An improved method for calculating the regional crop water footprint based on a hydrological process analysis

Abstract

Abstract. Fresh water is consumed during agricultural production. With the shortage of water resources, assessing the water use efficiency is crucial to effectively manage agricultural water resources. The water footprint is an improved index for water use evaluation, and it can reflect the quantity and types of water usage during crop growth. This study aims to establish a method for calculating the regional-scale water footprint of crop production based on hydrological processes, and the water footprint is quantified in terms of blue and green water. This method analyses the water-use process during the growth of crops, which includes irrigation, precipitation, groundwater, evapotranspiration, and drainage, and it ensures a more credible evaluation of water use. As illustrated by the case of the Hetao irrigation district (HID), China, the water footprint of wheat, corn and sunflowers were calculated using this method. The results show that canal water loss and evapotranspiration were responsible for most of the water consumption and accounted for 47.9 % and 41.8 % of the total consumption, respectively. The total water footprint of wheat, corn and sunflowers were 1380–2888, 942–1774 and 2095–4855 m3 t−1, respectively, and the blue footprint accounts for more than 86 %. The spatial distribution pattern of the green, blue and total water footprints for the three crops demonstrated that higher values occurred in the eastern part of the HID, which had more precipitation and was further away from the irrigation gate. This study offers a vital reference for improving the method used to calculate the crop water footprint.

Water Use Dynamics in Double Cropping of Rainfed Upland Rice and Irrigated Melons Produced Under Drought‐Prone Tropical Conditions

“…Alternatively in more recent years, other approaches have been adopted to estimate WF based on residually derived crop ET from soil or watershed water balances (Luan et al, ; Wang et al, ; Zhuo et al, ) or estimated via surface energy balance models using remote sensing products (Madugundu et al, ; Romaguera et al, ). The main challenges associated with these alternative approaches come from the difficulty of matching spatial and/or temporal resolution of crop ET estimates to the specific croplands and the uncertainties associated with their model inputs.…”

“…A detailed review of methods to estimate crop water use (CWU) or crop ET can be found in Allen et al (). In some studies, crop ET has been assumed to be equal to applied irrigation volumes (de Figueirêdo et al, ; Luan et al, ; Sun et al, ), which in turn impacts the reliability of WF estimates and results in disregarding of irrigation return flows, which are an important portion of the water cycle in agricultural settings. That is why empirical measurements of crop ET are key to providing realistic crop WFs that allow considering site‐specific meteorological and water availability conditions and permit accounting for irrigation return flows.…”

A conceptual framework for including irrigation supply chains in the water footprint concept: gross and net blue and green water footprints in agriculture in Pakistan

“…This possibility most often occurs when pumping groundwater by vertical drainage. Evaporation and seepage losses are also common for return flows (Luan et al, 2018).…”

“…CC BY 4.0 License. the irrigation technology (Luan et al, 2018). Traditionally, irrigation water losses in the supply chain were addressed under the classical approach of irrigation efficiency, which is the "ratio of water consumed by crops to total water withdrawals" (Israelsen, 1950).…”

Unravelling the Temporal-Spatial Distribution of the Agricultural Water Footprint in the Yangtze River Basin (YRB) of China

“…Major grain-producing areas and water shortage areas are often used as hot spots for the quantitative study of AWF [20,21]. The Provinces (such as Central Kalimantan of Indonesia [22]), states (such as Pernambuco in Brazil [23]), or irrigation districts (such as Hetao Irrigation District in China [24]), have also been the focus of crop water footprint research. In addition, some scholars have studied the crop water footprint and its composition through field experimental observation and investigation [25,26].…”