Using climate to relate water discharge and area in modern and ancient catchments

Abstract

Models relating sediment supply to catchment properties are important in order to use the geological record to deduce landscape evolution and interplay between tectonics and climate. Water discharge (Qw) is an important factor in the widely used ‘BQART’ model, which relates sediment load to a set of measurable catchment parameters. Although many of the factors in this equation may be independently estimated with some degree of certainty in ancient systems, water discharge (Qw) certainly cannot. An analysis of a world database of modern catchments with 1255 entries shows that the commonly applied equation relating catchment area (A) to water discharge (Qw = 0·075A0·8) does not predict water discharge from catchment area well in many cases (R2 = 0·5 and an error spanning about three orders of magnitude). This is because the method does not incorporate the effect of arid and wet climate on river water discharge. The inclusion of climate data into such estimations is an opportunity to refine these estimates, because generalized estimates of palaeoclimate can often be deduced on the basis of sedimentological data such as palaeosol types, mineralogy and palaeohydraulics. This paper investigates how the relationship between catchment area and river discharge varies with four runoff categories (arid, semi‐arid, humid and wet), which are recognizable in the geological record, and modifies the coefficient and exponent of the above‐mentioned equation according to these classes. This modified model yields improved results in relating discharge to catchment area (R2 = 0·95 and error spanning one order of magnitude) when core, outcrop or regional palaeoclimate reconstruction data are available in non‐arid systems. Arid systems have an inherently variable water discharge, and catchment area is less important as a control due to downstream losses. The model here is sufficient for many geological applications and makes it possible to include variations in catchment humidity in mass‐flux estimates in ancient settings.

Can sediment supply variations create sequences? Insights from stratigraphic forward modelling

“…The average water discharge in wet cycles is a few times bigger than that in dry cycles. For example, if a 1.67*10 4 km 2 catchment transits from arid (0–100 mm/yr run‐off) to semi‐arid (100–250 mm/yr run‐off) (Eide, Müller, & Helland‐Hansen, ; Milliman & Farnsworth, ), its water discharge ranges from 0–500 m 3 /s to 500–1,250 m 3 /s.…”

Manifestation of Tectonic and Climatic Perturbations in Deep-Time Stratigraphy – An Example From the Paleocene Succession Offshore Western Norway

“…Paleo water discharge is therefore estimated using the inferred size of the catchment together with the overall climatic setting (Syvitski and Milliman, 2007). Here we use a revised version of the discharge prediction as suggested by Eide et al (2018) for wet climates, so that Q = 0.0873A 0.9164 .…”

Predicting sediment discharges and erosion rates in deep time—examples from the late Cretaceous North American continent

“…To refine catchment‐averaged palaeoclimate at catchment/regional scales, water discharge and mean annual temperature estimates can be supported using Cretaceous climate zone maps deduced from large palaeontological, sedimentological and mineralogical data sets (Chumakov et al, 1995), which have since been reproduced (Hay & Floegel, 2012; Skelton, Spicer, Kelley, & Gilmour, 2003). Also, where broad estimates of palaeoclimate can be inferred from preservation of climatically sensitive sediments etc., water discharge can be estimated using drainage area and one of four runoff categories, following Eide et al (2018). Beyond water discharge estimates, constraints on catchment‐averaged temperature might be inferred from terrestrial surface temperature proxies (see Supplementary Information S1).…”

“…We suggest that use of subsurface and surface runoff data to estimate Q and Qs can be applied at catchment-scales where runoff-derived Q estimates can be corroborated by geological evidence (e.g. identification of catchment runoff class from geological indicators, as discussed in Eide et al, 2018).…”

“…Relative to other suspended sediment discharge models (e.g. Cohen, Kettner, Syvitski, & Fekete, 2013; Pelletier, 2012), BQART is well‐suited to geologic application as it has comparatively low data requirements (see discussion in Allen et al, 2013; Eide, Müller, & Helland‐Hansen, 2018; Helland‐Hansen, Sømme, Martinsen, Lunt, & Thurmond, 2016)—this is ideal when one is dealing with an incomplete rock record as it minimises assumptions. Various authors have used BQART to model Qs in Quaternary systems on 10 2 –10 5 year timescales, and have calibrated BQART estimates with preserved sediment thicknesses (Sømme, Piper, Deptuck, & Helland‐Hansen, 2011; Watkins et al, 2018) or catchment‐averaged denudation rates derived from cosmogenic 10 Be (Hidy, Gosse, Blum, & Gibling, 2014).…”