, as it significantly affects crop growth and yield. The present study mainly focuses on the robustly investigated capability of dual-polarized Sentinel-1 SAR–derived vegetation descriptors in the water cloud model (WCM) in surface soil moisture (SSM) retrieval over wheat crops. The vegetation descriptors used in the study are radar vegetation index (RVI), backscattering ratio, polarimetric radar vegetation index (PRVI), dual polarization SAR vegetation index (DPSVI), and dual polarimetric radar vegetation index (DpRVI). The results of the WCM model illustrate that all the models show acceptable results, which confirms that this vegetative descriptor can be useful to estimate the accurate soil moisture over the wheat crop in the study area, except for DPSVI. Furthermore, the results revealed that model performances gradually decrease as the crop enters the complex stages. In summary, the overall finding demonstrates that PRVI outperformed other models in terms of statistical indicators value for calibration (R
2
= 0.728, NSE = 0.727, PBIAS = − 2.67%, and RMSE = 2.985%) and validation (R
2
= 0.728, NSE = 0.684, PBIAS = − 13.666%, and RMSE = 4.106%). Thus, overall results proved that the WCM model has considerable potential to retrieve SSM over wheat crops from Sentinel-1 satellite data. This study will be beneficial for regional water resources managers for proper allocation of irrigation water, effective irrigation management, and enhanced irrigation efficiency within the regions.
Journal Article
Irrigation Management Scale and Water Application Method to Improve Yield and Water Productivity of Field-Grown Strawberries
Improvements in water productivity are of primary importance for maintaining agricultural productivity and sustainability. Water potential-based irrigation management has proven effective for this purpose with many different crops, including strawberries. However, problems related to spatial variability of soil properties and irrigation efficiency were reported when applying this management method to strawberries in soils with rock fragments. In this study, a field-scale experiment was performed to evaluate the impacts of three irrigation management scales and a pulsed water application method on strawberry yield and water productivity. An analytical solution to Richards’ equation was also used to establish critical soil water potentials for this crop and evaluate the effects of the variability in the soil properties. Results showed that spatial variability of soil properties at the experimental site was important but not enough to influence crop response to irrigation practices. The studied properties did not present any spatial structure that could allow establishing specific management zones. A four-fold reduction in the size of the irrigation management zones had no effect on yield and increased the water applications. Pulsed application led to significant yield (22%) and water productivity (36%) increases compared with the standard water application method used by the producer at the experimental site.
Journal Article