M4 – Hydraulic model: irrigation-groundwater interaction

Partner: RWTH-IWW in cooperation with UAF and PMIU

Objective
In order to investigate the interaction of irrigation channels with groundwater, a groundwater flow model of the Rechna Doab is set up in DHI-FEFLOW as well as a 1D surface water flow model of the rivers and irrigation channels in SOBEK. These two models are coupled using the OpenMI standard and a proprietary coupling interface between Feflow and OpenMI, developed by RWTH-IWW.

Current Results
Groundwater hydraulic head hydrographs of 588 wells suggest that groundwater levels are constant or even rising in the study area for the last decade. Trends of falling groundwater were observed in 33% of the wells, located partly in the tail end of the irrigation system. A groundwater flow model (FEFLOW), considering all major irrigation channels, was set up for the Rechna Doab including LCC. The model utilizes groundwater recharge data of M3, classified land use data of M1, and abstraction rates given by farmer interviews in M5. Budget analysis suggests that leakage from irrigation channels is the largest single contributor to the groundwater balance.

Expected Outcome
The models will continuously be updated and refined as new and more precise data becomes available from field surveys or from models of project partners. A validation of the groundwater model using GRACE satellite data is ongoing.

Next steps include the model calibration and verification. Later on we will then look into modeling different future scenarios in close cooperation with other project partners.