Pedology: A Hydrogeological Perspective

In a finite earth with concerns about sustainable use of natural resources, earth science disciplines are moving toward appreciating their respective roles in understanding the interlinked functioning of hydrological, erosional, and nutritional cycles. This move provides motivation for exploring the connections between hydrogeology and pedology as components of a larger whole. As pointed out by Jenny (1941) in his concluding chapter, soils can be studied through mapping their spatial distribution (Marbut's geographical method), and through comprehending soil attributes as functions of soil‐forming factors (Jenny's functional method). As Jenny further recognized, the conversion of the functional “knowledge to specific field conditions is impossible unless the areal distribution of soil formers is known.” Ultimately, therefore, the vision of pedology is “the union of the geographical and the functional method,” to comprehend “the soil body in its natural position,” and to understand spatial distribution of soil assemblages. Hydrogeology is concerned with the physical and chemical modification of the materials of the earth's crust by water, and the transport of energy, suspended and dissolved constituents and nutrients from the time water enters the subsurface to the time it goes back to the atmosphere. Hydrogeology thus provides a rationale, through the unifying action of flowing water, to achieve an integration of the geographical and the functional methods envisioned by Hans Jenny. This paper examines the conceptual‐philosophical threads that connect pedology and hydrogeology. In the process, the role of soil geomorphology is also addressed.