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Accueil du site → Doctorat → Israel → Isotopic composition of rainfall and runoff in a small arid basin with implications for deep percolation

Ben-Gurion University of the Negev (1995)

Isotopic composition of rainfall and runoff in a small arid basin with implications for deep percolation

Dody, Avraham

Titre : Isotopic composition of rainfall and runoff in a small arid basin with implications for deep percolation

Auteur : Dody, Avraham

Université de soutenance : Ben-Gurion University of the Negev

Grade : Doctor of Philosophy PhD 1995

Description
The aim of this work was to elaborate on overland flow runoff processes and to characterize the isotopic composition of potential recharge in an arid rocky watershed. Unique field observations were obtained from an arid watershed in the Negev Highlands, Israel, through utilization of the dynamic variations in the isotopic composition of rainfall and runoff. The hydrological system’s inputs are rainfall and its isotopic composition. Three independent methods were used to follow the water movement from rainfall through runoff to subsurface flow : a. Study of the isotopic evolution from rainfall to runoff. b. Identification of subsurface flow in an unsaturated zone, by (1) tracing with sodium bromide ; and (2) using a neutron probe to follow the changes in the soil moisture, in profiles with depth of 4 m each, throughout one year. Rainfall and runoff were sampled in eight storms. High variability in the isotopic composition of rainfall was observed during any single rainstorm. Two types of rain storms are distinguished isotopically. The first type had quite a constant composition during the rain shower, and the second type was characterized by a wave shape distribution in the isotopic composition of the rain shower. The isotopic distribution in the runoff at the outlet of the basin appeared often not to be correlated to the isotopic patterns of the associated rain storm. In some cases runoff water was found to be more isotopically depleted with respect to the rainfall. The differences could not be explained by evaporation.

Mots clés : Arid regions. — Groundwater. — Hydrologic cycle — Mathematical models. — Radioisotopes in hydrology. — Rain and rainfall. — Runoff.

Présentation (IAEA / INIS)

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