Abstract. The growing pressure on natural freshwater resources and the projected climate
variability are expected to increase the need for water storage during rainy
periods. Evaporative losses present a challenge for the efficiency of water
storage in reservoirs, especially in arid regions with chronic water
shortages. Among the available methods for suppressing evaporative losses,
self-assembling floating elements offer a simple and scalable solution,
especially for small reservoirs. The use of floating elements has often been
empirically based; we thus seek a framework for systematic consideration of
floating element properties, local climate and reservoir conditions to better
predict evaporative loss, energy balance and heat fluxes from covered water
reservoirs. We linked the energy balance of the water column with energy
considerations of the floating elements. Results suggest significant
suppression of evaporative losses from covered reservoirs in which incoming
radiative energy is partitioned to sensible and long wave fluxes that reduce
latent heat flux and thus increase the Bowen ratio over covered water
reservoirs. Model findings were consistent with laboratory-scale observations
using an uncovered and covered small basin. The study offers a physically
based framework for testing design scenarios in terms of evaporation
suppression efficiency for various climatic conditions; it hence strengthens
the science in the basis of this important water resource conservation
strategy.
Evaporation suppression and energy balance of water reservoirs covered with self-assembling floating elements
