Estimation of water losses through evapotranspiration of aquatic weeds in the Nile River (Case study: Rosetta Branch)

Abstract

Aquatic weeds management and estimation of water losses from evapotranspiration must be taken into consideration in order to reduce water losses. The objective of this research is estimating the water losses through evapotranspiration of aquatic weeds in the Rosetta Branch in order to identify the quantities of water that could be saved when applying appropriate maintenance programs for aquatic weeds. To achieve the objective of this research, the research team identify areas of infection of the aquatic weeds using field visits, determine its coordinates using GPS and Satellite imagery (Landsat-8) and estimate of water losses through evapotranspiration of aquatic weeds by using the following evapotranspiration equation: ETc = ETo × Kc. The result for estimation of the average annual water losses through evapotranspiration of aquatic weeds in the Rosetta Branch during one year (from December 2015 to November 2016) were 21.3 million m 3 /year, 0.7 million m 3 /year and 1.1 million m 3 /year for water hyacinth, Common Reed and Torpedo grass, respectively.

Quantification of the Evaporation Rates from Six Types of Wetland Cover in Palo Verde National Park, Costa Rica

“…The presence of macrophytes increases considerably the evaporation from open water bodies [30,40]. Any increment in the number of plants per unit of area in an open water surface represents an augment in the physiological water demand for those plants [38]. For this reason the intermediate daily evaporation rate of the Mixed cover is similar to the evaporation rate of the T. dominguensis cover.…”

“…From the 100 macrophytes reported in Palo Verde National Park [14,15], only T. dominguensis and E. crassipes [28,[34][35][36][37] have published values of evaporation in other regions (e.g., Suriname, South Africa, United States). The effect of invasive plants as T. dominguensis and E. crassipes in wetlands is linked to the increment of evaporation and the subsequent reduction of the water surfaces [38][39][40].…”

Estimation of Water Losses Through Evapotranspiration of Water Hyacinth (Eichhornia crassipes)

“…The stages of the activity consisted of normalizing data, making RGB composite images, sharpening composite images, delineating lake water surface limits, calculating Reservoir water surface area and analyzing changes in lake water surface area (Indonesian National Institute of Aeronautics and Space, 2015). Using the NDVI index to highlight plants (weeds), at each date with the equation 1as follows (Ali and El-Din Khedr, 2018). Identification of water hyacinth is determined using RGB composite image (R = NIR + SWIR, G = NIR, B = NIR-Red) or composite image of RGB 562 (Suwargana, 2010;Dube et al, 2017) and analyzed by supervised classification methods using ENVI 5.3 software and ArcGIS 10.4.…”

“…The surface area of water hyacinth influences the amount of water loss, the low cover of water hyacinth has an impact on the amount of water loss is low, as well as extensive cover conditions have an impact on the amount of greater water loss (Arp et al, 2017;Ali and El-Din Khedr, 2018). The lowest water loss occurred on 21 October 2014, although the average evapotranspiration rate of water hyacinth in October was the highest at 6.16 mm day -1 (Figure 8), however, the cover area of the water hyacinth was recorded as the lowest, which is around 1.29% of the total surface area of the reservoir with an area of 2,969,400 m 2 .…”

“…The highest monthly evapotranspiration occurred in October 2014 at 6.16 mm day -1 and the lowest occurred in June 2013 at 3.60 m day -1 . According toAli and El-Din Khedr (2018) that the average evapotranspiration rate of water hyacinth is 2.3 times greater than evaporation of free surface in the same area.…”