Browsing by Author "Johnson, C."

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    A novel modelling toolkit for unpacking the Water-Energy-Food-Environment (WEFE) nexus of agricultural development
    (2022) Correa Cano, M. E.; Salmoral, G.; Rey, D.; Knox, J. W.; Graves, A.; Melo Contreras, Óscar; Foster Bonnette, William; Naranjo, L.; Zegarra, E.; Johnson, C.; Viteri Salazar, O.; Yan, X.
    Increasing food demand has led to significant agricultural expansion globally with negative impacts on resources and the environment, a perfect manifestation of the Water-Energy-Food-Environment nexus. Whilst many tools have been developed to understand the complexity of the Water-Energy-Food-Environment nexus most have failed to explicitly consider biophysical and socio-economic aspects simultaneously. A novel Water-Energy-Food-Environment modelling toolkit is developed that integrates both these components by combining different modelling approaches including irrigation simulation, economic modelling and life cycle environmental assessment. The toolkit is demonstrated using two major agro-export crops (asparagus and table grapes) in the Ica Valley, Peru, a severely water-stressed region. The toolkit was able to provide novel insights into the implications of different farming practices on resource efficiency at the field level in relation to water and energy, under contrasting future scenarios reflecting socio-economic outcomes at the local to regional levels (e.g., food prices, employment, and income) as well as environmental impacts at local to global scales. This information enables different stakeholders to better understand the interlinkages and inter-dependences between the Water-Energy-Food-Environment nexus elements and the complex impacts of agricultural expansion beyond the immediate sector and its geographical extent, helping decision makers design more coordinated agricultural policies and support sustainable agricultural transformation
  • Thumbnail Image
    Item
  • No Thumbnail Available
    Item
    The RR Lyrae Instability Strip in the Split Horizontal Branch Globular Cluster NGC 6569
    (2015) Kunder, A.; Stetson, P. B.; Catelan, Marcio; Walker, A.; Cassisi, S.; Johnson, C.; Soto, M.
    The first calibrated broadband BVI time-series photometry is obtained for the RR Lyrae variable stars in the split horizontal branch (HB) cluster NGC 6569. As a result, a sizeable population of 27 RR Lyrae variables has been identified. An eclipsing binary in the RR Lyrae instability strip was also found, which is most likely a field star. The 12 fundamental-mode RR Lyrae variables (RR0) have an average period of [P]RR0= 0.57±0.02 d and the 15 first-overtone variables (RR1) have an average period of [P]RR1=0.30±0.01 d. The mean periods of the RR Lyrae stars are consistent with an Oosterhoff I designation, and the number ratio of RR1- to RR0-type variables, N1/NRR=0.56, is more consistent with an Oosterhoff II designation. Compared to the M3 variables, the NGC 6569 RR Lyrae variables are not shifted to a longer periods at a given amplitude, making it unlikely that these stars are He-enhanced. The similarity in the periods and amplitudes between the RR Lyrae stars in NGC 6569 and the bulge field RR Lyrae population may indicate similar formation conditions.