A Framework for Charting Water-Energy-Land Nexus Solutions for the Indus Basin

The Indus Basin, home to approximately 300-million people, has a total area of 1.12 million km² (47 % Pakistan, 39 % India, 6 % Afghanistan, and 8 % China) and the highest density of irrigated land in the world. The region's rapid population and economic growth in recent decades is expected to continue in the next decades leading to growing demands for water, energy and food. With no abundant surface water left in the basin for future expansion and accelerating use of fossil groundwater as a result, long-term management of water-energy-food systems dependent on water is fundamental for the sustainable development of the region. Here, we present an open source computing framework or tool designed to aid decision-makers with complex planning regarding the integrated development of water, energy and land resources in the Indus Basin. The NExus Solutions Tool (NEST) links an engineering-economic model, representing investment and allocation decisions across water, energy and land-use sectors, to a hydrological model, representing the detailed biophysical processes at high spatial and temporal resolutions. NEST provides insights into: (1) the vulnerability of surface water and groundwater resources to future socioeconomic and climatic change; and (2) how policies, technological solutions and investments can improve the sustainability of water, energy and land transformation pathways while avoiding unintended side effects and minimizing trade-offs among sectors. NEST features explicit representations of existing transboundary policies and planned investments. Scenario analyses demonstrate the capabilities of NEST to provide new insights into the cost and characteristics of long-term infrastructure pathways aligned with the United Nations' Sustainable Development Goals for water, energy and food. NEST is readily adaptable to other river basins or administrative regions.