Abstract
The coordinated use of surface- and ground-water over time and space as two components of a single irrigation system is of outmost importance in many rural areas of the world, in order to assure crop production sustainability, to restore ongoing and to prevent future issues related to freshwater quality and quantity mismanagement/deterioration. New technological solutions, such as GIS-integrated simulation models, may provide reliable tools in order to evaluate impacts in space and time and to properly manage conjunctive use of surface water and groundwater and water-constrained agricultural production. After presenting the common open source simulation programs for dealing with conjunctive use, we discuss and present the integration of the Farm Process (FMP; embedded in the USGS’s MODFLOW One-Water Hydrologic Model) coupled to a Crop Growth Module (CGM) within the open source and public domain QGIS-integrated FREEWAT platform. Using FMP in FREEWAT gains the benefit of the spatial environment and data management tools of a GIS solution, and to perform proper analysis of dynamically integrated terms of the hydrological cycle, to effectively balance crop water demand and supply from different sources of water. A simple hypothetic, yet realistic, application of the proposed approach with FMP and CGM is presented, simulating the yield of irrigated sunflower at harvest in a Mediterranean area. Results provide an insight on the potential exploitation of the developed solution, including, but not limited, to: quantitative temporal analysis of irrigation water sources, detailed analysis of evaporation and transpiration terms (from irrigation, groundwater or rainfall). The coupling of FMP with CGM to estimate crop yield at harvest provides further management tools when dealing with crop productivity. In the simulated case study, the analysis of the water balance terms allowed identifying the relevance of the groundwater contribution to ETc-act, highlighting the role of natural root uptake. The proposed solution is thought to be deployed by water authorities, large farms and public/private companies managing irrigation areas. The use of these tools calls for dedicated capacity building to boost digitalization in the agricultural water sector in order to achieve data-based agricultural water management.
Highlights
During the last decades, freshwater resources have been facing growing pressure, due to both human impacts and climate changes (Anandhi and Kannan, 2018; Azhoni et al, 2018; Deligios et al, 2018; Ehsani et al, 2017; Shukla et al, 2018; Vrzel et al, 2018)
We describe the capabilities and modeling tools to assess and evaluate conjunctive management of water in rural areas that are made available through the coupling of Farm Process (FMP) with Crop Growth Module (CGM) and their integration into the FREEWAT platform
The impact of groundwater withdrawal may be tested against local regulations with specific regards to regulated drawdown in case of agricultural areas affected by aquifer overexploitation
Summary
Freshwater resources have been facing growing pressure, due to both human impacts and climate changes (Anandhi and Kannan, 2018; Azhoni et al, 2018; Deligios et al, 2018; Ehsani et al, 2017; Shukla et al, 2018; Vrzel et al, 2018). This holds especially true in the rural environment, where the bulk of water abstraction takes place (Gruère et al, 2018; Li et al, 2016; Sun et al., 2017).
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