Climate service derived indicators to assess the impact of climate change on local river assimilative capacity

Climate change and river water pollution: An application to the Ganges in Kanpur

“…Let us denote this natural absorptive capacity at time $$t$$ by $${X}_{0}.$$ Then, it follows that this natural capacity ought to be functionally related to the mean total reduction in the Ganges river's natural pollution absorbing capacity in the time interval $$[0,{t}]$$ given in Equation (2). Let us express this functional relationship by writing $$${X}_{0}=f\{E[R(t)]\},$$$where $${f}^{^{\prime} }\{\bullet \}\lt 0.$$ Note that our mathematical description in Equation (4) of the relationship between $${X}_{0}$$ and $$E[R(t)]$$ and the point that the function $$f\{\bullet \}$$ is decreasing in the argument $$E[R(t)]$$ are entirely consistent with our evidence based—see Farinosi et al (2019), Chapra et al (2021), and Ziogas et al (2021)—previous discussion of these matters in the first paragraph of Section 2. In addition and in words, what Equation (4) is telling us is intuitively plausible: If the mean total reduction in the natural pollution absorbing capacity up to time $$t$$ increases then the Ganges river's actual natural capacity for absorbing pollution at time $$t$$ decreases.…”

“…Now, the Ganges, like all rivers, has a natural capacity for absorbing pollutants that are deposited into it 7 . However, the work of Farinosi et al (2019), Chapra et al (2021), and Ziogas et al (2021) tells us that with the onset of climate change, over time, river water flows are expected to decline and this, along with other factors, is very likely to probabilistically diminish the natural capacity of a river such as the Ganges to absorb pollutants that are deposited into it.…”