ADAPTATION TO A CHANGING CLIMATE
MARITIME
CASE STUDY
WATER SHORTAGES AND THE PANAMA CANAL
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Future Present
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Figure 8. Probability distributions of water level in Lake Gatun observed in recent decades and projected for late this century - assuming no adaptation
Water level [feet]
Risk-based adaptation analysis Our analysis calculates the expected monetary losses due to low water levels during the dry season (January to April) in present and future climates. We start by modelling water flow in the Canal’s catchment area, accounting for contributions: rainfall and consequent river discharge, regulated release from artificial reservoirs losses: evaporation, flow through locks, municipal and industrial demands The main climate-related variables are rainfall and evaporation. For “present climate” these are derived from observations over the period 1950 to 2000. For future climate, projections over the period 2060 to 2100 are made by global climate models. Here we use the CMIP5 dataset. The other variables are derived from observations and future projections of municipal and industrial water demands, and of water consumption by locks in present and future configurations. Water levels may be affected by these system changes as well as by climate change.
A Bayesian Network (BN) is used to model the water levels in the lake probabilistically. This process takes probability distributions for the various inputs such as rainfall, and combines them to provide probabilities of different resulting water levels. Publicly available data and weather observations obtained from National Oceanic and Atmospheric Administration (NOAA) were used to compute the probabilistic features of the modelled variables and include these in the BN. Water levels with no adaptation In a baseline scenario with no adaptation, our results suggest that climatic and system changes will tend to dry out the Canal. This can be seen in Figure 8, showing present and future probability distributions of water level at the midst of the dry season (end of February). The mean future levels are about 5 feet (1.5) meters lower, enough to force the temporary closure of the Canal almost every year. A considerable amount of this reduction is due to system changes: increases in water demand due to enhanced Canal operations and growth in the local population and economy. This highlights the importance of evaluating system changes along with climatic ones when performing an adaptation analysis.
DNV GL@2014. [WWW.DNVGL.COM/CLIMATE-ADAPTATION]