Articles | Volume 21, issue 7
Hydrol. Earth Syst. Sci., 21, 3671–3685, 2017
Hydrol. Earth Syst. Sci., 21, 3671–3685, 2017

Research article 20 Jul 2017

Research article | 20 Jul 2017

Coupling biophysical processes and water rights to simulate spatially distributed water use in an intensively managed hydrologic system

Bangshuai Han1,2, Shawn G. Benner2, John P. Bolte3, Kellie B. Vache3, and Alejandro N. Flores2 Bangshuai Han et al.
  • 1Natural Resources and Environmental Management, Ball State University, Muncie, IN, 47306, USA
  • 2Geosciences, Boise State University, Boise, ID, 83725, USA
  • 3Biological & Ecological Engineering, Oregon State University, Corvallis, OR, 97333, USA

Abstract. Humans have significantly altered the redistribution of water in intensively managed hydrologic systems, shifting the spatiotemporal patterns of surface water. Evaluating water availability requires integration of hydrologic processes and associated human influences. In this study, we summarize the development and evaluation of an extensible hydrologic model that explicitly integrates water rights to spatially distribute irrigation waters in a semi-arid agricultural region in the western US, using the Envision integrated modeling platform. The model captures both human and biophysical systems, particularly the diversion of water from the Boise River, which is the main water source that supports irrigated agriculture in this region. In agricultural areas, water demand is estimated as a function of crop type and local environmental conditions. Surface water to meet crop demand is diverted from the stream reaches, constrained by the amount of water available in the stream, the water-rights-appropriated amount, and the priority dates associated with particular places of use. Results, measured by flow rates at gaged stream and canal locations within the study area, suggest that the impacts of irrigation activities on the magnitude and timing of flows through this intensively managed system are well captured. The multi-year averaged diverted water from the Boise River matches observations well, reflecting the appropriation of water according to the water rights database. Because of the spatially explicit implementation of surface water diversion, the model can help diagnose places and times where water resources are likely insufficient to meet agricultural water demands, and inform future water management decisions.

Short summary
The western US relies heavily on irrigation water which is allocated following local water rights. We develop and test a novel model that explicitly integrates water rights into a conceptual hydrologic model to spatially allocate irrigation water. The model well captures the timing and magnitude of irrigation water allocation in our study area and is applicable to semi-arid regions with similar water right regulations. The results could inform future water policies and management decisions.