Hydrology, Soil Moisture, and Evapotranspiration

The long-term goal of this project is to develop the cosmic-ray neutron method for real-time mobile soil moisture mapping capabilities and to advance our understanding of the petrophysical transform, which converts the measured property (the intensity of low-energy neutrons) into the variable of interest (the area-average soil moisture). This research will also assess the potential of using remote sensing products to estimate the required local ancillary information for the petrophysical transform as opposed to the current practice of local direct sampling.

Investigators: Trenton Franz (University of Nebraska-Lincoln), Hydroinnova LLC, and Quaesta Instruments

Funding: DOD CRREL ($50,000, 2014-2015)

Drylands cover 40% of the continent of Africa, and are the basis for traditional pastoralist social ecological systems, in which societies have adapted to rely heavily or entirely on livestock production fortheir livelihoods in harsh and variable environments. Modernity has brought drastic political, social andland use changes, as well as unprecedented population growth, land degradation and more frequent droughts that decimate herds. Here the project team will employ complex adaptive system approaches to evaluate emerging patterns of vulnerability in two pastoralist communities in Kenya which have begun to diversify into maize agriculture alongside their struggling livestock-based livelihood system. We will adopt approaches to investigate how mixed land use affects the sensitivity of range productivity to drought and shifting grazing pressures; how composition and inequities in household livestock assets create differential patterns of risk exposure associated with entry into agriculture; and how evolving landuse institutions affect the coping capacity and resilience at individual and collective scales.

Investigators: Elizabeth King (UGA) and Laura German (UGA) (Franz consultant from UNL)

Funding: NSF Dynamics of Coupled Natural and Human Systems ($249,000, 2013-2015

In order to feed the growing world population by 2050, the FAO estimates a needed increase of 70% in cereal grains, placing a greater demand on dwindling water resources. Irrigation agriculture accounts for 40% of global food production, yet it is estimated that 60% of the 2,500 trillion liters of water used globally for agriculture each year is wasted through inadequate water conservation, distribution losses, and inappropriate irrigation times and rates. A salient solution is to irrigate only when and where water is needed, but a fundamental cause of excess water use is our inability to quantify soil moisture at the application scales where management decisions are made. Our limited knowledge of how soil moisture is organized across scales not only hampers our ability to better manage agricultural water efficiency but is also a fundamental question in hydrology. The long-term goal is to understand how soil moisture is organized across scales. The goal of this project is to further our understanding of how soil moisture is organized at intermediate scales where water management decisions are made but that have been largely underrepresented due to technologic and practical limitations. To overcome these limitations, the team will incorporate a suite of nested hydrogeophysical observations with different measurement areas/volumes and focus our observations in agricultural irrigation settings, which offer an ideal experimental setting.

Investigators: Trenton Franz (UNL) and Derek Heeren (UNL)

Funding: NSF Hydrologic Sciences (In Review)