RELATIONSHIP BETWEEN THROUGHFLOW GENERATION AND THE SOLUTE CONCENTRATION OF SOIL AND STREAM WATER

Variation in solute concentrations of soil and stream water during throughflow events was studied at Bicknoller Combe, Somerset, England. The main hydrological process acting in the catchment involves a delayed throughflow discharge pulse a day or 2 after the rainfall event. During period of storm runoff, coincident with the rainfall, the solutes in the stream are diluted, but their concentration in the throughflow remains unchanged. During the delayed throughflow pulse, concentrations of both soil and steam water increase. This is due to additional leaching from the soil in hollows where saturated moisture conditions prevail. The results suggest that 2 distinct erosional environments may exist: on the spurs, leaching seems to be related solely to infiltration processes, whilst in the hollows, saturated throughflow also contributes to the solute removal. This contrast in erosional processes may perhaps account for the difference in slope form and development between the hollow and spur zones. -Author