Integrating groundwater irrigation into hydrological simulation of India: Case of improving model representation of anthropogenic water use impact using GRACE

L. Longuevergne,H. Xie,C. Ringler,B.R. Scanlon

doi:10.1016/j.ejrh.2020.100681

Abstract

Study regionIndia Study focusIndia boasts the largest irrigated agricultural system in the world relying on groundwater. To address the strong linkages between the natural groundwater and the anthropogenic irrigated system requires innovative hydrological modeling geared at informing national policies on groundwater management and future development of irrigated agriculture. For this, we developed a predictive, integrated hydrological and groundwater use model and evaluated the model using total water storage (TWS) data from the Gravity Recovery and Climate Experiment (GRACE). The utility of the model was demonstrated in a case study in which the model was applied to project the groundwater balance in northwest India under four RCP (Representative Concentration Pathways) scenarios. New hydrological insights for the regionThe model shows good identifiability to GRACE data in northwest India and with incorporated groundwater irrigation simulation module the model can adequately replicate the declining trend in TWS over this region. It is concluded that by assuming a unchanged pattern of agricultural water use climate change is likely to help reduce the magnitude of the groundwater deficit, but the beneficial effect is insufficient to halt the trend of groundwater depletion. This result provides new evidence for the importance of groundwater conservation through changes in cropping patterns and improved groundwater governance.

Highlights

Hydrological research traditionally focuses on physical processes, but the importance of investigating linkages between the anthroposphere and the hydrosphere has been well recognized (Wagener et al, 2010)
What distinguishes our study from these studies is that past applications of Gravity Recovery and Climate Experiment (GRACE) total water storage (TWS) data in India focused on using trends derived from the GRACE TWS data to estimate historical groundwater depletion rates while our study developed a predictive model with enhanced representation of linkages between groundwater irrigation and groundwater storage
India is a country with intensive groundwater-fed irrigated agriculture; and the large extraction of groundwater for food production has created concerns about the sustainability of groundwater resources for both current and future citizens

Summary

Introduction

Hydrological research traditionally focuses on physical processes, but the importance of investigating linkages between the anthroposphere and the hydrosphere has been well recognized (Wagener et al, 2010). GRACE TWS data provide observations of terrestrial total water storage anomalies that integrate variations of all vertical components of water storages and have been applied for groundwater resources assessments in India at a national scale by Rodell et al (2009); Tiwari et al (2009); Chen et al (2014); Long et al (2016) and Asoka et al (2017) etc. They were used by Barik et al (2017) to examine the food-water-energy nexus in India over recent time periods. The prospects of extending the model to provide fuller analysis to inform policy making for groundwater management and groundwater-fed irrigated agriculture under changing climate and socioeconomic conditions are discussed

SWAT and watershed delineation

HRU definition

Irrigation and groundwater storage simulation

GRACE data and comparison of SWAT- and GRACE-based TWS variation data

Climate data and spin-up

Results of model identification

Assessing impacts of climate change on groundwater storage in northwest India

Conclusions and discussions